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posted on 07 August 2017

August 7, 2017 Weather and Climate Report - Short Monsoon Break - East Cool

Written by Sig Silber

The forecast is for a short (perhaps one week or less) break in the Southwest Monsoon especially as it impacts Arizona and Southern California. NOAA adopts new color coding which complicates knowing when their forecast was off because it is now harder to interpret the forecast maps. Very clever! Death Valley sets World Temperature Record. PDO turns negative. NOAA "adjusts" ONI values that were prepping for an El Nino call. Wavenumber - 5 suggests rapid changes.


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The Seasonal Outlook Update Report was published on Saturday July 22 and can be accessed here. 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.

NOAA  "Adjusts" the ONI Record.

August 7, 2017 ONI Record.

Not only has NOAA released a Neutral MJJ value for the ONI, they went back and changed the AMJ ONI value to 0.4 from 0.5. We have been steadfast at challenging both the prediction of an El Nino for this winter and the actual reporting by NOAA of the surface anomalies in the Equatorial Pacific. It is not a crime to adjust data values as the analysis of data proceeds but it does raise questions.

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 a West/East divide re temperature with the southern border agreeing to some extent with the West and for precipitation a North/South divide but the wet anomaly is far larger than the dry/Normal anomaly. It is pretty much the same as last week except for the extreme Southwest. 

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 August 7, 2017, as I am looking at the above graphic, I see the Sonoran Monsoon having retreated away from the U.S. Border but a lot of moisture moving up the Gulf Coast.

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 further south than one expect this time of the year.

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 see Tropical Storm Franklin moving into the Gulf of Mexico from the Caribbean and indirectly impacting the Gulf Coast and the Southeast. .

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

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 tropical events are expected to impact CONUS. If that changes, we will provide an update. Franklin may in two weeks reinvigorate the Southwest Monsoon.

Tropical Storm Franklin

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 looks like a Winter Pattern. 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 (about to move into Canada) having a  surface central pressure of 1000 hPa. There is a trailing low with surface central pressure of 1000 hPa. NOAA appears to interpret this differently as described in the discussion they released to day which is shown later in this report.
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 and has a surface central pressure of 1024 hPa. Remember this is the Day 6 pattern not the current pattern. Also notice that this is not the usual the summer position of that semipermanent High. Moisture entering from the Pacific related to the Polar Jet Stream is now able to enter CONUS in the Northwest. It is also a pattern that will tend to suppress the Southwest Monsoon.
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. You can see it is further south than usual for this time of the year. Remember this is a H3 view meaning a view at 30,000 feet which is about six miles high.
If you look closely you can attempt to see the Four Corners high. But you may have to look for it in Mexico or Texas as it is not in its usual location. Look for wind vectors that indicate clockwise motion.

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 (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.

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 lot of moisture East of the Rocky Mountains and tending to be south rather than north. Six inches of precipitation in seven days can create flooding problems.

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 a Great Lakes trough, another trough setting up for the West a Rocky Mountain Ridge and an AWOL Four Corners High which may be along the Rio Grande border of Texas and Mexico. Oops. That was before my trip to Subway to do final editing. Now I see a High in the Gulf of Mexico. Is that the wayward Four Corners High?
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.

Small 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 August 7, 2017 was 4 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 August 7, 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 August 7, 2017

August 13 to August 21 August 19 to September 1

Days 6 - 10: Most of CONUS West plus Southern Florida and South Texas is warm. To the east and north it is cool and even farther to the east it is Neutral.  Alaska is mostly cool with the Aleutians and the Panhandle warm.

For CONUS, the Northwest and South Central are cool and Southern Florida and the Great Lakes/Northeast is warm. Most of Alaska is cool..

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.

Week 2:  As the period evolves, the cool anomaly moderates and shifts to the east and south a bit.
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.

August Temperature Outlook Updated on July 31, 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.

ASO 2017 Temperature Outlook Issued on July 20, 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 August 7, 2017 was 4 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 August 7, 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 August 7, 2017

August 13 to August 21  August 19 to September 1, 2017

Days 6 -10: Generally for CONUS it is wet in the Northwest and dry in the Monsoon States especially west of the Continental Divide The center which corresponds roughly with the area projected to be cool is projected to be wet. Alaska is wet but neutral to the west and the Aleutians.

