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posted on 18 July 2017

July 17, 2017 Weather and Climate Report - Burst or Break?

Written by Sig Silber

NOAA keeps predicting a Monsoonal burst or surge (increase in Monsoonal moisture entering CONUS) depending on your choice of term. But the local forecasters keep on seeing reasons why it will not fully develop. This tension is again being played out this week. It is not clear how it will play out. More below in this week's full report. We also discuss the implications of burst or no burst. A "Break" in the action of the Monsoon is not anticipated.


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Forecast Summary with a Focus on the Southwest Monsoon.

  Temperature Precipitation
 6 - 10 Day  6- 10 Day Temperature Forecast.  6 - 10 Day
 8 - 14 Day 6 - 14 Day Temperature Forecast  8 - 14 Day precipitation forecast

 

This is what I am looking at Monday Night. It might be different if you do not read my report until after 10 am to 11 am EDT on Tuesday as the above maps will have updated and may look a little different. I thought of freezing these graphics (so they would not update and change) but decided against it. What you can see is that in many places where it is forecast to be wet, it is also forecast to be cool or at least less warm. Also you can see that when the Southwest Monsoon is forecast to be very strong, it can impact a lot of states north and northeast of the primary Monsoon states in the Southwest. In the forecast shown above it may be that the Southwest Monsoon is providing sub-tropical moisture to the Great Lakes Trough. So when the graphics are shown this way, one can compare them up and down which relates to change in time and one can compare them left to right which compares temperature versus precipitation. The diagonals might be of interest also as that compares a characteristic in one time period with the other characteristic in the next time period e.g. does temperature in the 6 - 10 Day Period correlate with precipitation in the 8 -14 day period or does precipitation in the earlier period correlate with temperature in the following period?
This method of reverse engineering of the forecasting models from the graphic map output  is a technique that I employ quite often.
Notice the surge shown in the Week 6 - 14 Day Outlook and notice that in what NOAA calls Week 2 i.e. Days 8 -14 the surge is interrupted by a dry anomaly originating from the Northwest and the wet anomaly is reduced to the more proximal Monsoon States and a remnant distal wet anomaly that plays out in the Northeast. Actually that remnant showed up in the graphic yesterday but is not there today and please realize that today is on day later so things can change even without the forecast changing simply due to different dates being included in the 6 to 10 and 8 to 14 day forecasts. All of this is complicated by the lack of agreement among the forecast models which is not surprising as very small changes in the drivers of the Monsoon change the impacts north of the Monsoon Core which is located in Mexico. Unfortunately, our ability to refine these forecasts at this point does not exist. But I thought it would be useful to attempt to explain partially what the impacts are of a Monsoonal Burst of which one might expect a small number each summer. This possible "burst" is somewhat marginal in that many factors have to fall into place for this coming week to have a Monsoon much stronger than is typical for this time of the year. But that may happen.

This (click to read) is a pretty good article from the Tucson NWS. Tucson is the center of analysis of the Southwest Monsoon.

It is not a long article  Some parts of great interest include.

A height above 5950m is indicative of a strong monsoon ridge with hot temperatures underneath. It also tends to lead to stronger easterly flow aloft south of the ridge. A height below 5880m is indicative of a weak monsoon ridge, with slightly cooler temperatures underneath. It also means weaker easterly winds south of the ridge, and the tendency for the high to shift south and allow drier westerly winds aloft to penetrate into the monsoon region

It is pretty  interesting to me that a change of 70 meters which is less than a football field has such a big impact. I realize that I do not have a graphic in this report that shows the 500 millibar height. One graphic shows the 500 millibar thickness which is very related but not exactly the same thing.

The stages as they apply to Arizona are also of interest.

  • Ramp-Up: Mid June through early July
  • Onset: late June through mid July
  • Peak: mid July through mid August
  • Late Monsoon: mid August through early September
  • Decay: late August-late September
We are in mid-July so we should be in the Peak at least for Arizona and we may be. One could develop a different timetable for New Mexico and Nevada, Utah and Colorado etc.

Atmospheric Anomalies July 14, 2017

You can see the big change in near-surface temperatures west of the Great Lakes but in Canada and in the Southwest from the second half of June to the first half of July. Unfortunately I do not know enough to be able to tell if the current heat pattern in the Southwest is unusual for this time of the year. Without knowing for sure, it does seem to be further north and west than I would expect but again I do not have similar graphics for prior years that I can access easily to make that comparison. That information exists. One can see Japan on this graphic. Again I don't know if it being warm there is meaningful
I have a bit of a beef with NOAA on their definition of anomalies. I do not trust the base with which actuals are compared to determine anomalies. So I am not totally confident that what I am looking at is specifically related to the dates shown. If is really warmer than usual for those dates? I am just not sure.

A. Focus on Alaska and CONUS (all U.S.. except Hawaii)

First 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

Below is the same graphic as above but without the animation to show the current situation with respect to water vapor imagery for North America. It also covers more of CONUS.

 Water Vapor Imagery

Tonight, Monday evening July 17, 2017, as I am looking at the above graphic, I see the bulk of the Monsoon Activity in Arizona and there is not much else going on. You can see the impacts of the Southwest Monsoon extending north to the North Central and Great Lakes states but the impact does not seem to be very significant.

Looking at the current activity of the Jet Stream.

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.

Current Jet Stream

One sees the current jet stream above. It is again way north and in most places it is in Canada.

This graphic provides a good indication of where the moisture is. It is a bit different than just moisture imagery as it is quantitative.

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

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.
This evening we do not see very much on shore but there are three cyclones off shore of Mexico. There is some activity in Canada. 

You can convert the above graphic in to a flexible forecasting tool by clicking here.  One can obtain views of different geographical areas by clicking here

60 Hour Forecast.

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.

current highs and lows

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.

Tropical Activity

But let's not forget the upcoming Hurricane Season. It may be getting off to an early start. So we need to start watching this graphic again.

Eastern Pacific Two Day Tropical Weather Outlook

When there is activity and I have not provided the specific links to the storm of interest, one can obtain that information at this link.  At this point in time, none of the "X"s shown are expected to impact CONUS. If that changes we will provide an update.

U.S.  3 Day to  7 Day Forecasts

Below is a graphic which highlights the forecasted surface Highs and the Lows re air pressure on Day 6. The Day 3 forecast can be found here. I used to present the Day 3 with a link to Day 6 but showing Day 6 may be more useful.

