econintersect .com

FREE NEWSLETTER: Econintersect sends a nightly newsletter highlighting news events of the day, and providing a summary of new articles posted on the website. Econintersect will not sell or pass your email address to others per our privacy policy. You can cancel this subscription at any time by selecting the unsubscribing link in the footer of each email.

posted on 23 January 2018

January 22, 2018 Weather and Climate Report - We Update NOAA's Report

Written by Sig Silber

In addition to our usual focus on the next twenty-five days, we will spend a little time on the more recent information not available to NOAA when they prepared their January 18 Seasonal Outlook Update.  This may show up in their end of January Update (for February) but mostly impacts this Summer. We will also try to better explain the MJO which is a less understood driver of World weather and right now is impacting CONUS significantly. If nothing else, it will be useful for doing crossword puzzles.

  MJO Impacts three more weeks

Please share this article - Go to very top of page, right hand side for social media buttons.

Some housekeeping: There was a new Seasonal Outlook issued by NOAA on January 18 which we reported on January 20 which you can access here.
Remember if you leave this page to go to links or if you have clicked to enlarge a graphic, in order to get back you need to hit the return arrow usually located on the left of your URL box on the upper left of the screen. Also most of the small graphics are designed to become full size when you click on them. If that does not work, an alternative way to view the larger graphics is to right click and then hit "view image".  That should always work.
 If you have additional suggestions for improvement, please make them in the comments section following the article.

We concluded in the Seasonal Outlook  Report that we issued on Saturday January 20 that the NOAA January 18 may have been out of date to some extent when issued. One reason for that  is a question as ot whether or not they incorporated the information that was released on January 19 with the Week 3-4 Report. They may have had that information and may not have but we consider that information very important. The full report that accompanied the Week 3- 4 Report appears later but this part seems to us to be very important.

Inconsistencies in the various statistical and dynamical model guidance for the week 3-4 temperature outlook leads to uncertainty and lower probabilities. Changes in the temperature forecast between weeks 3 and 4 are consistent with impacts of the propagation of the active MJO across the western Pacific. Likely above normal temperatures over much of the eastern CONUS in week 3 forecasts from the CFS and ECMWF ensemble models give way to near normal or below normal temperature forecasts for much of the northeastern CONUS in week 4. Increased probabilities of above normal temperatures are indicated for the week 3-4 period mean over the Southeast CONUS, from the Mississippi to the Atlantic, and from the Gulf of Mexico to the Ohio Valley and Mid-Atlantic region, relying somewhat on lower uncertainty for week 3 than week 4.

Now let's talk about the MJO

The article below is a good resource and is pretty much the key paper on the MJO. I extracted a part of the text. I took out the references to graphics and footnotes but the graphics are in the referenced article. After the extracted text, I provide two graphics that are identical to the ones in the B. Geerts and M. Wheeler article. The MJO is a classic meteorological pattern and the graphics are fairly standard and identical or similar graphics are used by all the people who write articles.

I might have used a different article by Jon Gottschalck et al. I have a lot of respect for Jon Gottschalck and this article explains some things in a clearer manner than the article below. With respect to the MJO, we have to understand that we are talking about the tropics and in the tropics you do not have coriolis forces so storms there do not have cyclonic circulation so one does not notice that a storm has arrived because their roof has been blown off and it is hard to tell common precipitation events from the MJO. With satellite imagery, we can. It may be out of sequence but this  paragraph from the Gottschalck et al paper is very important.

IV. Interannual Variability of the MJO

There  is  strong  year-to-year  variability  in  MJO  activity with periods  of  strong  activity  followed  by  long periods in which the oscillation is weak or absent (Hendon et al. 1999; Zhang, 2005). There is evidence that the  interannual  variability  of  the  MJO  is  partly  linked  to  the  ENSO  cycle.  Strong  MJO  activity  is  often observed during weak La Niña years or during ENSO-neutral years, while weak or absent MJO activity is typically  associated  with  strong  El  Niño  episodes.

We are either in a weak La Nina or actually now in ENSO Neutral so it is not surprising that the MJO has emerged as being very important right now. That is why I decided to provide some background information. The following is excellent. The Gottschalk paper is very good taking a different slant that is focused more on the impacts of the MJO rather than the explanation of the MJO but it also does that and uses some of the same graphics I am showing below. So read both if you have sufficient interest.

Back now to the B. Geerts and M. Wheeler paper.


In the tropics weather is not as predictable as in mid-latitudes. That is because in mid-latitudes the weather variables (clouds, precipitation, wind, temperature, and pressure) are largely governed by the upper-tropospheric Rossby waves, which interact with surface weather in a process called baroclinic instability. In the tropics there is no such dominant instability or wave motion, and therefore the weather is less predictable for the 1-10 day period. Until recently it was believed that tropical weather variations on time scales less than a year were essentially random.

In 1971 Roland Madden and Paul Julian stumbled upon a 40-50 day oscillation when analyzing zonal wind anomalies in the tropical Pacific. They used ten years of pressure records at Canton (at 2.8 degrees S in the Pacific) and upper level winds at Singapore. The oscillation of surface and upper-level winds was remarkably clear in Singapore. Until the early 1980's little attention was paid to this oscillation, which became known as the Madden and Julian Oscillation (MJO), and some scientists questioned its global significance. Since the 1982-83 El Niño event, low-frequency variations in the tropics, both on intra-annual (less than a year) and inter-annual (more than a year) timescales, have received much more attention, and the number of MJO-related publications grew rapidly.

The MJO, also referred to as the 30-60 day or 40-50 day oscillation, turns out to be the main intra-annual fluctuation that explains weather variations in the tropics. The MJO affects the entire tropical troposphere but is most evident in the Indian and western Pacific Oceans. The MJO involves variations in wind, sea surface temperature (SST), cloudiness, and rainfall. Because most tropical rainfall is convective, and convective cloud tops are very cold (emitting little longwave radiation), the MJO is most obvious in the variation of outgoing longwave radiation (OLR), as measured by an infrared sensor on a satellite.

Figure 1 (from Elleman 1997) [Editors Note: You can find this graphic in the referenced article but it is not necessary to understand this discussion] shows how the OLR anomalies in the eastern hemisphere propagate to the east at around 5 m/s. The OLR signal in the western hemisphere is weaker, and the recurrence interval for the eastward propagating OLR anomalies in the eastern hemisphere is about 30 to 60 days. How exactly the anomaly propagates from the dateline to Africa (i.e. through the western hemisphere) is not well understood. It appears that near the dateline a weak Kelvin wave propagates eastward and poleward at a speed exceeding 10 m/s.

Associated with the propagation of convective anomalies, the MJO involves variations in the global circulation. The MJO affects the intensity and break periods of the Asian and Australian monsoons and interacts with El Niño. Wet spells in the Australian monsoon occur about 40 days apart. Fairly weak correlations with the midlatitude rainfall patterns and jet stream characteristics have also been found (2).

Structure of a Madden-Julian wave

Within the center of suppressed convection, clear skies associated with a stronger-than-normal trade wind inversion allow more shortwave radiation to reach the ocean surface, causing a slight SST increase as the wave travels eastward. The Trade winds too are stronger than normal, explaining enhanced evaporation from the sea surface.

Easterly winds (and the evaporation rate) weaken near the western edge of the suppressed convection region, and this leads to low-level moisture convergence. This triggers deep convection, leading to the other half of the OLR oscillation, i.e. the region of enhanced convection. This region is comprised of one or more super cloud clusters (SCCs) that move eastward along with the MJ wave. Within the SCCs, westward-moving cloud clusters form at the eastern edge of the SCC and die at the western edge. These smaller clusters have a lifetime of one to two days. In turn, the individual mesoscale convective systems within these smaller clusters typically move eastward, usually by discrete propagation, and have a lifetime of 6-12 hours. The SCCs travel eastward at 5-10 m/s, not as a long-lived storm complex, but rather as a moving wave or oscillation, i.e. the MJO. The MJO has a wavenumber of 1-2, that is at any time there are one or two areas around the equator with enhanced convection, and one or two with suppressed convection.

MJO Dynamics

Equatorially trapped waves (Kelvin and Rossby waves) that explain the evolution of an El Niño event are also the driving mechanism for the MJO. These waves occur in the entire troposphere from 30N to 30S, mainly in the eastern hemisphere. Surface air flows away from the suppressed convection in both zonal directions towards enhanced convection regions. In the upper troposphere, anomalous easterlies exit the west side of the enhanced convection.  The strong westerlies from the east side of the enhanced convection flow into the region of suppressed convection. When suppressed convection is strong from the Indian Ocean to the middle Pacific Ocean, anomalous cyclonic gyres at 200 mb trail the region of suppressed convection. Similarly, anticyclonic gyres at 200 mb trail the enhanced convection region once it becomes strong in the Indian and western Pacific Oceans. Gyres in the opposite sense are produced at surface, but they are much weaker than the ones at the tropopause. The zonal circulation and horizontal gyres are important processes by which the MJO shuffles mass around the tropics.

The explanation above is simplistic, in that it idealises the oscillation, as it isolates it from other variations. As mentioned before, the speed and size are variable, and the MJO mainly affects rainfall patterns in Indonesia and surrounding areas. Not all of the elements of the MJO -- convection, zonal wind, moisture convergence, and SST anomalies -- are always visible. It is only when the 30-60 day oscillations are extracted from a series of MJO events that the idealised picture of the MJO emerges. Consecutive oscillations have varying amplitudes, periods, and wavelengths. The MJO exhibits the mixed Kelvin-Rossby wave structure over the eastern hemisphere, but over the western hemisphere, it only shows a Kelvin wave structure. It moves through the eastern hemisphere at around 5 m/s and through the western hemisphere at a higher speed (at least 10 m/s). The oscillation is stronger in the northern hemisphere winter. It is also in this season that the negative OLR anomalies are most likely to propagate along the equator from the Indian Ocean to the central Pacific Ocean. In the northern hemisphere summer, many of the anomalies veer away from the tropics before they make it to the central Pacific.

