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posted on 22 August 2016

August 22, 2016 Weather and Climate Report - NOAA Updates Seasonal Outlook

Written by Sig Silber

 NOAA has released their Seasonal Update which comes out every third Thursday i.e. August 18.  It is surprisingly identical to the Seasonal Outlook issued a month ago. How does one get a job like that? It is a bit surprising given the downgrading of La Nina probabilities.  Click to read: "Pattern Change to Bring a Taste of September this Weekend"   "Here" is a video version of similar information.

 weather.caption

NOAA's 6 to 14 Day Outlook today is rated by them as having a 3 out of 5 level of confidence. I do not see it that way. Basically NOAA when establishing their level of confidence in a forecast puts a lot of weight on the spread of the forecasts among different forecasting tools. If the spread is tight, that to NOAA implies that they should have a high level of confidence in the forecast. In math that would be a necessary but not sufficient criteria. The forecasts changed dramatically over the weekend and the analogs with the conditions prevailing and presumably used to initialize the models correspond to two of the four most powerful El Nino's in modern history. So I do not have a 3 out of 5 level of confidence in the 6 to 14 Day Outlook issued today. That does not mean that these forecasts will not turn out to be valid.

Progress of the Southwest Monsoon

I found this statement from Thursday's 1:47 pm Phoenix NWS discussion interesting.

this set-up is more characteristic of post-Monsoon season synoptic patterns and even 500mb temperatures this morning were observed with readings more typical of October.

This statement for their Sunday 9:08 am discussion is also of interest:

However, this pattern will be undergoing subtle changes   the next 36 hours as shortwave energy and a more pronounced jet streak consolidate west of the srn California coast and ejects  eastward by Tuesday. This will keep the SW Conus is a W/NW flow  pattern for the entire week completely contradictory to the traditional monsoon. 

This does not mean that all of a sudden we are doing to have Fall weather. It does mean that there are signs of a change in pattern. The angle of incidence of the sun's rays are the same as every year (the changes from year to year are very slow: See Milankovitch Cycles). But the location of the Jet stream and some other important weather features are more consistent with later dates than the current date. It might be temporary or it might be that Fall will come early. Given the La Nina-ish nature of the ENSO Cycle right now, this should not be considered a big surprise.

Some may find this Monsoon Tracker useful. There are a choice of cities that  you can refer to and get the average and current precipitation by month for this Monsoon Season and historically back to 1892. It clearly shows that some locations depend on the summer Monsoon more than other locations. The data for August seems to be updated daily or at least very frequently.

Updated Seasonal Outlook

NOAA issued their updated Seasonal Outlook on the third Thursday of the month i.e. August 18, 2016 as is their normal schedule. Let's take a look.

Prior Temperature Outlook for SON 2016

SON 2016 Temperature Outlook Issued July 21, 2016

New Temperature Outlook for SON 2016

SON 2016 Temperature Outlook Issued on August 18, 2016

Mostly a slight reduction in probabilities of the warm anomaly in Montana and North Dakota. 

Prior Precipitation Outlook for SON 2016

SON Precipitation Outlook Issued on July 21, 2016

New Precipitation Outlook for SON 2016

SON 2016 Precipitation Outlook issued August 18, 2016

There is not much change. There were four CONUS anomalies shown last month for the SON three-month period. Now (and it is a month later with respect to the amount of information that NOAA has) the four anomalies have moved around just a bit and the small Northwest wet anomaly is gone. With respect to Alaska (which is not part of CONUS), the wet anomaly has shrunk and only shows up for the Alaskan Panhandle. This is not a big change.

Now let us focus on the long-term situation.

Prior 14 Month Temperature Outlook: Sep 2016 - Oct 2017

July 21, 2016 14 Month Temperature Outlook Sep 2016 - October 2017

New 14 Month Temperature Outlook: Oct 2016 - Nov 2017

14 Month Temperature Issued August 18, 2016

To compare maps from one release to another one needs to remember that the new release drops one three-month period and adds a later one. So to make the comparisons one has to shift the new maps to the right one position and that makes the map on the right drop down to become the left-most map in the next level. I do not have a computer software tool for doing that for you so you have to do it mentally. When I do the comparison I print them out and put them side by side and number the same three-month maps 1, 2, 3,.....,11 in both sets of maps to make it easier for me to easily compare the same three-month period in the new with the previous forecast. One uses the same procedure to compare the precipitation maps. Based on this procedure, I conclude that:

The changes are almost non-existent. There is a smaller EC area shown for JAS 2017. Big Deal!!!

Prior 14 Month Precipitation Outlook: Sep 2016 - Oct 2017

July 21, 2016 14 month Precipitation Outlook Sep 2016 - Oct 2017

New 14 Month Precipitation Outlook: Oct 2016 - Nov 2017

14 Month Temperature Outlook Issued on August 18, 2016

The precipitation changes are essentially non-existent. 

If you want larger versions of each map (temperature and precipitation) you can find them here. And each of those maps can be clicked on to further enlarge them.

Excerpts (significantly reorganized and with some of the redundancy removed) from the Discussion released by NOAA on August 18, 2016. Headings that are "Initial Cap" only rather than all caps were added by the Author of this Weekly Report for clarity. Also we have organized the sequence of the sections of NOAA Discussion to first present the Atmospheric Conditions and then the Current Month, the Three or Four-month period, and finally the remainder of the 15 Month Forecast. We think that sequence with the three- to four-month period broken out separately, makes the discussion more useful for more readers.

CURRENT ATMOSPHERIC AND OCEANIC CONDITIONS

PACIFIC SST ANOMALIES ARE MOSTLY 1-2 DEGREES C BELOW AVERAGE CLOSE TO THE EQUATOR FROM ABOUT 170W EASTWARD TO 100W, WHILE ABOVE AVERAGE SSTS PREVAIL FROM ABOUT 170E TO THE MARITIME CONTINENT. THE MOST RECENT THREE-MONTH AVERAGE NINO 3.4 SST ANOMALY IS +0.18 DEGREE C FOR MJJ. [Editor's Note: This indicated that the El Nino had ended]. THE LATEST WEEKLY NINO 3.4 ANOMALY HAS NOW DECREASED TO -0.5 DEGREE C. A LARGE RESERVOIR OF ANOMALOUSLY COOL SUBSURFACE WATERS EXTENDS TO MORE THAN 150 METERS BELOW THE SURFACE, WITH THE LARGEST NEGATIVE ANOMALIES 3-4 DEGREES C BELOW AVERAGE AT A DEPTH OF ABOUT 125 METERS, BETWEEN 140W-160W. POSITIVE OLR ANOMALIES (SUPPRESSED CONVECTION) WERE PRESENT OVER THE EQUATORIAL PACIFIC, WHILE NEGATIVE OLR ANOMALIES (ENHANCED CONVECTION) IS PRESENT OVER INDONESIA, DURING THE PAST 30-DAYS. LOW-LEVEL, EASTERLY TRADE WINDS AT THE 850-HPA LEVEL HAVE BEEN NEAR AVERAGE DURING THE PAST MONTH, WHILE THE UPPER-LEVEL, 200-HPA WINDS ARE ANOMALOUSLY WESTERLY OVER THE EQUATORIAL PACIFIC FROM THE DATE LINE EASTWARD TO 150W. ANOMALOUS INTEGRATED EQUATORIAL PACIFIC OCEAN HEAT CONTENT FROM THE SURFACE TO 300 METERS DEPTH HAS BEEN PERSISTENTLY NEGATIVE FOR THE LAST SEVERAL MONTHS. NEGATIVE OCEAN HEAT CONTENT ANOMALIES INCREASE THE CHANCE OF DEVELOPMENT OF LA NINA CONDITIONS DURING THE REMAINDER OF 2016. THE EXTRATROPICAL PACIFIC OCEAN REMAINS CONSISTENT WITH THE POSITIVE PHASE OF THE PACIFIC DECADAL OSCILLATION (PDO) WITH ABOVE AVERAGE SSTS IN THE NORTH PACIFIC, AND TO THE SOUTH OF ALASKA, AND ALONG THE COAST OF SOUTHERN CALIFORNIA. POSITIVE SST ANOMALIES PERSIST IN THE WESTERN ATLANTIC NEAR THE U.S. EAST COAST, AND THE THE GULF OF MEXICO.

