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posted on 06 December 2016

December 5, 2016 Weather and Climate Report - December Update - Zonal Prevails

Written by Sig Silber

Global Warming takes a break at least for CONUS as cold is the forecast for the Northern Tier of CONUS (and points North). It first looked like this would be a meridional pattern bringing record cold down to the Southwest but the Jet Stream turned zonal in the nick of time. So the cold air is being distributed more equitably. Waiting for NOAA to walk back their incongruous La Nina Advisory...probably December 8.

 weather.caption

First some housekeeping information. Working on a Glossary of Terms but right now it is only partially operational. It will be possible increasingly to look up acronyms etc by going to the GEI Weather Page Glossary. Also for those who want the forecasts beyond three months, we reported previously on the November 17 NOAA 15-Month Forecast and compared the first ten months of the NOAA Outlook with that of JAMSTEC in a special Update that you can get to by clicking here. We will of course publish a new 15 Month Update Report shortly after December 15, 2016. Remember if you leave this page to visit links provided in this article, you can return by hitting your "Back Arrow", usually top left corner of your screen just to the left of the URL box.

NOAA Update of their December Outlook

NOAA has, as usual, issued an update for the month following the last day of the prior month. This update was issued on November 30 and rather than have a Special Update that covers simply the next month, we combined that report with our Regular Weekly Report and we will discuss that first by comparing the Updated Outlook for December to the Early Outlook for December issued on November November 17. 

Temperature

Prior Outlook Issued on November 17, 2016

December  Early Temperature Outlook Issued on November 17, 2016

Updated Outlook Issued on November 30, 2016

December Updated Temperature Outlook Updated on November 30, 2016

The new Outlook is totally different confirming that this is in no way a typical La Nina. But I do not have a lot of confidence in this updated forecast. It is very  highly weighted to the first week of December.

Precipitation

Prior Outlook Issued on November 17, 2016

December  Precipitation Early Outlook Issued on November 17, 2016

Updated Precipitation Outlook Issued on November 30, 2016

December 2016, Precipitation Outlook Updated on  November 30, 2016

This is also quite different but not totally. Certainly the forecast for the Southeast is flipped from dry to wet.

Below is the discussion issued with this update.

30-DAY OUTLOOK DISCUSSION FOR DECEMBER 2016

THE UPDATED MONTHLY TEMPERATURE AND PRECIPITATION OUTLOOKS FOR DECEMBER 2016 ARE BASED ON THE LATEST DYNAMICAL MODEL GUIDANCE, WPC TEMPERATURE AND PRECIPITATION FORECASTS DURING THE FIRST WEEK OF DECEMBER, THE CPC 6-10/8-14 DAY TEMPERATURE AND PRECIPITATION OUTLOOKS, AND CPC'S EXPERIMENTAL WEEKS 3-4 TEMPERATURE AND PRECIPITATION OUTLOOKS. SINCE THE FUTURE MJO EVOLUTION AND ITS POTENTIAL INFLUENCE ON THE EXTRATROPICAL CIRCULATION PATTERN ARE NOT CERTAIN DURING THE NEXT MONTH, THE MJO WAS NOT CONSIDERED A MAJOR FACTOR IN THE REVISED OUTLOOKS.

LARGE CHANGES WERE NECESSARY IN THE TEMPERATURE OUTLOOK, DUE TO A HIGHLY AMPLIFIED RIDGE FORECAST OVER THE BERING SEA WITH A DOWNSTREAM AMPLIFIED TROUGH ACROSS THE CONTINENTAL U.S. LIKELY PERSISTING THROUGH THE FIRST HALF OF DECEMBER. THIS LONGWAVE PATTERN YIELDS A MUCH COLDER OUTLOOK ACROSS THE CONTINENTAL U.S. AND ALASKA THAN WHAT THE DYNAMICAL MODEL GUIDANCE INDICATED AT MID-MONTH. TEMPERATURES ARE EXPECTED TO AVERAGE 5 TO 10 DEGREES F, OR MORE, BELOW NORMAL ACROSS MUCH OF THE WESTERN U.S. DURING THE FIRST WEEK OF DECEMBER. ALSO, POSITIVE ANOMALIES IN SNOW COVERAGE CURRENTLY EXIST ACROSS THE GREAT BASIN AND INTERMOUNTAIN WEST, RAISING CONFIDENCE IN BELOW-NORMAL TEMPERATURES FOR THESE AREAS. THEREFORE, BELOW-NORMAL TEMPERATURES ARE FAVORED FOR MUCH OF THE WESTERN U.S. IN THE REVISED OUTLOOK. THE HIGHEST PROBABILITIES FOR BELOW-NORMAL TEMPERATURES ARE FORECAST FOR THE NORTHERN ROCKIES AND NORTHERN HIGH PLAINS WHERE ARCTIC HIGH PRESSURE IS EXPECTED TO RESULT IN THE LARGEST NEGATIVE TEMPERATURE ANOMALIES DURING EARLY DECEMBER AND BELOW-NORMAL TEMPERATURES ARE MOST LIKELY TO PERSIST INTO THE SECOND WEEK OF DECEMBER. INCREASED CHANCES FOR BELOW-NORMAL TEMPERATURES EXTEND EAST TO THE GREAT PLAINS WHERE THE CPC 6-10/8-14 DAY OUTLOOKS FAVOR BELOW-NORMAL TEMPERATURES AS MODIFIED ARCTIC AIR IS FORECAST TO AFFECT THIS REGION AT LEAST EARLY IN THE MONTH. FORECAST CONFIDENCE IS LOWEST ALONG THE EAST COAST DUE TO VARIABLE TEMPERATURES FORECAST DURING EARLY DECEMBER, FOLLOWED BY MORE UNCERTAINTY IN THE LONGWAVE PATTERN ACROSS EASTERN NORTH AMERICA LATER IN THE MONTH. SINCE THE EAST COAST IS EXPECTED TO RESIDE ON THE RELATIVELY WARM SIDE OF MULTIPLE LOW PRESSURE SYSTEMS TRACKING ACROSS THE EAST-CENTRAL U.S. EARLY IN THE MONTH, A SLIGHT TILT IN THE ODDS FOR ABOVE-NORMAL TEMPERATURES IS FORECAST FOR THE NORTHEAST AND PARTS OF FLORIDA.[Editor's Note:Chances are this cold air will work it's way to the East Coast and  NOAA will gradually recognize this.]