For CONUS, the Northwest is dry. A wet anomaly extends from Texas to Virginia but does not include Florida.  Northern Alaska is dry possibly connected to the same weather pattern forecast to have CONUS Northwest dry.

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.

Week 2: For CONUS, there is not much change but the large wet anomaly moderates and moves to the east. Western Alaska but not the Aleutians also becomes wet.

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.

August 2017 Precipitation Updated on July 31, 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.

ASO 2017 Precipitation Outlook Issued on July 15, 2017

Here is the NOAA discussion released today August 7. 2017

6-10 DAY OUTLOOK FOR AUG 13 - 17 2017  

TODAY'S DYNAMICAL MODELS ARE IN FAIRLY GOOD AGREEMENT ON THE PREDICTED MID-TROPOSPHERIC FLOW PATTERN ACROSS THE FORECAST DOMAIN. A ZONAL WAVE NUMBER-5 PATTERN IS EXPECTED OVER THE MIDDLE AND HIGH LATITUDES OF THE NORTHERN HEMISPHERE, WHICH REPRESENTS A CONSIDERABLE AMOUNT OF SHORTER-WAVELENGTH ACTIVITY. THIS, IN TURN, FAVORS MORE UNCERTAINTY IN THE TIMING OF INDIVIDUAL SHORTWAVE FEATURES EMBEDDED WITHIN THE MEAN FLOW. THE MANUAL 500-HPA HEIGHT BLEND DEPICTS A MEAN TROUGH OVER ALASKA, AND A RIDGE OVER THE EAST-CENTRAL PACIFIC. WHERE THESE TWO FEATURES MEET OVER THE GULF OF ALASKA, THERE IS AN ENHANCED HEIGHT GRADIENT, AND ENHANCED WESTERLY FLOW ALOFT. THIS TROUGH IS APPARENTLY FORCED TO SPLIT INTO TWO TROUGHS, ONE ON EITHER SIDE OF THE RIDGE, WHICH HELPS CONTRIBUTE TO THE HIGHER ZONAL WAVENUMBER MENTIONED ABOVE.  [Editor's note: I am not a meteorologist but I read the maps differently and do not see what NOAA is reporting.  But to a large extent it matters not if we have a split trough or if there were two troughs from the get-go which is what I have seen looking at the relevant graphics each day this week]. NORTH AMERICA IS ANTICIPATED TO BE UNDER A TROUGH-RIDGE-TROUGH PATTERN, WITH CONSIDERABLE AMPLITUDE. POSITIVE HEIGHT ANOMALIES IN EXCESS OF +180 METERS ARE FORECAST IN THE VICINITY OF NORTHERN HUDSON BAY. THE ECMWF ENSEMBLE MEAN CONTINUES TO OUTSCORE THE OTHER DYNAMICAL MODELS, AND WAS THEREFORE GIVEN THE HIGHEST WEIGHT IN THE MANUAL HEIGHT BLEND. THE VARIOUS SPAGHETTI MAPS (5820 METER LEVEL) DEPICT LOW SPREAD WITH REGARD TO THE PREDICTED TROUGHS OVER THE WESTERN AND EASTERN THIRDS OF NORTH AMERICA, THOUGH MODERATE TO HIGH SPREAD IS PREDICTED WITH REGARD TO THE EXPECTED RIDGE OVER CENTRAL NORTH AMERICA.  

ODDS OF BELOW NORMAL TEMPERATURES ARE ELEVATED OVER MOST OF ALASKA, AND FROM APPROXIMATELY THE CENTRAL AND SOUTHERN ROCKIES EASTWARD TO THE APPALACHIANS. THIS IS GENERALLY DUE TO THE FORECAST PROXIMITY OF 500-HPA TROUGHS AND NEAR TO BELOW NORMAL HEIGHTS. ABOVE NORMAL TEMPERATURES ARE FAVORED FROM THE NORTHERN ROCKIES SOUTHWESTWARD ACROSS CALIFORNIA, SOUTHERN TEXAS, FLORIDA AND THE IMMEDIATE SOUTHERN ATLANTIC COAST, COASTAL NEW ENGLAND, THE SOUTHERN ALASKA PANHANDLE, AND THE ALEUTIANS. THIS IS GENERALLY ATTRIBUTED TO NEAR OR MODESTLY ABOVE NORMAL HEIGHTS NEAR AND TO THE SOUTH OF PREDICTED BAROCLINIC ZONES, AND/OR RELATIVELY WARM SEA-SURFACE TEMPERATURES.

