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posted on 02 August 2016

August 1, 2016 Weather and Climate Report - NOAA Updates August Outlook - EC

Written by Sig Silber

NOAA issued their update for August and it is not a major change but the warm anomalies cover a smaller area. The 6 - 14 Day Forecast has according to NOAA a low level of confidence because the pattern of Highs and Lows, or should I say lack of pattern,  provides little basis for making forecasts other than climatology although NOAA did their best - thus the designation EC (equal chances). But the alternative definition of EC is Equally Clueless and I do not mean that in a negative way but Summer weather is difficult to predict. Weather during transitions from El Nino to La Nina is also difficult to forecast. 

 weather.caption

 

Transitions from PDO Negative to PDO Positive are difficult to forecast and this past El Nino may have provided a false Positive which may soon return to Negative. The AMO also is a challenge as it is close to Neutral so that may complicate forecasting as opposed to when it is solidly Positive or Negative.

From Sunday's Albuquerque NWS Technical Discussion.

Synopsis...

a classic monsoon pattern is expected to develop this week with a significant uptick in shower and thunderstorm coverage across  western areas Monday, and much of the region Tuesday through Thursday. Locally if not fairly widespread heavy rainfall is  expected as atmospheric moisture approaches record daily values,  especially central and western New Mexico, and storm motions remain slow but transition to a more traditional south to north movement. Enhanced flows in small streams and creeks as well as Arroyo and localized flash flooding will be a concern as the week progresses. Afternoon temperatures will trend downward to slightly below normal for the west while eastern areas will remain near seasonal.

The forecasts call for the Monsoonal Plume to impact Arizona first and gradually shift to the east with greater impact on New Mexico. Other states impacted might include Utah, Colorado, Wyoming, South Dakota, Nebraska, Oklahoma, Texas and possible some states east of Texas. So this would be the first true Monsoonal Burst of this Monsoon Season. It may be brief.

NOAA Update of their August Outlook

NOAA has, as usual, issued an update for the month following the last day of the prior month. This update was issued on July 31 and we will discuss that first by comparing the Updated Outlook to the Early Outlook issued on July 21. 

Temperature

Prior Outlook Issued on July 21, 2016

August Early Temperature Outlook Issued on July 21, 2016

Updated Temperature Outlook Issued on July 31, 2016

July 2016 Temperature Outlook Updated on June 30, 2016

The EC (Equal Chances of being warmer or cooler than climatology) area has now expanded to cover a large part of CONUS. Even where warmer is shown, the probabilities have been lowered in many cases.

Precipitation

Prior Outlook Issued on July 21, 2016

July Precipitation Early Outlook Issued on July 21, 2016

Updated Outlook Issued on June 30

August 2016, Early Precipitation Outlook Issued on July 31, 2016

The Great Lakes dry anomaly has been removed. The dry anomaly centered on Louisiana and Alabama has been extend to the west into Eastern Texas. The Northern Plains wet anomaly has been reoriented/rotated and the Southwest Monsoon has been expanded to include Colorado and more of New Mexico.

Below is the discussion issued with this update.

30-DAY OUTLOOK DISCUSSION FOR AUGUST 2016  

THE UPDATES TO THE OUTLOOKS FOR TEMPERATURE AND PRECIPITATION FOR AUGUST 2016 ARE BASED PRIMARILY ON RECENT DYNAMICAL MODEL OUTPUTS AND THE LATEST OFFICIAL FORECAST PRODUCTS FROM CPC (INCLUDING THE 6-10 DAY, 8-14 DAY, AND WEEK 3-4 OUTLOOKS) AND WPC (DAYS 1-7 MEAN TEMPERATURE ANOMALIES AND QPF [Editor's Note: QPF   means Quantitative Precipitation Forecast] OUT THROUGH 7 DAYS). MONTHLY FORECASTS OF MJO ACTIVITY AND TRENDS IN SEA-SURFACE TEMPERATURES  (SSTS) ARE ALSO CONSIDERED.