BASED ON SHORT-TERM AND CPC'S 6-10/8-14 DAY PRECIPITATION OUTLOOKS, INCREASED CHANCES FOR ABOVE-MEDIAN PRECIPITATION ARE FORECAST ACROSS THE PACIFIC NORTHWEST, NORTHERN GREAT BASIN, AND NORTH-CENTRAL ROCKIES/HIGH PLAINS. ARCTIC HIGH PRESSURE SHIFTING SOUTH FROM WESTERN CANADA EARLY IN THE MONTH IS EXPECTED TO ENHANCE UPSLOPE FLOW AND PRECIPITATION ACROSS THE NORTHERN AND CENTRAL HIGH PLAINS. DOWNSTREAM OF THE AMPLIFIED UPPER-LEVEL TROUGH EARLY IN THE MONTH, ABOVE-MEDIAN PRECIPITATION IS FAVORED ALONG THIS PREDICTED STORM TRACK. THE HIGHEST ODDS FOR ABOVE-MEDIAN PRECIPITATION ARE FORECAST ACROSS SOUTHEAST TEXAS AND LOUISIANA WHERE THE PRECIPITATION TOTALS PREDICTED DURING THE FIRST WEEK OF DECEMBER ARE NEAR OR ABOVE THE DECEMBER NORMAL. THE MOST LIKELY AREA FOR BELOW-MEDIAN PRECIPITATION EXISTS ACROSS THE FLORIDA PENINSULA DUE TO RIDGING ALOFT DURING EARLY DECEMBER AND IT IS CONSISTENT WITH THE LOW-FREQUENCY BASE STATE.

ARCTIC HIGH PRESSURE WITH ANOMALOUS NORTHERLY FLOW IS EXPECTED TO RESULT IN LARGE NEGATIVE TEMPERATURE ANOMALIES ACROSS MOST OF MAINLAND ALASKA AND THE ALASKA PANHANDLE DURING EARLY DECEMBER. BASED ON THESE LARGE NEGATIVE TEMPERATURE ANOMALIES, BELOW-NORMAL TEMPERATURES ARE FAVORED IN THE REVISED TEMPERATURE OUTLOOK. ABOVE-NORMAL SSTS CONTINUE TO FAVOR ABOVE-NORMAL TEMPERATURES ACROSS THE ALEUTIANS AND COASTAL SOUTHWEST ALASKA. ENHANCED ODDS FOR BELOW-MEDIAN PRECIPITATION PREDICTED FOR COASTAL SOUTHERN ALASKA ARE CONSISTENT WITH RECENT DAILY RUNS OF THE CFS MODEL AND ANOMALOUS OFFSHORE FLOW EARLY DURING DECEMBER.

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

December plus December 2016  -  February 2017 Outlook


December and DJF  Updated on November 30, 2016

I am not doing the map subtracting process this time because the December temperature map is so very different from the map issued on November 17 that it is clearly not part of the three-month average. And based on the updated December Map, the three-month average seems likely to no longer be a solid forecast. So my methodology of subtracting December from the Three-Month average to estimate the two-month period January/February is likely to be unreliable.

A. Focus on Alaska and CONUS (all U.S. except Hawaii) - Let's Focus on the Current (Right Now to 5 Days Out) Weather Situation.

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

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

Image credit:  Center for Western Weather and Water Extremes, Scripps/UCSD.  More explanation can be found at Atmospheric Rivers (Click to read full Weather Underground Dr. Bob Henson article)

To turn the above into a forecasting tool click here and you will have a dashboard for a short-term forecasting model.

Notice that right now the major moisture inflow is mostly from the subtropical flow across Mexico into the Southeast.                                                                .

Here is a national animation of weather fronts and precipitation forecasts with four 6-hour projections of the conditions that will apply covering the next 24 hours and a second day of two 12-hour projections the second of which is the forecast for 48 hours out and to the extent it applies for 12 hours, this animation is intended to provide coverage out to 60 hours. Beyond 60 hours, additional maps are available at links provided below.

current highs and lows

The explanation for the coding used in these maps, i.e. the full legend, can be found here although it includes some symbols that are no longer shown in the graphic because they are implemented by color coding.

U.S.  3 Day to  7 Day Forecasts

Below is a graphic which highlights the forecasted surface Highs and the Lows re air pressure on Day 3. The Day 6 forecast can be found here.

Day 3 Weather Forecast

The Aleutian Low was showing Sunday as a large split Low with central air pressure of 976 hPa for the portion centered over Kamchatka and weak at 1004 hPa in the portion southwest in the Gull of Alaska pretty much as one would expect with ENSO Neutral. But this evening things are very different and remember this is a Day 3 Forecast. As I look at the graphic, now the situation near North America has not changed much. The lobe of the Aleutian Low in the Gulf of Alaska has a Central Pressure of 996 hPa. But the situation to the west over Siberia is very confusing and there is a High (can't read the pressure from the graphic) in or near the Bering Straits which apparently is considered to be a Block perhaps like the Rex Blocks I have described the past two weeks but am not describing this week. I do not see much of an impact but it is tending to move the pattern to the south to some extent.  The average sea level air pressure in the winter is 1001 hPa and 994 hPa for a non-split Low. This graphic changes every six hours.
The High Pressure off of California, the familiar RRR, was not there Sunday but is there today with Central Pressure of 1024 hPa. Thus, right now the RRR (Ridiculously Resilient Ridge) would not be doing its job of protecting the West Coast from Pacific storms and also providing northerly winds for California except that it is so far south that it actually is steering storms into California. The NOAA forecasts do not seem to recognize the good job the RRR has been doing to prevent Pacific Storms from impacting CONUS.
I provided this  K - 12 write up that provides a simple explanation on the importance of semipermanent Highs and Lows and another link that discussed possible changes in the patterns of these highs and lows which could be related to a Climate Shift (cycle) in the Pacific or Global Warming. Remember this is a forecast for Day 3. It is not the current situation but Day 3 is not very far out.

You can enlarge the below daily (days 3 - 7) weather maps for CONUS only by clicking on Three Day or  Four Day or Five Day or Day Six or Day Seven

Short term forecasts

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

Seven Day WPC Quantitative precipitation forecast

That is a lot of moisture expected in the Northwest and Southeast/East.

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. Remember that 540 relates to sea level.

7 Day 500 MB Geopotential Forecast

Thinking about clockwise movements around High Pressure Systems and counter- clockwise movements around Low Pressure Systems provides a lot of information.
What you can see in the above graphic is a strong mid-CONUS trough. Remember this is a forecast  for Day 7. Note the 540 Thickness Line re the above discussion of thickness and snow likelihood. The 540 line now substantially intrudes into CONUS. Meteorological Winter began on December 1.

The graphic below is the Eastern Pacific a 24 hr loop of recent readings. It does a good job of showing what is going on right now.

Eastern Pacific

The winds and moisture approaching the West are of most interest. You can clearly see the split flow of the Jet Stream and the flows into California which is not currently blocked by the RRR and the subtropical  flow through Mexico and into Texas and from there into the Mid-Atlantic States.

The graphic below (which is a bit redundant with the above) updates automatically so it most likely will look different by the time you look at it as the tropical weather patterns unlike the patterns north of 30N are generally moving from east to west but right now are moving from west to east. This graphic highlights tropical activity. Unlike the above which shows recent history, the below graphic is a satellite image with the forecast of tropical events superimposed on the satellite image. There is no significant "new" tropical activity that would appear to impact CONUS forecast for the beginning of this week.