ODDS OF BELOW NORMAL PRECIPITATION ARE FAVORED OVER THE WESTERN AND CENTRAL GREAT LAKES REGION, IN THE SUBSIDENCE REGION WEST OF A TROUGH AXIS. ABOVE NORMAL PRECIPITATION IS FAVORED OVER MOST OF THE CONUS, AND ALL BUT SOUTHWESTERN PORTIONS OF ALASKA. THIS IS ATTRIBUTED PRIMARILY TO MOIST FLOW IN ADVANCE OF MID-LEVEL TROUGHS, AND THE PROXIMITY OF BAROCLINIC ZONES.

FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO FAIRLY GOOD MODEL AGREEMENT, OFFSET SOMEWHAT BY THE INCREASED ZONAL WAVENUMBER AND THE SPREAD MAPS.  

8-14 DAY OUTLOOK FOR AUG 15 - 21 2017 

TODAY'S ENSEMBLE MEAN SOLUTIONS FOR WEEK-2 ARE IN REASONABLE AGREEMENT, AND SHOW GOOD CONTINUITY WITH THE 6-10 DAY PERIOD. MOST MODEL RUNS PREDICT A DEAMPLIFIED FLOW PATTERN ACROSS THE FORECAST DOMAIN, WITH THE EXCEPTION OF THE LAST 3 RUNS OF THE DETERMINISTIC GFS (0Z, 6Z, AND 12Z), WHICH CONTINUE TO FORECAST A HIGH-AMPLITUDE FLOW PATTERN.  

THE PREDICTED WEEK-2 TEMPERATURE OUTLOOK DEPICTS A COOLER SOLUTION (THAN THE 6-10 DAY TEMPERATURE OUTLOOK) ACROSS MUCH OF THE NORTHWESTERN QUARTER OF THE CONUS, AS A TROUGH IS EXPECTED TO PUSH ACROSS THAT REGION. SOME WARMING IS ALSO INDICATED ACROSS THE FAR NORTHERN BORDER STATES, EAST OF THE CONTINENTAL DIVIDE. THIS IS CONSISTENT WITH CPC'S TEMPERATURE CONSOLIDATION FORECAST, AND THE AUTO-BLEND TEMPERATURE FORECAST. THE WEEK-2 PRECIPITATION OUTLOOK ALSO DIFFERS FROM ITS 6-10 DAY COUNTERPART IN SEVERAL WAYS. THE FAVORED AREA OF BELOW NORMAL PRECIPITATION OVER THE GREAT LAKES IN THE 6-10 DAY PERIOD BECOMES MORE UNCERTAIN DURING WEEK-2, WARRANTING A FORECAST OF NEAR NORMAL PRECIPITATION. THE HIGHER PROBABILITIES FOR ABOVE NORMAL PRECIPITATION FROM THE CENTRAL AND SOUTHERN PLAINS ACROSS THE LOWER MISSISSIPPI VALLEY HAVE BEEN REDUCED CONSIDERABLY DUE TO INCREASED DIFFERENCES IN MODEL GUIDANCE.

FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: NEAR AVERAGE, 3 OUT OF 5, DUE TO REASONABLE MODEL AGREEMENT AND CONTINUITY WITH THE 6-10 DAY OUTLOOK.

THE NEXT SET OF LONG-LEAD MONTHLY AND SEASONAL OUTLOOKS WILL BE RELEASED ON  AUGUST 17

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 28, 1962 Neutral - +  
Jul 31, 1974 La Nina - (t) -  
Aug 1, 1977 Neutral +(t) -  
Aug 2, 1977 Neutral +(t) -  
Aug 11, 1977 Neutral +(t) -  
Aug 12, 1977 Neutral +(t) -  
Aug 7, 1981 Neutral + -  
Aug 2, 1993 La Nina + -  
Aug 5, 2009 Neutral +(t) +  

(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 July 28 to August 12 which is only 15 days which is very tight set of analogs. 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 August 4. These analogs are centered on 3 days and 4 days ago (August 3 or August 4). 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 seven ENSO Neutral Analogs and two La Nina analogs. The phases of the ocean cycles of the analogs are most consistent with McCabe A which is the wet scenario for the Southwest and Great Lakes area and to the east. Thus I am less confident than NOAA about their 6 - 14 day outlook.

