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posted on 21 January 2018

NOAA and JAMSTEC Seasonal Outlooks - Is NOAA Slow to Adjust?

Written by Sig Silber

The main focus of this report is the NOAA February, Three-Month and 15-Month Forecasts, the JAMSTEC Three-Season Forecast, and a comparison of the JAMSTEC with the NOAA forecast. There are some areas of agreement for the first season (Spring) and then more divergence for Summer. NOAA only addresses temperature for next Winter while JAMSTEC forecasts a dry West and a wet East. The differences in the forecasts are due to relatively small differences in the estimates of the timing of the demise of the La Nina Conditions and the forecasts for what follows for this coming Summer and Winter. We address the possibility that NOAA is behind the curve re the ENSO Transition.

NOAA Slow to Adjust


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We do not make it a habit to criticize NOAA but their report this month seems to not be as current as it should be with the forecasts of the demise of the La Nina changing rapidly and pretty much in the direction of an earlier demise than most had forecast. This in our opinion compromises the NOAA 15-month forecast beyond the most current months.

As a prelude, we present two sets of graphical information. First the changing assessment by the CPC/IRI which NOAA depends on but which releases its update on January 19 while the prepared NOAA Report was issued on January 18 and secondly very different forecasts of the main NOAA Nino 3.4 Forecast Model and the JAMSTEC Nino 3.4 Forecast Model.

None of this shows which Meteorological Agency is more correct but it does show that it is a volatile situation.

CPC-IRI ENSO Analysis Released on January 19, 2018

Notice than from week to week the FMA probabilities changed from favoring La Nina to Equal Changes. We have previously commented that we believed that La Nina was fading faster than the meteorologists had been predicting mostly because they probably were not looking at the data.

Here are the key model forecasts for the Nino 3.4 Index which is the most important Index for forecasting the phases of ENSO.

Let us look at them side by side. You can click on the images to enlarge them.

NOAA CFSv2 Model JAMSTEC
January 19, 2018 CFSv2 Model Forecast

January 1, 2018 JAMSTEC Forecast

 

You can see the huge difference here where the NOAA Model shows the Nino 3.4 Index remaining in borderline La Nina territory indefinitely while the JAMSTEC model shows the index leaving La Nina Territory perhaps in February but certainly in March and rising now. Of course NOAA does not rely only on the CFSv2 Model but we believe it is a major factor in their forecast maps not changing for the last three iterations of the Seasonal Update Report.
Again, NOAA may be shown to be correct. But it does appear that this month they are slow to react.

Some Housekeeping Issues.

The next Regular Weekly Weather and Climate Report will be published on Monday January 22, 2018. We will cover some information there that is not in tonight's report because it is subsequent to the publication date of the NOAA Update which was Thursday January 18. If you are reading this Update Report and wish to transfer to the Current Weather and Climate Report, Click Here for the list of Weather Posts. That link takes you to the archive of all weather articles written by Sig Silber so you can if the new Weekly Weather Report has been published go there or back to an earlier report but please keep in mind that the graphics in earlier reports in some cases auto-update and the text may no longer apply to the graphics shown. 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.

This report is organized into a summary that has two tables of graphics that show the temperature and precipitation forecasts for the upcoming three seasons and then a lengthy analysis which is organized into three parts:

A. A full discussion of the recent NOAA Seasonal Outlook

B. A comparison between the NOAA and JAMSTEC Forecasts.

C. An analysis of the forecasts for ENSO by NOAA and JAMSTEC and others including the Australian Bureau of Meteorology and other factors influencing the forecasts. This sequence is a change from our usual approach and in way very different than the way I think as the forecast maps are the result of the analysis of current conditions and the forecasts for the drivers of weather. But this reorganization is intended to make the report more readable for those who are mostly interested in the forecasts rather than the "why" behind the  forecasts. To a very large extent, the "why" as perceived by NOAA is very well covered in the NOAA Discussion which is included in Part A. But for those who want more detail, it is available in Part C.