We can track tropical storms here.

Eastern Pacific Tropical Storms

Below is the current water vapor Imagery for North America.

 Water Vapor Imagery

Tonight, Monday evening December 5, 2016 (and this is the current situation not an animation of recent history), as I am looking at the above graphic, we see again the flow into the now unguarded California and the flow into Texas and from there up into New England. That flow has actually now moved further east and one can hardly even see that this started much further west and now looks like it originates in the Gulf of Mexico but this is really Pacific moisture that has crossed into the Atlantic Basin a frequent occurrence this year.                                                                         .

Looking at the current activity of the Jet Stream.

First the current situation. 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. The sub-Jetstream level intensity winds shown by the vectors in this graphic are also very important in understanding the impacts north and south of the Jet Stream which is the higher-speed part of the wind circulation and is shown in gray on this map. In some cases however a Low-Pressure System becomes separated or "cut off" from the Jet Stream. In that case it's movements may be more difficult to predict until that disturbance is again recaptured by the Jet Stream. This usually is more significant for the lower half of CONUS i.e. further south than the Jet Stream.

Current Jet Stream

One sees the jet stream diving into the Southwest which has brought a series of storms to the Southwest and from there they travel in a northeast direction. Recently, the trough has changed appearance to reflect the Jet  split stream. Also the Northern Branch has become more zonal and earlier today was north of Arizona and New Mexico but that has changed in the last six hours and is now a bit further south. Not sure if that means the cold intrusion will reach further south.

Now looking at the 5 Day Forecast

Jet Stream Five Days Out .

You can see the transition to Zonal Flow. That is an impressively wide jet stream.

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

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

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

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

air pressure and altitude
Re the above, H8 is a frequently used abbreviation for the height of the 850 millibar level, H7 is the 700 mb level, H5 is the 500 mb level, H3 is the 300 mb level. So if you see those abbreviations in a weather forecast you will know what they are talking about.

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

Four- Week Outlook

I am going to show the three-month DJF Outlook (for reference purposes although I do not have a lot of confidence in it), the Updated Outlook for the single month of December,  the 6 - 10 Day and 8 - 14 Day Maps and the Week 3 -  4 Experimental Outlook. I use "EC" in my discussions although NOAA sometimes uses "EC" (Equal Chances) and sometimes uses "N" (Normal) to pretty much indicate the same thing although "N" may be more definitive.  

First - Temperature

Here is the Three-Month DJF Temperature Outlook issued on November 17, 2016:

DJF Temperature Outlook Issued on November 17, 2016

Here is the Temperature Outlook for December Issued on November 30, 2016

December Temperature Outlook Issued on Novermber 30, 2016

 6 - 10 Day Temperature Outlook Issued Today

6 - 10 Day Temperature Outlook

8 - 14 Day Temperature Outlook Issued Today  

8-14 Day Temperature Outlook

Looking further out.

Prior forecast

November 28, 2016 Week 3-4 Temperature Forecast.

This week's forecast (I usually only show the current forecast but this week I also showed the forecast made last week)

Experimental Week 3-4 Temperature Outlook

Remember, the bottom graphic which is the current graphic addresses the period one week later than the graphic above (but since it is a two-week forecast, there is one week of overlap and one week dropped and another week added. Also, this is an experimental forecasting system. It does not seem unreasonable.
Last week we said: "Given that it is hard to even describe the above sequence, one wonders what the chances are that it will happen as shown in the maps." It didn't or at least the forecast maps have adjusted. Let's reassess the situation.
As I view these maps on Monday December 5 (two of the five update each day and one (the Week 3 - 4 Outlook) updates every Friday, it appears that the pattern during December 11 to December 19 will start with a cool Alaska, warm Southern Tier consolidating in the Southwest and cool Northern Tier that shifts to the east and south. The pattern then morphs into a pattern that has a cool Alaska, cool North Central CONUS and a warm Southern Tier but EC along the Atlantic Coast. This sequence may not  work out as forecast but it seems like it could in the sense that one can see how the situation could evolve from the 6 - 10 forecast to the 8 to 14 day forecast to the Week 2-3 experimental forecast. A concern would be can the cool anomaly clear the East Coast in time. To be "warm" with respect to anomalies means warmer than usual for this time of year and "cool" with respect to anomalies means cooler than usual for this time of the year. The graphic shows the level of probability of being different from EC.

Now - Precipitation

Here is the three-month DJF Precipitation Outlook issued on November 17, 2016 that I do not have much confidence in.

DJF 2016-2017 Precipitation Outlook Issued on November 17, 2016

And here is the Updated Precipitation Outlook for December Issued on November 30, 2016

December 2016 Updated  Precipitation Outlook Issued on Novemer 30, 2016

6 - 10 Day Precipitation Outlook Issued Today

6 - 10 Day Precipitation Outlook

8 - 14 Day Precipitation Outlook Issued Today

Current 8 - 14 Day Precipitation Outlook

Looking further out.

Last week's forecast

November 28, 2016 Week 3-4 Precipitation Forecast

This week's forecast (I usually only show the current forecast but this week I also showed the prior forecast to allow comparison).

Weeks 3 and 4 Experimental Forecast..

Remember that this is a forecast that is one week later but being a forecast for two weeks has one week of overlap with one week deleted and one week added. It is an experimental forecast and does not look outrageous but clearly is a big change for the Southwest and Northeast.

As I view these maps on Monday December 5 (two of the five update each day and one (the Week 3 - 4 Outlook) updates every Friday, it looks like precipitation for December 11 to December 19 will begin with Alaska and the Southwest dry and pretty much the rest of CONUS wet with EC between the dry and wet anomalies and then morph into a pattern with Alaska and the Southern Tier dry and the Northwest and Northeast wet. Unlike the temperature sequence,  the transition between December 13 - 19  and the December 17  - 30 maps appears to be fairly abrupt but that does not mean it  will not happen that way given the 3 - 4 Experimental Forecast covers a two-weak period. When discussing anomalies, "wet" means wetter than usual for this time of the year and "dry" means drier than usual for this time of the year. The graphic shows the level of probability of being different from EC.

.

Here is the NOAA discussion released today December 5, 2016.

6-10 DAY OUTLOOK FOR DEC 11 - 15 2016

TODAY'S MODELS EXHIBIT GOOD AGREEMENT ON THE PREDICTED 500-HPA HEIGHT PATTERN. ABOVE NORMAL HEIGHTS ARE PREDICTED OVER THE BERING STRAIT AND MOST OF THE SOUTHERN TIER OF THE CONUS. TROUGHING OVER CANADA AND THE NORTHERN CONUS ARE ALSO AGREED UPON IN THE MODELS. THE MODELS SHOW SOME DISAGREEMENT IN THE HEIGHTS OVER THE GREAT PLAINS, WITH THE 500-HPA HEIGHTS IN THE EUROPEAN ENSEMBLE MEAN A LITTLE LOWER THAN IN THE GEFS, AND THE 500-HPA HEIGHTS IN THE CANADIAN ENSEMBLE MEAN MUCH HIGHER OVER THE SOUTHERN CONUS. DESPITE THOSE DIFFERENCES, THE OVERALL PATTERNS AGREE ON A BLOCK OFF THE CENTRAL PACIFIC AND AN ENHANCED JET OVER THE CONUS.  