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 29, 2017

July 29, 2017 30 Day Temperature and Precipitation Departures

Fairly similar to the report from the prior week with a bit less drought in the Northwest. 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 August 5, 2017

Augustt 7, 2017 30 Day Temperature and Precipitation Departures

The Eastern half of CONUS has cooled down. Southern West Coast has been less dry. 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 into August so we are more than 1/6 between the set of positions shown above for July and the ones shown for January. For CONUS the seasonal repositioning of the Bermuda High and the Pacific High are very significant. Notice the Summer position of the Pacific High.

Forecast for Today

Temperature at 2 Meters

Notice that below the map there is a tabulation of magnitude of the current anomalies by region. Notice the cool CONUS Northeast. Same story from North Africa to Eastern Siberia i.e. warmer than climatology.

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). Much of Europe is wet. South America south of the ITCZ is dry. Africa south of the Equator and the ITCZ is dry. And CONUS West 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

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 but this week the Pacific is more complex than last week. The Low in the Gulf of Alaska CHANGES EVERYTHING. The westward extension of the Bermuda High is less impressive and probably will have less impact on CONUS Southern Tier weather both the Southeast directly and the Southwest Monsoon indirectly. You can see the Arctic storm and the storms bordering Antarctica.

Looking Out a Few Months

Here is the precipitation forecast from Queensland Australia:

Rising SOI  forecast for August to October 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 falling SOI to a rising SOI. It is more like a La Nina forecast than a El Nino forecast. CONUS looks pretty dry, Europe pretty wet. India wet, Australia 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.

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, Caspian and Mediterranean Seas are very warm as is the Persian Gulf.

Warm.

Warm south of Mainland Alaska

Warm off Baja and in Sea of Cortez

.

Warm off Nova Scotia.

Western Gulf of Mexico slightly warm

Hudson Bay very warm

Warm
The Tropical Pacific

Cool east of 140 W. Cool around Maritime Continent. Neutral elsewhere.

Africa West of Australia North, South and East of Australia

West of South America

East of South America

Mostly Neutral. Cool to the west south of 10S

Neutral Warm to the east. Cool to the south and southwest Cool off Peru and Ecuador Warm 30S to 40S. Slightly cool off 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.

August 7, 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

Black Sea, Caspian Sea, Mediterranean are cooling.  So they are warm but becoming less warm.

Overall intense warming.

Below the warming area there is at about 30N and west of the Dateline and area that is cooling.

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

Cooling offshore of the Northwest and extending beyond 150W

Warming around Nova Scotia.

Warming in Western Antilles.

Slight warming.
The Tropical Pacific Cooling to the West. Warming to the east. Cooling in the Center where Nino 3.4 is measured.
Africa West of Australia North, South and East of Australia West of South America East of South America
Fairly stable to the west, warming in the East to and beyond Madagascar

Warming to the  northwest, cooling to the southwest

Cooling to the southeast.

Stable .

Warming off of 30S

 

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 +0.30 +0.32 +0.2
June +0.19 +0.31  0.0
July -0.41    0.0 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 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 August 7 for what is shown as Week Two, the period August 9 to August 15, 2017 we see wet conditions* over a small part of the Maritime Continent, in Africa just north of the Equator and the U.S. Southeast north of Florida. We see dry conditions* impacting most of India.
* 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 but not south as I had anticipated but to the north. Most like soon it will be totally 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 also 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)

LAND

LAND

0

0

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

175E

160W

25

10

0C or cooler Anomaly (coolish neutral)

160W

120W

40

40

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

120W

LAND

25

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 August 7, in the afternoon working from the August 6 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 +0.3 +0.3
B. 160W to 150W +0.3 +0.3
C. 150W to 140W +0.2 +0.3
D. 140W to 130W +0.1 +0.2
E. 130W to 120W -0.3 +0.1
Total +0.6 +1.2
Total divided by five i.e. the Daily Nino 3.4 Index (+0.6)/5 = +0.1 (+1.2)/5= +0.2

 

My estimate of the daily Nino 3.4 SST anomaly tonight is +0.2 which is an ENSO Neutral Value.  NOAA has also reported the weekly Nino 3.4 to be +0.2 which is an ENSO Neutral value but higher than last week which ended a fairly long string of weekly values +0.5 or higher. We did not believe that the value reported last week was correct. But small differences (one tenth of a degree) make very difference.
Nino 4.0 is reported the same as last week at +0.2. Nino 3 is the same at +0.1. Nino 1 + 2 which extends from the Equator south rather than being centered on the Equator is reported a bit lower at -0.I. 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. Most likely it will be negative for a while.
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 and this week dramatically. The same data in table form but going back a couple of more years can be found here.