Day 6 Weather Forecast

When I look at this Day 6 forecast, it is certainly no longer a Winter Pattern. The Aleutian Low has turned from a semi-permanent feature into a train of Lows which one expects this time of the year. Remember, this is a forecast for Day 6 not the current situation. In the Day 6 forecast there is a large low in the Gulf of Alaska as there would be during the winter. It has a surface central pressure of 1012 hPa. That does not sound very low but it is all relative.
The High Pressure off of the West Coast, the familiar RRR or more properly called the Eastern Pacific Semi-tropical High or the Hawaiian High, is large with surface central air pressure of 1024 hPa. Remember this is the Day 6 pattern not the current pattern. Also notice that this is the summer position of that semipermanent High (shifted to the north but right now pushed south by the Low in the Gulf of Alaska). Moisture entering from the Pacific related to the Polar Jet Stream is less likely with this pattern. At some point, the heating of the land will draw in moisture from the tropics i.e. a Monsoon. It is not forecast to be a particularly strong Monsoon this year but it is underway.
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.

Now looking at the Day 5 Jet Stream Forecast.

Jet Stream Five Days Out .

This is a Day 5 forecast by one model. It is similar to the current pattern  but has less meridional movement (e.g. dips) and thus crosses CONUS more rapidly. Remember this is a H3 view meaning a view at 30,000 feet which is about six miles high.

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.

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, 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.

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.

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

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

Seven Day WPC Quantitative precipitation forecast

We see a wet pattern that is mostly in the Great Lakes Area and to the west. We also see the forecast track of the Southwest Monsoon having impacts over a large area. I am just a bit less confident than NOAA in that part of the forecast which it seems impacts the Northern Plains and Great Lakes Region. It is interesting to think about how much interaction there is between these two weather systems. It is difficult to imagine that a Canadian Trough would produce close to five inches of rain in a week without getting some of that moisture delivered to it via the Southwest Monsoon.

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 general signifies equal chances for snow at sea level locations.Thickness of 600 or more suggests very intensely heat and fire danger.

7 Day 500 MB Geopotential Forecast

Thinking about clockwise movements around High Pressure Systems and counter- clockwise movements around Low Pressure Systems provides a lot of information.
What we see for Day 7 is the Four Corners High with the High moving around a lot. The disagreement among the models is not easily shown graphically and in this case is not shown. What also is important is the shape and that is not easily surmised from this graphic. When elongated west to east it is not as effective at drawing moist air north to the west of the High. Draw a circle around that H and add an arrow pointing clockwise and you can determine the 10,000 feet wind directions. The big question is where those winds either cross water bodies or bring up moist subtropical air from Mexico. The Low off of Baja California (it was shown six hours ago but not not shown) could trigger a moisture surge up into Southern California and Arizona. The Ridge over the Rocky Mountains should allow the Four Corners High to be sufficiently far north not to shut down the Southwest Monsoon. But if the High stays to the west it will not allow a Gulf of California Surge producing a Burst. Also note that the High is a split high which introduces additional dynamics. We also see a West Coast Trough and an East Coast Trough. We also see the Bermuda High stretched to the west and potentially making Florida wet.
Remember this is a forecast for Day 7. Note the 540 Thickness Line re the above discussion of thickness and snow likelihood. Thickness lines near or over 600 tend to suggest very warm temperatures. Sometimes Meteorologists work with the 500 mb heights which provides somewhat similar readings to the "Thickness" lines but IMO provide slightly less specific information. The Southwest Heat Wave appears to have relented to some extent as more clouds have moved in.

Four- Week Outlook

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

I am starting with a summary of small images of the three short-term maps. This summary provides a quick look. I could have made it so you could click and enlarge the small images but for the moment I prefer that you go past the summary for the larger versions because if I set up such links, the chances increase that you will not back out of the link properly and get lost. For most people the summary with the small images will be sufficient. Following the graphic with the three small images, you can find the larger maps and a discussion and for reference purposes I then also provide the forecast map for the current or soon to be current full month and the three-month forecast map. These are issued and updated less frequently than the first three maps shown.

mall Images of Temperature Maps
6 to 10 Days 8 to 14 Days Weeks 3 and 4
6 to 10 Day 8 - 14 Weeks 3 and 4
The above shows the progression of forecasts from six days out through four weeks out. Larger maps with discussion appear below. But this set of three maps paints a pretty good picture of what the forecast is.

 

Now the larger maps followed by a discussion that describes what is happening and any inconsistences that I see.

6 - 10 Day Temperature Outlook issued today (Note the NOAA Level of Confidence in the Forecast Released on July 17, 2017 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 July 17, 2017 was 3 out of 5).

 

8-14 Day Temperature Outlook

Looking further out.

Experimental Week 3-4 Temperature Outlook

Consolidation of 6 - 10, 8 - 14 and Experimental Week 3-4 Temperature Forecasts

Interpreted on July 17, 2017

July 23 to July 31 July 29 to August 11

Days 6 - 10: Most of CONUS is warm. There is a small EC and partially cool area where the Monsoon is forecast to be getting started: rain cools things down. There is another EC area in the Northeast which into New England and the Great Lakes becomes a cool anomaly. Alaska except for the extreme Northeast is warm.

There is a cool anomaly related to the more intense part of the Southwest Monsoon since rain cools. Alaska is warm, The East Coast extending in the south to the west along the Gulf of Mexico is warm and the Northwest quadrant of CONUS is warm

The transition to the pattern shown in the Week 3 - 4 Forecast from the pattern shown in the 8-14 Day forecast appears to be feasible for the western half of CONUS but not so much for the eastern half..

Week 2:  As the period evolves, the pattern does not change very much but the Northeast EC areas extends much further down into parts of the Southeast..
Remember the Week 3-4 Experimental Outlook was issued last Friday and I am looking at the 6 - 10 and 8 - 14 day forecasts issued today i.e. Monday. So that explains the overlap of dates. Remember that the Week 3 - 4 Forecast covers two weeks so it can appear to not mesh perfectly but actually do so over the two-week period. For all three time periods, in between the cool and warm anomalies it is usually EC i.e. the boundary is usually not sharp.

 

Reference Forecasts Full Month and Three Months.