PREDICTED RIDGING OVER THE BERING STRAIT FAVORS BELOW AVERAGE TEMPERATURES AS COLD AIR IS FORECAST TO FUNNEL SOUTHWARD OVER MOST OF ALASKA AND ACROSS CANADA TO THE NORTHERN ROCKIES, GREAT PLAINS AND GREAT LAKES REGION. ABOVE NORMAL SSTS FAVOR ABOVE NORMAL TEMPERATURES FOR PORTIONS OF NORTHERN COASTAL ALASKA AND THE ALEUTIANS. ABOVE AVERAGE HEIGHTS AND LOW-LEVEL HIGH PRESSURE IMPLY ABOVE NORMAL TEMPERATURES FOR THE SOUTHERN TIER OF THE CONUS. 

THE RIDGING OVER THE BERING STRAIT FAVORS A DRIER PATTERN OVER ALASKA AS STORMS WOULD BE DEFLECTED SOUTHWARD. THE SOUTHWARD DISPLACED STORM TRACK, ALIGNED WITH THE SOUTHERN PERIPHERY OF THE TROUGH OVER CENTRAL CANADA, FAVORS ABOVE MEDIAN  PRECIPITATION FOR THE CENTRAL AND NORTHERN ROCKIES, AND FROM THE TENNESSEE VALLEY TO THE GREAT LAKES REGION. THE SLIGHT RIDGING FORECAST OVER THE SOUTHWEST FAVORS BELOW MEDIAN PRECIPITATION FROM SOUTHERN CALIFORNIA TO TEXAS.

FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO  GOOD OVERALL AGREEMENT AMONG THE VARIOUS MODELS AND TOOLS, AND GENERALLY LOW TO MODERATE SPREAD AMONG THE ENSEMBLE MEMBERS

8-14 DAY OUTLOOK FOR DEC 13 - 19 2016 

DURING THE 8-14 DAY PERIOD, MODEL AGREEMENT REMAINS GOOD, ALTHOUGH DISCREPANCIES GROW COMPARED TO THE 6-10 DAY PERIOD. A BLOCKING STRUCTURE IS STILL PREDICTED OVER THE CENTRAL PACIFIC WITH TROUGHING NEAR HAWAII AND RIDGING OVER THE BERING SEA. TROUGHING IS PREDICTED OVER CENTRAL CANADA. THE MODELS DISAGREE ON THE SOUTHERN EXTENT OF THE TROUGHING, WITH THE EUROPEAN ENSEMBLE MEAN DROPPING HEIGHTS OVER THE SOUTHEAST CONUS AND RAISING 500-HPA HEIGHTS OVER THE WESTERN CONUS. THE GFS MAINTAINS A BROAD TROUGH OVER MUCH OF THE CONUS WITH ONLY A MODERATE RAISING OF HEIGHTS FROM THE 6-10 DAY PERIOD. THE CANADIAN  ENSEMBLE MEAN DRAMATICALLY RAISES HEIGHTS OVER THE WESTERN CONUS. THE 500-HPA MANUAL BLEND INCORPORATES THE EUROPEAN ENSEMBLE AND THE GFS BASED SOLUTIONS.

THE RESULTANT BLEND FAVORS BELOW NORMAL TEMPERATURES OVER MUCH OF ALASKA AND THE NORTHERN CONUS AS COLD AIR IS LIKELY TO FLOW SOUTHWARD, EAST OF THE PREDICTED RIDGE OVER THE BERING SEA. THE COLDER AIR IS EXPECTED TO WORK 

SOUTHWARD TO THE GREAT PLAINS, GREAT LAKES REGION, THE ENTIRETY OF THE MISSISSIPPI VALLEY, MID-ATLANTIC AND THE NORTHEAST. WITH THE HEIGHTS PREDICTED TO RISE SLIGHTLY OVER THE WESTERN CONUS, TEMPERATURES ARE EXPECTED TO BE ABOVE NORMAL OVER THE GREAT BASIN AND SOUTHWEST. 

RIDGING PREDICTED OVER THE SOUTHWEST FAVORS BELOW NORMAL PRECIPITATION. THE  ACTIVE STORM TRACK IS PREDICTED FROM THE PACIFIC NORTHWEST TO THE GREAT LAKES REGION, FAVORING ABOVE MEDIAN PRECIPITATION IN THOSE REGIONS. FRONTS ASSOCIATED WITH THE STORM TRACK FAVOR ABOVE MEDIAN PRECIPITATION FOR PORTIONS OF THE SOUTHEAST, ALTHOUGH PROBABILITIES ARE LOWER BECAUSE UNCERTAINTY IS HIGHER OVER THAT REGION.

FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: AVERAGE, 3 OUT OF 5, DUE TO GOOD MODEL AGREEMENT, TEMPERED BY DISAGREEMENTS IN THE PREDICTED HEIGHTS OVER THE SOUTHEAST CONUS.

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

Analogs to the Outlook.

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

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

Day

ENSO

Phase

PDO AMO

Other Comments

Dec 10, 1955 La Nina - + Strong La Nina
Dec 6, 1961 Neutral - +  
Dec 17, 1967 La Nina - - Very Short La Nina
Dec 18, 1967 La Nina - - Very Short La Nina
Dec  18, 1968 El Nino - - Modoki Type II
Nov 18, 1973 La Nina - - Following Strong El Nino
Nov 19, 1973 La Nina - - Following Strong El Nino
Dec 12, 1987 El Nino + N Modoki Type I

 

(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 November 18 to December 18 which is 31 days which is similar to last week. I have not calculated the centroid of this distribution which would be the better way to look at things but the midpoint, which is a lot easier to calculate, is about December 2. These analogs are centered on 3 days and 4 days ago (November 30 or December 1). So the analogs could be considered pretty much in sync with the calendar meaning that we will be getting weather that normally would occur at about this time of year.

For more information on Analogs see discussion in the GEI Weather Page Glossary.

There are two El Nino Analogs (why are there any?), five La Nina Analogs and one ENSO Neutral Analog. The phase of the ocean cycles in the analogs points strongly towards McCabe Condition B. There are some aspects of the 6 - 14 Day Forecast that are consistent with McCabe Condition B.

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

McCabe Condition Main Characteristics
A Very Little Drought. Southern Tier and Northern Tier from Dakotas East Wet
B More wet than dry but Great Plains Dry
C Northern Tier and Mid-Atlantic Drought
D Southwest Drought extending to the North and also the Great Lakes

 

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

Historical Anomaly Analysis

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

Recent CONUS Weather

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

Here is the 30 Days ending November 26, 2016

November 26 2016 30 Day temperature and precipitation departures.