RECENT OUTPUTS FROM CFS INDICATE INCREASED UNCERTAINTY IN THE TEMPERATURE OUTLOOK OVER THE GREAT PLAINS AND NORTHEAST. MONTHLY FORECASTS OF MJO FROM THE EUROPEAN CENTER FAVOR PHASES 5 AND 6, [Editor's Note: Click to read article which describes the Phases] WHICH WOULD FAVOR COOLER SOLUTIONS DURING LATE SUMMER OVER THE NORTHEAST. GIVEN THOSE FACTORS, THE AREA WHERE ABOVE NORMAL TEMPERATURES ARE FAVORED WAS REMOVED FROM THE NORTHEAST. THE MOST CONSISTENT SIGNALS FOR ABOVE AVERAGE TEMPERATURES IN THE MODELS AND STATISTICAL TOOLS ARE OVER THE SOUTHEAST AND GREAT BASIN, SO ONLY MINOR EDITS ARE MADE IN THOSE REGIONS. SHORTER TERM OUTLOOKS FAVOR BELOW NORMAL TEMPERATURES OVER THE NORTHWEST, SO THE ODDS FOR ABOVE NORMAL TEMPERATURES ON THE MONTHLY TIMESCALE WERE REDUCED, BUT NOT REMOVED, AS THE PRECIPITATION OUTLOOK FAVORS BELOW MEDIAN PRECIPITATION, WHICH WOULD CONTRIBUTE TO ABOVE NORMAL TEMPERATURES.

MINOR REVISIONS WERE MADE TO THE PRECIPITATION OUTLOOK. QPF OUTLOOKS THROUGH 7 DAYS INDICATE MODERATE TO HEAVY PRECIPITATION OVER THE GREAT LAKES AND PORTIONS OF THE NORTHEAST, SO THE AREA WHERE BELOW MEDIAN PRECIPITATION IS FAVORED WAS REMOVED. THE AREA WHERE BELOW MEDIAN PRECIPITATION IS FAVORED OVER THE SOUTHEAST IS SHIFTED SLIGHTLY WESTWARD OVER TEXAS AND NORTHWARD AWAY FROM THE IMMEDIATE GULF COAST, ACCOUNTING FOR SHORT-TERM OUTLOOKS AND RECENT MODEL GUIDANCE. ABOVE MEDIAN PRECIPITATION IS STILL FAVORED FROM THE NORTHERN GREAT PLAINS TO THE MIDWEST, AND OVER THE SOUTHWEST, WHILE BELOW MEDIAN PRECIPITATION IS STILL FAVORED OVER THE PACIFIC NORTHWEST.

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

August plus  August - September- October Outlook


August  2016 plus ASo Issued on July 31, 2016

One can mentally subtract the August Outlook from the three-month Outlook and create the Outlook for the last two months in the three-month period namely September and October 2016. If one does that you might conclude that:

the areas shown as EC for August will need to have higher probabilities for being warmer than shown in the three-month average to work out. With respect to precipitation, that subtraction would show that the area of the Monsoon in August would need to be drier than climatology in September and October for the EC to work out for three-month average but that is not very believable. EC is more likely.

One has to keep in mind that we are now subtracting an August Map issued on July 31 from a July 21 three-month map so it is less reliable than the exercise we went through two weeks ago. We are assuming that the three-month outlook issued on July 21 would not change if it was released today. The results in the box above might be an indication of how September and October will differ from the three-month outlook or it might alternatively indicate how the three-month outlook might be modified if issued today. I am thinking that this may well be the case.

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.

Here is 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 "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.

7 Day 500 MB Geopotential Forecast

Sunday evening we saw the Four Corners High forecast on Day 7 to be just about over El Paso Texas. Earlier Sunday it was forecast on Day 7 to be in the Southeast corner of New Mexico which would be very favorable for the Monsoon. Monday afternoon it was forecast on Day 7 to be in Central Texas a bit east and that would not be favorable for the Monsoon mostly due to being both east and north. Monday evening it is forecast on Day 7 to be on the Arizona/New Mexico border close to the Mexico Border which also is probably not a favorable location. So if the location of the Four Corners High is like Darts, it is not possible to forecast the Southwest Monsoon. If one draws or imagines a one-inch in radius circle overlain on the Four Corners High with an arrow showing the wind pattern is clockwise (anticyclone), one can imagine where moisture might be being drawling into the edge of the High Pressure System. One also sees two small troughs: one on the West Coast and another moving off the East Coast. There is a cutoff low above the Eastern Trough so that part of Canada may have more impacts than further south in CONUS.