Below is the Temperature Outlook for the month shown in the Legend. This map is first issued on the Third Thursday of the Month for the following month and then 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.  Note that the three maps shown at the beginning of this discussion on temperature may cover a slightly different time period since they update as the month progresses and the map below covers a particular month shown in the Legend. It is useful if one wants to understand how that month is forecast to play out.

July Temperature Outlook Updated on June 30, 2017

Here is the Temperature Outlook issued on the date and for the three-month period shown in the Map Legend. Again this is provided for reference only. It is the same map that is included in our Saturday night report that follows the NOAA third Thursday of the month Seasonal Outlook Update. It provides a longer time frame than the above maps. It uses a totally different methodology as it is not possible to use the dynamical models to project out three months. The dynamical models work by figuring out how the current conditions will evolve over a fairly short period of time. To look out three months or longer the approach is more statistical using the forecasted ENSO Phase and Climate Trends.

The theory behind using dynamical models for short-term forecasts (6  10 Days, 8 - 14 Days, and recently Weeks 3-4) and statistical models (Monthly and Three-Months) for longer-term forecasts makes perfect sense but sometimes we see that the short term forecasts and then the actuals do not match the statistical forecasts very well. This tells us that either the statistical forecasts were based on incorrect assumptions or that the actual weather patterns are different from what we might have expected.

JAS 2017 Temperature Outlook Issued on June 15, 2017

Now - Precipitation

I am starting with a summary of small images of the three short-term maps. This summary provides a quick look. I could have made it so you could click and enlarge the small images but for the moment I prefer that you go past the summary for the larger versions because if I set up such links, the chances increase that you will not back out of the link properly and get lost. For most people, the summary with the small images will be sufficient. Following the graphic with the three small images, you can find the larger maps and a discussion and for reference purposes I then also provide the forecast map for the current or soon to be current full month and the three-month forecast map. These are issued and updated less frequently than the first three maps shown.

Small Images of Precipitation Maps
6 to 10 Day 8 to 14 Day Weeks 3 and 4
6 to 10 Day 8 - 14 Weeks 3 and 4
The above shows the progression of forecasts from six days out through four weeks out. Larger maps with discussion appear below. But this set of three maps paints a pretty good picture of what the forecast is.

 

Now the larger maps followed by a discussion that describes what is happening and any inconsistencies that I see.

6 - 10 Day Precipitation Outlook Issued Today (Note the NOAA Level of Confidence in the Forecast Released on July 17, 2017 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 July 17, 2017 was 3 out of 5)

Current 8 - 14 Day Precipitation Outlook

Looking further out.

Weeks 3 and 4 Experimental Forecast..

Consolidation of 6 - 10, 8 - 14, and Week 3-4 Precipitation Forecasts

Interpreted on July 17, 2017

July 23 to July 31  July 29 to August 11, 2017

Days 6 -10: Generally for CONUS it is dry in the Northwest and Southeast with the Monsoon probably the key driver of the wet anomaly that originates in the Southwest but then extends to the northeast into the Northeast Quadrant of CONUS. Alaska is mostly wet but dry towards and into the Aleutians. NOAA is quite bullish on how far the Monsoon will carry precipitation to the north and east.

For CONUS, the Northwest, Northern and Western Alaska and the Great Lakes are dry. A wet anomaly is centered on The Four Corners but extends to the southeast all the way to the Florida Panhandle.

The transition to the pattern shown in the Week 3 - 4 Forecast from the pattern shown in the 8-14 Day forecast appears to be somewhat feasible but with less area shown as anomalies than one might expect especially in the Eastern Part of CONUS.

Week 2: The Monsoonal flow is less intense leading to the unified wet anomaly become a more traditional Southwest wet anomaly with a remnant of the prior diagonal wet anomaly persisting in the Northeast for a while but either being overwhelmed by the dry anomaly or forced to the south.

Remember the Week 3-4 Experimental Outlook was issued last Friday and I am looking at the 6 - 10 and 8 - 14 day forecasts issued today i.e. Monday. So that explains the overlap of dates. Remember that the Week 3 - 4 Forecast covers two weeks so it can appear to not mesh perfectly but actually do so over the two-week period. In between the dry and wet anomalies, it is usually EC i.e. the boundary is usually not sharp.

 

Reference Forecasts Full Month and Three Months.

Below is the Precipitation Outlook for the month shown in the Legend. This map is first issued on the Third Thursday of the Month for the following month and then 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. Note that the three maps shown at the beginning of this discussion about precipitation may cover a slightly different time period since they update as the month progresses and the map below covers a particular month shown in the Legend. It is useful if one wants to understand how that month is forecast to play out.

July 2017 Precipitation Outlook Updated on June 30, 2017

Below is the Precipitation Outlook issued on the date and for the three-month period shown in the Map Legend. Again, this is provided for reference only. It is the same map that is included in our Saturday night report that follows the NOAA third Thursday of the month Seasonal Outlook Update. It provides a longer time frame than the above maps. It uses a totally different methodology as it is not possible to use the dynamical models to project out three months. The dynamical models work by figuring out how the current conditions will evolve over a fairly short period of time. To look out three months or longer, the approach is more statistical using the forecasted ENSO Phase and Climate Trends.

The theory behind using dynamical models for short-term forecasts (6 - 10 Days, 8 - 14 Days and recently Weeks 3-4) and statistical models for longer-term forecasts (Month and three months) makes perfect sense but sometimes we see that the short-term forecasts and then the actuals do not match the statistical forecasts very well. This tells us that either the statistical forecasts were based on incorrect assumptions or that the actual weather patterns are different from what we might have expected.

JAS 2017 Precipitation Outlook Issued on June 15, 2017

Here is the NOAA discussion released today July 17, 2017

6-10 DAY OUTLOOK FOR JUL 23 - 27 2017  

TODAY'S MODELS ARE IN GOOD AGREEMENT ON THE PREDICTED 500-HPA HEIGHT PATTERN ACROSS THE U.S. TROUGHS ARE PREDICTED IN THE GULF OF ALASKA AND IN THE EASTERN U.S., WHILE RIDGING IS FORECAST OVER PARTS OF ALASKA AND THE WESTERN U.S. FORECAST HEIGHTS ARE ABOVE NORMAL ACROSS ALASKA DUE TO THE FORECAST RIDGING, AND BELOW NORMAL NEAR THE PACIFIC NORTHWEST DUE TO THE FORECAST TROUGH. THE RIDGE/TROUGH PATTERN PREDICTED ACROSS THE CONUS IS TYPICAL FOR THIS TIME OF YEAR, EXCEPT IS EXPECTED TO BE A BIT MORE AMPLIFIED THAN USUAL, RESULTING IN SLIGHTLY POSITIVE HEIGHT ANOMALIES IN NORTHERN PARTS OF THE WEST, AND SLIGHTLY NEGATIVE HEIGHT ANOMALIES IN NORTHERN PARTS OF THE EAST. 