DURING THE FIRST HALF OF AUGUST, ABOVE AVERAGE CONVECTION HAS DEVELOPED OVER THE WESTERN PACIFIC, WITH MULTIPLE TROPICAL CYCLONES FORMING. MOST MJO INDICES HAVE AMPLIFIED IN A DIRECTION INDICATING ENHANCED CONVECTION OVER THE WESTERN PACIFIC. GOING FORWARD, MOST MODELS CONTINUE TO INDICATE CONVECTION OVER THE WESTERN PACIFIC, WHICH COULD HAVE A DOWNSTREAM IMPACT ON THE CIRCULATION OVER NORTH AMERICA, ALTHOUGH THAT CONNECTION IS MORE ROBUST LATER IN THE MONTH BECAUSE OF THE DYNAMICS OF THE SEASONAL PROGRESSION OF THE EAST ASIAN JET STREAM. DYNAMICAL MODELS ARE LIKELY THE BEST TOOLS TO CAPTURE THIS POTENTIAL IMPACT. THEREFORE, THE OUTLOOKS RELY PRIMARILY UPON THE LATEST DYNAMICAL MODEL GUIDANCE FROM THE NCEP CLIMATE FORECAST SYSTEM (CFS), THE NORTH AMERICAN MULTI-MODEL ENSEMBLE (NMME), THE INTERNATIONAL MULTI-MODEL ENSEMBLE (IMME), AND MODEL GUIDANCE FOR WEEKS 3 AND 4 FROM THE CFS, JAPAN METEOROLOGICAL AGENCY (JMA), AND ECMWF, WITH LESSER INPUTS FROM TOOLS BASED ON CURRENT SOIL MOISTURE CONDITIONS.

PROGNOSTIC DISCUSSION OF SST FORECASTS

THE CPC SST CONSOLIDATION PREDICTS A WEAK LA NINA BEGINNING IN ASO 2016 AND CONTINUING THROUGHOUT THE AUTUMN AND MUCH OF WINTER, WITH A PEAK AMPLITUDE IN SST ANOMALY OF -0.7 DEGREE C BELOW AVERAGE DURING THE DJF 2016-17 SEASON. PREDICTIONS FROM THE NORTH AMERICAN MULTI-MODEL ENSEMBLE (NMME) MEMBERS INDICATE A RANGE OF NINO 3.4 ANOMALIES, WITH THE ENSEMBLE MEAN NEAR -0.5 C FROM AUGUST THROUGH DECEMBER. THE CPC/IRI CONSENSUS FORECAST INDICATES LA NINA IS SLIGHTLY FAVORED TO DEVELOP DURING ASO 2016, WITH ABOUT A 55-60 PERCENT CHANCE OF LA NINA DURING THE AUTUMN AND WINTER 2016-17.

30-DAY OUTLOOK DISCUSSION FOR SEPTEMBER 2016

THE SEPTEMBER 2016 TEMPERATURE AND PRECIPITATION OUTLOOKS ARE BASED ON DYNAMICAL MODEL GUIDANCE AND, TO A LESSER EXTENT, STATISTICAL TOOLS. THE IMPACT OF CURRENT SOIL MOISTURE CONDITIONS ON THE TEMPERATURES DURING THE FOLLOWING MONTH BEGINS TO WANE IN THE AUTUMN, BUT THERE IS STILL A RESPECTABLE CORRELATION OVER THE SOUTHERN GREAT PLAINS BETWEEN AUGUST SOIL MOISTURE AND SEPTEMBER TEMPERATURES. ENSO IS NOW IN NEUTRAL PHASE.

Temperature

MOST DYNAMICAL MODELS FROM THE NMME SUITE INDICATE GENERALLY ABOVE AVERAGE TEMPERATURES FOR SEPTEMBER 2016. ANY AREAS WHERE NEAR OR BELOW AVERAGE CONDITIONS ARE INDICATED ARE OVER THE CENTRAL PORTIONS OF THE CONUS. CURRENTLY HIGH SOIL MOISTURE OVER THE SOUTHERN GREAT PLAINS WOULD FAVOR NEAR TO BELOW AVERAGE TEMPERATURES OVER THAT REGION, WHILE UNCERTAINTY AMONG THE MODELS (NMME AND IMME) PROHIBITS THE DEPICTION OF A SIGNAL FROM THE NORTHERN GREAT PLAINS TO THE GREAT LAKES REGION. MORE AGREEMENT RETURNS OVER THE NORTHEAST, WHERE TOOLS INDICATE ABOVE AVERAGE TEMPERATURES ARE FAVORED, AND OVER THE WESTERN CONUS FROM THE ROCKIES TO THE WEST COAST, WHERE MODELS AND TRENDS FAVOR ABOVE AVERAGE TEMPERATURES. SSTS 1.5-3.5 DEGREES C ABOVE AVERAGE IN THE VICINITY OF ALASKA FAVOR ABOVE AVERAGE TEMPERATURES FOR SOUTHERN AND WESTERN ALASKA, WHILE TRENDS FAVOR ABOVE AVERAGE TEMPERATURES FOR THE NORTH SLOPE.

Precipitation

THE PRECIPITATION OUTLOOK FOR SEPTEMBER CONTAINS A HIGH AMOUNT OF UNCERTAINTY. MODEL SIGNALS ARE SPARSE IN COVERAGE, AND WEAK EVEN WHERE SIGNALS PASS THROUGH THE CALIBRATION METHODS. TRENDS FAVOR BELOW AVERAGE PRECIPITATION OVER THE SOUTHWEST WHILE MOST MODELS IN THE NMME SUITE FAVOR ABOVE AVERAGE PRECIPITATION. THE OFFICIAL OUTLOOK FAVORS ABOVE AVERAGE PRECIPITATION, BUT OVER A SMALLER AREA THAN WHAT THE DYNAMICAL MODELS INDICATE TO ACCOUNT FOR THE UNCERTAINTY RAISED BY CONFLICTING GUIDANCE. OVER THE NORTHERN GREAT PLAINS, ABOUT HALF OF THE MODELS DEPICT ABOVE AVERAGE PRECIPITATION AND TRENDS FROM THE SEASONAL OPTIMAL CLIMATE NORMALS HAVE LITTLE TO NO SIGNAL, SO NO SIGNAL IS DEPICTED. TRENDS AND MODELS DEPICT BELOW AVERAGE PRECIPITATION FOR THE NORTHWEST AND FROM THE SOUTHERN GREAT PLAINS TO THE SOUTHEAST. MODEL FORECASTS SUPPORT ABOVE AVERAGE PRECIPITATION FOR SOUTHERN ALASKA, ALTHOUGH THEY VARY IN WHERE THE HIGHEST AMOUNTS ARE LIKELY TO OCCUR, SO THE OFFICIAL FORECAST COVERS ALL OF THE AREAS WHERE THE NMME MODELS FAVOR ABOVE AVERAGE PRECIPITATION. [Editors Note: I think they are saying that the actual precipitation might exceed the forecast].

Three-Month Outlook (September – October – November

Temperature

THE TEMPERATURE OUTLOOK FOR SON 2016 IS SIMILAR TO THE OUTLOOK MADE LAST MONTH FOR THE SAME TARGET PERIOD. ABOVE NORMAL MEAN TEMPERATURES ARE FAVORED ACROSS THE ENTIRE CONTIGUOUS UNITED STATES AND ALASKA. THE GREATEST PROBABILITIES FOR THE CONUS INCLUDE THE SOUTHWESTERN STATES (IN EXCESS OF 60 PERCENT), THE GULF COAST ENVIRONS AND FROM THE EASTERN GREAT LAKES TO THE NORTHERN ATLANTIC COAST (IN EXCESS OF 50 PERCENT). THESE AREAS ARE BASED ON THE LATEST AVAILABLE CLIMATE MODELS, SUCH AS THE CALIBRATED PROBABILITIES FROM THE NATIONAL MULTI-MODEL ENSEMBLE (PAC), IMME, CFS, CANADIAN MODELS, AND ON HISTORICAL TRENDS. A BROAD AREA OF SLIGHTLY ENHANCED PROBABILITIES FOR ABOVE NORMAL TEMPERATURES (33-40 PERCENT) IS INDICATED FROM THE FAR NORTHERN ROCKIES EASTWARD TO THE UPPER MISSISSIPPI VALLEY. THIS REPRESENTS THE EARLY EFFECTS OF A DEVELOPING WEAK LA NINA. FOR ALASKA, THE GREATEST PROBABILITIES OF ABOVE NORMAL TEMPERATURES INCLUDE THE SOUTHERN THIRD OF THE STATE (IN EXCESS OF 60 PERCENT), AND THE NORTHERN THIRD OF ALASKA (GREATER THAN 70 PERCENT).  THIS IS LARGELY DUE TO WARMING TRENDS OVER THE PAST FEW DECADES AND THE ASSOCIATED DELAYED ONSET OF SEA ICE FORMATION (AND REDUCED COVERAGE OF MULTI-YEAR ICE) ACROSS THE NEARBY ARCTIC OCEAN.

Precipitation

THE SON 2016 PRECIPITATION OUTLOOK INDICATES INCREASED PROBABILITIES OF ABOVE-MEDIAN PRECIPITATION ACROSS THE NORTHERN GREAT PLAINS AND ALASKA PANHANDLE, BASED PRIMARILY ON AVAILABLE CLIMATE MODEL GUIDANCE. BELOW-MEDIAN PRECIPITATION IS FAVORED IN NEVADA AND ADJACENT PARTS OF CALIFORNIA, AS WELL AS OVER THE LOWER MISSISSIPPI VALLEY, THE INTERIOR SOUTHEAST, TENNESSEE, THE SOUTHERN APPALACHIANS, AND MUCH OF KENTUCKY. THIS IS BASED ON MODEL GUIDANCE, AND ON HISTORICAL PRECIPITATION TRENDS FOR THE SON SEASON.