Now two key  graphics that are identical to the ones in the above paper but not shown as these reproduce better. Everyone uses the same graphics.           

MJO Wave

You can see the approximately 20 Day Active Phase of the MJO Wave and how areas of high convection move around the Globe along the Equator. It is most intense along the Equator but the impacts extend north and south into the middle latitudes and thus after a lag impact CONUS. The exact speed and strength of the MJO are difficult to forecast and are more noticeable in certain years than others. This may be a winter where the MJO is important.   

MJO vertical structure

Notice the difference between the upper and lower atmosphere circulation, in front of the wave, and as the wave passes, Northern Hemisphere and Southern Hemisphere as the wave is moving along the Equator.

NOAA Graphic Source and also for more information

There are many forecast models but here is the way the information is often presented. The solid line is the history and the green line is the forecast. The distance from the origin indicates the strength of the MJO. The eight sectors are useful for understanding impacts. As you can see as  you look further out in time the variation among model results makes it difficult to arrive at a realistic forecast.

MJO Index

Here is the more complete recent NOAA Update Report.

Because it is Winter we make it easy to get a snow forecast. This is the six-hour snow forecast.

6 hr Snow

Looking further out.

NOAA Snow Forecast looking ahead to Days 4,5 (top Row) 6 and 7 (bottom row). When you view these graphics you can click on them to enlarge them.

Day 4 Day 5
Day 6 Snow Forecast Day 7 Snow


I think they are only showing large areas so locally there could be other areas especially at high elevation that also receive significant snowfall. The pattern is clearly across the northern tier of CONUS with the major impact in the Northeast as the cool anomaly moves east. You can obtain additional forecasts here..

A. Now we return to our  regular approach and focus on Alaska and CONUS (all U.S.. except Hawaii) 

I am starting with a summary first for temperature and then for precipitation of small images of the three short-term maps. You can click on these maps to see larger versions. The easiest way to return to this report is by using the "Back Arrow" usually found top left corner of your screen to the left of the URL Box. Larger maps are available later in the article with the discussion and analysis.

For most people, the summary with the small images will be sufficient. Later in the article for those with sufficient interest there is a full description of the factors determining the maps shown here with a detailed analysis of the ENSO situation which so dramatically impacts the forecasts below.

First Temperature

6 - 10 Day Forecast Temperature

Transitioning from the 6 to 10 day outlook on the left (also called Week One) to the 8 to 14 day outlook (Week Two) on the right                          →

8 - 14 Day Temperature

The pattern does not change much in the East in week two   but does for the West.

To the right is the week 3 and 4 Forecast.

There is only a warm anomaly in Alaska and a western oriented cool anomaly along the Northern Tier of CONUS and two warm anomalies, the largest covering most of the eastern third of CONUS                    →                

3 - 4 Week Temperature


←  The transition from the 8 -14 day forecast shown above to the week 3/4 shown to the left seems feasible.


And then Precipitation

6 - 10 Day Forecast Precipitation

Transitioning from the 6 to 10 day outlook on the left to the 8 to 14 day outlook on the right.                          →

8 - 14 Day Precipitation

Mostly a continuation of the pattern into the second week (Days 8 - 14) with the northern wet anomaly extending into the Great Plains.

To the right is the week 3 and 4 Experimental Forecast.    →               

Western Alaska is wet. Western CONUS is dry. There are five anomalies shown for CONUS. It is kind of like from left to right: dry - wet-  dry - wet - dry which probably corresponds to the troughs.
3 - 4 Week Precipitation


←  The transition from the 8 -14 day forecast shown above to the week 3/4 shown to the left seems feasible.


Let us focus on the Current (Right Now to 5 Days Out) Weather Situation.

Water Vapor.

This view of the past 24 hours provides a lot of insight as to what is happening.

Eastern Pacific Animation

You can see moisture entering the West Coast from the Pacific. Below is the same graphic as above but without the animation to show the current situation with respect to water vapor imagery for Western North America.

Water Vapor Imagery

Tonight, Monday evening January 22, 2018, as I am looking at the above graphic, you see moisture entering the West Coast and also moving into CONUS just east of Texas (difficult to see in this graphic but you can see the moisture streaming across Mexico).

This graphic is about Atmospheric Rivers i.e. thick concentrated movements of water moisture. More explanation on Atmospheric Rivers can be found by clicking here or if you want more theoretical information by clicking here. The idea is that we have now concluded that moisture often moves via narrow but deep channels in the atmosphere (especially when the source of the moisture is over water) rather than being very spread out. This raises the potential for extreme precipitation events. You can convert this graphic into a flexible forecasting tool by clicking here. One can obtain views of different geographical areas by clicking here.

 Center for Western Weather and Water Extremes, Scripps/UCSD.

We see moisture moving into Texas from the Gulf of Mexico

Day One CONUS Forecast

Day Two CONUS Forecast

Day 1 Forecast Map

Day 2 Forecast

There is a lot of snow shown along the Northern Tier.

Earlier I have provided snow forecasts for day 4 through 7 and a link to earlier days.

These graphics update and can be clicked on to enlarge but my brief comments are only applicable to what I see on Tuesday night prior to publishing.

60 Hour Forecast Animation

Here is a national animation of weather fronts and precipitation forecasts with four 6-hour projections of the conditions that will apply covering the next 24 hours and a second day of two 12-hour projections the second of which is the forecast for 48 hours out and to the extent it applies for 12 hours, this animation is intended to provide coverage out to 60 hours. Beyond 60 hours, additional maps are available at links provided below. The explanation for the coding used in these maps, i.e. the full legend, can be found here although it includes some symbols that are no longer shown in the graphic because they are implemented by color coding.

current highs and lows

You can enlarge the below daily (days 3 - 7) weather maps for CONUS by clicking on Day 3 or Day 4 or Day 5 or Day 6 or Day 7. These maps auto-update so whenever you click on them they will be forecast maps for the number of days in the future shown.

Short term forecasts

What is Behind the Forecasts? Let us try to understand what NOAA is looking at when they issue these forecasts.

Below is a graphic which highlights the forecasted surface Highs and the Lows re air pressure on Day 7. The Day 3 forecast can be found here. the Day 6 Forecast can be found here. Actually all the small graphics below can be clicked on to enlarge them.

Day 7 Highs and Lows

When I look at this Day 7 forecast, there is a large Low in the Gulf of Alaska with surface central pressure of 996 hPa and a follow-on Low over by Kamchatka with surface central pressure of 992 hPa. The Low in the Gulf of Alaska would appear to be well positioned to pump moisture into the West Coast but further north than suggested in the NOAA forecast maps e.g. British Columbia rather than Washington State and Oregon. Again there is a High over the Rocky Mountains with surface central pressure of 1032 hPa. It may tend to keep the storm pattern to the north. There is also an Arctic High north of Alaska (but moving inland) with surface central pressure of 1040 hPa and this will keep most of Alaska "brisk". There is also a High off the East Coast with surface central pressure of 1036 hPa and it can impact Florida with Atlantic moist air. But it seems to be moving to the north and east and thus may not have much of an impact.

I provided this K - 12 write up that provides a simple explanation on the importance of semipermanent Highs and Lows and another link that discussed possible changes in the patterns of these highs and lows which could be related to a Climate Shift (cycle) in the Pacific or Global Warming. Remember this is a forecast for Day 6. It is not the current situation.

The table below showing the Day 3, Day 4, Day 5, Day 6 and Day 7 of this graphic can be useful in thinking about how the pattern of Highs and Lows is expect to move during the week.

Day 3 Day 4
Day 5 Day 6

From left to right and then down, Days 3 and 4 top row, Days 5 and 6 second row and Day 7 to the right. These are small images but you can if you want click on them and get larger images but even with the small images you can trace the evolution of the pattern. The graphics update but my commentary below does not so it is just a guide for how to read these graphics.

Day 7

There is tendency  for the Aleutian Low to move inland and that contributes to Southern Alaska being "brisk" due to offshore winds and may also contribute to keeping the storm track to the north.

Things to look for in general are the position and strength of the Aleutian Low, the Hawaiian High and any troughs especially if they extend far to the south and are over water.

Looking at the current activity of the Jet Stream.  The below graphics and the above graphics are very related.

Not all weather is controlled by the Jet Stream (which is a high altitude phenomenon) but it does play a major role in steering storm systems especially in the winter The sub-Jet Stream level intensity winds shown by the vectors in this graphic are also very important in understanding the impacts north and south of the Jet Stream which is the higher-speed part of the wind circulation and is shown in gray on this map. In some cases however a Low-Pressure System becomes separated or "cut off" from the Jet Stream. In that case it's movements may be more difficult to predict until that disturbance is again recaptured by the Jet Stream. This usually is more significant for the lower half of CONUS with the cutoff lows being further south than the Jet Stream. Some basic information on how to interpret the impact of jet streams on weather can be found here and here.  I have not provided the ability to click to get larger images as I believe the smaller  images shown are easy to read.

Current Day 5
Current Jet Stream Jet Stream Five Days Out
You can see Jet Stream moving across CONUS. By Day 5 it is more progressive than meridional.

Putting the Jet Stream into Motion and Looking Forward a Few Days Also

To see how the pattern is projected to evolve, please click here. In addition to the shaded areas which show an interpretation of the Jet Stream, one can also see the wind vectors (arrows) at the 300 Mb level.

This longer animation shows how the jet stream is crossing the Pacific and when it reaches the U.S. West Coast is going every which way.

Click here to gain access to a very flexible computer graphic. You can adjust what is being displayed by clicking on "earth" adjusting the parameters and then clicking again on "earth" to remove the menu. Right now it is set up to show the 500 hPa wind patterns which is the main way of looking at synoptic weather patterns. This amazing graphic covers North and South America. It could be included in the Worldwide weather forecast section of this report but it is useful here re understanding the wind circulation patterns.