FORECAST RIDGING OVER MOST OF ALASKA INCREASES THE CHANCES OF ABOVE NORMAL TEMPERATURES THERE, EXCEPT IN NORTHEAST ALASKA WHERE FORECAST ONSHORE WINDS ARE EXPECTED TO TRANSPORT RELATIVELY COLD AIR ONSHORE, AND FOR PARTS OF THE ALASKA PENINSULA WHERE PREDICTED NEGATIVE HEIGHT ANOMALIES FAVOR BELOW NORMAL TEMPERATURES. FORECAST RIDGING IN THE WESTERN CONUS INCREASES THE LIKELIHOOD OF ABOVE NORMAL TEMPERATURES IN THE WEST, EXCEPT IN PARTS OF THE SOUTHWEST WHERE INCREASED CLOUDINESS AND MONSOON-RELATED RAINFALL ARE FORECAST. ABOVE NORMAL TEMPERATURES ARE FORECAST FROM THE SOUTH-CENTRAL PLAINS INTO THE SOUTHEAST AND MID-ATLANTIC, CONSISTENT WITH TODAY'S DYNAMICAL MODEL-BASED TEMPERATURE TOOLS. TROUGHING AND NEGATIVE HEIGHT ANOMALIES IN THE GREAT LAKES REGION AND NORTHEAST ENHANCE THE CHANCES FOR BELOW NORMAL TEMPERATURES IN THOSE AREAS.

THE STORM TRACK OVER ALASKA IS FORECAST TO BE FARTHER NORTH THAN USUAL, DUE TO THE PREDICTED RIDGE, FAVORING BELOW NORMAL PRECIPITATION FOR PARTS OF THE ALEUTIANS AND COASTAL MAINLAND ALASKA, AND ABOVE NORMAL PRECIPITATION FOR THE REST OF ALASKA. RIDGING IN THE WESTERN CONUS INCREASES CHANCES FOR BELOW NORMAL PRECIPITATION FROM THE PACIFIC NORTHWEST, EASTWARD TO THE GREAT LAKES REGION. ABOVE NORMAL PRECIPITATION IS FAVORED FOR PARTS OF THE SOUTHWEST, DUE TO INCREASED MONSOON ACTIVITY. A FRONTAL BOUNDARY FORECAST TO PERSIST ACROSS THE CENTRAL PLAINS, EAST TO THE MID-ATLANTIC AND NORTHEAST FOR PART OF THE 6-10 DAY PERIOD INCREASES THE LIKELIHOOD OF ABOVE NORMAL PRECIPITATION FOR THOSE AREAS. BELOW NORMAL PRECIPITATION IS FAVORED FOR PARTS OF TEXAS AND FLORIDA, CONSISTENT WITH DYNAMICAL-MODEL PRECIPITATION TOOLS.

FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: AVERAGE, 3 OUT OF 5, DUE TO GOOD MODEL AGREEMENT, BUT WEAK LARGE-SCALE ANOMALIES.

8-14 DAY OUTLOOK FOR JUL 25 - 31 2017 

THE PATTERN FORECAST DURING THE WEEK-2 PERIOD IS VERY SIMILAR TO THE 6-10 DAY PERIOD, EXCEPT LESS AMPLIFIED DUE TO INCREASED UNCERTAINTY AND ENSEMBLE SPREAD, AND SHIFTED EASTWARD A BIT. THE TEMPERATURE PROBABILITY FORECAST FOR WEEK-2 IS SIMILAR TO THE 6-10 DAY PERIOD, EXCEPT THE AREA OF NEAR TO BELOW NORMAL TEMPERATURES IS SHIFTED SOUTH AND EAST IN THE EASTERN CONUS, COINCIDING WITH A SHIFT EASTWARD IN THE TROUGH. THE PRECIPITATION PROBABILITY FORECAST IS ALSO SHIFTED EAST AND SOUTH IN THE EASTERN CONUS BECAUSE OF THE PREDICTED SOUTHEASTWARD PROGRESSION OF THE FRONTAL BOUNDARY FROM THE 6-10 DAY PERIOD TO THE WEEK-2 PERIOD.

FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: AVERAGE, 3 OUT OF 5, DUE TO GOOD MODEL AGREEMENT, BUT WEAK LARGE-SCALE ANOMALIES.

THE NEXT SET OF LONG-LEAD MONTHLY AND SEASONAL OUTLOOKS WILL BE RELEASED ON  JULY 20

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.

Centered

Day

ENSO

Phase

PDO AMO

Other Comments

Jul 21, 1955 La Nina - +  
Jul 22, 1955 La Nina - +  
Jul 4, 1985 La Nina + - Tail End
Jul 5, 1985 La Nina + - Tail End
Jul 5, 1989 Neutral + + Following a Strong La Nina
Jul 6, 1989 Neutral + + Following a Strong La Nina
Jul 30, 1997 El Nino + + Start of MegaNino
Jul 31, 1997 El Nino + + Start of MegaNino
Jun 27, 2001 Neutral - +  
Jun 28, 2001 Neutral - +  

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

One thing that jumped out at me right away was the spread among the analogs from June 27 to July 31 which is 34 days which is a bit wider than 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 July 13. These analogs are centered on 3 days and 4 days ago (July 13 or July 14). So the analogs could be considered to be in sync with the calendar meaning that we will be getting weather that we would normally be getting this time of the year. For more information on Analogs see discussion in the GEI Weather Page Glossary.

There are two pairs of ENSO Neutral Analogs, two pairs of La Nina analogs, and one pair of El Nino Analogs which might be considered as cancelling each other out and suggesting ENSO Neutral. This is the first time that I recall there being five pairs of analogs meaning five sets of analogs that differ only by a single day. It is pretty like five analogs each of which lasted for two days. The phases of the ocean cycles of the analogs are most consistent with all of the McCabe Conditions except for McCabe B which is generally wet with the Great Plains and Northeast Dry. Since the forecast is somewhat contractor to McCabe B and the analogs exclude McCabe B that might be thought of as support for the forecast.