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.

Western Pacific Tropical Activity

The above graphic shows the movement of tropical storms towards Asia in the lower latitudes and the return of storms towards CONUS in the mid-latitudes. It is a little bit Helter-Skelter right now.

 Water Vapor Imagery

As I am looking at the above graphic Monday evening August 1, the Monsoonal Moisture Boundary (MMB) has crossed the Arizona and Western New Mexico border. As discussed in the preamble to this report, it looks like a Monsoonal Burst will occur this week.

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.

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 July 26, 2016 Version and looking at Week 2 of that forecast.
Tropical Hazards

Mostly for the period August 3, 2016 to Aug 9, 2016, I see a moderate probability of wet conditions for the Maritime Continent, extreme Southeast China, and Sudan.

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 is now a single band of tropical moisture and it is down by Southern Mexico. There is some minimal moisture also arriving via the Gulf of California and possibly partially related to the tropical storms that are clearly noted in this graphic. But the storms are not curving around and coming aground but heading out to sea rapidly. There is subtropical moisture that creates the occasional thunderstorm. Things could improve quickly but for now it is a minimal Monsoon. I am skeptical about this Monsoon really starting to impact CONUS in a significant way on a consistent basis but this week appears to be a Monsoonal Burst. 

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 extended into the Bering Sea and 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.  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 and it is not a larger differential.

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 is no longer further south than usual for this time of the year. Thus it is less likely to be  suppressing the Southwest Monsoon..

Current Jet Stream

And below is the forecast out five days with a continuation of the overall northern tendency in the pattern but a somewhat reduction in the tendency for the westerlies to partially suppress the Southwest Monsoon. Pay attention to the wind vector arrows in addition to the areas shaded as being part of the Jet Stream. Some days they are cooperating and some days they are not. Notice the vectors with easterly direction entering California. This will impact the Monsoonal Moisture Plume. 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 and such levels and much higher are in New Mexico and Arizona now. Levels much higher than 1.2 inches of water could lead to hail.

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

The waters off of Japan remain warm. The Indian Ocean is cool especially off of Africa and now also off the southern coast of Australia. But water northwest of Australia to Indonesia is warm and suggestive of a La Nina Warm Pool but perhaps less intense than recently (see the four week change analysis in the following graphic). The waters off of New Zealand are warm to the north but not the south.
The overall Northern Pacific is indeed PDO Positive (the horseshoe pattern with the cool anomaly inside the horseshoe shape) but is not as obvious. The cool anomaly is pretty small in area. 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. 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.The waters northeast of South America are warm which could show up as tropical activity. The water off the West Coast of North America is warm especially off of Baja California. 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 waters of the Gulf of Mexico are warm. 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 waters north of Antarctica East of South America are uniformly colder than climatology. 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 1, 2016 Four Week change in weekly SSTs

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 different pattern of cooling along the Equator in the Pacific. Where there has been changes in the cool anomaly, those changes stretch further north and south. But to the east and west of that area, there has not been much change. The Indian Ocean continues to cool. The warming in the North/Central Pacific is again slightly less intense. Of interest is the reduction in the warm anomaly off of Baja California. The East Coast of North America continues to warm but at a reduced pace. The Gulf of Mexico has reduced warm anomalies. The area of the Northwest Coast of Africa has ceased changing. The cool anomaly southeast of South America has resumed its warming (becoming less cool). 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 ASO Outlook, the recently updated Outlook for the single month of August, the 6 - 10 Day and 8 - 14 Day Maps and the Week 3 -  4 Experimental Outlook