500 MB Mid-Atmosphere View

The map below is the mid-atmosphere 7-Day chart rather than the surface highs and lows and weather features. In some cases it provides a clearer less confusing picture as it shows only the major pressure gradients. This graphic auto-updates so when you look at it you will see NOAA's latest thinking. The speed at which these troughs and ridges travel across the nation will determine the timing of weather impacts. This graphic auto-updates I think every six hours and it changes a lot. Because "Thickness Lines" are shown by those green lines on this graphic, it is a good place to define "Thickness" and its uses. The 540 Level generally signifies equal chances for snow at sea level locations. Thickness of 600 or more suggests very intensely heat and fire danger. Sometimes Meteorologists work with the 500 mb heights which provide somewhat similar readings to the "Thickness" lines but IMO provide slightly less specific information. Thinking about clockwise movements around High Pressure Systems and counter- clockwise movements around Low Pressure Systems provides a lot of information.

7 Day 500 MB Geopotential Forecast

What we see for Day 7 is again similar to the situation in recent weeks with a huge trough over Central CONUS trough with ridges to the west and east of the trough. There is not much intrusion into CONUS of the 540 Thickness line so we are not likely talking about a bitter cold pattern. You can also see the next potential Pacific trough off shore as I view this on Monday afternoon. Editor’s Note: Looking at this after publishing, the trough is now already projected on Day 7 to be moving offshore of the East Coast and the trailing trough is now forecast on Day 7 to be over the Rocky Mountains. So I do not know if the pattern changed that much while I was having dinner and finalizing the article or if the computers caught up.]

Here is the seven-day cumulative precipitation forecast. More information is available here.

Seven Day WPC Quantitative precipitation forecast

We see a wet Northwest and a moist Eastern half of CONUS but with more extreme precipitation along the Gulf Coast.

Four- Week Outlook: Looking Beyond Days 1 to 5, What is the Forecast for the Following Three + Weeks?

I use "EC" in my discussions although NOAA sometimes uses "EC" (Equal Chances) and sometimes uses "N" (Normal) to pretty much indicate the same thing although "N" may be more definitive.

First - Temperature

6 - 10 Day Temperature Outlook issued today (Note the NOAA Level of Confidence in the Forecast Released on January 22, 2018 was 3 out of 5

6 - 10 Day Temperature Outlook

8 - 14 Day Temperature Outlook issued today (Note the NOAA Level of Confidence in the Forecast Released on January 22, 2018 was 2 out of 5).

8-14 Day Temperature Outlook

Looking further out.

Experimental Week 3-4 Temperature Outlook

Now - Precipitation

6 - 10 Day Precipitation Outlook Issued Today (Note the NOAA Level of Confidence in the Forecast Released on January 22, 2018 was 3 out of 5)

6 - 10 Day Precipitation Outlook

8 - 14 Day Precipitation Outlook Issued Today (Note the NOAA Level of Confidence in the Forecast Released on January 22, 2018 was 2 out of 5)

Current 8 - 14 Day Precipitation Outlook

Looking further out.

Weeks 3 and 4 Experimental Forecast..

Here is the 6 - 14 Day NOAA discussion released today January 22, 2018 and the Week 3/4 discussion released Friday January 19, 2018

6-10 DAY OUTLOOK FOR JAN 28 - FEB 01, 2018





8-14 DAY OUTLOOK FOR JAN 30 - FEB 05, 2018 






Week 3-4 Forecast Discussion Valid Sat Feb 03 2018-Fri Feb 16 2018

La Nina conditions currently are present across the equatorial Pacific Ocean. Equatorial sea surface temperatures (SSTs) are below average across the central and eastern Pacific Ocean. The MJO remains active with enhanced convection centered over the Maritime Continent. The week 3-4 temperature and precipitation outlooks rely on calibrated dynamical model guidance from the CFS, ECMWF and JMA, as well as statistical guidance that utilizes ENSO, MJO, and decadal timescale trends. Additional guidance is obtained from the experimental SubX dynamical multi-model ensemble (MME).

The various model guidance supporting the week 3-4 outlook is in fair agreement over much of North America. Dynamical models are generally predicting ridging and above average 500-hPa heights over the North Pacific, below average 500-hPa heights and troughing over eastern Canada and the northern-central CONUS, and above average 500-hPa heights over the Southeast region extending into the Atlantic. There are variations in the predicted circulation pattern in the various model forecasts. The CFS predicts a more amplified trough over the central CONUS relative to the ECMWF. The SubX MME mean 500-hPa height forecast is somewhat similar to the ECMWF forecast, with a slight westward shift in ridging over the North Pacific and troughing over North America.

Inconsistencies in the various statistical and dynamical model guidance for the week 3-4 temperature outlook leads to uncertainty and lower probabilities. Changes in the temperature forecast between weeks 3 and 4 are consistent with impacts of the propagation of the active MJO across the western Pacific. Likely above normal temperatures over much of the eastern CONUS in week 3 forecasts from the CFS and ECMWF ensemble models give way to near normal or below normal temperature forecasts for much of the northeastern CONUS in week 4. Increased probabilities of above normal temperatures are indicated for the week 3-4 period mean over the Southeast CONUS, from the Mississippi to the Atlantic, and from the Gulf of Mexico to the Ohio Valley and Mid-Atlantic region, relying somewhat on lower uncertainty for week 3 than week 4. Uncertainty in forecasts for the Northeast leads to equal chances of above and below normal temperatures for this region. Calibrated probabilities of above and below normal temperatures from the CFS and ECMWF ensemble models indicate increased probability of below normal temperatures for the northern-central CONUS, from eastern Washington to the western Great Lakes and southward into the Central Plains. While there is an increased likelihood of below normal temperatures for other areas of the west in week 3, this is offset by changes in the pattern in week 4. Above normal temperatures are likely for much of the Southwest for the week 3-4 period average. Above normal temperatures are indicated by most model guidance for much of Alaska, including the southern coast, southwestern Alaska, the Aleutians, and the North Slope.

Guidance for the week 3-4 precipitation outlook is fairly consistent among most dynamical model guidance. Calibrated probability forecasts from the ECMWF and CFS, as well as the SubX MME mean anomalies, indicate increased probabilities of above median precipitation for much of the Southeast, from east Texas across the Lower Mississippi Valley, stretching to the Ohio River in the north and the Atlantic coast in the east. Below median precipitation is more likely for the Florida Peninsula to the south, with probabilities exceeding 60 percent. Below median precipitation is more likely for parts of the Midwest, including the Upper Mississippi Valley and western Great Lakes regions. Troughing over the northern-central CONUS leads to increased probabilities of above median precipitation over western areas of the Northern Plains. Below median precipitation is more likely west of the Rocky Mountains ahead of the predicted ridge. Above median precipitation is likely over parts of southwestern Alaska, as indicated by most dynamical model forecasts.

Sea-surface temperature anomalies are currently slightly negative near the western Hawaiian Islands, and near zero to the east. Dynamical model forecasts from the SubX member models indicate above normal temperatures are likely for eastern stations, including Hilo, Kahului and Honolulu. Dynamical model guidance favors above median precipitation for all of Hawaii, which is consistent with ongoing La Nina conditions.

Some might find this analysis which you need to click to read interesting as the organization which prepares it focuses on the Pacific Ocean and looks at things from a very detailed perspective and their analysis provides a lot of information on the history and evolution of ENSO events.

Analogs to the Outlook.

Now let us take a detailed look at the "Analogs" which NOAA provides related to the 5 day period centered on 3 days ago and the 7 day period centered on 4 days ago. "Analog" means that the weather pattern then resembles the recent weather pattern and was used in some way to predict the 6 - 14 day Outlook.

Here are today's analogs in chronological order although this information is also available with the analog dates listed by the level of correlation. I find the chronological order easier for me to work with. There is a second set of analogs associated with the Outlook but I have not been regularly analyzing this second set of information. The first set which is what I am using today applies to the 5 and 7 day observed pattern prior to today. The second set, which I am not using, relates to the correlation of the forecasted outlook 6 - 10 days out with similar patterns that have occurred in the past during the dates covered by the 6 - 10 Day Outlook. The second set of analogs may also be useful information but they put the first set of analogs in the discussion with the second set available by a link so I am assuming that the first set of analogs is the most meaningful and I find it so.






Other Comments

Jan 20, 1951 Neutral - +  
Jan 22, 1951 Neutral - +  
Jan 26, 1954 El Nino - +  
Jan 1, 1956 La Nina - +  
Jan 1, 1966 El Nino - -  
Jan 12, 1968 Neutral - -  
Jan 28, 1999 (2) La Nina - + Following the MegaNino
Jan 11, 2000 La Nina - N Following the MegaNino
Jan 7, 2008 La Nina - +  

(t) = a month where the Ocean Cycle Index has just changed or does change the following month.

The spread among the analogs from January 1 to January 28 is 28 days which is similar to last week. I have not calculated the centroid of this distribution which would be the better way to look at things but the midpoint, which is a lot easier to calculate, is about January 15. These analogs are centered on 3 days and 4 days ago (January 18 or January 19). So the analogs could be considered to be a bit out of sync with respect to weather that is we are likely to be getting weather that is similar to some extent to what we would expect to normally be getting a few days earlier. For more information on Analogs see discussion in the GEI Weather Page Glossary.  For sure it is a rough measure as there are so many historical patterns but not enough to be a perfect match with current conditions. I use it mainly to see how our current conditions match against somewhat similar patterns and the ocean phases that prevailed during those prior patterns. If everything lines up I have my own measure of confidence in the NOAA forecast. Similar initial conditions should lead to similar weather. I am a mathematician so that is how I think about models.

Including the duplicates, there are three Neutral Analogs, five La Nina analogs and two El Nino Analogs. The phases of the analogs again this week favor McCabe condition D. McCabe D is consistent with the Southwest Drought aspect of the NOAA 6 - 10 Day Forecast adding support to the level of confidence indicated by NOAA but not consistent with the 8 - 14 Day NOAA forecast also supporting their low level of confidence in their 8 - 14 Day forecast. The Analogs are not consistent with the position of the Aleutian Low which is much like an El Nino position. But perhaps the fact that the Aleutian Low is so far east that it is partially on land explains this.