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.

McCabe Maps modified to include the subtitles

Sometimes it is easier to work in black and white especially if you print this report so there is a black and white version from the later report by the same authors. Darker corresponds to red in the color graphic i.e. higher probability of drought.

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.

Looking Out Beyond Three Months.

The Monthly Seasonal Outlook Update which we published Saturday June 17 can be accessed by clicking here. It looks out 15 months for NOAA (the next month plus 14 more) and for JAMSTEC three three-month periods which right now is through February 2018. So it is a very useful reference and it gets updated each month. We will publish an Update on Saturday July 22. 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.

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.

Here is the 30 Days ending July 8, 2017

July 8, 2017 30 Day Temperature and Precipitation Departures

Not much change but a bit warmer in the Northeast. Remember, this is a 30 average so the most distant seven days are removed and the most recent seven days are added.

And the 30 Days ending July 15, 2017

July 15, 2017 30 Day Temperature and Precipitation Departures

  The big change is that now you can see the Monsoon IN MEXICO. Remember, this is a 30 average so the most distant seven days are removed and the most recent seven days are added.

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

Same as above but for July

I will be including the above two graphics regularly as they really help with understanding why things are happening the way they are. I think the (at least intermediate) Source is The Weather Channel and I was able to download the full presentation with difficulty and you can attempt the same thing by clicking here.
I think these two slides are from a much larger set but these two really highlight the position of the Bermuda High which they are calling the Azores High in the January slide 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 July now so the set of positions shown above for July apply. For CONUS the seasonal repositioning of the Bermuda High and the Pacific High are very significant. Notice the Summer position of the Pacific High. It may be slightly out of position right now (too far south) but that should change very soon.

Forecast for Today

Temperature at 2 Meters

Notice that below the map there is a tabulation of magnitude of the current anomalies by region. The persistence of the extreme cool anomaly for Antarctica is quite interesting.

Maine Reanalyer

This graphic is actuals not anomalies as is the case in the temperature map. We again see the dry area from North Africa through Asia (other than Southeast Asia) as well as most areas south of the Equator. Much of North America and Europe also is dry.

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

Temperature

BOM Current Temperature Wedensday

The pattern of hot from North Africa through India continues in the Day 6 Forecast with North American being  part of the pattern. Please remember this graphic updates every six hours so the diurnal pattern can confuse the reader.

Precipitation

BOM World Preciptation  Wednesday

Notice that in the Day 6 Forecast, we again see the Atlantic and Pacific dominated by High Pressure. The westward extension of the Bermuda High is very impressive and probably will have a significant impact on CONUS Southern Tier weather both the Southeast directly and the Southwest Monsoon indirectly.

Looking Out a Few Months

Here is the precipitation forecast from Queensland Australia:

Falling SOI  forecast for July to September 2017.

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 change from the forecast last month due to the change from a rising SOI  to a falling SOI. It is more like an El Nino forecast than a La Nina forecast.

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.

And when we look at the current Sea Surface anomalies below, we see a lot of them not just along the Equator related to ENSO.[NOAA may be having problems updating their daily SST Anomaly Report so I am working with the latest version that I have]

Daily SST Anomalies

First the categorization of the anomalies.

Mediterranean, Black Sea and Caspian Sea Western Pacific West of North America East of North America North Atlantic
The Black Sea Sea and the  Mediterranean are warm.

Mixed. Cool at 40N to 50N and warm at 30N. But on an overall basis it is warm especial around Japan.

Yellow Sea warm

Very warm in the Bering Straights. Warm south of Aleutians. 

Warm off Baja and in Sea of Cortez.

Warm but a bit cool out to sea off Newfoundland.

Hudson Bay very warm

Mixed
The Tropical Pacific

Neutral with warmish cast.

Africa West of Australia North, South and East of Australia West of South America East of South America

Slightly cool in Gulf of Guinea. A bit warm to the East

Cool to the southwest and northwest Slightly warm to the east. Cool south of 40S Warm south of  40S. Cool at 20S

 

What you see in the below graphic is the change in the anomaly over the last four weeks So you have to refer to the graphic above this one to really interpret the below graphic as what we are seeing here is the change in the anomalies. So blue means a trend that is either cooler or less warm than four weeks ago. Red means a trend that is warmer or less cool than four weeks ago. So this graphic is a way of understanding how the anomalies shown in the above graphic have changed over the past four weeks. It is important to understand the distinction between these two graphics. The top one shows the recent conditions, the bottom one shows the direction of change.

July 17, 2017 four week change is SST Anomalies

The categorization of the four week change in the anomalies.

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

Eastern Mediterranean is warming.

Overall warming.

Persian Gulf cooling.

Intense warming west of Baja California and in Gulf of California.

Warming.

Warming in the Northern GOM

Cooling.
The Tropical Pacific Mixed east of 120W, stable elsewhere.
Africa West of Australia North, South and East of Australia West of South America East of South America

Cooling to the southwest

Cooling east to and beyond Madagascar

Cool to the northwest

Stable

Cooling off of Ecuador.

Cooling off of 20S

 

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 -0.68 +0.39 -0.3
November +0.84 +0.40  0.0
December +0.55 +0.34 -0.1
January +0.10 +0.23  0.0
February +0.04 +0.23 +0.2
March +0.12 +0.17 +0.0
April +0.52 +0.29 +0.2
May +0.31 +0.32 +0.2
June +0.17 +0.31  0.0

 

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 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. Mostly I see as I look at this on July 17 for what is shown as Week Two, the period July 19, 2017 to July 25, 2017, we see wet conditions* over the U.S. Southwest, impacting the Maritime Continent and in West Africa just north of the Equator. We see dry conditions* impacting Central America and Western Indonesia.
* 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.

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.

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 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.

Notice in the bottom graphic the big difference between temperature anomalies south of the Equator and north of the Equator. This creates a dynamic situation.

Current SST and wind anomalies

Location Bar for Nino 3.4 Area Above and Below
------------------------------------------------  A       B       C      D       E       -----------------

 

If one were to track this day by day over the past month one would see both the northern intrusion from south of the Equator strengthening (temperature) but being squeezed from both the east and the west. We now see it gradually being squeezed back south and eventually out of the Nino 3.4 Measurement Area. There is now also some cooler water in the eastern end of the Nino 3.4 Measurement Area and just to the west.