Longer Term Outlook October 2016 Through November 2017

THE PREDICTED TRANSITION TO LA NINA CONDITIONS AND THE MOST LIKELY IMPACTS ARE CONSIDERED FOR THE SEASONAL OUTLOOKS PRIMARILY BEGINNING IN OND 2016 THROUGH THE WINTER INTO EARLY SPRING, 2017. IN ADDITION TO DYNAMICAL MODEL GUIDANCE FROM THE NMME, THE SEASONAL OUTLOOKS ARE ALSO BASED ON THE NCEP CLIMATE FORECAST SYSTEM (CFS), THE INTERNATIONAL MULTI-MODEL ENSEMBLE (IMME), A SST-BASED CONSTRUCTED ANALOG AND OTHER ADDITIONAL STATISTICAL TOOLS, INCLUDING REGRESSION-BASED IMPACTS OF ENSO, AND DECADAL TRENDS INHERENT IN THE CPC CONSOLIDATION (CON) TOOL.

TEMPERATURE

THE TEMPERATURE OUTLOOKS FROM OND 2016 THROUGH AMJ 2017 INCLUDE THE ANTICIPATED IMPACTS OF A WEAK LA NINA. APPROXIMATELY THE SOUTHERN HALF OF THE CONUS IS FAVORED TO HAVE ABOVE NORMAL TEMPERATURES THROUGHOUT THESE LEADS, WITH THE HIGHEST PROBABILITIES EXPECTED ACROSS THE SOUTHWESTERN STATES (IN EXCESS OF 50 PERCENT FROM OND 2016 THROUGH MAM 2017). CLIMATE MODELS AND HISTORICAL TRENDS WERE ALSO INCORPORATED INTO THESE OUTLOOKS. FOR APPROXIMATELY THE NORTHERN HALF OF THE CONUS, HOWEVER, A COMBINATION OF BELOW NORMAL TEMPERATURES AND EC IS FAVORED THROUGHOUT THESE LEADS. STARTING IN OND, A SMALL AREA OF EC IS FAVORED ACROSS THE NORTHERN GREAT PLAINS, AND ABOVE NORMAL TEMPERATURES ARE FAVORED THROUGHOUT THE REMAINDER OF THE NORTHERN CONUS. THE HIGHEST PROBABILITIES (IN EXCESS OF 40 PERCENT) ARE INDICATED OVER THE EASTERN GREAT LAKES AND THE NORTHEAST, DUE TO A COMBINATION OF TEMPERATURE TRENDS AND CLIMATE MODEL GUIDANCE. DURING NDJ, THE AREA OF PREDICTED EC EXPANDS EASTWARD AND SOUTHEASTWARD TO INCLUDE MOST OF THE REMAINDER OF THE NORTHERN CONUS. THE EXCEPTION IS NORTHERN NEW ENGLAND, WHERE LINGERING ABOVE NORMAL TEMPERATURES ARE FAVORED. FROM DJF 2016-17 THROUGH AMJ 2017, AN AREA OF BELOW NORMAL

TEMPERATURES IS EXPECTED TO DEVELOP, INITIALLY OVER THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY, FOLLOWED BY EASTWARD EXPANSION TO MICHIGAN AND WESTWARD EXPANSION TO WASHINGTON AND OREGON DURING JFM AND FMA 2017. BY MAM AND AMJ 2017, THE COVERAGE OF BELOW NORMAL TEMPERATURES IS EXPECTED TO DIMINISH IN SIZE, WITH ABOVE NORMAL TEMPERATURES ANTICIPATED TO SHIFT INTO THE MID-ATLANTIC AND SOUTHERN GREAT LAKES BY AMJ.

THE LATTER LEADS, MJJ THROUGH SON 2017, ARE PRIMARILY BASED ON LONGER-TERM TEMPERATURE TRENDS, WITH ELEVATED PROBABILITIES OF ABOVE NORMAL TEMPERATURES ACROSS MUCH OF THE CONUS.

IN ALASKA, HISTORICAL TEMPERATURE TRENDS AND MOST OF THE AVAILABLE CLIMATE MODEL GUIDANCE FAVOR ABOVE NORMAL TEMPERATURES FOR THE FIRST TWO LEADS. THE EXPECTATION OF A WEAK LA NINA FORMS THE BASIS FOR EC INCREASING IN COVERAGE ACROSS THE SOUTHERN PORTION OF THE STATE DURING NDJ AND DJF. BELOW NORMAL TEMPERATURES ARE FAVORED TO DEVELOP ACROSS THE PANHANDLE AND SOUTHEAST PART OF THE MAINLAND DURING JFM AND FMA, AND ABOVE NORMAL TEMPERATURES ARE FORECAST TO PERSIST OVER NORTHWESTERN ALASKA. FROM MAM TO SON 2017, THE ALASKA TEMPERATURE OUTLOOK IS PRIMARILY ATTRIBUTED TO TRENDS, WITH ABOVE NORMAL TEMPERATURES FAVORED INITIALLY ACROSS THE NORTH SLOPE DURING MAM AND AMJ, WHICH THEN EXPANDS SOUTHWARD TO INCLUDE THE ENTIRE STATE BY JAS, ASO, AND SON 2017.

PRECIPITATION

FROM OND 2016 THROUGH MAM 2017, THE ANTICIPATED IMPACTS OF A WEAK LA NINA ARE DEPICTED. THESE IMPACTS INCLUDE ABOVE MEDIAN PRECIPITATION EXPANDING WESTWARD TO INCLUDE THE NORTHERN ROCKIES AND PACIFIC NORTHWEST, WHICH REDUCES IN SIZE BY FMA AND MAM TO INCLUDE THE PACIFIC NORTHWEST. ABOVE MEDIAN PRECIPITATION IS ALSO FAVORED TO DEVELOP ACROSS THE GREAT LAKES, OHIO VALLEY, EASTERN PORTIONS OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY, AND THE TENNESSEE VALLEY DURING THE DJF, JFM, AND FMA SEASONS. THIS WET SIGNAL IS OFTEN OBSERVED DURING LA NINA WINTERS, AND USUALLY WINDS DOWN DURING MAM AND AMJ. IN CONTRAST, BELOW MEDIAN PRECIPITATION IS FAVORED TO INCREASE IN AREAL COVERAGE DURING OND AND NDJ TO INCLUDE MOST OF THE SOUTHERN CONUS. THIS RELATIVELY DRY SIGNAL IS FORECAST TO CONTINUE ACROSS THE SOUTHERN STATES THROUGH THE MAM SEASON, AS IS TYPICAL OF LA NINA WINTERS. BY AMJ 2017, THE PRECIPITATION OUTLOOKS ARE BASED ALMOST EXCLUSIVELY ON HISTORICAL TRENDS AS INDICATED BY THE CPC CONSOLIDATION TOOL. ABOVE MEDIAN PRECIPITATION IS FAVORED ACROSS THE GREAT LAKES IN AMJ AND MJJ, WHICH SHIFTS EASTWARD TO THE NORTHEAST STATES DURING JJA, JAS, AND ASO, WITH A RESIDUAL WET SIGNAL REMAINING OVER MAINE BY SON 2017. DURING JJA AND JAS, A DRY TREND IS FAVORED OVER THE PACIFIC NORTHWEST AND NORTHERN ROCKIES.

IN ALASKA, CLIMATE MODEL GUIDANCE GENERALLY SUPPORTS ABOVE MEDIAN PRECIPITATION FOR THE PANHANDLE IN BOTH SON AND OND, WITH THE WET SIGNAL SHIFTING TO FAR NORTHERN AND WESTERN ALASKA DURING THE SUBSEQUENT 3 SEASONS (NDJ, DJF, AND JFM). BELOW MEDIAN PRECIPITATION IS FAVORED ACROSS THE SOUTHERN COAST OF MAINLAND ALASKA FROM NDJ THROUGH JFM. THIS IS A COMMON FEATURE OF LA NINA WINTERS. FOR FMA 2017 AND BEYOND, THERE IS NO DISCERNIBLE TILT IN THE ODDS TOWARDS ANY ONE PRECIPITATION CATEGORY.


It would be helpful if NOAA divided "Decadal Trends" in the impact of the AMO and PDO and the impact of the secular trend of Global Warming. As it is, the reader is left with trying to figure out what NOAA is saying when they discuss Decadal Trends.


Sometimes it is useful to compare the present month outlook to the three-month outlook           

September  2016 plus SON Issued on August 18, 2016

One can mentally subtract the September Outlook from the three-month Outlook and create the Outlook for the last two months in the three-month period namely October and November 2016. When I do that, I deduce that:

With respect to temperature, there is a lot of EC in September but everywhere is warm on average for the three months so those places shown as EC in September may need higher probabilities for being warm in October and November to have the three month probabilities work out. With respect to precipitation, it is a lot more complicated primarily for Western CONUS. There are two anomalies in September and two in the three-month period but in different places. So it is sort of like EC is the norm but there are two deviations from EC in September which need to be canceled out for the three-month period to be EC which means the opposite anomalies might show up in October and November. Similarly the two anomalies in the thee-month period do not show up in September so their probabilities in October and November may need to have higher probabilities for the three-month average to work out.
Of all of these differences between August and the three-month average, the main difference is a suggestion that with respect to precipitation, September will still reflect El Nino and October and November will reflect La Nina.