The seminal work on the impact of the PDO and AMO on U.S. climate can be found here. Water Planners might usefully pay attention to the low-frequency cycles such as the AMO and the PDO as the media tends to focus on the current and short-term forecasts to the exclusion of what we can reasonably anticipate over multi-decadal periods of time. One of the major reasons that I write this weather and climate column is to encourage a more long-term and World view of weather.

In color Black and White same graphics
McCabe Maps modified to include the subtitles McCabe Conditions from 2007 report with labels corrected with authors permission


McCabe Condition Main Characteristics
A Very Little Drought. Southern Tier and Northern Tier from Dakotas East Wet. Some drought on East Coast.
B More wet than dry but Great Plains and Northeast are dry.
C Northern Tier and Mid-Atlantic Drought
D Southwest Drought extending to the North and also the Great Lakes. This is the most drought-prone combination of Ocean Phases.


You may have to squint but the drought probabilities are shown on the map and also indicated by the color coding with shades of red indicating higher than 25% of the years are drought years (25% or less of average precipitation for that area) and shades of blue indicating less than 25% of the years are drought years. Thus drought is defined as the condition that occurs 25% of the time and this ties in nicely with each of the four pairs of two phases of the AMO and PDO.

Historical Anomaly Analysis

When I see the same dates showing up often I find it interesting to consult this list.

Recent CONUS Weather

This is provided mainly to see the pattern in the weather that has occurred recently.

And the 30 Days ending January 13, 2018 And the 30 Days ending January 20, 2018

January 13, 2018 30 Day Temperature and Precipitation Departures

January 20, 2018 30 Day Temperature and Precipitation Departures
This is a big change for sure. The Drought is easing up and the cold anomaly also is less intense but extends a bit further west along the Northern Tier.

The pattern is more extreme both precipitation and temperature anomalies.

Remember, these maps are a 30 average so the most distant seven days are removed and the most recent seven days are added.

Reference Forecasts Full Month and Three Months.

Below are the Temperature followed by the Precipitation Outlooks for the month and three months shown in the Legend. These map are issued on the Third Thursday of the Month. The maps for the following month (but not the three-month maps) are updated on the last day of the month. The 6 - 10 day and 8 - 14 Day update daily and the Week 3/4 Map Updates every Friday so usually these are more up to date. Also the three shorter-term maps will generally cover a slightly different time period since they update daily as the month progresses. But these reference maps are sometimes useful if one wants to understand how the current month was originally forecast to play out.

February Temperature Outlook Issued on January 18, 2018 To the left is the full month Temperature Outlook. To the right is the three-month Temperature outlook FMA Temperature  Issued on January 18,2018
February 2018 Precipitation Outlook Updated on January 18, 2018 To the left is the full month Precipitation outlook. To the right is the three-month Precipitation outlook. FMA 2018 Precipitation Outlook Issued on January 18,  2018


B. Beyond Alaska and CONUS Let's Look at the World which of Course also includes Alaska and CONUS

It is Useful to Understand the Semipermanent Pattern that Control our Weather and Consider how These Change from Winter to Summer. These two graphics (click on each one to enlarge) are from a much larger set available from the Weather Channel.  They highlight the position of the Bermuda High which they are calling the Azores High in the January graphic and is often called NASH and it has a very big impact on CONUS Southeast weather and also the Southwest. You also see the north/south migration of the Pacific High which also has many names and which is extremely important for CONUS weather and it also shows the change of location of the ITCZ which I think is key to understanding the Indian Monsoon. A lot of things become much clearer when you understand these semi-permanent features some of which have cycles within the year, longer period cycles and may be impacted by Global Warming. We are now in late-January and should beginning to return to the set of positions shown above for July. For CONUS, the seasonal repositioning of the Bermuda High and the Pacific High are very significant. Notice the Winter position of the Pacific High.

Same as above but for July

Forecast for Today (you can click on the maps to enlarge them)

This graphic is anomalies i.e. deviations from normal not the actual temperatures. This graphic is actuals not anomalies as is the case in the temperature map.
Temperature at 2 Meters Maine Reanalyer

Notice that below the map there is a tabulation of magnitude of the current anomalies by region. Overall it is warm except parts of Canada and northeast Asia

We again see the dry belt stretching from Northern Africa to Eastern Asia and now to a larger extent including Southeast Asia,


Additional Maps showing different weather variables can be found here.

Forecast for Day 6 (Currently Set for Day 6 but the reader can change that)

World Weather Forecast produced by the Australian Bureau of Meteorology. Unfortunately I do not know how to extract the control panel and embed it into my report so that you could use the tool within my report. But if you visit it Click Here and you will be able to use the tool to view temperature or many other things for THE WORLD. It can forecast out for a week. Pretty cool. Return to this report by using the "Back Arrow" usually found top left corner of your screen to the left of the URL Box. It may require hitting it a few times depending on how deep you are into the BOM tool. Below are the current worldwide precipitation and temperature forecasts for six days out. They will auto-update and be current for Day 6 whenever you view them. If you want the forecast for a different day Click Here



BOM Current Temperature Wedensday

BOM World Preciptation  Wednesday

Please remember this graphic updates every six hours so the diurnal pattern can confuse the reader.  Australia is very warm. I do not see anything worth commenting on. I am curious as to whether this is a Wave Number 4 or 5 Pattern.


And now we have experimental forecasts from the U.S. NAEFS Model.

Temperature Precipitation

NAEFS 8 - 14 Day Temperature

NAEFS Experimental World Precipitation

Eastern Asia, Canada and Northern South America are cool. You definitely see the La Nina pattern for North America. Northwest Africa is very dry and Europe is wet.


Looking Out a Few Months

Here is the precipitation forecast from Queensland Australia:

Rapidly falling SOI  forecast for January to March 2018

It is kind of amazing that you can make a worldwide forecast based on just one parameter the SOI and changes in the SOI. Notice the continuance of the underlying driver of the SOI having been consistently positive. CONUS except for the Northwest looks fairly wet, Eastern Australia is wet. 

JAMSTEC Forecasts

One can always find the latest JAMSTEC maps by clicking this link. You will find additional maps that I do not general cover in my monthly Update Report. Remember if you leave this page to visit links provided in this article, you can return by hitting your "Back Arrow", usually top left corner of your screen just to the left of the URL box.

Sea Surface Temperature (SST) Departures from Normal for this Time of the Year i.e. Anomalies

My focus here is sea surface temperature anomalies as they are one of the two largest factors determining weather around the World. If we want to have a good feel for future weather we need to look at the oceans as our weather mostly comes from oceans and we need to look at

  • Surface temperature anomalies (weather develops from the ocean surface  and
  • the changes in the temperature anomalies since that may provide clues as to how the surface anomalies will change based on the current trend of changes. This is not that easy to do since the oceans are deep, there are many currents, winds have an impact etc. Two ways that are available to use are to look at the change in the situation today compared to the average over a period of time and NOAA also produces a graphic of monthly changes. I use both. The first set of graphics is simply looking at the average compared to today and that is below.
Three Month Average Anomaly Current Anomaly
Three month average anomaly Daily SST Anomaly
La Nina shows up It now looks fairly similar to the three-month average.


And when we look in more detail at the current Sea Surface anomalies below, we see a lot of them not just along the Equator related to ENSO.

                              First the categorization of the current daily SST anomalies.

Mediterranean, Black Sea and Caspian Sea Western Pacific West of North America North and East of North America North Atlantic

Mediterranean Neutral

Black Sea and Caspian Sea Warm

Fairly Neutral

Mostly Neutral

Warm off Baja

Slightly Warm in Davis Strait

Fairly Neutral but  warm north of Scandinavia.


Pacific cool east of Dateline. But dark blues are turning to light blues. Gap off of Ecuador and Peru.

SST Daily Anomalies
Africa West of Australia North, South and East of Australia

West of South America

East of South America

Warm west of Africa Gulf of Guinea but also a bit  further south.

Cool offshore southeast of Africa including south of  Madagascar

Moderately  cool way offshore

Warm south and southeast all the way to and beyond New Zealand

Cool but now mostly offshore

Warm anomaly way offshore at 40S.

Warm 20S south and off 40S


Then we look at the change in the anomalies.  Here it gets a little tricky as for the NOAA graphic that we usually use, red does not mean a warm anomaly but a warming of the anomaly which could mean more warm or less cool and blue does not mean cool but more cool or less warm.  

But in preparation for NOAA not issuing their weekly ENSO Report on Monday I did something differently and show (they are quite small) the monthly average SST and the current Daily Average SST. So I do not have a graphic that shows the change  in SST but rather two graphics that I can compare to estimate the change in SST, So I have done that.

It would have been better if instead of the monthly average I had the daily levels from a month ago. I did not save that graphic and it might be available in an archive but I did not have the time to look for it. But to some extent this process works just as well but one has to do more work to sort it  out.

Mediterranean, Black Sea and Caspian Sea Western North Pacific West of North America East of North America North Atlantic

Black Sea and Caspian Sea warming

Warming East of  Japan.

Nothing significant


More warming off of Nova Scotia

More warming north of Scandinavia

Equator Eastern Pacific now Neural Offshore of Ecuador and Peru
January 15, 2018 Change in SST Anomalies Use This. Daily SST Anomaly
Africa West of Australia North, South and East of Australia West of South America East of South America
Cooling off West Africa in Gulf of Guinea and further south has changed to warming

Warming off of Southwest Africa

Offshore cool anomaly fading.

Warming  Southeast of Australia less intense.

Cool anomaly is further west

Warming south of 30S


I did not interpret the below graphic this week as I was not sure it would be available so I used an alternative approach above but here is the graphic and everyone can interpret it themselves,

January 22, 1018 Change in weekly SST Anomalies

This may be a good time to show the recent values to the indices most commonly used to describe the overall spacial pattern of temperatures in the (Northern Hemisphere) Pacific and the (Northern Hemisphere) Atlantic and the Dipole Pattern in the Indian Ocean.

Most Recent Six Months of Index Values   PDO Click for full list

AMO click for full list.