The below table only looks at the Equator 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   

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)

LAND

LAND

0

0

+0.5C to +1C (marginal)

175W

120W

55

50

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

120W

110W

10

0

0C or cooler Anomaly (coolish neutral)

110W

LAND

15

0

 

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 July 17, in the afternoon working from the July 16 TAO/TRITON report [Although the TAO/TRITON Graphic appears to update once a day, in reality it updates more frequently.], this is what I calculated.

Calculation of ONI from TAO/TRITON Graphic
Anomaly Segment Estimated Anomaly
  Last Week This Week
A. 170W to 160W +0.7 +0.7
B. 160W to 150W +1.0 +0.8
C. 150W to 140W +1.0 +0.9
D. 140W to 130W +0.7 +0.6
E. 130W to 120W +0.3 +0.4
Total +3.7 +3.4
Total divided by five i.e. the Daily Nino 3.4 Index (+3.7)/5 = +0.7 (+3.4)/5 = +0.7

 

My estimate of the daily Nino 3.4 SST anomaly tonight is again +0.7 which is an El Nino value. NOAA has reported the weekly Nino 3.4 to be +0.5 which is a marginal El Nino Value and lower than last week.
Nino 4.0 is reported lower than last week at +0.5. Nino 3 is higher at +0.4. Nino 1 + 2 which extends from the Equator south rather than being centered on the Equator is reported higher 0.0. I believe 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. Notice that Nino 4.0 and 3.4 have been declining. The same data in table form but going back a couple of more years can be found here.

July 17, 2017 Nino Readings

This is probably the best place to 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. It is strange to me that the Asian forecasting services generally conclude that that this cool ENSO Phase is not a La Nina but a near La Nina and NOAA concludes it is a La Nina. It is the same ocean. The reported readings are very close but the Asian readings are generally slightly higher (less La Nina-ish) than the NOAA reading and their cut-off points for declaring a La Nina are a bit different and the parts of the Equator they look at are a bit different. It might be explained by what part of the ENSO pattern impacts their area of geography but it just seems to me that NOAA has been a bit over eager. And I wonder why.

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.

July 17, 2017 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 which shows the current readings is now light yellow which is not El Nino warm but clearly on the warm side of Neutral. 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.
Week to week there have been no substantial changes since the far East Pacific cooled down. It is ENSO Neutral with a warm bias. But the cool area east of 100W has expanded and we see another cool area perhaps at 120W. These are not in the Nino 3.4 Measurement Area but are important never-the-less.

I had stopped showing the below graphic which is more focused on the Equator but looks down to 300 meters rather than just being the surface. But recently there has been sufficient change to warrant including this graphic. And now that we are back tracking a possible El Nino it is the graphic of choice.

July 17, 2017 Upper Ocean Heat Anoma

The bottom of the Hovmoeller shows the current situation. The Cool Event is long gone. But what might be successive Kevin waves initiating an El Nino are still not very impressive. If you look from the bottom of the graphic up you can see that any La Nina conditions ended in December. There is not much change from the prior week. But what I am really looking for is the left portion of the graphic the Pacific Warm Pool and I don't see much change. Reds are what is needed for an El Nino. There is a warm area shown between 145W and 130W which creates the marginal El Nino values of the Nino 3.4 Index. This may be a combination of warm water rising and warm water moving north into the area covered by this graphic. It looks like it might be drifting to the east and possibly fading but it is hard to be sure about that. We also see to the far left a white area. That needs to be brown or red for there to be an El Nino.

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). 

.July 17, 2017 Kelvin Wave Analysis.

We now have warmer water near the surface from about 148W to 128W which is sufficient to raise the Nino 3.4 reading and keep it there for a little while. The warm pod to the west at depth has risen a bit and shrunk a lot and no longer appears to be a factor. To the east it looks like there is not much happening. It is like everything else we look at ENSO Neutral to the high side and can be interpreted as marginally El Nino and soon to be clearly ENSO Neutral.

Now for a more detailed look (there is some redundancy with the above graphic). Notice by the date of the graphic (dated July 12, 2017) that the lag in getting this information posted so the current situation may be a bit different than shown although this graphic was just updated this afternoon. The date shown is the midpoint of a five-day period with that date as the center of the five-day period.

Below is the pair of graphics that I regularly provide.

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 and today in particular, 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.

Subsurface Heat Anomalies

Re the top graphic, let us first look at surface temperature anomalies. There is an area of neutral water off the coast of Ecuador.There is warm water from 110W to 155W and within that anomaly somewhat warmer water from 130W to 150W. Subsurface Temperature Anomalies: There is east of 175W no warm water below 100 meters and very little warm water west of 175W. There is no way the Nino 3.4 Index can remain at the current level.
The bottom half of the graphic (Absolute Values which highlights the Thermocline) is now more useful as we track the transition from last winter's ENSO Cool Event to ENSO Neutral to ENSO Neutral with a warm bias which may possibly become an El Nino. More likely we will soon see the situation change to ENSO Neutral with a warm bias and then to just plain ENSO Neutral. It shows the thermocline between warm and cool water. The 28C Isotherm is now located further west at about 160W. This graphic does not show a 27.5C anomaly which might more precisely indicate where convection is likely to occur. The 27C isotherm is now at 140W. The 25C Isotherm reaches the surface at 120W. What we have is ENSO Neutral.
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. At this point, we have gone to ENSO Neutral but not El Nino although the situation is essentially the dividing line between El Nino and ENSO Neutral.
The conditions to create an El Nino simply do not exist.

Here are the above graphics as a time sequence animation. You may have to click on them to get the animation going.

Equatorial Temperature Simulation

Isotherm Simulation

And now Let us look at the Atmosphere.

Low-Level Wind Anomalies near the Equator

Here are the low-level wind anomalies.

Low Level Wlind Anomalies

We now see westerlies all over the Equator which should be favorable for the development of an El Nino but do not seem to be having much of an impact.

And now the Outgoing Long wave Radiation (OLR) Anomalies which tells us where convection has been taking place. 