.The temperature pattern has not changed much but soon will. The drought pattern in the West has eased a bit.

And the 30 Days ending December 3, 2016

December 5, 2016 30 Day Temperature and Precipitation Departures

.The temperature warm anomalies have moderated. So has the precipitation pattern. Remember only seven days are added and seven more distant days removed so a 30 average with one week changing is designed to react slowly to the change.

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

Near Term

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

Although I can not display the interactive control panel in my article, I can display any of the graphics it provides so below are the current worldwide precipitation and temperature forecasts for three days out. They will auto-update and be current for Day 3 whenever you view them. If you want the forecast for a different day Click Here

Precipitation

BOM World Preciptation  Wednesday

Notice the extreme low pressure in the Gulf of Alaska and the wet conditions for the Maritime Continent and south of Asia. Brazil is again wet. Remember this is a forecast three days out.

Temperature

BOM Current Temperature Wedensday

Notice the cool anomaly in CONUS along the Rocky Mountains and again further east really in Canada. Also Australia looks to be very warm. And the Himalayas look to be very cold.

Looking Out a Few Months

This is the new precipitation forecast from Queensland Australia.

Queensland Dec -  Feb Precipitation Forecast.

But the above is based on October/November having a rapid rise in SOI which was not the case so I used the option where you can change the assumption to a relatively stable SOI and generated a second forecast.Stable near zero SOIL  forecast for Dec - Feb.

It is kind of amazing that you can make a worldwide forecast based on just one parameter the SOI and changes in the SOI. Recently, we ran a weather column with the Title El Nino or La Nina? The point of that article was simply that ENSO is not solid La Nina at this point. We are getting mixed signals. This project may be based on a mixed signal but it also is based on the lag between the SOI and weather impacts so it may be valid even if the SOI begins to increase now.

Here is the JAMSTEC three month Temperature Forecast.
 

DJF 2016.2017 Temperature JAMSTEC

It is mostly warm but with notable cool areas in Northern Brazil, Australia, and Greenland and Mongolia. 

And here is the three month JAMSTEC  Precipitation Forecast.

D 2016 JF Jamstec Precipitation Forecast

Of interest is the wet Brazil and dry Maritime Continent and parts of Southeast Asia.

And then to get more focus, I extracted and enlarged an image for Europe on the left and CONUS on the right.

JAMSTEC Nov 1, 2016 DJF Focus on Europe CONUS Extract from the Nov 1 Jamstec Precipitation Forecast

 

For many purposes 55N latitude is the dividing line in Europe in regards to the Arctic Oscillation (AO) and the North Atlantic Oscillation (NAO) Impacts. You see that here with Scandinavia wet and southern Europe dry. It is suggestive of AO+. The NAO is highly correlated with the AO so  it is also suggestive of NAO +. For CONUS it is a La Nina pattern but different than shown below for NOAA and it is not a North/South divide. 

There is a short JAMSTEC discussion that relates the seasonal outlook to their El Nino and El Nino Modoki forecasts and this was issued on Tuesday November 22, so here it is:

Nov. 23, 2016 Prediction from 1st Nov., 2016

ENSO forecast:

According to the SINTEX-F prediction, the current La Niña Modoki/La Niña state will continue until spring. [Editor's Note: They explain what they mean by this being a Modoki rather than a true La Nina in a very long detailed explanation which focuses on the Modoki aspects of this Cool Event. We will discuss that next Monday but the simple explanation is that the cool anomaly is not well connected to the coast of South America]. That state will then start decaying and the tropical Pacific will return to a normal state by summer. The model prediction appears to be consistent so far with the observed evolution of the sea surface temperature (SST) anomalies

Indian Ocean forecast:

The negative Indian Ocean Dipole will keep decaying and disappear in winter. The Ningaloo Nino will appear off the west coast of Australia in late austral summer and persist until late austral fall.

Regional forecast:

On a seasonal scale, most part of the globe will experience a warmer-than-normal condition, while some parts of northern Brazil, Australia, and Mongolia will experience a colder-than-normal condition in the boreal winter.

According to the seasonally averaged rainfall prediction, most parts of southern China, southeastern Africa, southern Europe, and eastern/western U.S. will experience a drier condition during boreal winter, while most parts of Brazil, western Central Africa, and South Africa will experience a wetter-than-normal condition. Australia will receive above normal rainfall during austral summer. Northern parts of Japan (including Hokkaido) will be cooler and drier than normal while southern parts of Japan will generally be warmer than normal in winter. However, we note that fluctuating mid- and -high latitude climate in winter may not be captured well by the current model.

Additional forecasts from JAMSTEC including future time periods can be found at this link.

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

My focus here is sea surface temperature anomalies as they are one of the two largest factors determining weather around the World.

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

Daily SST Anomaly

What happened to the presumed La Nina? Did it go into Hibernation? I wonder if NOAA has noticed?
Remember this discussion is all about anomalies not absolute temperatures...so it is deviation from seasonal norms.
The waters north and east of Japan remain very cool as are the waters southwest of Kamchatka Siberia, The Central Indian Ocean is now basically IOD Neutral. The waters off the Southern Coast of Australia are cool but the East Coast is slightly warm. Water north of Australia is slightly warm but less so than one would expect with La Nina. The waters southeast of Africa are cool but to the south are a bit warm. To the west of Africa especially south of the Gulf of Guinea the water is warm.
The overall Northern Pacific no longer looks to be PDO Positive (the horseshoe pattern with the cool anomaly inside the horseshoe shape there) mostly because of the lack of warm water east and south of the cool water. But the cool anomaly is growing. The NOAA Pacific Decadal Oscillation (PDO) Index as reported by NOAA (Washington University also reports the PDO but using a different methodology which results in higher index numbers) has been 2016-January 0.79, 2016- February 1.23, 2016- March 1.55, 2016- April  1.59. 2016- May 1.40, 2016-June 0.76, 2016-July 0.12, 2016-August-0.90, 2016- September -1.09, 2016- October -0.88. The above would make the PDO now NEGATIVE but may becoming less NEGATIVE. Here is the list of PDO values.
The waters west of CONUS are now pretty much neutral probably due to the northerly winds creating upwelling. The Gulf of California is almost neutral. Further north, the Gulf of Alaska is warm close to land with the Bering Straits also warm.but not overly impressive,
The Black Sea is neutral and the Caspian Sea is now just slightly cool. The Mediterranean is just slightly warm.
The Tropical Pacific is NEUTRAL in the Nino 3.4 Measurement areas but cooler to the east connecting to land. That is somewhat of a change.
The U.S. Great Lakes are slightly warm. The North Atlantic is warm. North of Scandinavia and to the east is it is very warm. The Northern and Western Gulf of Mexico is warm.  The waters north of Antarctica East of South America are now warm which is a big change but with a little cool  water further south.
I have some additional commentary on this static analysis of the anomalies below where I examine the four-week change in these anomalies. The list of Atlantic Multidecadal Oscillation (AMO) values can be found here.
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 over the last four weeks. 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 week's version of the graphic to the prior week and report on the differences below.  