Let's Now Focus on the Current (Right Now to 5 Days Out) Weather Situation.

A more complete version of this report with daily forecasts is available In Part II. This is a summary of that more extensive report.  Worldwide Weather: Current and Three-Month Outlooks: 15 Month Outlooks will take you directly to that set of information but it may take a few seconds for your browser to go through the two-step process of getting to Page II and then moving to the Section within Page II that is specified by this link.

Characteristics of a Weekly Weather Column.

Many graphics in this report are auto-updated by the source of the graphic. It is always my choice as the writer to allow these graphics to auto-update or "freeze them" to what they looked like when I write the article. Generally speaking graphics in research themes which appear above this point do not auto-update as they come from published scientific papers. When I make the decision to allow certain graphics to auto-update, it creates two issues:

A. As the graphic updates, my commentary becomes out of sync with the new version of the graphic. This can be very extreme if for example you take a look at my report from months ago.

B. On rare occasions, source sites for graphics go down and the graphic does not appear in the article and you probably see white space.  If you experience such an event and that graphic is important to your understanding of the report, please return later to view my weather and climate column.  Sometimes the "outage" is only for several minutes, but often the duration can be a number of hours or even one or more days.  We feel that this inconvenience is preferable to looking at "frozen" weather map images that do not update since I write the article on Monday evenings and you probably do not read it until Tuesday and perhaps later in the week. So I want you to have the advantage of seeing the most up-to-date graphics. If the source is down, the white space is the price paid for most of the time being able to see the latest available graphics.

First, 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 the link provided above.

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.

Atmospheric Rivers (Click to read full Weather Underground Dr. Bob Henson article)  I provided that link last week but I am providing it again as it is a new and important concept.

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

Image credit:Center for Western Weather and Water Extremes, Scripps/UCSD.  The scale is water content but with a velocity component also as in kilograms per meter per second. I am not sure how that works as "m" is a one dimensional metric. I think the explanation is that they integrate the moisture from the ground up to 500 mb. At any rate, redder is wetter.

Click Here for a World Precipitation Forecast produced by the Australian Bureau of Meteorology. Unfortunately I do not know how to extract the map only so to see it you have to click where I said "click here". You can adjust the settings to show Temperature or many other things for THE WORLD. It can forecast out for a week. Pretty cool!

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. I am leaving this explanation in the report but it may not be very significant until next October or so which now is less than two months away. .

7 Day 500 MB Geopotential Forecast

Not sure one can rely on this graphic to locate the Four Corners High. If it showed up on this graphic, one could draw or imagine a one-inch or so in radius circle overlain on the Four Corners High with an arrow showing the wind pattern is clockwise (anticyclone). One can then imagine where moisture might be being drawn into the edge of the High Pressure System.
What you can see in this graphic is the forecast of a CONUS Trough. The High shown in the extreme southeast if it was a little further south would tend to operate much like the Four Corners High and be pulling in Gulf of Mexico moisture to the west of the High. They do not not need more there right now.  This evening the Four Corners High is shown along the Arizona and New Mexico border and close to the Mexican Border. That (if it came about) would tend to provide precipitation to Western Arizona and extreme Southeast California. Thinking about clockwise movements around High Pressure Systems and counter- clockwise movements around Low Pressure Systems provides a lot of information.

The MJO has had significant impacts this winter but the impact on August is not likely to be very noticeable other than alternatively accelerating and decelerating the development of the La Nina. It is forecast to be more significant in September. But that is seeming to be less likely i.e. the forecasts of the MJO are all over the place and not suggesting a strong Active or Inactive Phase of the MJO any time soon. It may be October before it really is able to be factored in.

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 and the return of storms towards CONUS in the mid-latitudes. This is recent data in motion (last 24 hours) not a forecast.

Eastern Pacific 

The above is the Eastern Pacific again a 24hr loop of recent readings. It does a good job of showing what is going on right now. I wish I know how to join them and show them side by side. Below is the current water vapor Imagery.for North America. 

 Water Vapor Imagery

Tonight, Monday evening August 22 (and this is the current situation not an animation of recent history), as I am looking at the above graphic, the Monsoonal Moisture Boundary (MMB) is not consistently crossing the Arizona and Western New Mexico border. The moisture seen in Northern Arizona and New Mexico and the Texas Panhandle is mostly of Pacific origin.  There is some activity over by Texas and Eastern Texas at that. It is very consistent with the Atmospheric River graphic shown earlier in this report. There is a lot of Northern Tier activity which fits with the Jet Stream graphic I show later in this report.

This graphic updates automatically so it most likely will look different by the time you look at it as the weather patterns are moving from west to east except for the Southwest Monsoon.

Below is an analysis of projected tropical hazards and benefits over an approximately two-week period. This graphic is scheduled to update on Tuesday and I am reading the August 16, 2016 Version and looking at Week 2 of that forecast.
Tropical Hazards

Mostly for the period August 24, 2016 to Aug 30, 2016, I see very little impact of land areas. But there is a threat of tropical activity impacting the Caribbean but probably the following week. .

Eastern Pacific Tropical Storms

For CONUS, the above graphic is more specific and near term with interpretation and has a focus on tropical storms.  It does not cover as wide an area e.g. it does not cover the Western Pacific or the Atlantic far east of the U.S. It is actually a convenient graphic for tracking the Southwest Monsoon. As you can see, there continues to be a single band of tropical moisture and it is down by Southern Mexico and Central America. There is also tropical moisture west of the Gulf of Mexico which seems to be impacting Texas. In general the tropical storms are not curving around and coming aground but heading out to sea rapidly. There is subtropical moisture that creates the occasional thunderstorm. For now it is a minimal Monsoon (The Phoenix NWS refers to the Monsoonal situation as "High Grade", "Low Grade" and "No Grade". This is definitely somewhere between a "Low Grade" and a "No Grade" Monsoon  at this point re Arizona and New Mexico. I am skeptical about this Monsoon really starting to impact CONUS in a significant way on a consistent basis. Where I live in the Santa Fe New Mexico area, it feels like Fall is here. Summer is over. But we have other weather patterns that are bringing us rain and lightning. Lost power twice Sunday Night and had more work to do. And then there is the final adding of updated graphics and editing on Monday so I hope the weather and PNM and CenturyLink cooperate.

Below is a graphic which highlights the forecasted surface Highs and the Lows re air pressure on Day 6 (the Day 3 forecast is available on Page II of this Report). This graphic also auto-updates.

Day 6 Weather Forecast

The Aleutian Low is not the controlling factor during the summer.
The High Pressure off of California, the familiar RRR, is here and quite large and strong. The RRR continues to do a good job of protecting the West Coast from Pacific storms and also providing northerly winds for California. It is normal for this time of the year unlike during the winter. But it is so far north and offshore that one sees the Low (which has been a series of Lows) that has formed off California. That Low will have impacts. Recently, 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. For CONUS, we do not see a lot of strong Highs or Lows. You can look at the difference in the shown air pressure for the Highs and the Lows over CONUS and it is not a larger differential. Remember this is a forecast for Day 6. It is not the current situation.

Looking at the current activity of the Jet Stream.

The path of the current weather pattern is fairly clear from this graphic and it is across the Northern Tier of CONUS and over Canada and again is further south than usual for this time of the year. The sub-Jetstream level intensity winds shown by the vectors in this graphic are very important. Lately, they have tended to disrupt the generation of tall cumulus clouds in Arizona and New Mexico which are needed to have a significant precipitation from the Southwest Monsoon. West and Northwest winds sweeping into Southern California and Arizona and even extending into Northern Mexico are likely to be suppressing the Southwest Monsoon. This suggests that Fall is here.

Current Jet Stream

air pressure and altitude
Re the above, H8 is 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.
Also the ideal situation is for the mid-level to be cooler than the Boundary Level. You need to have a steep decline in temperature at higher altitudes for the atmosphere to be unstable and create a significant number of healthy clouds and storms. The Devil is in the details. So there can be very higher PWATs i.e. the amount of moisture in the water column at a particular location but still no precipitation if there is no convection. A PWAT of 1.2 inches of water is sort of a summer trigger point,  Levels much higher than 1.2 inches of water could lead to hail. But in the absence of instability, nothing happens. Those westerlies are one reason why there has been less instability than optimal for the Southwest Monsoon to be productive.

Below is the forecast out five days.

There is a continuation in the tendency for the westerlies to partially suppress the Southwest Monsoon especially in Arizona where the winds are forecast to be westerlies or northwesterlies.  But Texas seems to be in the best position to receive monsoonal related precipitation. There are other weather features impacting Arizona and New Mexico which produce precipitation based on more Fall-like weather patterns but with the Monsoonal Moisture somewhat in place. So we have some hybrid types of weather patterns right now. You generally need a combination of moisture and dynamics and right now some of the moisture is coming from the Monsoon but the dynamics are coming from more Fall-like weather patterns. 