OLR Anomalies Along the Equator

The pattern has changed. We no longer see suppressed Outgoing Long Wave Radiation (OLR) at the Dateline (no longer dry) but we again see enhanced OLR at 120E ( wet)

And Now the Air Pressure which Shows up Mostly in 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 July 17 was reported as -0.65  which is an ENSO Neutral value. The 90 Day Average was reported at -2.75 which is also an ENSO Neutral value. Looking at both the 30 and 90 day averages is useful and right now both are in agreement. They seem to be tracking the Nino 3.4 Index pretty well and reflect the downturn in marginal El Nino Conditions and short-term conditions in the Western Pacific where there there had been a long string of negative values for a while. .

 

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 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

The newly issued on July 13, 2001 CPC/IRI Meteorologist survey is shown on the left. The earlier June 15 IRI/CPC fully model-based report is shown on the right.

July 13. 2017 CPC/IRI Update two graphics side by side.

There is a big difference between the perspective on June 15 and July 13. The green (ENSO Neutral) bars and the red (El Nino) bars were pretty much shown as equally likely in OND (2017) and NDJ 2017/2018 in the June 15th Report. The newer but survey based and not as scientific report shows the green (ENSO Neutral) bars higher than the red (El Nino) bars at all times. The probabilities associated with the red (El Nino) bars decline as the period evolves.

Here is the Discussion that was issued in Coordination with the CPC/IRI Report.

EL NIÑO/SOUTHERN OSCILLATION (ENSO) DIAGNOSTIC DISCUSSION  issued by

CLIMATE PREDICTION CENTER/NCEP/NWS  and the International Research Institute for Climate and Society  13 July 2017

ENSO Alert System Status: Not Active

Synopsis: ENSO-neutral is favored (~50 to 55% chance) into the Northern Hemisphere winter 2017-18.

During June, ENSO-neutral continued, although equatorial sea surface temperatures (SSTs) remained above average in the central and east-central Pacific Ocean. The latest weekly Niño index values were near +0.5°C in the Niño-4 and Niño-3.4 regions, and closer to zero in the Niño-3 and Niño-1+2 regions . The upper-ocean heat content anomaly was above average during June, reflecting above-average sub-surface temperatures across the central and eastern Pacific. In the atmosphere, tropical convection was suppressed over the west-central tropical Pacific and enhanced over the Maritime Continent. The lower-level and upper-level winds were near average over most of the tropical Pacific, and the Southern Oscillation Index (SOI) and Equatorial SOI were slightly negative to near-zero. Overall, the ocean and atmosphere system remains consistent with ENSO-neutral.

Some models predict the onset of El Niño (3-month average Niño-3.4 index at or greater than 0.5°C) during the Northern Hemisphere summer. However, more than half of the models favor ENSO-neutral through the remainder of 2017. These predictions, along with the near-average atmospheric conditions over the Pacific, lead forecasters to favor ENSO-neutral into the winter (~50 to 55% chance). However, chances for El Niño remain elevated (~35-45%) relative to the long-term average. In summary, ENSO-neutral is favored (~50 to 55% chance) into the Northern Hemisphere winter 2017-18

This discussion is a consolidated effort of the National Oceanic and Atmospheric Administration (NOAA), NOAA’s National Weather Service, and their funded institutions. Oceanic and atmospheric conditions are updated weekly on the Climate Prediction Center web site (El Niño/La Niña Current Conditions and Expert Discussions). Forecasts are also updated monthly in the Forecast Forum of CPC's Climate Diagnostics Bulletin. Additional perspectives and analysis are also available in an ENSO blog. The next ENSO Diagnostics Discussion is scheduled for 10 August 2017.

Climate Prediction Center National Centers for Environmental Prediction  NOAA/National Weather Service College Park, MD 20740

Here is the primary NOAA model.

CFSv2 spread and bias correct ENSO forecast

The estimated current value of the Nino 3.4 Temperature Anomaly after the adjustments have been applied is about 0.5 for July which is a borderline El Nino/Neutral value but it heads pretty much straight down from there.But we are starting to see this model flirting with La Nina conditions for a short period of time this 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. 

From Tropical Tidbits.com

CDAS Legacy System

The above is from a legacy "frozen" NOAA system meaning the software is maintained but not updated. It seems to show a cycle in the Nino 3.4 Index Values. I see that as I monitor the TAO/TRITON graphic. My best guess is that it is related to the MJO but it certainly is intriguing. I do not need to draw in the lines for you to see that the Nino 3.4 Index as reported by CDAS has moved above the 0C line and is now reporting a warm anomaly but not yet an increasing warm anomaly.

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

Discussion Issued July 16, 2017

Tropical Pacific Ocean warmer than average, but ENSO neutral to stay for 2017

he El Niño-Southern Oscillation (ENSO) remains neutral. All climate models surveyed by the Bureau indicate the tropical Pacific Ocean is likely to stay ENSO neutral for the rest of 2017.

Sea surface temperatures (SSTs) in the central tropical Pacific (the NINO3.4 region) have been warmer than average, though still in the neutral range, since mid-April. The current NINO3.4 value of +0.5 °C is the result of a localised warm anomaly. The overall sea surface temperature pattern is inconsistent with a developing El Niño, meaning further ocean warming and El Niño development remains unlikely. This is reflected in neutral ENSO outlooks from all international climate models surveyed. Other indicators of ENSO, such as the Southern Oscillation Index, cloudiness near the Date Line, and trade winds also remain at neutral levels.

Here is the JAMSTEC July 1 forecast of the Nino 3.4 values which are the most looked at index used to forecast El Nino.

JAMSTEC July 1, 2017 ENSO Forecast.

As you can see this is now a totally ENSO Neutral pattern. It is a shocking critique of the models that they got this wrong when it was obvious from the beginning that this was not going to be an El Nino winter.

Here is the discussion that corresponds to the JAMSTEC July 1 Nino 3.4 Forecast. We will issue our analysis of the NOAA and JAMSTEC Seasonal Outlooks on Saturday July 22.

Jul. 13, 2017

Prediction from 1st Jul., 2017

ENSO forecast:

A slightly warmer-than-normal sea surface temperature is predicted for the whole tropical Pacific. This condition will persist until boreal winter. Then, it will return into a neutral state by next spring.

Indian Ocean forecast:

All ensemble members of SINTEX-F continue to predict a positive Indian Ocean Dipole [Editor's Note: The Australian BOM disagrees see BOM graphic and discussion below] ; the ensemble mean prediction suggests that it peaks in boreal fall. In accord to the positive IOD evolution, sea level anomalies are expected to be negative (positive) in the eastern (western) tropical Indian Ocean.