Indian Ocean Dipole (Values read off graph)
October   -0.67 +0.39 -0.3
November   +0.84 +0.40 0.0
December   +0.56 +0.34 -0.1
January   +0.12 +0.23 0.0
February   +0.05 +0.23 +0.2
March   +0.14 +0.17 +0.0
April   +0.53 +0.29 +0.2
May   +0.29 +0.32 +0.2
June   +0.21 +0.31 0.0
July   -0.50 +0.31 0.0
August   -0.62 +0.31 +0.4
September   -0.25 +0.35 +0.2
October   -0.61 +0.44  0.0
November   -0.46 +0.35  0.0
December 2017   -0.18 +0.36 -0.4 Est

Switching gears, below is an analysis of projected tropical hazards and benefits over an approximately two-week period.

Tropical Hazards

This graphic updates on Tuesdays and I usually post on Monday which is almost a week later than when this graphic was last updated. So Week Two applies at the time I write this article on Monday but by the time you read it on Tuesday, the Week Two that I am looking at is updated and becomes Week One. So if you are reading this after Monday Night look at the Top Row, which will be the current week. 
Mostly I see as I look at this on January 22 for what is shown as Week two, the period January 24, 2018 to January 30, 2018, we see wet conditions* for Northern Australia and the Philippines and cyclone development potential* for the tip of Northern Australia and a dry* area for Eastern Brazil and Eastern Africa west of Madagascar.

 * Moderate Confidence that the indicated anomaly will be in the upper or lower third of the historical range as indicated in the Legend. ** High Confidence that the indicated anomaly will be in the upper or lower third of the historical range as indicated in the Legend.

C. Progress of ENSO

A major driver of weather is Surface Ocean Temperatures. Evaporation only occurs from the Surface of Water. So we are very interested in the temperatures of water especially when these temperatures deviate from seasonal norms thus creating an anomaly. The geographical distribution of the anomalies is very important. To a substantial extent, the temperature anomalies along the Equator have disproportionate impact on weather so we study them intensely and that is what the ENSO (El Nino - Southern Oscillation) cycle is all about. Subsurface water can be thought of as the future surface temperatures. They may have only indirect impacts on current weather but they have major impacts on future weather by changing the temperature of the water surface. Winds and Convection (evaporation forming clouds) is weather and is a result of the Phases of ENSO and also a feedback loop that perpetuates the current Phase of ENSO or changes it. That is why we monitor winds and convection along or near the Equator especially the Equator in the Eastern Pacific.

Starting with Surface Conditions.

TAO/TRITON GRAPHIC (a good way of viewing data related to the part of the Equator and the waters close to the Equator in the Eastern Pacific where we monitor to determining the current phase of ENSO. It is probably not necessary in order to follow the discussion below, but here is a link to TAO/TRITON terminology.

And here is the current version of the TAO/TRITON Graphic. The top part shows the actual temperatures, the bottom part shows the anomalies i.e. the deviation from normal.

Current SST and wind anomalies

Location Bar for Nino 3.4 Area Above and Below

------------------------------------------------ A B C D E -----------------


NOAA concluded earlier today that the TAO/TRITON display was not mission critical even though it was computer generated and did not require any manpower so as of 6 pm Mountain Time they had not updated the TAO/TRION graphic. I should have saved the version from yesterday but I had printed it so I scanned it into my article but it is not in color but works and it is what I used today. I see now that NOAA has allowed their graphic to update. It does not seem to be very different than what appeared yesterday so I am comfortable having done my calculations from the scanned in version of yesterday's graphic which is shown below..

January 21, TAO/TRITON Graphic scanned from printed copy

The below table only looks at the Equator (and starting this week I am including large anomalies just off the Equator also) and shows the extent of anomalies along the Equator. The ONI Measurement Area is the 50 degrees of Longitude between 170W and 120W and extends 5 degrees of Latitude North and South of the Equator so the above table is just a guide and a way of tracking the changes. The top rows show El Nino anomalies. The two rows just below that break point contribute to ENSO Neutral.

Subareas of the Anomaly

Westward Extension


Eastward Extension


Degrees of Coverage Total by ENSO Phase


Portion in Nino 3.4 Measurement Area

These Rows below show the Extent of El Nino Impact on the Equator  

1C to 1.5C (strong)






+0.5C to +1C (marginal)





These Rows Below Show the Extent of ENSO Neutral Impacts on the Equator  
0.5C or cooler Anomaly (warmish neutral)






0C or cooler Anomaly (coolish neutral)







These Rows Below Show the Extent of La Nina Impacts on the Equator.  
-0.5C or cooler Anomaly








-1.0C or cooler Anomaly





-1.5C or cooler Anomaly





-2.0C or cooler Anomaly





-2.5C or cooler Anomaly





This week again only 33 degrees of longitude along the Equator in the Nino 3.4 Measurement Area registers La Nina values. The other 17 degrees register Neutral. That is not the case for the full +5N and +5S width of the Nino 3.4 Measurement Area but in this analysis we are just looking at the Equator.

My Calculation of the Nino 3.4 Index

I calculate the current value of the Nino 3.4 Index each Monday using a method that I have devised. To refine my calculation, I have divided the 170W to 120W Nino 3.4 measuring area into five subregions (which I have designated from west to east as A through E) with a location bar shown under the TAO/TRITON Graphic). I use a rough estimation approach to integrate what I see below and record that in the table I have constructed. Then I take the average of the anomalies I estimated for each of the five subregions.

So as of Monday January 22 in the afternoon working from the January 20 TAO/TRITON report [as the current report was not available due to the Government Shutdown], this is what I calculated:

Calculation of Nino 3.4 from TAO/TRITON Graphic

Anomaly Segment Estimated Anomaly
  Last Week This Week
A. 170W to 160W -0.2 -0.5
B. 160W to 150W -0.3 -0.3
C. 150W to 140W -0.6 -0.3
D. 140W to 130W -0.7 -0.6
E. 130W to 120W -1.3 -0.5
Total -3.1 -2.2
Total divided by five i.e. the Daily Nino 3.4 Index (-3.1)/5 = -0.6 (-2.2)/5 = -0.4

Notice in my calculations that the western two segments as I divide the Nino 3.4 Measurement Area record as Neutral and the three segments to the east record as La Nina values.

My estimate of the daily Nino 3.4 SST anomaly tonight is -0.4 which is an ENSO Neutral value not a La Nina value. If I had rounded slightly differently I could have produced a -0.5 borderline La Nina value. NOAA has reported the weekly Nino 3.4 to be -06 which is a marginal La Nina value. Nino 4 is reported a little cooler this week at -0.3. Nino 3 is warmer at -0.9. Nino 1 + 2 which extends from the Equator south rather than being centered on the Equator is reported warmer at -0.6. It was up there close to 3 at one time so this index has been declining quite a bit and also fluctuating quite a bit which is not surprising as it is the area most impacted by the Upwelling off the coast. So it is an indication of the interaction between surface water and rising cool water. Thus it is subject to larger changes. I am only showing the currently issued version of the NINO SST Index Table as the prior values are shown in the small graphics on the right with this graphic. The same data in graphic form but going back a couple of more years can be found here.  The full table of values can be found here.

The cool anomaly pretty much remained in the same location this week and again records as La Nina.

January 22, 2018 Nino Readings

This graphic brings the Nino 3.4 up to date and is easy to read.

BOM Nino 3.4

You can see that this is a double dip La Nina.

This is probably the best place to AGAIN express the thought that this way of measuring an ENSO event leaves a lot to be desired. Only the surface interacts with the atmosphere and is able to influence weather. The subsurface tells us how long the surface will remain cool (or warm). Anomalies are deviations from "Normal". NOAA calculates and determines what is "Normal" which changes due to long ocean cycles and Global Warming. So to some extent, the system is "rigged". Hopefully it is rigged to assist in providing improved weather forecasts. But to assume that any numbers reported can be assumed to be accurate to a high level of precision is foolhardy.

This overlaps with the next topic but I will show it here.

January 22, 2018 Upper Ocean Heat anamaly

The discussion in this slide says it better than I could. One might compare the current reading to Oct/Nov 2016. We may be at Peak La Nina but it has now only a few months to run and we are starting our La Nina Demise Count Down.  But we are not yet ready to predict the end of La Nina readings. Perhaps we are. Let's say that his Active MJO Phase will temporarily put the Nino 3.4 Index in Neutral Territory. It will rebound to La Nina Territory and the La Nina be over by March but perhaps late February. I was planning to try to graph the slope of the decline to make a prediction as to when it reaches -0.5C. But it already has. It would seem easier to do it that way than to run dollars of machine time to run the NOAA models but I am very old fashioned. The problem is the Nino 3.4 index is measured at the surface so I need to get the correlation of the subsurface cool reservoir to the surface Nino 3.4 Measurements. I think that is what the models do but anything a model can do, one can do with a straight edge. That is Sig Silber's rule. For most purposes the World is linear. The CDAS graphic which we also show is another way to do the same thing as is the BOM SOI graphic.

A side by side comparison can be useful

Comparison Week Probably Third Week of December 2017 Current Week

Equatorial (0 - 300) meter heat content As reported December 18, 2017

January 22, 2018 Upper Ocean Heat anamaly


You can see the relentless decline in the Eastern Pacific cool-water anomaly. It is now basically neutral but the cool water is still on the surface with the warmer anomalies sub-surface. That will change.

Sea Surface Temperature and Anomalies

It is the ocean surface that interacts with the atmosphere and causes convection and also the warming and cooling of the atmosphere. So we are interested in the actual ocean surface temperatures and the departure from seasonal normal temperatures which is called "departures" or "anomalies". Since warm water facilitates evaporation which results in cloud convection, the pattern of SST anomalies suggests how the weather pattern east of the anomalies will be different than normal.

January 22, 2018 Equatorial Pacific SST Anomalies

A major advantage of the Hovmoeller method of displaying information is that it shows the history so I do not need to show a sequence of snapshots of the conditions at different points in time. This Hovmoeller provides a good way to visually see the evolution of this ENSO event. I have decided to use the prettied-up version that comes out on Mondays rather that the version that auto-updates daily because the SST Departures on the Equator do not change rapidly and the prettied-up version is so much easier to read. The bottom of the Hovmoeller shows the current readings. Remember the +5, -5 degree strip around the Equator that is being reported in this graphic. So it is the surface but not just the Equator.