Jet Stream Five Days Out

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. 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.

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

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

Click here to gain access to a very flexible computer graphic. You can adjust what is being displayed by clicking on "earth" adjusting the parameters and then clicking again on "earth" to remove the menu. Right now it is set up to show the 500 hPa wind patterns which is the main way of looking at synoptic weather patterns.

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

Daily SST Anomaly

Remember this discussion is all about anomalies not absolute temperatures...so it is deviation from seasonal norms.
The waters off of Japan especially between Japan and China remain warm. The Indian Ocean is now more cool than warm. The southern coast of Australia is especially cool but the Southeast Coast is warm. .Water northwest of Australia is warm but less so than recently. The waters south of Africa are warm.
The overall Northern Pacific is perhaps PDO Positive (the horseshoe pattern with the cool anomaly inside the horseshoe shape) but is not as obvious and may not record as PDO+ as the waters just off the West Coast are cool not warm. The cool anomaly now is a belt south of a large intense warm anomaly. The Pacific Decadal Oscillation (PDO) Index rose to 2.4 in March which with El Nino fading may be significant. It was up to 2.62 in April but eased to 2.35 in May and then to +0.78 in June and now down to +0.18 for July. The question remains about the PDO. Is it acting independently of the El Nino or is this the change from PDO- to PDO+ that would signal a multi-decadal change in the Pacific. I anticipate that the PDO will turn negative as the La Nina gains control. Here is the list of PDO values.
The water directly west of South America is not showing much of a strong La Nina pattern even though El Nino is history. There is a narrow cool anomaly in the Pacific right along the Equator in the La Nina Measurement Area but it does not extend very far north or south of the Equator but may be beginning to do so. It is gradually stretching west. But the connection to Ecuador is weak. In fact the water off of Peru is warm.  It is a La Nina pattern but too weak yet to qualify as an official La Nina. It may ultimately turn out to be a La Nina Modoki i.e. shifted to the west more than the typical La Nina.The water off the West Coast  of Central America is warm. The remnants of El Nino have circled back and are mostly dissipated. Further north, the Gulf of Alaska is quite warm. That really is the most impressive feature of the overall pattern.
The water off the East Coast of CONUS is very warm covering a large area. The list of Atlantic Multidecadal Oscillation (AMO) values can be found here. Further north in the Atlantic east of Newfoundland the North Atlantic is becoming warmer than normal and the cool anomaly seems to be fading. The cool anomaly off shore of Northwest Africa is now a warm anomaly. The waters north of Antarctica East of South America are uniformly colder than climatology but we see some warm anomalies north of that pattern and partially intruding into that pattern. I have some additional commentary on this static analysis of the anomalies below where I examine the four-week change in these anomalies.
Since these are "departures" or "anomalies", it is not a seasonal pattern that is being shown it is the changes from what we would expect on a seasonal basis. It is important to understand that and interpret my comments above in the context of anomalies not absolute temperatures.

Below I show the changes over the last month in the Sea Surface Temperature (SST) anomalies.

Comparing a four-week graphic to a prior four-week graphic is always tricky since only 25% of the data has changed and I am not showing the former graphic (it is in last week's report). I add the new one to my draft report, compare and comment on the change and then delete the old one to keep this report to a manageable size. Also it is important to recognize that what you see in this graphic is the change in the anomaly. So blue means either cooler or less warm. Red means warmer or less cool. So you have to refer to the graphic above this one to really interpret this graphic as what we are seeing here is the change in the anomalies. What we see in this graphic is four weeks of change not the current absolute anomalies which are shown in the above graphic. It is not derivatives in the mathematical sense but deltas. They are somewhat similar. The graphic above this one has no time component. It is simply the deviation from climatology and this graphic below shows the four week change in the deviation from climatology. So it is a bit like the first (graphic above) and second (graphic below) derivatives but not exactly. I take it a step further by comparing this weeks version of the graphic to the prior week and report on the differences below.  

August 22, 2016 Four Week Change in SST Departures

What I see as I look at both last week's version of this graphic and the current one (before deleting the prior version) is a slightly different pattern of changes in the anomalies along the Equator in the Pacific. The anomalies are more centralized in a narrower range of longitudes between 150W and 110W. The Indian Ocean is indicating a moderation in the changes in anomalies. Same goes for the The U.S. West Coast except for an area offshore at approximately 20N and stretching from 110W to 130W where the anomalies are warmer. It is possibly reflecting the passage of cyclones..not sure. Perhaps it is symmetry but you see a similar pattern in the Southern Hemisphere in the Western Pacific. The Atlantic anomalies both North Atlantic and South Atlantic are moderating. The North/Central and Western Pacific anomalies this week are more intense and perhaps the most significant feature that I see. I am not an expert on this but it does not look like the PDO is getting stronger. Remember we are talking about changes in the anomalies something like a second derivative so you have to refer to the graphic above this one to know if blue is cool or less warm and if red is warm or less cool.  

Four- Week Outlook

I am going to show the three-month SON Outlook (for reference purposes), the Early Outlook for the single month of September, the 6 - 10 Day and 8 - 14 Day Maps and the Week 3 -  4 Experimental Outlook.  I could also show the August Monthly forecast as we are only on August 22 but the 6 - 10  Day Forecast issued today is much more up to date than  the August updated forecast which was issued on July 31.

First - Temperature

Here is the Three-Month SON Temperature Outlook issued on August 18, 2016:

SON Temperature Outlook Issued on August 18, 2016

Here is the Early Temperature Outlook for September Issued on August 18, 2016

September Early Temperature Outlook Updated on August 18, 2016

 6 - 10 Day Temperature Outlook

6 - 10 Day Temperature Outlook

8 - 14 Day Temperature Outlook   

8-14 Day Temperature Outlook

Looking further out.

Experimental Week 3-4 Temperature Outlook

As I view these maps on August 22 (two of the five update each day and one updates every Friday), it appears that one feature through September 16 will during the last week of August and the first week of September be a warm  East Coast with this pattern continuing into September. But what about the rest of CONUS? I  can not figure out the pattern but you have the graphics to look at and interpret yourself. Alaska starts warm and remains warm so there is consistency there. The above week 3-4 graphic updates automatically on Fridays. When it is updated on Friday that cool anomaly may no longer be shown and it all may be EC.

Now - Precipitation 

Here is the three-month SON Precipitation Outlook issued on August 18, 2016 21, 2016:

SON Precipitation Outlook Issued on August 18, 2016

And here is the Early Outlook for September Precipitation Issued on August 18, 2016

September 2016 Early Precipitation Outlook Issued on August 18, 2016

6 - 10 Day Precipitation Outlook

6 - 10 Day Precipitation Outlook

8 - 14 Day Precipitation Outlook 

Current 8 - 14 Day Precipitation Outlook

Weeks 3 and 4 Experimental Forecast..

As I view these maps on August 22 (two of the five update each day and one updates every Friday), it looks like precipitation leading up to September 16 is tending for the last week of August and the first week of September to be wet in the Northern Tier from the Rocky Mountains to the East Coast. Most of the West is dry with a tendency for that dry anomaly to extend towards the East Coast but not including the Western Gulf Coast. It is not clear how this morphs into the 3 - 4 Week Outlook shown above which updates automatically on Fridays.

You may notice that for the 3 - 4 week outlooks, the precipitation and temperature anomalies tend to be opposites. That is a common summer pattern where wetter means cooler and drier means warmer. In the winter, snow means cooler to some extent. Right now NOAA is using their precipitation forecast in their Week 3 - 4 Outlooks to figure out where there will be relief from a very hot summer. That does not seem to be the case as much for the 6 - 14 Day Outlooks.

Here is the NOAA discussion released today August 22, 2016.

6-10 DAY OUTLOOK FOR AUG 28 - SEP 01, 2016  

TODAY'S MODEL SOLUTIONS ARE IN FAIR AGREEMENT ON THE OVERALL 500-HPA FLOW PATTERN OVER THE FORECAST DOMAIN. MODELS ARE FORECASTING A TROUGH OVER THE GULF OF ALASKA AND OFF THE WEST COAST. A BROAD, WEAK RIDGE OVER THE CONUS WITH POSITIVE HEIGHT ANOMALIES OVER THE EASTERN CONUS. MEANWHILE, THE SUB-TROPICAL HIGH IS FORECAST TO BE STRONG OVER THE SOUTHERN CONUS. THE ENSEMBLE SPAGHETTI DIAGRAMS INDICATE MODERATE TO HIGH SPREAD ACROSS THE MAJORITY OF THE FORECAST DOMAIN. THE HIGHER WEIGHTS IN TODAY'S OFFICIAL 500-HPA BLEND WERE GIVEN TO THE ENSEMBLE MEAN SOLUTIONS BASED PRIMARILY ON CONSIDERATIONS OF RECENT SKILL.  