Regional forecast:

On a seasonal scale, most part of the globe will experience a warmer-than-normal condition, while some parts of central Russia and central U. S. will experience a colder-than-normal condition in the boreal fall.

As regards to the seasonally averaged rainfall, a wetter-than-normal condition is predicted for some parts of East Africa and West Africa during the boreal fall, whereas most parts of Indonesia, Australia, eastern China, and Brazil will experience a drier condition during the boreal fall. Those are partly due to the positive Indian Ocean Dipole.

Most parts of Japan will experience moderately warmer-than-normal and drier-than-normal conditions in the boreal fall. The wind and pressure anomalies averaged in September-November suggest that Japan might be covered by an equivalent barotropic high. Those may be due to the combined effect of "the monsoon-desert mechanism" of the positive Indian Ocean Dipole and "the Silk Road pattern" along the Asian jet.

Indian Ocean IOD (It updates every two weeks)

The IOD Forecast is indirectly related to ENSO but in a complex way.

IOD POAMA Model Run

Discussion Issued July 16, 2017

The Indian Ocean Dipole (IOD) is neutral. The weekly index value to 16 July was −0.14 °C. However, two of six climate models suggest positive IOD thresholds could be reached in the coming months. Only one of these models suggests these will last long enough to be considered a positive IOD event. Positive IOD events are typically associated with below average winter and spring rainfall over central and southern Australia.

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 there is reduced interest as to whether or not this Summer and Fall will be El Nino situations. It would seem that the chances of other than a marginal El Nino are fairly low.

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. JAMSTEC was suggesting that if there is an El Nino in the winter of 2017/2018 this could signify that the PDO had entered its Positive Phase. 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. JAMSTEC was suggesting it might occur very soon. But their strong El Nino forecast appears to have been premature. So our assessment 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.

E. Relevant Recent Articles and Reports

Weather in the News

Rainfall and Population in China

15 inch precipitation line

Source: I think there are some important rivers coming down from the Himalayas that play a role also but I find this map very interesting.

Weather Research in the News

Flash Flooding Takes its Toll of the Unaware.

Flooding a Problem in Illinois also but the Terrain is not as Deadly.

Global Warming in the News

I don't Understand This

Usually removing cyclicality is the correct procedure so I have not studied this report enough (and do not plan to) to know if the procedures were done incorrectly as the authors claim. It may get further discussion in the Alt-Global Warming Media.

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 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
  • Weaker
  • Stronger
  • Part of Decay Process
  • Counteracts Easterlies
  • Enhances Easterlies
Western Pacific Westerlies
  • Stronger
  • May Create or Stimulate the Onset of El Nino via Kelvin Waves
  • Weaker
  • Part of Decay Process
  • Strengthens Westerlies
  • Weakens Westerlies
MJO Active Phase
  • More  likely
  • Stimulates
  • Less likely and weak
  • Retards development of a new La Nina
  • Stimulates the Jet Stream
 
MJO Inactive Phase
  • 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

With respect to relating analog dates to ENSO Events, the following table might be useful. In most cases this table will allow the reader to draw appropriate conclusions from NOAA supplied analogs. If the analogs are not associated with an El Nino or La Nina they probably are not as easily interpreted. Remember, an analog is indicating a similarity to a weather pattern in the past. So if the analogs are not associated with a prior El Nino or prior La Nina the computer models are not likely to generate a forecast that is consistent with an El Nino or a La Nina.

  El Ninos La Ninas
  Start Finish Max ONI PDO AMO Start Finish Max ONI PDO AMO
            DJF 1950 J FM 1951 -1.4 - N
T   JJA 1951  DJF     1952 0.9 - +          
   DJF 1953  DJF     1954 0.8 - + AMJ 1954  AMJ 1956 -1.6 - +
M MAM 1957  JJA     1958 1.7 + -          
M SON 1958 JFM     1959 0.6 + -          
M   JJA 1963 JFM     1964 1.2 - - AMJ 1964  DJF 1965 -0.8 - -
M  MJJ 1965 MAM    1966 1.8 - - NDJ 1967 MAM 1968 -0.8 - -
M OND 1968 MJJ      1969 1.0 - -          
T  JAS 1969  DJF     1970 0.8 N -  JJA 1970  DJF 1972 -1.3 - -
T AMJ 1972 FMA     1973 2.0 - - MJJ 1973 JJA 1974 -1.9 - -
            SON 1974 FMA 1976 -1.6 - -
T ASO 1976 JFM     1977 0.8 + -          
M ASO 1977 DJF      1978 0.8 N            
M SON 1979 JFM     1980 0.6 + -          
T MAM 1982  MJJ     1983 2.1 + - SON 1984 MJJ 1985 -1.1 + -
M ASO 1986  JFM    1988 1.6 + - AMJ 1988 AMJ 1989 -1.8 - -
M MJJ 1991  JJA     1992 1.6 + -          
M SON 1994  FMA    1995 1.0 - - JAS\ 1995 FMA 1996 -1.0 + +
T AMJ 1997  AMJ    1998 2.3 + + JJA  1998 FMA 2001 -1.6 - +
M MJJ 2002  JFM    2003 1.3 + N          
M  JJA 2004 MAM    2005 0.7 + +          
T ASO 2006 DJF      2007 0.9 - + JAS  2007  MJJ 2008 -1.4 - +
M JJA 2009 MAM     2010 1.3 N + JJA  2010 MAM 2011 -1.3 + +
            JAS 2011 JFM  2012 -0.9 - +
T MAM 2015 AMJ     2016 2.3 + N  JAS 2016 NDJ  2016 -0.8*  + +

 

*The GEI Weather and Climate Report does not accept this as a legitimate La Nina. It is not unusual for different Meteorological Agencies to maintain different lists of El Ninos and La Ninas. This is usually because the criteria for classification differ slightly. Obviously the GEI Weather and Climate Report has no standing but nevertheless for any analysis we do, we will either not include or asterisk this La Nina to indicate that NOAA  has it on their list and we consider that to be Fake News. The alternative is to conclude that the other Meteorological Agencies are not able to measuring things correctly. .

ONI Recent History

ONI History Updated on July 10, 2017

The Apr/May/Jun preliminary was reported as +0.5. This means that we would still need four consecutive values of +0.5 or greater for this to be an El Nino and that is not going to happen. The full history of the ONI readings can be found here. The MEI index readings can be found here.

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

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