December 5,  2016 four week change is SST anomalies

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 this week towards the Dateline the warming along the Equator is impressive. The Pacific cooling trend north of 40N continues to be less intense except off the Coast of CONUS which is very significant. South of Australia the trend is warmer rather than cooler. West of Africa in the Gulf of Guinea the trend has stabilized and similarly south and east of Africa. East if South American the cooling trend has stabilized. 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.  

Look at the Western Pacific in Motion.`

Western Pacific Tropical Activity

The above graphic which I believe covers the area from the Dateline west to 100E and from the Equator north to 45N normally shows the movement of tropical storms towards Asia in the lower latitudes (Trade Winds) and the return of storms towards CONUS in the mid-latitudes (Prevailing Westerlies). This is recent data in motion (last 24 hours) not a forecast. But it provides a pretty good idea of what is heading towards Southeast Asia and the Maritime Continent. It also shows what is headed back towards CONUS. Information on Western Pacific storms can be found here. This is an unofficial private source but one that is easy to read.

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 November 29, 2016 Version and looking at Week 2 of that forecast.
Tropical Hazards

Mostly I see for Week Two (this graphic updates on Tuesdays and I post on Monday which is almost  a week later so Week Two applies unless I go back on Tuesday and update the discussion when the map updates), the period December 7, 2016 to December 13, 2016, it will likely be wet and stormy south of Mainland Asia including to a lesser extent the Maritime Continent but dry further west in the Indian Ocean.

C. Progress of the Cool ENSO Event

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

Starting with Surface Conditions.

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

I have deleted many of the TAO/TRITON graphics we looked at when we were watching El Nino develop and decline. But I saved this 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. Since most of my graphics auto-update,  in order to be able to view a prior version of a particular graphic, I "freeze it" by basically cut and paste to a graphics file and then embed that "frozen graphic" in my article.

January 19, 2016 Frozen TAU/TRITON Graphic

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

The above should be compared to the bottom part of the following graphic. Notice the pattern is remarkably similar. The difference is that in January, the anomaly was a warm anomaly stretching from 130W to 160W and now it is a cool anomaly. When it was a warm anomaly, it was a 3C anomaly in the center ring. Now the center ring is a -0.5C anomaly. So this is opposite to last winter but the intensity is a third or less of the situation last winter.

Current SST and wind anomalies

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

 

I have not provided here the information needed to assess the shift in the cool pool to the east and now south but it is certainly dramatic.

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*

160E

155E

Land

155W

105

50

50
0C or cooler Anomaly

170E

155W

LAND

Land

95

50

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

155W

145W

LAND

Land

60

35

50
-1C or cooler Anomaly

140W

140W

LAND

105W

45

20

35
-1.5C or cooler Anomaly

LAND

135W

LAND

120W

0

0

0

 

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 today only 35 degrees of water anomalies cool enough to be a La Nina. Subtracting 35 degrees from the 50 degrees you end up with 15 degrees of ENSO Neutral and 35 degrees of water cool enough to qualify as La Nina i.e. temperature anomalies more negative than -0.5C. There are today 20 degrees of water along the Equator in the ONI Measurement that is -1C or less which would be cool enough to be a moderate La Nina when just looking at the Equator and there are 0 degrees of -1.5C water. 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 had until recently remained relatively warm especially west of 150W. But now the cool anomaly is fairly well distributed within the Nino 3.4 Measurement Area but the cooler water below is not reaching the surface rapidly and is slowly dissipating.

I calculate the current value of the ONI index (really the value of NINO 3.4 as the ONI is not reported as a daily value) each week using a method that I have devised. To refine my calculation, I have divided the 170W to 120W Nino 3.4 measuring area into five subregions (which I have designated from west to east as A through E) with a location bar shown under the TAO/TRITON Graphic). I use a rough estimation approach to integrate what I see below and record that in the table I have constructed. Then I take the average of the anomalies I estimated for each of the five subregions.

So as of Monday December 5, in the afternoon working from the December 4 TAO/TRITON report, this is what I calculated. [Although the TAO/TRITON Graphic appears to update once a day, in reality it updates more frequently.]

Calculation of ONI from TAO/TRITON Graphic
Anomaly Segment Estimated Anomaly
  Last Week This Week
A. 170W to 160W +0.1 +0.3
B. 160W to 150W +0.1 +0.0
C. 150W to 140W -0.2 -0.3
D. 140W to 130W -0.3 -0.6
E. 130W to 120W -0.3 -0.7
Total -0.6 -1.3
Total divided by five subregions i.e. the ONI (-0.6)5 = -0.1 (-1.3)/5 = -0.3

 

My estimate of the daily Nino 3.4 SST anomaly has become more negative at -0.3 which remains an ENSO Neutral value. NOAA has again reported the weekly ONI to be ENSO Neutral at -0.4. This is the third week in a row that NOAA has reported an ENSO neutral value for Nino 3.4. I wonder if they have noticed that.
Nino 4.0 is reported as being slightly warmer than last week at -0.2. Nino 3 is being reported cooler at -0.5.  Nino 1 + 2 which extends from the Equator south rather than being centered on the Equator is now much warmer at positive +0.1 which is a change from last week but back to the recent pattern. What is left of this Cool Event is now focused on the Eastern Pacific.
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 table form but going back a couple of more years can be found here. 

December 5, 2016 Nino Readings

From Tropical Tidbits.com

CDAS Legacy System

This is from a legacy "frozen" NOAA system meaning the software is maintained but not updated. It seems to show a cycle in the Nino 3.4 Index Values. I see that as I monitor the TAO/TRITON graphic. My best guess is that it is related to the MJO but it certainly is intriguing. If this was read like a stock chart one might conclude that there had been a triple bottom and an upside breakout. Below is a "frozen" version of this graphic with the trend lines for the highs and lows added by the author of this article. .

December 5, 2016 Tropical Tidbits CDAS Nino 3.4 with lines drawn in by Sig Silber

It is kind of a declining wedge (bullish) with an upside breakout not able to move through the upside resistance at +0.4C.  Look for a down phase of the cycle now but most likely not piercing the bottom line drawn.

Sea Surface Temperature and Anomalies

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

December 5, 2016 Equatorial Pacific SST Anomalies

A major advantage of the Hovmoeller method of displaying information is that it shows the history so I do not need to show a sequence of snapshots of the conditions at different points in time. This Hovmoeller provides a good way to visually see the evolution of this ENSO event. I have decided to use the prettied-up version that comes out on Mondays rather that the version that auto-updates daily because the SST Departures on the Equator do not change rapidly and the prettied-up version is so much easier to read. You can see that the cool anomaly (bottom of the Hovmoeller is vanishing right before our eyes with almost no blue, more white and now some yellow. This graphic explains to a large extent the small week to week changes in the Nino 3.4 Index Reading. Remember the +5, -5 degree strip around the Equator that is being reported in this graphic. So it is the surface but not just the Equator.
There is a clear pattern of the Cool Anomaly vanishing first in the western end of the Nino 3.4 Measurement Area and strengthening in the Eastern End. This has been perhaps accelerated by a mild Inactive Phase of the MJO.
The Cool Event sure looks like it has peaked and is in decline. There are now other reasons to believe it is not temporary but the decline phase of this quasi-La Nina Modoki.