POSITIVE HEIGHT ANOMALIES AND SOUTHERLY LOW-LEVEL FLOW FAVOR ABOVE NORMAL TEMPERATURES FOR ALASKA. ABOVE NORMAL HEIGHTS OVER THE EASTERN CONUS LEAD TO INCREASED CHANCES FOR ABOVE NORMAL TEMPERATURES FOR THAT AREA. ENHANCED  PROBABILITIES FOR BELOW NORMAL TEMPERATURES ARE INDICATED FOR NORTHERN CALIFORNIA AND SOUTHWESTERN TEXAS CONSISTENT WITH GEFS REFORECAST GUIDANCE AND BIAS CORRECTED TEMPERATURES FROM THE 0Z ECMWF ENSEMBLE MEMBERS. ANOMALOUS SOUTHERLY LOW-LEVEL FLOW FORECAST OVER THE SOUTHERN PLATEAU REGION INCREASES THE LIKELIHOOD OF ABOVE NORMAL TEMPERATURES THERE. 

BELOW MEDIAN PRECIPITATION IS FAVORED FOR MUCH OF THE WESTERN AND SOUTHEAST CONUS IN ASSOCIATION WITH PREDICTED SUBTROPICAL RIDGING. ABOVE MEDIAN PRECIPITATION IS FAVORED FOR THE NORTHEASTERN CONUS AND PARTS OF THE WEST GULF COAST REGION CONSISTENT WITH PRECIPITATION ESTIMATES FROM THE GFS AND ECMWF ENSEMBLE MEMBERS. ABOVE MEDIAN PRECIPITATION IS FAVORED FOR NORTHERN ALASKA IN ASSOCIATION WITH AN ANTICIPATED TROUGH. BELOW MEDIAN PRECIPITATION IS FAVORED FOR SOUTH ALASKA AND THE ALASKA PANHANDLE UNDERNEATH PREDICTED RIDGING.

FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOUT AVERAGE, 3 OUT OF 5, DUE TO FAIR AGREEMENT AMONG THE MODELS AND THE TOOLS.

8-14 DAY OUTLOOK FOR AUG 30 - SEP 05, 2016 

THE WEEK TWO 500-HPA ENSEMBLE MEAN SOLUTIONS FEATURE A RETROGRESSION OF THE OVERALL PATTERN RELATIVE TO THE 6-10 DAY PERIOD. A SUBTROPICAL RIDGE IS  FORECAST TO DOMINATE THE WEST-CENTRAL CONUS WHILE TROUGHS ARE PREDICTED OVER THE NORTHEASTERN CONUS AND OFF THE PACIFIC NORTHWEST COAST. WEAK HEIGHT ANOMALIES ARE PREDICTED FOR ALL MOST CONUS. THE WEEK-TWO 500-HPA MANUAL HEIGHT BLEND IS COMPOSED PRIMARILY OF THE ENSEMBLE MEAN SOLUTIONS. 

PREDICTED SUBTROPICAL RIDGING IS EXPECTED TO CONTINUE TO FAVOR ABOVE NORMAL TEMPERATURES FOR THE MOST CONUS EXCEPT FOR THE NORTHWESTERN, WHERE ENHANCED  PROBABILITIES FOR BELOW NORMAL TEMPERATURES ARE INDICATED FOR GEFS REFORECAST GUIDANCE AND BIAS CORRECTED TEMPERATURES FROM THE 0Z ECMWF ENSEMBLE MEMBERS. 

ENHANCED PROBABILITIES FOR ABOVE NORMAL TEMPERATURES FOR ALASKA IN ASSOCIATION  WITH A RIDGING BEHIND THE PACIFIC COAST TROUGH. 

BELOW MEDIAN PRECIPITATION IS FAVORED FOR MUCH OF THE WESTERN AND THE SOUTHEASTERN CONUS IN ASSOCIATION WITH THE PREDICTED RIDGE. THE POTENTIAL FOR MOIST FLOW ASSOCIATED WITH THE TROPICAL MOISTURE LEADS TO ENHANCED PROBABILITIES OF NEAR TO ABOVE MEDIAN PRECIPITATION FOR THE GULF COAST REGION AND ATLANTIC COAST. GEFS REFORECAST GUIDANCE FAVORS ABOVE MEDIAN PRECIPITATION FOR THE NORTHEASTERN CONUS. THERE ARE ENHANCED PROBABILITIES OF ABOVE MEDIAN PRECIPITATION FOR ALASKA DUE TO A FORECAST TROUGH, EXCEPT FOR THE ALASKA PANHANDLE.

FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: ABOUT AVERAGE, 3 OUT OF 5, DUE TO FAIR AGREEMENT AMONG THE MODELS AND THE TOOLS.

THE NEXT SET OF LONG-LEAD MONTHLY AND SEASONAL OUTLOOKS WILL BE RELEASED ON SEPTEMBER 15.

Some might find this analysis interesting as the organization which prepares it 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.

Day

ENSO

Phase

PDO AMO

Other Comments

Sept 2, 1953 Neutral -(t) +  
Sept 3, 1953 Neutral -(t) +  
Sept 1, 1968 Neutral N(t) - Just before an El Nino Modoki Type II
Sept 4, 1968 Neutral N(t) - Just before an El Nino Modoki Type II
Sept 3, 1972 El Nino N - Fourth Strongest El Nino in Modern Times
Aug 4, 1993 Neutral + -  
Aug 15, 1997 El Nino + + 1997 MegaNino

(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 August 4 to September 3  which is two days over four weeks. 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 19. These analogs are centered on 3 days and 4 days ago (August 18 or 19). So the analogs could be considered pretty much in sync with the calendar.   However there are five of the unduplicated analogs in the first week of September which suggests a different conclusion i.e. that we are further along with weather than the calendar would suggest.

I think NOAA would appreciate it if I said that these analogs are not a substitute for their very sophisticated forecasting software and I am not suggesting that they are. I present them partially for curiosity purposes but also to see how current conditions correlate with medium and low frequency cycles. The medium frequency cycle I track is ENSO and the two low- frequency cycles I track are the PDO and AMO. When I see that forecasts are consistent with the current phases of these cycles (as represented by the analogs), that seems very suggestive to me that our weather is probably fairly easy to forecast. If the analogs are all over the place then I have to wonder if the forecasts are good or if our weather is just not related to these cycles. That certainly can be the case. So I am doing some research here and you are seeing how I look at things. I hope you find it interesting.

There is this time two El Nino Analogs (why are there any?), ZERO La Nina Analogs, and five ENSO Neutral Analogs. The phases of the ocean cycles in the analogs are inconclusive with respect to McCabe Conditions. But many of the analogs seem to be associated with changes in the Phase of the PDO. Also four of the analogs are associated with El Nino's including two of the four most powerful El Nino's in modern history. So I have less confidence in this forecast than NOAA does.

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

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

Historical Anomaly Analysis

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

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 1.0 - + JAS 2007  MJJ 2008 -1.4 - +
M JJA 2009 MAM 2010 1.3 N + JJA 2010 MAM 2011 -1.4 + +
            JAS 2011 FMA 2012 -0.9 - +
T MAM 2015 NA 1.0 + N          

 

Progress of the Cool ENSO Event

Let us start with the SOI.

Below is the Southern Oscillation Index (SOI) reported by Queensland, Australia. The first column is the tentative daily reading, the second is the 30 day moving/running average and the third is the 90 day moving/running average.

Date Current Reading 30-Day Average 90 Day Average
Aug 16    -3.04 +5.26 +2.93
Aug 17    -2.79 +5.16 +3.07
Aug 18    -3.16 +4.54 +2.84
Aug 19   +6.25 +4.05 +2.83
Aug 20   +3.64 +3.67 +2.84
Aug 21 +11.53 +3.69 +2.87
Aug 22 +14.08 +3.54 +2.87

The 30-day average, which is the most widely used measure, as of August 22 is reported at +3.54 which is down from last week and ENSO Neutral with a La Nina tilt. The 90-day average at +2.87 is essentially unchanged from last week and is also ENSO Neutral. Usually but not always the 90 day average changes more slowly than the 30 day average but it depends on what values drop out. The disparity between the two is one reason why we look at both. Different agencies use a different range to classify the SOI as being El Nino or La Nina. The strictest range is -5 for El Nino and +5 for La Nina. Some meteorological agencies sometimes use -8 or +8. So the range +5 to -5 is clearly neutral and above +8 is clearly La Nina and below -8 is clearly El Nino and between -8 and -5 and +5 to + 8 is somewhat marginal but suggestive of El Nino if negative and La Nina if positive.

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. August has not been particularly favorable for La Nina development and neither will be September in terms of the MJO. The MJO being Inactive is more favorable for La Nina than the MJO being Active. It is complicated in that some models predict a strong active MJO for September which normally means westerlies which is negative for the development of the La Nina. But the MJO goes back and forth from being Active, Inactive, strong and weak so in has mostly a short-term impact. Right now the impact is fairly muted. It tends to be more important when the situation is ENSO Neutral and the MJO can start the process of an El Nino getting started.

Low-Level Wind Anomalies

Here are the low-level wind anomalies. Until a few days ago we were seeing westerly anomalies everywhere in the Pacific along the Equator which are to some extent retarding the development of the La Nina. Now suddenly we see some easterly anomalies. This back and forth is possibly related to the MJO. One looks for intense colors on this Hovmoeller. We do not see any right now.