First - Temperature

Here is the Three-Month ASO Temperature Outlook issued on July 21 , 2016:

ASO Temperature Outlook Issued on July 21, 2016

Here is the Updated Temperature Outlook for August Issued on July 31, 2016

August  Temperature Outlook Updated on July 31, 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 1 (two of the five update each day and one updates every Friday), it appears that the main features through August 26 will during the beginning of August will be a cool anomaly in the Northwest extending to the east and south with the rest of CONUS mostly warm except for a tendency for the Northern Tier to be EC. Later in the month, we see a transformation to a large EC anomaly forming in the area of the Rocky Mountains east to the East Coast with a cool anomaly in the center of the EC area but further north than previously shown.  Alaska starts warm and remains warm.

Now - Precipitation 

Here is the three-month ASO Precipitation Outlook issued on July 21, 2016:

ASO Precipitation Outlook Issued on July 21, 2016

And here is the Updated Outlook for August Precipitation Issued on July 31, 2016

August 2016  Precipitation Outlook Issued on July 31, 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 1 (two of the five update each day and one updates every Friday), it looks like precipitation leading up to August 26 is tending for the first part of August to be wet in the central part of CONUS extending somewhat to the east transforming as the month evolves into a series of dry/wet/dry anomalies from northwest to southeast. That would typically be a sequence of High - Low - High Air Pressure Systems extending diagonally across CONUS from the Northwest southeast to the Southeast. It is fairly typical of a period of time when the Monsoon is not very active but you can see that the Central Wet Anomaly extends downward into Northeast Arizona and Northern and Northwest New Mexico. We may see that wet anomaly shrink the next time the 3-4 Week Forecast is run which will be this coming Friday and that graphic will auto-update in this report.   .

Here are excerpts from the NOAA discussion released today August 1, 2016.

6-10 DAY OUTLOOK FOR AUG 07 - 11 2016  

TODAY'S MODEL SOLUTIONS ARE IN GOOD AGREEMENT ON THE OVERALL 500-HPA FLOW PATTERN OVER THE FORECAST DOMAIN. MODELS ARE FORECASTING A CLOSED 500-HPA LOW OVER WESTERN ALASKA, 500-HPA TROUGHS NEAR THE WEST COAST OF THE CONUS AND OVER EASTERN CANADA, AND A BROAD 500-HPA RIDGE OVER THE CENTRAL CONUS. THOUGH THERE IS GOOD AGREEMENT, THIS PATTERN IS RELATIVELY CLOSE TO THE CLIMATOLOGICAL PATTERN FOR THIS TIME OF YEAR, SO FORECAST 500-HPA HEIGHT ANOMALIES ARE SMALL.  TODAY'S MANUAL 500-HPA HEIGHT BLEND INDICATES VERY SMALL ANOMALIES OVER MOST OF THE COUNTRY. THE EXCEPTIONS ARE WESTERN ALASKA AND NEW ENGLAND, WHERE NEGATIVE 500-HPA HEIGHT ANOMALIES ARE FORECAST.

DESPITE BELOW NORMAL HEIGHTS FORECAST OVER ALASKA DURING THE 6-10 DAY PERIOD,  SOUTHERLY LOW-LEVEL WINDS AND AVERAGE SSTS IN THE GULF OF ALASKA FAVOR ABOVE NORMAL TEMPERATURES OVER ALL OF ALASKA. THE TROUGHS AND SLIGHTLY BELOW AVERAGE 500-HPA HEIGHT ANOMALIES OVER THE WESTERN CONUS AND NEW ENGLAND LEAD TO INCREASED CHANCES FOR NEAR TO BELOW NORMAL TEMPERATURES FOR MUCH OF THE WESTERN THIRD OF THE CONUS, AND THE NORTHEAST. SOUTHERLY LOW-LEVEL WINDS FAVORS ABOVE NORMAL TEMPERATURES FOR PARTS OF THE SOUTHWEST. A 500-HPA RIDGE OVER THE SOUTHERN CONUS, SOUTHERLY LOW-LEVEL WINDS AND ABOVE AVERAGE SSTS IN THE GULF OF MEXICO INCREASE THE LIKELIHOOD FOR ABOVE AVERAGE TEMPERATURES FROM THE SOUTH CENTRAL PLAINS, EAST TO THE MID-ATLANTIC AND SOUTHEAST.