In recent weeks I have stopped showing the below graphic which is more focused on the Equator but looks down to 300 meters rather than just being the surface. There has until this week been almost no change from the prior week but over the last month there has been sufficient change to warrant including this graphic this week.

December 5, 2016 Upper Ocean Heat Anoma

NOAA has now dashed-in the upwelling phase of the multiple Kelvin Waves that has created this pseudo-La Nina and you can see that it is playing out just as NOAA upgrades the status of this Cool Event. It is pretty clear that this cool event has peaked and is in the decline phase. It is a disgrace. You can even see what might become a downwelling  Kelvin Wave that will settle the matter.

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

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 and an average of the subsurface heat content to a more detailed view from the surface down.

Current Sub-Surface Conditions.  Notice by the date of the graphic (dated November 29, 2016) that the lag in getting this information posted so the current situation may be a bit different than shown although this graphic was updated today so it is more current than usual. The date shown is the midpoint of a five-day period with that date as the center of the five-day period.

And now the pair of graphics that I regularly provide.

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. At different times and today in particular, I have discussed the difference between the actual values and the deviation of the actual values from what is defined as current climatology (which adjusts every ten years) and how both measures are useful but for different purposes.

The top graphic shows surface temperature anomalies. The coolest water at the surface shows up only in very small non-connected areas.  Water of La Nina coolness but not very intense shows up along the Equator from Dateline to the Coast of Ecuador but with significant gaps of less cool water. The -1C water shows most strongly east of the Nino 3.4 Measurement Area and only very sporadically between 170W to 120W namely 165W to 155W. Notice that the cool anomaly in excess of -1C no longer exists within the Nino 3.4 Measurement Area and appears to be rotating to towards the coast and diminishing in size..How is this cool event to be sustained? It  almost looks like 140W to 120W is about to go totally Neutral.
Notice the warm water at depth west of 165E. We also see some warm water below the cool anomaly. It is not a Kelvin Wave but may be a sign of things to come.

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 again located close to the Dateline at about 175E. This graphic does not show a 27.5C anomaly which might more precisely indicate where convection is likely to occur. The 27C isotherm has perhaps shifted back a bit to 170W so we do not have ideal conditions for significant convection along the Equator east of the Dateline which is a characteristic of a Cool Event. Notice the steepness of the 28C, 27C and 26C Isotherms but they are less steep than recently especially the 26C Isotherm. The 25C isotherm remains at 150W. The 20C Isotherm has moved close to the surface but is not reaching the surface this week. 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 Nino 3.4 Index. So it is still a battle going on with La Nina nudging ahead but not looking like it can sustain itself. It seems to have peaked and begun to decline.
It is why the models are having a hard time figuring out if this it a real deal La Nina or simply a Cool Event that comes close to being a La Nina. They should catch up with the human eye shortly.

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

Although I did not fully 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.

December 5,  2016 Subsurface Temperatures.

There is cool water from 170W to the coast of Ecuador. But the coolest water, however, is only reaching the surface in the Nino 3.4 Measurement Area in two very small areas one very small at around 165W to 155W another which is almost just a point contact with the surface at about 145W. The cooler than -1C anomaly no longer exists in the Nino 3.4 Measurement Area. So there is not much chance of the Nino 3.4 readings rising dramatically any time soon. And there is warmer water under the cool anomaly. The coolest water is over to the east where La Nina is not measured by NOAA. This is probably not the best place to express the thought but this way of measuring an ENSO event leaves a lot to be desired. Only the surface interacts with the atmosphere and is able to influence weather. The subsurface tells us how long the surface will remain cool (or warm). Anomalies are deviations from "Normal". NOAA calculates and determines what is "Normal" which changes due to long ocean cycles and Global Warming. So to some extent, the system is "rigged". Hopefully it is rigged to assist in providing improved weather forecasts. But to assume that any numbers reported can be assumed to be accurate to a high level of precision is foolhardy. It is strange to me that the Asian forecasting services generally conclude that that this cool ENSO Phase is not a La Nina but a near La Nina and NOAA concludes it is a La Nina but they express their confidence in that declaration in percentages. It is the same ocean. The reported readings are very close but the Asian readings are generally slightly higher (less La Nina-ish) than the NOAA reading and their cut-off points for declaring a La Nina are a bit different and the parts of the Equator they look at are a bit different. It might be explained by what part of the ENSO pattern impacts their area of geography but it just seems to me that NOAA is a bit over eager. And I wonder why.

And now Let us look at the Atmosphere.

Low-Level Wind Anomalies near the Equator

Here are the low-level wind anomalies.

Low Level Wlind Anomalies

The Easterlies (the blue) are suddenly again no longer there in the Eastern Pacific probably because of MJO action. I know there is no acknowledged MJO right now but there are diminished Easterlies as if there was an active phase of the MJO right now in the Eastern Pacific. There are Easterlies in the Central Pacific. Some of the forecasts call for a weak Inactive Phase of the MJO which should enhance he Easterlies in the Eastern Pacific.

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

OLR Anomalies Along the Equator

This the graphic used by NOAA to justify the upgrade in status of the Cool Event  based on cloudiness near the Dateline. In the above graphic, the area of convection has expanded westward consistent with the prior wind anomalies. 

And Now the Air Pressure which Shows up Mostly in an Index called the SOI.

This index provides an easy way to assess the location of and the relative strength of the Convection (Low Pressure) and the Subsidence (High Pressure) near the Equator. Experience shows that the extent to which the Atmospheric Air Pressure at Tahiti exceeds the Atmospheric Pressure at Darwin Australia when normalized is substantially correlated with the Precipitation Pattern of the entire World.

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
Nov 29 +3.31 +0.49 +3.27
Nov 30 +0.76 +0.68 +3.49
Dec 1 -5.35 +0.19 +2.99
Dec 2 -7.32 -0.66 +2.72
Dec 3 -7.06 -1.35 +2.49
Dec 4 -1.92 -1.47 +2.44
Dec 5 +6.49 -1.30 +2.52

 

The 30-day average, which is the most widely used measure, as of December 5 is reported at -1.30 which is not much changed since last week. The 90-day average at +2.52 is less La Nina-ish than last week. 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. (Sustained values over +7 are usually associated with La Nina and less than -7 are usually associated with El Nino). To some extent it is the change in the SOI that is of most importance. It had been increasing but may now be stabilizing or going down. That could change but for now the SOI is not signaling a La Nina but ENSO Neutral.