The only really cool area west of 130W is now gone and it is also less cool off the coast of Ecuador.

This next graphic is more focused on the Equator and looks down to 300 meters rather than just being the surface.

January 22, 2018 Upper Ocean Heat Anoma

The bottom of the Hovmoeller shows the current situation.

We now have the Kelvin Wave that will put an end to this La Nina. Also notice there really is no cool water west of 110W meaning the La Nina is over even if not yet so reported.

Let us look in more detail at the Equatorial Water Temperatures.

We are now going to look at a three-dimensional view of the Equator and move from the surface view and an average of the subsurface heat content to a more detailed view from the surface down This graphic provides both a summary perspective and a history (small images on the right).

.January 22, 2018 Kelvin Wave Analysis.

Significant  change since last week. The subsurface warm anomaly west of now 130W is again stronger. Last week It was clear that the cool anomaly had fractured into two pieces at about 130W. Now that western part is almost gone. Also way to the right we see warm water at the surface. It is not a large anomaly but certainly not indicative of La Nina. Another part of the cool anomaly may be splitting off. The La Nina is in the decline phase and we believe NOAA will soon announce that as in mid February. They appear to be resistant to that but they will have no choice as the La Nina will no longer exist. 

Anomalies are strange. You can not really tell for sure if the blue area is colder or warmer than the water above or below. All you know is that it is cooler than usual for this time of the year. A later graphic will provide more information. Aside from buoyancy the currents tend to bring water from that depth up to the surface mostly farther east.

Now for a more detailed look. Below is the pair of graphics that I regularly provide. The date shown is the midpoint of a five-day period with that date as the center of the five-day period. The bottom graphic shows the absolute values, the upper graphic shows anomalies compared to what one might expect at this time of the year in the various areas both 130E to 90W Longitude and from the surface down to 450 meters. At different times I have discussed the difference between the actual values and the deviation of the actual values from what is defined as current climatology (which adjusts every ten years except along the Equator where it is adjusted every five years) and how both measures are useful for other purposes.

There is cold water from the 170W to Land. At  the west end of the cool anomaly it is not consistently even 100 meters deep (it was once over 200 meters deep). We now have warm water developing west of the Dateline and crossing the Dateline at depth all the way to 130W and beyond. Thus it is now intruding far into the Eastern Pacific Nino 3.4 Measurement Area but at depth not at the surface. La Nina's days are numbered but in terms of a month or two not weeks or days.
The 28C Isotherm is at the Dateline, the 27C Isotherm is at the 170W, the 25C Isotherm is now all the way to 140W and the 20C Isotherm no longer is reaching the surface. So the pattern has shifted east substantially but that may be due ot the MJO and may reverse soon.

The flattening of the Isotherm Pattern is an indication of ENSO Neutral just as the steepening of the pattern indicates La Nina or El Nino depending on where the slope shows the warm or cool pool to be. That flattening has occurred and we have gone to a Weak La Nina thermocline.

Tracking the change.

Sepember 15, 2017 Subsurface Water Temperatures Equatorial Ocean Subsurface as of January 13, 2018


I have "frozen" the graphic on the left side above which shows the situation as reported for September 15, 2017. The one on the right which is the current situation. The situation with the cool anomaly is not much different east of the Dateline from the situation as reported for September 15, 2017 but it is a little different. West of the Dateline it looks a lot different  i.e. warmer. We use the graphic on the left as a reference to see how the current situation changes over time. The subsurface warm anomaly has progressed to the east and strengthened substantially. It is not ready to displace or dilute the Eastern Pacific Cool Anomaly just yet but it will not be long. We now see the warm anomaly appearing below the cool anomaly.

And now let us look at the atmosphere.

This graphic shows the Low-Level Wind Anomalies near the Equator.

The 850 hPa level is above the surface but close to the surface.

And now the Outgoing Long-wave Radiation (OLR) Anomalies which tells us where convection has been taking place. The bottom of a Hovmoeller graphic shows the most recent readings.
Low Level Wlind Anomalies

OLR Anomalies Along the Equator

Reds and browns would be suppressed easterlies or enhanced westerlies and are typical of El Nino. We have the opposite. We see suppressed Outgoing Long Wave Radiation (OLR) at the Dateline i.e (dry) and we  see enhanced OLR at 120E ( wet)


And Now the Air Pressure to Confirm that the Atmosphere is Reacting to the Sea Surface Temperature Pattern. The most Common way to do that is to use an Index called the SOI.

This index provides an easy way to assess the location of and the relative strength of the Convection (Low Pressure) and the Subsidence (High Pressure) near the Equator. Experience shows that the extent to which the Atmospheric Air Pressure at Tahiti exceeds the Atmospheric Pressure at Darwin Australia when normalized is substantially correlated with the Precipitation Pattern of the entire World. At this point there seems to be no need to show the daily preliminary values of the SOI but we can work with the 30 day and 90 day values.

Current SOI Readings

The 30 Day Average on January 22, 2018  was reported as 3.21 which is clearly NOT a La Nina value. The 90 Day Average was reported at 4.20 which also is a Neutral ENSO value. Looking at both the 30 and 90 day averages is useful and right now both are in agreement with the 90 day lagging the 30 day as one would expect. But the 30 day SOI is no longer confirming that we have La Nina Conditions nor is the 90 Day. The trend: October/November/December is down i.e. less La Nina-ish and almost a transition to El Nino. So Queensland in their forecast is basing it on a declining SOI and that forecast is shown elsewhere in this report..


SOI = 10 X [ Pdiff - Pdiffav ]/ SD(Pdiff) where Pdiff = (average Tahiti MSLP for the month) - (average Darwin MSLP for the month), Pdiffav = long term average of Pdiff for the month in question, and SD(Pdiff) = long term standard deviation of Pdiff for the month in question. So really it is comparing the extent to which Tahiti is more cloudy than Darwin, Australia. During El Nino we expect Darwin Australia to have lower air pressure and more convection than Tahiti (Negative SOI especially lower than -7 correlates with El Nino Conditions). During La Nina we expect the Warm Pool to be further east resulting in Positive SOI values greater than +7).

To some extent it is the change in the SOI that is of most importance. The MJO or Madden Julian Oscillation is an important factor in regulating the SOI and Ocean Equatorial Kelvin Waves and other tropical weather characteristics. More information on the MJO can be found here. Here is another good resource.

Forecasting the Evolution of ENSO

Here is the primary NOAA model for forecasting the ENSO Cycle. The CDAS model is a legacy "frozen" NOAA system meaning the software is maintained but not updated. We find it convenient to obtain this graphic from Tropical

CFSv2 spread and bias correct ENSO forecast

CDAS Legacy System

This model is forecasting a La Nina. It probably is the most aggressive model re being so definitive about the ENSO Phase for this Fall and Winter. Click here to see a month by month version of the same model but without some of the correction methodologies applied. It gives us a better picture of the further out months as we are looking at monthly estimates versus three-month averages. Notice that since mid-October, the Nino 3.4 Index had been in a declining channel. But it looks like that downward trend has stopped and the Index has bottomed and suddenly is rising very quickly. The CDAS data It is not in conflict with the primary NOAA model but shows daily values rather then smoothing them out like the CFSv2 Model does.

The CFS.v2 is not the only forecast tool used by NOAA. The CPC/IRI Analysis which is produced out of The International Research Institute (IRI) for Climate and Society at Columbia University is also very important to NOAA.

And now we have a recent update.

january 19, 2018 CPC/IRI ENSO Analysis.

If you scrutinized the latest analysis from the earlier, what you see is that in the earlier analysis the time when the probability of La Nina versus Neutral was MAM and now is FMA one month earlier so that is the difference in the forecasts. As an aside, we think it may happen even sooner.

January 19, 2018 CPC/IRI ENSO Analysis

This is the discussion

IRI ENSO Forecast

IRI Technical ENSO Update Published: January 19, 2018

Note: The SST anomalies cited below refer to the OISSTv2 SST data set, and not ERSSTv4. OISSTv2 is often used for real-time analysis and model initialization, while ERSSTv4 is used for retrospective official ENSO diagnosis because it is more homogeneous over time, allowing for more accurate comparisons among ENSO events that are years apart. During ENSO events, OISSTv2 often shows stronger anomalies than ERSSTv4, and during very strong events the two datasets may differ by as much as 0.5 C. Additionally, the ERSSTv4 may tend to be cooler than OISSTv2, because ERSSTv4 is expressed relative to a base period that is updated every 5 years, while the base period of OISSTv2 is updated every 10 years and so, half of the time, is based on a slightly older period and does not account as much for the slow warming trend in the tropical Pacific SST.

Recent and Current Conditions

In mid-January 2018, the NINO3.4 SST anomaly was in the upper portion of the weak La Niña range. For December the SST anomaly was -0.79 C, indicating weak La Niña, and for October-December it was -0.70 C, also in that range. The IRI’s definition of El Niño, like NOAA/Climate Prediction Center’s, requires that the SST anomaly in the Nino3.4 region (5S-5N; 170W-120W) exceed 0.5 C. Similarly, for La Niña, the anomaly must be -0.5 C or less. The climatological probabilities for La Niña, neutral, and El Niño conditions vary seasonally, and are shown in a table at the bottom of this page for each 3-month season. The most recent weekly anomaly in the Nino3.4 region was -0.9, showing weak La Niña. The pertinent atmospheric variables, including the lower level zonal wind anomalies, the Southern Oscillation Index and the anomalies of outgoing longwave radiation (convection), have been showing patterns suggestive of La Niña, although the Southern Oscillation has been weak recently. Subsurface temperature anomalies across the eastern equatorial Pacific, while recently weakening significantly, are also still consistent with La Niña. Given the current and recent SST anomalies, the subsurface profile and the La Niña patterns in most key atmospheric variables, it appears we are in the later stage of a weak La Niña.