ONSHORE LOW-LEVEL FLOW FORECAST OVER ALASKA, FROM THE GULF OF ALASKA, FAVORS ABOVE MEDIAN PRECIPITATION FOR MUCH OF ALASKA, EXCEPT THE NORTH SHORE, WHERE LOW-LEVEL WINDS ARE FORECAST TO BE OFFSHORE AND DOWNSLOPING, LEADING TO AN INCREASED LIKELIHOOD FOR BELOW MEDIAN PRECIPITATION. DUE TO RELATIVELY LOW STORM SYSTEM ACTIVITY IN WESTERN CONUS, NEAR TO BELOW MEDIAN PRECIPITATION IS FAVORED THERE. INCREASED STORM SYSTEM ACTIVITY DROPPING SOUTH FROM CANADA FAVORS ABOVE MEDIAN PRECIPITATION IN PARTS OF THE NORTHERN PLAINS. A FRONT FORECAST TO MOVE FROM THE GREAT LAKES REGION, SOUTH INTO THE SOUTHEAST, DURING THE PERIOD ENHANCES CHANCES FOR ABOVE MEDIAN PRECIPITATION FOR PARTS OF THE EASTERN U.S. THE GREAT LAKES AND NORTHEAST ARE FORECAST TO BE IN THE WAKE OF THAT SAME FRONT, LEADING TO AN INCREASED LIKELIHOOD FOR BELOW MEDIAN PRECIPITATION THERE. ANY FRONTAL ACTIVITY IS EXPECTED TO REMAIN NORTH OF MUCH OF THE FLORIDA PENINSULA, FAVORING BELOW MEDIAN PRECIPITATION THERE.

FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: WELL BELOW AVERAGE, 1 OUT OF 5,  DUE TO VERY SMALL 500-HPA ANOMALIES FORECAST, AND DISAGREEMENT AMONG THE FORECAST TOOLS.

8-14 DAY OUTLOOK FOR AUG 09 - 15 2016 

THE PATTERN FORECAST FOR THE WEEK-2 PERIOD IS VERY SIMILAR TO THE 6-10 DAY  PERIOD, EXCEPT THAT THE EASTERN TROUGH IS FORECAST TO MOVE EAST A BIT, AND  RIDGING OVER THE NORTH CENTRAL U.S. IS EXPECTED TO STRENGTHEN. THE TEMPERATURE PROBABILITY FORECAST IN THE WEEK-2 PERIOD IS ALSO VERY SIMILAR TO THE 6-10 DAY PERIOD, EXCEPT THAT WITH A BUILDING RIDGE, THE PROBABILITIES FOR ABOVE NORMAL  TEMPERATURES INCREASE IN THE SOUTH AND EAST, AND FAVORED BELOW NORMAL  TEMPERATURES FROM THE 6-10 DAY PERIOD IN THE WESTERN U.S. AND NORTHEAST ARE REPLACED WITH FAVORED NEAR TO ABOVE NORMAL TEMPERATURES.

THE PRECIPITATION PROBABILITY FORECAST IN THE WEEK-2 PERIOD PERIOD IS ALSO SIMILAR TO THE 6-10 DAY PERIOD, WITH A COUPLE OF EXCEPTIONS. AS INCREASED FRONTAL ACTIVITY IS FORECAST TO ENTER THE GREAT LAKES REGION AND THE NORTHEAST,  NEAR TO ABOVE MEDIAN PRECIPITATION IS FAVORED IN THOSE AREAS IN THE WEEK-2  PERIOD, COMPARED TO THE 6-10 DAY PERIOD. THE POSSIBILITY OF INCREASED TROPICAL  MOISTURE AVAILABLE IN THE CARIBBEAN REGION FAVORS NEAR MEDIAN PRECIPITATION FOR THE FLORIDA PENINSULA IN THE WEEK-2 PERIOD, COMPARED TO BELOW MEDIAN IN THE 6-10 DAY PERIOD.

FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: WELL BELOW AVERAGE, 1 OUT OF 5,  DUE TO VERY SMALL 500-HPA ANOMALIES FORECAST, AND DISAGREEMENT AMONG THE  FORECAST TOOLS.

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

July 24,1954 La Nina N -  
July 30, 1969 La Nina N N  
July 31, 1969 La Nina N N  
August 8, 1973 La Nina - -  
August 9, 1993 Neutral + -  
August 8, 2000 La Nina - + Following the 1997 MegaNino
August 9, 2002 El Nino - + Modoki Type I
July 29, 2003 Neutral + +  
August 1, 2003 Neutral + +  
August 3, 2003 Neutral + +  

 

One thing that jumped out at me right away was the spread among the analogs from July 24 to August 9 which is only two day over two 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 1. These analogs are centered on 3 days and 4 days ago (July 28 or 29). I am kind of concluding that current conditions (as represented in the historical analogs) are generally three or four days further advanced relative to a normal summer pattern.

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 one El Nino Analog (why are there any?), five La Nina Analogs, and four ENSO Neutral Analogs. For the first time we see a number of La Nina 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 transitions of the Ocean Phases. This is consistent with the difficulty that the weather forecasting models appear to be having.

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
July 26 +12.65 +3.65 +2.57
July 27  +2.09 +3.39 +2.77
July 28   -8.99 +2.81 +2.92
July 29   -2.71 +2.71 +3.14
July 30  +9.91 +3.11 +3.35
July 31 +21.24 +3.76 +3.64
Aug 1 +11.96 +4.23 +3.81

 

The 30-day average, which is the most widely used measure, as of August 1 is reported at +4.23 which is a bit more La Nina-ish than last week and which still Neutral is also clearly tilted towards La Nina. The 90-day average at +3.81 is also Neutral but now no longer on the El Nino side of Neutral and quite La Nina-ish. Usually but not always the 90 day average changes more slowly than the 30 day average but it depends on what values drop out. 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 uses -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 will not be particularly favorable for La Nina development but it may happen anyway but September is likely to be very favorable for the development of La Nina in terms of the MJO. It is complicated in that some models predict a strong active MJO for September which normally means westerlies. But the reports I am reading suggest that there will be westerlies west of the Dateline and Easterlies east of the Dateline which may work to create a La Nina Modoki. It should be interesting to see how this plays out.

Low-Level Wind Anomalies

Here are the low-level wind anomalies. We now see westerly anomalies which are to some extent retarding the development of the La Nina.

Low Level Wlind Anomalies

And now the Outgoing Longwave Anomalies which tells us where convection has been taking place.

OLR Anomalies Along the Equator

In the above graphic, we see basically no convection along the Equator.

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:

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 mostly between 140W and 130W which is not a large area. Water of La Nina coolness but not very intense shows up along the Equator from 170W to the Coast of Ecuador. The cold subsurface water appears to be somewhat slow to rise to the surface. The -3C anomaly appears to have again shrunk since last week which is hard to explain. It is hardly evident at all.

The bottom half of the graphic (Absolute Values which highlights the Thermocline) perhaps is now more useful as we shift our focus and begin tracking the progress of this new Cool Event.

It shows the thermocline between warm and cool water. The 28C Isotherm is still located 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 about 160W with the 25C isotherm at about 140W. Surprisingly, the 20C Isotherm remains down at about 25 meters and not moving closer to the surface very rapidly but the 24C, 23C, and 22C isotherms reach the surface. So we do not have significant convection along the Equator east of the Dateline. But the amount of warm water just west of the Dateline is 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 the JAMSTEC forecast of the ONI Index.

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.

We seem to be having a number of things going on at the same time. The cool anomaly extends further into the Pacific but  is not as intense near the coast of South America.or further to the west north of the Equator.