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. November has not been particularly favorable for La Nina development and most likely neither will be December in terms of the MJO.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.The MJO being Inactive is more favorable for La Nina than the MJO being Active. But the MJO goes back and forth from being Active, Inactive, strong and weak so it has mostly a short-term impact. It is possible that a weak Inactive Phase of the MJO might give this dying La Nina a little reprieve. .

Lately, the impact has been fairly muted. But the change in the SOI recently and some other changes suggest that we are having an Active Phase of the MJO even if such is not being reported and what we have is not the MJO but something else that is impacting the cool pool in a similar way as an Active MJO would. The forecast for the MJO is updated weekly and can be found here. If the MJO is not in its Active Phase then perhaps some other pattern is impacting the SOI and also shifting the cool pool to the east. We are also having a non-split fairly strong Jet Stream which is also consistent with an Active MJO. So I am calling it a Stealth MJO.

The MJO tends to be more important when the situation is ENSO Neutral and the MJO can start the process of an El Nino getting started. It is less significant re the initiation of a La Nina but is a factor. It is surprising how weak the MJO has been for months. But it may account for what seems like a cycling of the estimate of Nino 3.4 as the cool water is blown first to the west and then to the east. This impacts the upwelling also.

Forecasting the Evolution of ENSO

The below is first the early-month report from CPC/IRI which I call the reading of the tea leaves in that it is based on a combination of model results and a survey of the views of meteorologists. Recently the early month analysis has been more favorable for a la Nina than the later in the month model-based analysis.I think meteorologists like action so they prefer either El Nino or La Nina to Neutral. But the models are dispassionate about it. November 10, 2016 IRI/CPC Consensus based ENSO forecast.

And now we have the more recent fully model-based version .

November 17, 2016 Model Based ENSO Forecast

There is not a lot of difference but the preference for La Nina conditions in NDJ is a bit less than a week earlier when the report was based mainly on a survey of meteorologist. When I see DJF I notice that January is the middle month in the DJF three-month period. Thus it seems that January is probably the last month that will have Nino 3.4 values equal to or under -0.5. When I look at the slightly higher probability for Nino 3.4 to be -0.5 or less as compared to Nino 3.4 to be in the Neutral Range, I am not blown away by the probability that we will be in La Nina condition into 2017..We are now past mid-November so to me the story-line should be the imminent end of the Cool Event rather than upgrading the Status of the Cool Event.

Here is the daily PDF and Spread Corrected version of the NOAA CFSv2 Forecast Model.

 CFS.V2 SST Forecast

Notice the NOAA forecast (which is not  generally recognized as a  very accurate tool) shows the value of NINO 3.4 enters the Neutral Range in December and remains less than 0C through the summer. Thus we should expect that NOAA on December 8 will lower the La Nina Status to reflect ENSO Neutral.  .

The full list of weekly values can be found here.

Forecasts from Other Meteorological Agencies.

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

Australia POAMA ENSO model run

Discussion (notice their threshold criteria are different from NOAA but also their actuals are higher than recorded by NOAA and yet Nino 3.4 is standard. So someone is incorrect OR WORSE.)

La Niña no longer likely in the coming months

The El Niño–Southern Oscillation (ENSO) in the tropical Pacific Ocean remains neutral (neither El Niño nor La Niña). Although some very weak La Niña-like patterns continue (such as cooler than normal ocean temperatures and reduced cloudiness in the central and eastern Pacific), La Niña thresholds have not been met. Climate models and current observations suggest these patterns will not persist. The likelihood of La Niña developing in the coming months is now low, and hence the Bureau’s ENSO Outlook has shifted from La Niña WATCH to INACTIVE.

The Indian Ocean Dipole (IOD) also remains neutral (neither positive nor negative), as is typical at this time of year. When ENSO and the IOD are neutral they have limited impact on Australian climate.

The climate of Australia, and other countries around the tropical Indian Ocean and western Pacific Ocean, has been strongly influenced during the second half of 2016 by both a strong negative IOD in the tropical Indian Ocean (that ended in November) and the weak La Niña-like pattern in the tropical Pacific (which has eased). This combination of climate drivers contributed to Australia observing its wettest May to September on record in 2016.

We also have the most recent JAMSTEC November 1 ENSO forecast. There should be a new version in a week or so.

JAMSTEC November 1, 2016 Two Year Enso Forecast

The model continues to show ENSO Neutral for the next two years (after what they call a weak La Nina Modoki ends). But the potential for an El Nino has been taken out of the forecast. The JAMSTEC Discussion is shown earlier in this report.

Indian Ocean IOD (It updates every two weeks)

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

IOD POAMA Model Run

Discussion

Indian Ocean Dipole outlooks

The Indian Ocean Dipole (IOD) is neutral. The weekly index value to 4 December was −0.02 °C.

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

However, the continued presence of much warmer than average water to the north and northwest of Australia may see continued influence on Australia, including enhanced rainfall.

D. Putting it all Together.

Looks like this Cool Event is no longer even properly described as La Nina Conditions Apply.

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 may follow  this ENSO Cool Event this summer or perhaps the Cool Event will last for one more year.  The AMO is pretty much neutral at this point (but more positive i.e. warm than I had expected) so it may need to become a bit more negative for the McCabe A pattern to become established. That seems to be slow to happen so I am thinking we need at least a couple more years for that to happen.

E. Relevant Recent Articles and Reports

Weather in the News

Arctic Oscillation and Polar Vortex Analysis and Forecasts

What does it mean? hard to say. The above link takes you to Jonah Cohen's latest blog. Last week he said: "low Arctic sea Ice is also related to a Northwestward espansion of the Siberian High". Whenever the location, size, strength etc of a semi-permanent High or Low is changed, that will impact weather. So that is what I found to be most interesting. The rest is forecasts and forecasts are made and updated on an ongoing basis. I  read the November 30 edition of the blog this evening but now there is a new version and I have not yet read it. I do think this is a very good meteorologist. And I could have listed this under the Global Warming category. I list it hear as I think the AO could be important this winter.

Weather Research in the News

Nothing to report.

Global Warming in the News

My unhappy Life as a Climate Heretic

Antarctic Rift What is that About?

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

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

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

2. Medium Frequency Cycles such as ENSO and IOD

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

4. Computer Models and Methodologies

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

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

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

1. Introduction

2. Climate Impacts of Global Warming

3. Economic Impacts of Global Warming

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

Useful Background Information

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          

 

ONI Recent History

ONI History Updated on December 5, 2016

The Aug/Sept/Oct reading has been issued and is currently listed as -0.7. The Sep/Oct/Nov preliminary estimate is -0.8 so there would now need for there to be two more periods of -0.5 or colder for this to be eligible to be formally recorded as a La Nina. I suspect there will be one more but not two. NOAA seems to be determined to make that happen. THEIR FUNDING MAY DEPEND ON THAT.

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

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

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