Expected Conditions

What is the outlook for the ENSO status going forward? The most recent official diagnosis and outlook was issued approximately one week ago in the NOAA/Climate Prediction Center ENSO Diagnostic Discussion, produced jointly by CPC and IRI; it stated that La Niña is strongly favored for the remainder of winter, with a likely transition to ENSO-neutral during spring. A La Niña Advisory was once again issued with that Discussion. The latest set of model ENSO predictions, from mid-January, now available in the IRI/CPC ENSO prediction plume, is discussed below. Those predictions suggest that the SST is most likely to stay in the weak La Niña range for January-March, followed by increasing chances for neutral during spring.

As of mid-December, 80% of the dynamical or statistical models predicts La Niña conditions for the initial Jan-Mar 2018 season, dropping to 48% for Feb-Apr and 28% for Mar-May. For these seasons, no model predicts El Niño conditions, so that the remaining probability is only for neutral conditions. At lead times of 3 or more months into the future, statistical and dynamical models that incorporate information about the ocean’s observed subsurface thermal structure generally exhibit higher predictive skill than those that do not. For the Apr-Jun 2018 season, among models that do use subsurface temperature information, 76% of models predicts neutral conditions and 19% predicts La Niña conditions. For all models, at longer lead times beginning with Feb-Apr 2018, predictions for ENSO-neutral conditions have more than a 50% probability, with probabilities of 75% or more for Apr-Jun to May-Jul. At the end of the forecast range, Aug-Oct and Sep-Nov, the probability for El Niño rises to near 40% and La Niña probabilities decrease to about 5-11%, leaving about 50-55% for neutral.

Note  – Only models that produce a new ENSO prediction every month are included in the above statement.

Caution is advised in interpreting the distribution of model predictions as the actual probabilities. At longer leads, the skill of the models degrades, and skill uncertainty must be convolved with the uncertainties from initial conditions and differing model physics, leading to more climatological probabilities in the long-lead ENSO Outlook than might be suggested by the suite of models. Furthermore, the expected skill of one model versus another has not been established using uniform validation procedures, which may cause a difference in the true probability distribution from that taken verbatim from the raw model predictions.

An alternative way to assess the probabilities of the three possible ENSO conditions is more quantitatively precise and less vulnerable to sampling errors than the categorical tallying method used above. This alternative method uses the mean of the predictions of all models on the plume, equally weighted, and constructs a standard error function centered on that mean. The standard error is Gaussian in shape, and has its width determined by an estimate of overall expected model skill for the season of the year and the lead time. Higher skill results in a relatively narrower error distribution, while low skill results in an error distribution with width approaching that of the historical observed distribution. This method shows probabilities for La Niña at 69% for Jan-Mar, 50% for Feb-Apr, 30% for Mar-May, and decreasing thereafter to 15-20% for Apr-Jun through Sep-Nov. Probabilities for neutral conditions begin at 31% for Jan-Mar, 50% for Feb-Apr, peak at 79% in Apr-Jun, after which they drop to less than 50% for Jul-Sep through Sep-Nov as El Niño probabilities rise, reaching 48% by Sep-Nov.  A plot of the probabilities generated from this most recent IRI/CPC ENSO prediction plume using the multi-model mean and the Gaussian standard error method summarizes the model consensus out to about 10 months into the future. The same cautions mentioned above for the distributional count of model predictions apply to this Gaussian standard error method of inferring probabilities, due to differing model biases and skills. In particular, this approach considers only the mean of the predictions, and not the total range across the models, nor the ensemble range within individual models.

In summary, the probabilities derived from the models on the IRI/CPC plume describe, on average, a preference for weak La Niña conditions for Jan-Mar 2018, a 50% chance for each of La Niña or neutral for Feb-Apr, and neutral having highest probability status from Mar-May through Jul-Sep. Chances for El Niño are small through Apr-Jun 2018, rising to 31% for Jun-Aug and up to 48% by Sep-Nov. A caution regarding this latest set of model-based ENSO plume predictions, is that factors such as known specific model biases and recent changes that the models may have missed will be taken into account in the next official outlook to be generated and issued early next month by CPC and IRI, which will include some human judgment in combination with the model guidance.

The above is based on looking at a variety of models and other information but we should not forget that NOAA has their own model.

CFSv2 spread and bias correct ENSO forecast

It is not in disagreement with the MAM assessment but suggests there is not much difference in weather impacts from ENSO after JFM as the estimate of the NINO 3.4 Index does not change very much through the end of the forecast period shown in the CFSv2 Model. If you look at the spread among different model runs which are shown on the graphic does the mean of the model runs mean anything? I think not.

Here is a another view of the same model with on the right the forecasts of the sea surface temperatures that result from the forecast. It is the model as of January 14 and is frozen i.e. will not update.

January 15, 2018 SST Outlook and CSFv2

And here is what is called the plume of a varied of forecast models.

January 19, 2018 Plume of ENSO Forecast Models.

This is the recently released version. It is difficult to find the NOAA NCEP model in the graphic but it is near the middle but lower than the mean. Notice all the models have bottomed and are rising going forward.

Forecasts from Other Meteorological Agencies.

Here is the Nino 3.4 report from the Australian BOM (it updates every two weeks)

Australia POAMA ENSO model run

And the ENSO Outlook Discussion Issued on January 16, 2018:

Weak La Niña continues over the Pacific

International climate models surveyed by the Bureau indicate that it is likely the event has reached, or will soon reach, its peak. Most of the models indicate that equatorial Pacific sea surface temperatures are likely to warm over the coming months, returning to neutral values between late in the austral summer and mid-autumn. However, three of the eight models maintain temperatures near La Niña thresholds well into the austral autumn. Only one out of the eight models maintains La Niña levels into winter (July).

Sea surface temperatures currently show a clear La Niña pattern, with coolest waters concentrated in the eastern Pacific Ocean. Likewise, some atmospheric indicators such as trade winds and cloudiness also show a clear La Niña signal. However, a continuing build-up of warmer water beneath the surface of the western Pacific is a likely precursor to the end of this event.

In order for 2017–18 to be classed as a La Niña year, thresholds need to be exceeded for at least three months. Most climate models surveyed by the Bureau suggest this event is likely to last through the southern summer, and decay in the early southern autumn of 2018, so these thresholds are likely to be met.

La Niña typically brings above average rainfall to eastern Australia during summer, particularly in northern New South Wales and Queensland. However, a weak La Niña will have less influence on Australian rainfall than a strong event. La Niña events can also increase the likelihood of prolonged warm spells for southeast Australia.

In order for 2017–18 to be considered a La Niña year, NINO3 or NINO3.4 values cooler than −0.8 °C need to be observed for at least three months.

Here is the most recent JAMSTEC forecast issued on January 1, 2018

January 1, 2018 JAMSTEC Forecast

And here is the short discussion issued with the January forecast.

Jan. 18, 2018

Prediction from 1st Jan., 2018

ENSO forecast:

The weak La Niña-like condition will persist until late spring. Then the tropical Pacific will return to a normal state by summer.

Indian Ocean forecast:

A normal state in the tropical Indian Ocean will persist until late spring. Then we expect evolution of a moderately positive Indian Ocean Dipole in summer. However, there is a large uncertainty in the prediction at present because of the large spread in the prediction plumes of the dipole mode index.

Regional forecast:

On a seasonal scale, most part of the globe will experience a warmer-than-normal condition, while some parts of northern/eastern U.S., northwestern Canada, Europe, India, northern Brazil, central and southern Africa, and northern Australia will experience a colder-than-normal condition in boreal spring. As regards to the seasonally averaged rainfall, a wetter-than-normal condition is predicted for some parts of the Philippines, East Australia, and northern Brazil during boreal spring, whereas most parts of Indonesia, Indo-China, Southeast Asia, eastern/southern U.S, and southern Brazil will experience a drier condition during boreal spring.

In spring, most parts of Japan will experience somewhat warmer-than-normal conditions. The southern part will experience drier-than-normal conditions.

Indian Ocean IOD (It updates every two weeks)

BOM IOD Forecast.

Indian Ocean Dipole Outlook  Discussion Issued January 16, 2018

The Indian Ocean Dipole (IOD) is neutral. The weekly index value to 14 January was −0.33 °C. All six of the climate models surveyed by the Bureau indicate that the IOD will remain neutral into the southern hemisphere winter of 2018.

The influence of the IOD on Australian climate is weak during December to April. This is because the monsoon trough shifts south over the tropical Indian Ocean changing wind patterns, which prevents the IOD pattern from being able to form.

The IOD Forecast is indirectly related to ENSO but in a complex way. It is important to understand how and where the IOD is measured.

IOD Measurement Regions

IOD Positive is the West Area being warmer than the East Area (with of course many adjustments/normalizations). IOD Negative is the East Area being warmer than the West Area. Notice that the Latitudinal extent of the western box is greater than that of the eastern box. This type of index is based on observing how these patterns impact weather and represent the best efforts of meteorological agencies to figure these things out. Global Warming may change the formulas probably slightly over time but it is costly and difficult to redo this sort of work because of long weather cycles.

D. Putting it all Together.

At this time it would seem a La Nina is here for this Winter and Spring with La Nina Conditions already in place. But the situation for next Summer is not yet clear. However, we are getting very close to being able to forecast the end of this La Nina event. But it may only be a temporary end for the Summer and next Fall as it may return for next Winter or Spring. But that is now looking less likely with ENSO Neutral highly likely.

Forecasting Beyond Five Years.

So in terms of long-term forecasting, none of this is very difficult to figure out actually if you are looking at say a five-year or longer forecast.

The research on Ocean Cycles is fairly conclusive and widely available to those who seek it out. I have provided a lot of information on this in prior weeks and all of that information is preserved in Part II of my report in the Section on Low Frequency Cycles 3. Low Frequency Cycles such as PDO, AMO, IOBD, EATS. It includes decade by decade predictions through 2050. Predicting a particular year is far harder.