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

Today

May 23, 2016

Today

May 2016

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

180W

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

155W

145W

LAND

Land

60

35

55
-1C or cooler Anomaly

140W

140W

LAND

105W

45

20

35
-1.5C or cooler Anomaly

120W

135W

LAND

120W

25

0

0

 

If you just look on the Equator, there are 35 degrees of La Nina anomalies with zero degrees of very cold water. There are 50 degrees of Neutral to La Nina and that is the maximum possible since the ENSO Measurement Area only stretches for 50 degrees. Subtracting 35 degrees from the 50 degrees you end up with 15 degrees of ENSO Neutral and 35 degrees of cool enough to qualify as La Nina (with zero -1.5C or less degrees of water cool enough to be a very strong La Nina) when just looking at the Equator. But away from the Equator it is generally warmer when a La Nina is trying to get started. So this table suggests La Nina but the water from 3N to 5N and more dramatically from 3S to 5S is still relatively warm especially west of 140W south of the Equator and remnant warmish water from 140W to 120W north of the Equator. There is a small -2C anomaly between 130W and 120W so that will be worth watching. Right now it is too small to have much of an impact. 

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 1, in the afternoon working from the July 31 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 +0.1
B. 160W to 150W +0.1 -0.1
C. 150W to 140W -0.5 -0.6
D. 140W to 130W -0.5 -1.0
E. 130W to 120W -0.5 -1.1
Total -1.1 -2.7
Total divided by five subregions i.e. the ONI (-1.1)/5 = -0.3 (-2.7)/5 = -0.5

 

My estimate of the daily Nino 3.4 ONI has increased (less negative) to -0.5.  NOAA has reported the weekly ONI to be -0.5 which is the borderline between neutral and La Nina territory.  Nino 4.0 is reported as being slightly less warm at at 0.2.  Nino 3 is being reported as slightly cooler at -0.6.  Nino 1 + 2 which extends from the Equator south rather than being centered on the Equator is being reported a bit less warm at 0.1.  WE REMAIN IN ENSO Neutral BUT WE HAVE HAD OUR THIRD LA NINA WEEKLY REPORT although this one is equivocal.  Three weeks are not definitive (the 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. 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.

August 1, 2016 Nino Readings

ONI Recent History

July 4, 2016 ONI History

The official reading for Apr/May/Jun is now reported as -0.7. 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 El Nino peaked in NDJ and is now declining 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 1, 2016 Subsurface Temperatures.

You can now see that the El Nino is totally gone however there is warm water west of the Dateline. The coolest water, however, is only reaching the surface from 135W to 145W. Either this La Nina is shy or it is a Modoki. Or it is just not happening as rapidly as one might have expected. I think it is not happening to the extent originally forecast. Further to the east outside of the ONI Measurement Area cool water is reaching the surface. Right now we have westerly anomalies. In September the MJO may move that water further west into the ONI Measurement Area and we may get colder ONI readings. On the right you see every second week of this graphic historically so you can follow the progression. Notice how the subsurface cool anomaly has shrunk over time.

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. Nevertheless 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 flirted with La Nina but that has been a bit reversed. The blue colored water is more visible between 120W and 170W so it contributes to the ONI calculation but further east there are some El Nino remnants. They do not show up in the ONI calculations but they are there.

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 1, 2016 Weekly Heat

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.

Recent CONUS Weather

Here is what May looked like:

May 30, 2016 30 Day Tempeature and Precipitation Departures

The final days of this El Nino behaved like an El Nino. Quite interesting.

But looking at a longer time period in this 90 days or approximately three months.  

May 30, 2016 90 Day Tempeature and Precipitation Departures

Looking at the three months (March - May), it certainly at least with respect to precipitation was more like a La Nina event than an El Nino event. Except for Texas. Northern California caught up and Northeast Mexico also. But Arizona, New Mexico and Southern California did not participate in this El Nino in 2016 although they did in the Fall of 2015. Variability is the norm

And then we started to track June.

Here is the 30 day period through June 25.

June 27, 2016, 30 Day Temperature and Precipitation Departures

It has sure been dry. I has also sure been warm.