August 7, 2017 Nino Readings

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. 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.

August 7, 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. One now sees a cool area at 150W and the cool area at 120W seems to be shifting to the west into the Nino 3.4 Measurement  Area so the Nino 3.4 Index is likely to turn negative but still remain in the neutral range.
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. The bottom sentence in the legend to the left of the graphic proper says it all.

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.

August 7, 2017 Upper Ocean Heat Anoma

The bottom of the Hovmoeller shows the current situation. The 2016 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 was a warm area shown between 145W and 130W which created the marginal El Nino values of the Nino 3.4 Index. It is no longer showing. We also see to the far left a white area and more white to the right of that. That needs to be brown or red for there to be an El Nino. No El Nino!  We even see a spot of blue which could be an Upwelling phase of the prior April/May Kelvin Wave. It is not very significant but should start showing up.

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). 

.August 7, 2017 Kelvin Wave Analysis.

We now have very little warm water near the surface. There is another graphic that shows it better. There is not enough cool water at depth to fully flip the situation to La Nina other for a month or so which is not long enough to be a La Nina but simply to create La Nina conditions for a month or two. But we will be on the cool side of Neutral with nothing to the west suggesting any change in the near term.

Now for a more detailed look (there is some redundancy with the above graphic). Notice by the date of the graphic (dated August 1, 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. Almost the entire surface of the Equatorial Pacific has a surface temperature consistent with ENSO Neutral. Subsurface Temperature Anomalies: There is a lot of cool water below 50 meters but not enough to cause a La Nina.. 
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 170W. 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 130W. What we have is ENSO Neutral but almost La Nina.
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 La Nina and ENSO Neutral.
The conditions to create an El Nino simply do not exist. The conditions to create a sustainable La Nina also do not appear to 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 August 6 was reported as +5.90 which is an ENSO Neutral value with a cool bias i.e. close to a La Nina value. The 90 Day Average was reported at +0.40 which is 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. Now the 30 day average is actually positive i.e. in the direction of a La Nina but still in the Neutral Range.

 

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

The newly issued on July 19 CPC/IRI  fully model-based report is shown on the right. The earlier July 13 IRI/CPC Meteorologist survey is shown on the left.

July 20. 2017 CPC/IRI Update two graphics side by side.

There is not much difference between the two.

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. Notice since mid-July the collapse of Nino 3.4 values from the range of 0.5C to 0.5C down to near Zero C but rebounding just a bit.

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 30, 2017

Tropical Pacific remains ENSO-neutral

The 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 have cooled over the past fortnight, but remain slightly warmer than average, and well within the neutral range. The 30-day Southern Oscillation Index (SOI) has been somewhat volatile over the past two months, but remains neutral. Other indicators

Here is the JAMSTEC June 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 30, 2017

The Indian Ocean Dipole (IOD) is neutral. The weekly index value to 30 July was +0.1 °C.  Four out of six climate models used by the Bureau predict the IOD will remain neutral for winter–spring of ENSO, such as cloudiness near the Date Line and trade winds also remain at neutral levels.

Two of the six climate models suggest positive IOD thresholds could be reached in the coming months but only one model maintains these values 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 was an El Nino in the winter of 2017/2018 this could signify that the PDO had entered its Positive Phase. But it seems unlikely that there will be an El Nino this winter.  So what does that mean? 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. 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.

E. Relevant Recent Articles and Reports

Weather in the News

Nothing to Report.

Weather Research in the News

Wavenumber - 5 and West Coast Winter Drought (Seems NOAA is fascinated by this even though the research applies to winters).

Global Warming in the News

Death Valley Sets World Monthly Temperature Record

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 August 7, 2017

The Apr/May/Jun preliminary was reported as +0.5. and now "adjusted" to 0.4. May/June/July has just been released at 0.3. This means that the NOAA El Nino watch is over. 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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