Low Level Wlind Anomalies

And now the Outgoing Longwave Anomalies which tells us where convection has been taking place which is essentially nowhere along the Equator for the entire Planet Earth. 

OLR Anomalies Along the Equator

In the above graphic, we see basically no convection along the Equator other than west of the Dateline.

Equatorial Subsurface Analysis

We are now going to change the way we look at a three dimensional view of the Equator and move from the surface view to the view from the surface down.

Current Sub-Surface Conditions.   Notice the lag in getting this information posted so the current situation may be a bit different than shown.

And now the pair of graphics that I regularly provide and which as I publish are currently able to be accessed from the NOAA website. There was a period of time when that website was up and down but it appears to be functioning well recently. :

Subsurface Heat Anomalies

The above pair of graphics showing the current situation has an upper and lower graphic. 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.

The top graphic shows surface temperature anomalies. The coolest water at the surface shows up only in small isolated areas.  Water of La Nina coolness but not very intense shows up along the Equator from 170W to the Coast of Ecuador. But there are pockets of water slightly warmer than -0.5C mixed in. The -1C water shows between 150W and 140W but that is only ten degrees of longitude. There is gap between 130W and 120W. That suggests the possibility that this will evolved into a cool Modoki pattern.

The bottom half of the graphic (Absolute Values which highlights the Thermocline) is now more useful as we track the progress of this new Cool Event.

It shows the thermocline between warm and cool water. The 28C Isotherm is now located close to the Dateline. 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 170W so we do not have ideal conditions for significant convection along the Equator east of the Dateline. The 25C isotherm is at about 150W. The 20C Isotherm has moved close to the surface but is not reaching the surface.  But the amount of warm water just west of the Dateline is also not real impressive either but growing but staying fairly far east. It is clearly a transition state and all of this is important not just for tracking this cool event but thinking about when the next El Nino might be triggered. This graphic helps understand the logic behind some of the forecasts of the ONI. For the bast five weeks we pretty much had weak La Nina conditions both in terms of water temperatures and the SOI but it appears to be transitory in the sense of moving back to Neutral this week..

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

TAO/TRITON GRAPHIC

We now have to change our focus from tracking the El Nino to tracking the transition to ENSO Neutral and most likely to ENSO La Nina. So I have deleted many of the TAO/TRITON graphics to show how the El Nino developed except one which was close to the maximum. It was not the maximum but it was the one that I froze which was the closest to the maximum that I saved. It is useful for comparing the current situation with the pattern that prevailed near the peak of the El Nino this past winter.

January 19, 2016 Frozen TAU/TRITON Graphic

And here is the current version of the TAO/TRITON Graphic.

Current SST and wind anomalies

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

 

The below table which only looks at the Equator shows the extent of anomalies along the Equator. I had split the table to show warm, neutral, and cool anomalies. The top rows showed El Nino anomalies. When there were no more El Nino anomalies along the Equator, I eliminated those rows. The two rows just below that break point contribute to ENSO Neutral and after another break the rows are associated with La Nina conditions. I have changed the reference date to May 23, 1016.

Comparing Now to May 23, 2016

Subareas of the Anomaly

Westward Extension Eastward Extension Degrees of Coverage

As of Today

May 23, 2016

As of Today

May 23 2016

As of Today

In Nino 3.4

May 23, 2016

These Rows Show the Extent of ENSO Neutral Impacts on the Equator
0.5C or cooler Anomaly

Dateline(180)

155E

Land

155W

85

50

50
0C or cooler Anomaly

170W

155W

Land

Land

75

50

60
These Rows Show the Extent of the La Nina Impacts on the Equator
-0.5C or cooler Anomaly

165W

145W

LAND

Land

70

45

55
-1C or cooler Anomaly

120W*

140W

LAND

105W

25

0

35
-1.5C or cooler Anomaly*

115W

135W

105W

120W

10

0

0

* There is a small -1C anomaly in the ONI Measurement area but as of today it is south of the Equator so I do not show it in the above table. 

If you just look on the Equator, there are 50 degrees of Longitude of Neutral to La Nina anomalies which is the maximum possible as the ONI Measurement Area is 50 degrees of Longitude wide and that also is the maximum possible since the ENSO Measurement Area only stretches for 50 degrees. There are 45 degrees of water anomalies cool enough to be a La Nina. Subtracting 45 degrees from the 50 degrees you end up with 5 degrees of ENSO Neutral and 45 degrees of water cool enough to qualify as La Nina i.e. temperature anomalies more negative than -0.5C. This is less La Nina-ish than last week. But there is zero water along the Equator in the ONI Measurement that is -1.5C or less which would be cool enough to be a  strong La Nina when just looking at the Equator. But the ONI Measurement Area 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. Away from the Equator it is generally warmer when a La Nina is trying to get started. The water from 3N to 5N and from 3S to 5S is still relatively warm especially west of 150W so that probably is why the ONI is still Neutral as of today. In fact as of the report today, there was no water along the Equator that was as cool as -1C in the ONI Measurement Area but there was a small -1C cool anomaly just south of the Equator. Where did the cool event go? It is now best described as a "Luke Cool" Event.

I calculate the ONI each week using a method that I have devised. To refine my calculation, I have divided the 170W to 120W ONI 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 22, in the afternoon working from the August 21 TAO/TRITON report, 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 -0.2
B. 160W to 150W -0.5 -0.6
C. 150W to 140W -0.8 -0.5
D. 140W to 130W -0.9 -0.4
E. 130W to 120W -0.8 -0.1
Total -2.7 -1.8
Total divided by five subregions i.e. the ONI (-2.7)/5 = -0.5 (-1.8)/5 = -0.4
My estimate of the daily Nino 3.4 ONI had declined to -0.4 which is clearly an ENSO Neutral value.  NOAA has reported the weekly ONI to be -0.5 which is marginal for La Nina.  Nino 4.0 is reported as being slightly warmer at at 0.0.  Nino 3 is being reported as warmer at at -0.5.  Nino 1 + 2 which extends from the Equator south rather than being centered on the Equator is being reported quite a bit warmer at +0.5.  WE REMAIN IN ENSO Neutral BUT WE HAVE HAD OUR sixth LA NINA WEEKLY REPORT although I question the calculation this week and wonder about the rounding e.g. if the actual number is say -0.48 and that is rounded up to -0.5 is that a La Nina value?  Quite frankly I think the NOAA ONI calculation is incorrect and I think the reason is that it is two or three days old i.e. D-3 to D-10 when the ONI was lower.  I believe my rough estimation approach is providing a more realistic ONI value right now. Six weeks are not definitive (the NOAA criteria for declaring an El Nino or La Nina includes five overlapping three-month periods with the appropriate conditions) but suggests the direction things are headed but other information suggests the ONI readings will soon be less negative and they are this week. I am only showing the currently issued version of the NINO SST Index Table as the prior values are shown in the small graphics on the right with this graphic. The same data in graphical form but going back a couple of more years can be found here.  NINO 1+ 2 stubbornly remains positive and determines the weather of Ecuador and Peru.

August 22, 2016 Nino Readings

ONI Recent History

August 8, 2016 ONI History

The official reading for May/Jun/Jul is now reported as +0.2. So  this El Nino is now officially over. I have discussed before the mystery of how the Nino 3.4 (ONI) CFSv2 values above get translated into the ERSST.v4 values shown below and if NOAA feels that working with two sets of books is a good way to operate, who am I argue. Many businesses do the same thing. As you can see this recent El Nino peaked in NDJ and has now ended and depending on what system you use it is either the 2nd or 3rd strongest El Nino since modern records were kept which is considered to be 1950. You could argue for it being #1 based on a week of readings but few are buying that argument. Still #2 or #3 means it is one of the strongest ever based on the way these events are measured. I will be writing more about that soon in a separate article. I believe the measurement system is inadequate re being useful in forecasting Worldwide weather impacts.

The full history of the ONI readings can be found here. The MEI index readings can be found here.

Although I did not discuss the Kelvin Waves earlier, now seems to be the best place to show the evolution of the subsurface temperatures which remains relevant. What we have is only the upwelling phase of the series of Kelvin waves last winter.

August 22, 2016 Subsurface Temperatures.

There is cool water from 170W to the coast of Ecuador. But the coolest water, however, is only reaching the surface from 150W to 140W which is just 10 degrees of longitude. There is also a huge gap in the coolest water between 130W and 110W. There are initial signs that this may evolve into a weak La Nina Modoki. We will get into the details in some future edition of this report if it becomes relevant but the key is the western part of the surface having  more extreme cool anomalies than further east. It is something that happens as the El Nina matures and has not happened yet but the above graphic suggests that it might be possible. 

SST Surface Anomaly Hovmoeller

Here is another way of looking at it: Unlike the Upper Ocean Heat Anomaly Hovmoeller (I call it the Kelvin Wave Hovmoeller) which takes an average down to 300 meters, this just measures the surface temperature anomaly. It is the surface that interacts with the atmosphere and causes convection and also the warming and cooling of the atmosphere. 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 snap shots of the conditions at different points in time. This Hovmoeller provides a good way to visually see the evolution of this ENSO event.  