The odds of a climate shift for the Pacific taking place has significantly increased. It may be in progress. The AMO is pretty much neutral at this point (but more positive i.e. warm than I had expected) so it may need to become a bit more negative for the "McCabe A" pattern to become established. That seems to be slow to happen so I am thinking we need at least a couple more years for that to happen. On the other hand, AMO- is what is showing up in the pre-forecast analogs that NOAA provides and which I report on. That might mean something. So our assessment is that the standard time for Climate Shifts in the Pacific are likely to prevail and it most likely will be a gradual process with a speed up in less than five years but more than two years. The next El Nino may be the trigger.

E. Relevant Recent Articles and Reports

Weather in the News

Nothing to report

Weather Research in the News

Nothing to report

Global Warming in the News

New Estimates for Climate Sensitivity

This is more in line with some of the studies. But  it is more in line with the data for the TCR.

Not sure how their methodology would provide estimates of the ECS.

Cox and colleagues instead "considered the year-to-year fluctuations in global temperature," said Richard Allan, a climate scientist at the University of Reading.

By analyzing the responsiveness of short-term changes in temperature to "nudges and bumps" in the climate system, he explained, they were able to exclude the outcomes that would have resulted in devastating increases of 4 C or more by 2100.

It is IMO a reasonable approach for estimating the transient response but not the response after feedback loops do whatever they are going to do.

F. Table of Contents for Page II of this Report Which Provides a lot of Background Information on Weather and Climate Science

The links below may take you directly to the set of information that you have selected but in some Internet Browsers it may first take you to the top of Page II where there is a TABLE OF CONTENTS and take a few extra seconds to get you to the specific section selected. If you do not feel like waiting, you can click a second time within the TABLE OF CONTENTS to get to the specific part of the webpage that interests you.

1. Very High Frequency (short-term) Cycles PNA, AO,NAO (but the AO and NAO may also have a low frequency component.)

2. Medium Frequency Cycles such as ENSO and IOD

3. Low Frequency Cycles such as PDO, AMO, IOBD, EATS.

4. Computer Models and Methodologies

5. Reserved for a Future Topic (Possibly Predictable Economic Impacts)

G. Table of Contents of Contents for Page III of this Report - Global Warming Which Some Call Climate Change.

The links below may take you directly to the set of information that you have selected but in some Internet Browsers it may first take you to the top of Page III where there is a TABLE OF CONTENTS and take a few extra seconds to get you to the specific section selected. If you do not feel like waiting, you can click a second time within the TABLE OF CONTENTS to get to the specific part of the webpage that interests you.

1. Introduction

2. Climate Impacts of Global Warming

3. Economic Impacts of Global Warming

4. Reports from Around the World on Impacts of Global Warming

H. Useful Background Information

The current conditions are measured by determining the deviation of actual sea surface temperatures from seasonal norms (adjusted for Global Warming) in certain parts of the Equatorial Pacific. The below diagram shows those areas where measurements are taken.

El Nino Zones

NOAA focuses on a combined area which is all of Region Nino 3 and part of Region Nino 4 and it is called Nino 3.4. They focus on that area as they believe it provides the best correlation with future weather for the U.S. primarily the Continental U.S. not including Alaska which is abbreviated as CONUS. The historical approach of measurement of the impact of the sea surface temperature pattern on the atmosphere is called the Southern Oscillation Index (SOI) which is the difference between the atmospheric pressure at Tahiti as compared to Darwin Australia. It was convenient to do this as weather stations already existed at those two locations and it is easier to have weather stations on land than at sea. It has proven to be quite a good measure. The best information on the SOI is produced by Queensland Australia and that information can be found here. SOI is based on Atmospheric pressure as a surrogate for Convection and Subsidence. Another approach made feasible by the use of satellites is to measure precipitation over the areas of interest and this is called the El Nino - Southern Oscillation (ENSO) Precipitation Index (ESPI). We covered that in a weekly Weather and Climate Report which can be found here. Our conclusion was that ESPI did not differentiate well between La Nina and Neutral. And there is now a newer measure not regularly used called the Multivariate ENSO Index (MEI). More information on MEI can be found here. The jury is still out on MEI and it it is not widely used.

The below diagram shows the usual location of the Indo-Pacific Warm Pool. When the warm water shifts to the east we have an El Nino; to the west a La Nina.

Western Pacific Warm Pool

Click for Source

Interaction between the MJO and ENSO

This Table is a first attempt at trying to relate the MJO to ENSO

El Nino La Nina MJO Active Phase MJO Inactive Phase Relationship of MJO and ENSO Eastern Pacific Easterlies Western Pacific Westerlies MJO Active Phase MJO Inactive Phase

  • Weaker
  • Stronger
  • Part of Decay Process
  • Counteracts Easterlies
  • Enhances Easterlies
  • Stronger
  • May Create or Stimulate the Onset of El Nino via Kelvin Waves
  • Weaker
  • Part of Decay Process
  • Strengthens Westerlies
  • Weakens Westerlies
  • More likely
  • Stimulates
  • Less likely and weak
  • Retards development of a new La Nina
  • Stimulates the Jet Stream
  • Less Likely
  • Suppresses
  • More likely but weak
  • Accelerates development of a new La Nina and the Decline of a mature La Nina
  • Slows the Jet Stream and can induce a Split Stream especially during a La Nina


Table needs more work. Is intended to show the interactions. What is more difficult is determining cause and effect. This is a Work in Progress.

History of ENSO Events as measured by the ONI

January 8, 2018 Revised Historical ONI Readins.

Note: Without fanfare the base climatology was recently changed from ERSST.V4 to ERSST.V5. This is done every five years and is totally proper but it does shuffle the deck re what were and were not ENSO events so it perhaps should have had more press but that is not the fault of NOAA but if they had kept me in the loop I would have covered it. I was not excluded just not included and did not notice it until after the fact. No big deal but it is important. 

The new SON reading of -0.9 is the second La Nina Reading. These would have to extend through JFM 2018 for this to be recorded as a La Nina. The chances of this are about  60:40. The full history of the ONI readings can be found here. The MEI index readings can be found here.

Four Quadrant Jet Streak Model Read more here This is very useful for guessing at weather as a trough passes through. It would apply to the states that are at the apex of the trough.

If the centripetal accelerations owing to flow curvature are small, then we can use the "straight" jet streak model. The schematic figure directly below shows a straight jet streak at the base of a trough in the height field. The core of maximum winds defining the jet streak is divided into four quadrants composed of the upstream (entrance) and downstream (exit) regions and the left and right quadrants, which are defined facing downwind.

Isotachs are shaded in blue for a westerly jet streak (single large arrow). Thick red lines denote geopotential height contours. Thick black vectors represent cross-stream (transverse) ageostrophic winds with magnitudes given by arrow length. Vertical cross sections transverse to the flow in the entrance and exit regions of the jet (J) are shown in the bottom panels along A-A' and B-B', respectively. Convergence and divergence at the jet level are denoted by "CON" and "DIV". "COLD" and "WARM" refer to the air masses defined by the green isentropes.

[Editor's Note: There are many undefined words in the above so here are some brief definitions. Isotachs are lines of equal wind speed. Convergence is when there is an inflow of air which tends to force the air higher with cooling and cloud formation. Divergence is when there is an outflow of air which tends to result in air sinking which causes drying and warming, Confluence is when two streams of air come together. Diffluence is when part of a stream of air splits off.]

Here is a time sequence animation. You may have to click on them to get the animation going.


Equatorial Temperature Simulation

Isotherm Simulation



When we discuss the jet stream and for other reasons, we often discuss different layers of the atmosphere. These are expressed in terms of the atmospheric pressure above that layer. It is kind of counter-intuitive to me. The below table may help the reader translate air pressure to the usual altitude and temperature one might expect at that level of air pressure. It is just an approximation but useful.

air pressure and altitude

Re the above, H8 is a frequently used abbreviation for the height of the 850 millibar level (which is intended to represent the atmosphere above the Boundary Layer most impacted by surface conditions), H7 is the 700 mb level, H5 is the 500 mb level, H3 is the 300 mb level. So if you see those abbreviations in a weather forecast you will know what they are talking about.

Tropical Activity Possibly Impacting CONUS.

Eastern Pacific Two Day Tropical Weather Outlook

When there is activity and I have not provided the specific links to the storm of "immediate" interest, one can obtain that information at this link. At this point in time, no (new) tropical events are expected to appear in this graphic during the next 48 hours. If that changes, we will provide an update.

Now let us look at the Western Pacific in Motion.

Western Pacific Tropical Activity

The above graphic which I believe covers the area from the Dateline west to 100E and from the Equator north to 45N normally shows the movement of tropical storms towards Asia in the lower latitudes (Trade Winds) and the return of storms towards CONUS in the mid-latitudes (Prevailing Westerlies). This is recent data not a forecast. But, it ties in with the Week 1 forecast in the graphic just above this graphic. Information on Western Pacific storms can be found by clicking here. This (click here to read) is an unofficial private source but one that is easy to read.

Click here for a list of Sig Silber's Weather Posts

>>>>> Scroll down to view and make comments <<<<<<

Make a Comment

Econintersect wants your comments, data and opinion on the articles posted. You can also comment using Facebook directly using he comment block below.

Econintersect Weather

Print this page or create a PDF file of this page
Print Friendly and PDF

The growing use of ad blocking software is creating a shortfall in covering our fixed expenses. Please consider a donation to Econintersect to allow continuing output of quality and balanced financial and economic news and analysis.

Keep up with economic news using our dynamic economic newspapers with the largest international coverage on the internet
Asia / Pacific
Middle East / Africa
USA Government

 navigate econintersect .com


Analysis Blog
News Blog
Investing Blog
Opinion Blog
Precious Metals Blog
Markets Blog
Video of the Day


Asia / Pacific
Middle East / Africa
USA Government

RSS Feeds / Social Media

Combined Econintersect Feed

Free Newsletter

Marketplace - Books & More

Economic Forecast

Content Contribution



  Top Economics Site Contributor TalkMarkets Contributor Finance Blogs Free PageRank Checker Active Search Results Google+

This Web Page by Steven Hansen ---- Copyright 2010 - 2018 Econintersect LLC - all rights reserved