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 23, 2016

July 25, 2016 30 Day temperature and precipitation departures.

And now one week later

August 1, 2016 30 Day temperature and precipitation departures.

The addition of one week and deletion of the earlier seven days really shows very little change but a slight moderation of the extremes.

We are now able to take a look at the three month history or at least a 90 day history.

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.

View from Australia

El Nino

Australia POAMA ENSO model run

Below is the discussion just released. Notice the discussion re forecasting a La Nina for next winter. POAMA is not currently predicting a La Nina. POAMA is the Australian Bureau of Meteorology (BOM) proprietary forecasting model. But the BOM also is not forecasting a La Nina at this point in time as per below:

La Niña WATCH remains, while strong negative Indian Ocean Dipole continues

Despite some cooling of the tropical Pacific Ocean surface waters, ENSO indicators remain neutral and well shy of La Niña thresholds. In contrast, a strong negative Indian Ocean Dipole (IOD) event continues, with ocean temperature well above average in the eastern Indian Ocean and below average near Africa.

All international climate models surveyed by the Bureau indicate the negative IOD will persist until the end of spring, which historically has brought increased rainfall to southern Australia. Sea surface temperatures have cooled slightly in the tropical Pacific over the past fortnight. Some atmospheric indicators have shifted slightly towards La Niña thresholds, but all remain within neutral bounds.

All climate models indicate more cooling of the tropical Pacific Ocean is likely, but only two of eight models exceed La Niña thresholds for an extended period. A La Niña WATCH (indicating a 50% chance of La Niña in 2016) remains, but if La Niña does develop it would most likely be weak.

May to July 2016 was Australia's third-wettest May–July on record. During negative IOD events, southern Australia typically experiences above average winter–spring rainfall and cooler than average daytime temperatures, with warmer daytime and night-time temperatures in northern Australia.

IOD (Indian Ocean Dipole)

IOD POAMA Model Run

The graphic comes with only a very short discussion and here is that discussion:

The Indian Ocean Dipole (IOD) remains negative, with cool SST anomalies present in the northwest of the Indian Ocean and warm anomalies over the eastern and central parts of the basin. The weekly index value to 31 July was −1.07 °C.

The Indian Ocean Dipole (IOD) index has been below the −0.4 °C negative IOD threshold for ten weeks, and below −1.0 °C for five weeks. This is the longest period of sub −1.0 °C values in at least the past 15 years.

International climate models indicate the negative IOD will persist over the southern winter and spring.

A negative IOD typically brings above average rainfall to southern Australia during winter–spring, cooler than normal daytime temperatures to southern Australia, and warmer daytime and night-time temperatures to northern Australia.

Information on the impact of a negative IOD on Australia can be found here.

Weather in the News

Nothing to report

Global Warming in the News

Role of trees better understood.

Putting it all Together.

This El Nino has ended in terms of currently satisfying the criteria. It is possible that officially it may not be declared dead until the end of July because the  Apr - May - Jun value of the ONI at -0.7 satisfies the 0.5 cutoff.

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 July 14, 2016 followed by the (Late Month) forecast issue on July 21, 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.

July 16, 2016, CPC/IRI ENSO Analysis

And now the Model -Based Analysis.

July 21, 2016, IRI-CPC Model-Based ENSO Analysis

Notice that with this release, the probabilities for La Nina remain similar to the July 14 analysis. The methodology of these two graphics are different but I think the results are consistent with other information that is available. The new forecast however extends further in time to MAM 2017 and shows the most likely ENSO condition at that point in time is Neutral..

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. Notice the blue members of the ensemble forecast which are the more recent ones. This week they suggest a slightly stronger La Nina.  Is the Mean of the forecast ensemble for the key periods OND and  NDJ 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 July 1 JAMSTEC model run. The mean of the model ensemble for the ONI in the NOAA model has recently turned higher (less La Nina-ish) for the Spring of the coming winter as you can see.

We now have the JAMSTEC forecast and their commentary

July 1, 2016 JAMSTEC ONI Forecast

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 and this appears to be the way this will 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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