SST Anomalies Hovmoeller

You read this Hovmoeller from bottom to top and you can clearly see how the El Nino ended and we are flirting with La Nina.

I do not usually show this NOAA Hovmoeller. It is similar to the above but reports the anomalies down to 300 meters but only on the Equator. If is useful in terms of estimating the subsurface cooling or warming that is in reserve. That heat content does not impact current weather but will impact future weather as it impacts the surface.

August 15, Upper Ocean Heat Anomaly

When I have shown it, I usually use the version that auto-updates but this version is a lot clearer. I use it mostly to show the Kelvin Waves. But I am showing it this time because it shows the deterioration of the cool anomaly. So the Upwelling phase of the prior Kelvin Wave is waning. That makes the La Nina call by some of the models suspect. I am showing last week's version above this text box followed by this week's version below this text box. You can clearly see the larger areas of lighter blue at the bottom which are the current readings. For the moment, this potential La Nina is dying. So the NOAA ONI readings are properly considered to be artifact.There is cool water from 180W to 140W along the Equator but that is not enough to have this coolish event labled a La Nina.

Here is the current version

August 22 Upper Ocean Heat Content

You can see some very subtle changes here. The most important perhaps is the slight movement to the east at around 140W. That is what is keeping this La Nina attempt from simply going away.

Recent CONUS Weather

Since it is not mid-Summer not Spring, I have decided to no longer show May.

Here is the 30 day period through July 3. It completes the month of June.

July 4, 2016, 30 Day Temperature and Precipitation Departures

Adding the seven days and removing the first seven days changed the precipitation picture for Arizona and Nevada and Texas. It also did so for the Northeast. It still presents mostly a warm and dry assessment of June, 2016..

And now we track July. Here is the temperature and precipitation anomalies for the 30 days ending July 30, 2016

August 1, 2016 30 Day temperature and precipitation departures.

We are now able to take a look at the three-month history or at least a 90 day history which is basically May through July.

August 1, 2016, 90 day Temperature and Precipitatin Departures.

Re precipitation, it is a similar pattern but not nearly as extreme. The Temperature departures a a bit different as in July the heat anomaly extended to the East Coast.

And now we start looking at August.

August 13, 2016 30 Day temperature and precipitation departures.

Not much  change from the  30 days ending July 30 which is two graphics above as the 90 day history is right above this graphic.

And now the 30 days ending August 20, 2016.

August 22, 2016 30 Day temperature and precipitation departures.

This week we see quite a lot of change. The precipitation in some ways looks like a Late El Nino Pattern with a very dry Northwest and Far West with a very wet Eastern Texas, Louisiana and Mississippi River Valley and Eastern Mexico. That is not surprising actually. The temperature pattern is similar to the prior week but more muted. Remember seven recent days are added as seven more distant days are removed in a 30-Day Average.

Weather Research in the News

Nothing to report

Weather in the News

Arctic Cyclones Impress

Louisiana flooding points to need to name weather events other than typical tropical cyclones.

Global Warming in the News

Saw this but I have no comment.

It would be wrong not to include it but including it does not imply that I think it is a balanced assessment of the situation.

Putting it all Together.

This El Nino has ended in terms of currently satisfying the criteria. We are now speculating on the winter of 2016/2017 which now according to some of the models seems likely to be a La Nina or Neutral with a La Nina bias. But Australia and Japan do not see it that way and are not calling for a La Nina at this point in time. So NOAA is a bit the Odd Man Out but it is mostly a question of degree. NOAA is calling for a borderline La Nina and the others are forecasting a La Nina-ish event that does not quite meet the criteria for being labeled a La Nina  and does not last long enough to meet the criteria.

The below is first the CPC/IRI (Early Month) forecast issued on August 11, 2016  followed by the (Late Month) forecast issued on August 18, 2016.  It is important to remember that the first report in each month is based on a survey of meteorologists and the second report later in the month is based on the analysis of the forecast models. It is a minor difference but a difference.

First  the Meteorologist Consensus Based Analysis. I assume they do it this way as to avoid forcing meteorologists to have to run their computers twice a month (some sarcasm expressed there).

August 11, 2016 CPC/IRI Probabilistic ENSO Forecast.

And then the more recent Model-Based Forecast.

August 18, 2016, IRI-CPC Model-Based ENSO Analysis

Notice that with this release, the probabilities for La Nina remain similar to the August 11 analysis until the FMA 2017 three-month period when relative likelihood of ENSO  Neutral begins to gain on La Nina.

We have suggested that it is possible that some of the models and in particular NOAA's model will be wrong about how fast the Eastern Pacific Warm Pool moves back towards its La Nina location and it may well be that next winter will be more of a Neutral year or even have some characteristics of an El Nino Modoki and thus be wetter than a typical year as the Warm Pool may still be more in the Central Pacific than shifted all the way west to its La Nina position.

 CFS.V2 SST Forecast

The mean of the NOAA model was until recently forecasting a fairly strong La Nina for next winter. The model gradually shifted to a weak La Nina Forecast and now to a marginal La Nina Forecast. Is the Mean of the forecast ensemble for the key periods NDJ and DJF below -0.5?  It  seems to be right now (-0.6?) but not by much or for very long. You can see the same thing in the Australian POAMA model and the August 1 JAMSTEC model run. The mean of the model ensemble for the ONI in the NOAA model has turned higher (less La Nina-ish) for the Spring of the coming winter as you can see. So this is forecast to be a short La Nina if it indeed actually meets the criteria to be recorded as a La Nina which remains to be seen. I doubt that this will be recorded as a La Nina since it most likely will only meet La Nina criteria for two or three overlapping three month periods not five.  But it is forecasted to be so close that whether it officially is logged in as a La Nina or Neutral, probably has very little impact on the weather we will have.

We now have the JAMSTEC August 1 ENSO forecast.

The model shows ENSO Neutral for the next two years..The discussion below the graphic is far more nuanced.

August 1, 2016 JAMSTEC ONI Forecast

Aug. 17, 2016 Prediction from 1st Aug., 2016

ENSO forecast:

The SINTEX-F model initialized with the SST condition observed on July 31st predicts a weak La Niña/La Niña Modoki state in coming months.  [Editor's Note: This article is already running too long so we will not discuss La Nina Modoki tonight but here is a good article to read for those with an interest in the topic]. Although the NCEP GODAS shows an anomalously cold subsurface condition almost all the way from central Pacific to eastern Pacific along the equator in July, the prediction has not picked the strong La Niña/La Niña Modoki signal yet. This might be a model bias due to the simple SST data assimilation scheme used in the initialization. However, we have noted similar prediction results in several other climate models.

Indian Ocean forecast:

As predicted earlier, the negative Indian Ocean Dipole (IOD) has actually emerged in the June-July SST anomalies of the NCEP GODAS data. The model continues predicting the negative IOD for the boreal fall; this will bring a wetter-than-normal (drier-than-normal) condition over the eastern (western) side of the Indian Ocean. There is high possibility of floods in the region near Sumatra and Java, and drought in East Africa. The negative IOD seems to have brought temporary relief to a hot summer over East Japan normally expected in an evolving La Niña year.

Regional forecast:

In boreal fall, as a seasonally averaged view, most part of the globe will experience a warmer-than-normal condition, while northern Brazil will experience a colder-than-normal condition.

According to the seasonally averaged rainfall prediction, U.S., Korea, eastern China, Indo-China and East Africa will experience a drier condition during boreal fall, while most parts of Indonesia and northwestern South America (including Colombia, Ecuador, and western Brazil) will experience a wetter-than-normal condition; this may be mostly due to the negative IOD and the evolving weak La Niña. Also, because of those climate conditions in Indian and Pacific Oceans, Australia is expected to receive above normal rainfall during austral spring and summer. The active South Pacific Convergence Zone (SPCZ) may play a role in this, too However, we expect a weak dry condition in the southwestern coastal region of Western Australia because of the evolution of weak Ningaloo Niña. [ Editor's Note: Explanation and even more detail.]

Most part of Japan will experience above normal temperature from summer through winter. We expect above normal precipitation in most part of Japan in September-October. However, it may be noted that the forecast skills in those mid- and high-latitudes on regional scales are still limited.

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 CONUS taking place has significantly increased. It may be in progress. It looks like it will require one more La Nina or ENSO Neutral event and this appears to be the way this might unfold. The AMO is pretty much neutral at this point 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..maybe as many as five.

TABLE OF CONTENTS FOR PART II OF THIS REPORT   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. 

A. Worldwide Weather: Current and Three-Month Outlooks: 15 Month Outlooks   (Usefully bookmarked as it provides automatically updated current weather conditions and forecasts at all times. It does not replace local forecasts but does provide U.S. national and regional forecasts and, with less detail, international forecasts)

B. Factors Impacting the Outlook

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.

C. Computer Models and Methodologies

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

TABLE OF CONTENTS FOR PART 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.

D1. Introduction

D2. Climate Impacts of Global Warming

D3. Economic Impacts of Global Warming

D4. Reports from Around the World on Impacts of Global Warming

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

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