For those who want a quick synopsis of the two forecasts, below is a summary of the temperature and precipitation forecasts for three time-periods and from left to right the NOAA forecast for Alaska and CONUS (the contiguous mid-latitude U.S), then JAMSTEC for North America (which includes Canada and Northern Mexico), and then JAMSTEC for Europe and surrounding areas. Larger graphics are provided later in the report. It is kind of a tease to keep you reading but you can see the evolution of the weather pattern through Spring. Summer and into Fall. For some readers, these two sets of summary graphics may be all the information they wish to look at and that is fine.

Temperature

  NOAA Alaska Plus CONUS JAMSTEC North America JAMSTEC Europe

MAM

Spring

Temp

MAM 2018 US Temperature Issued on January 18, 2018, NOAA Forecast MAM -2018 NA Temperature Based on Jan 1, 2018 JAMSTEC Forecast Mam 2018 Europe Temperature JAMSTEC Jan 1, 2018

JJA

Summer

Temp

JJA 2018 US Temperature Issued by NOAA on January 18, 2018 JJA 2018 NA Temperature based on JAMSTEC Jan 1, 2018 Forecast JJA- 2018 Europe Temperature based on JAMSTEC Jan 1  2018 Forecast

SON

FALL

Temp

SON 2018 Temperature Issued by NOAA on January 18, 2018 SON 2018 NA Temperature based on Jan 1, 2018 JAMSTEC Forecast SON 2018 Europe Temperature Based on Jan 1, 2018 Jamstec Forecast

 

There are not a lot of changes by season in the NOAA forecasts for CONUS and Alaska but there is quite a bit by JAMSTEC as in Spring the Northern Tier is very cool and this gradually moderates through Summer and Fall. For Southern Europe, it goes from cool to very warm to mixed.

Precipitation

  NOAA Alaska Plus CONUS JAMSTEC North America JAMSTEC Europe

MAM

Spring

Precip

MAM 2018 US Precipitation Issued by NOAA on January 18, 2018 MSM 2018 NA Precipitation Based on Jan 1, 2018 JAMSTEC Forecast MAM 2018 Europe JAMSTEC Precipitation Jan 1, 2018 Forecast

JJA

Summer

Precip

NOAA JJA Precipitation Issued on January 18, 2018 JJA 2018 NA Precipitation based on JAMSTEC Jan 1, 2018 Forecast JJA 2018 Europe Precipitation based on JAMSTEC Jan 1, 2018 Forecast

SON

Fall

Precip

SON 2018 Precipitation issued by NOAA on January 18, 2018 SON 2018 US Precipitation based on Jan 1, 2018  JAMSTEC Forecast SON 2018 Europe Precipitation Based on Jan 1, 2018 Jamstec Forecast

 

For NOAA with respect to CONUS precipitation, Spring exhibits a typical La Nina pattern which changes in Summer and is not forecast for Fall. JAMSTEC deviates from the NOAA forecast in Summer and makes a forecast for Fall. For Europe, JAMSTEC shows a progression of a dry anomaly that from season to season moves south.

A. Focus on the NOAA Update

A note about terminology; the deviations from climatology/normal are color coded but also labeled "A" for more than (above) normal and "B" for less than (below) normal. The area designated EC means Equal Chances of being more or less than normal. JAMSTEC relies on their color coding. In my comments I have used EC to cover all the situations where a clear anomaly is not shown. So the words "warm", "cool", "wet", "dry" should be generally interpreted as being relative to climatology/normal for that location and time of year.

First we will take a look at the NOAA Early Outlook for February 2018. It is called the Early Outlook because it will be updated at the end of January. Only the February Outlook will be updated at that time.

Temperature

February 2018 Early Temperature Report Issued on January 18, 2018

Precipitation

February 2018 Early Precipitation Outlook Issued on January 18, 2018

We have nothing to compare these maps with as NOAA does not in their Update provide a forecast for each of the subsequent two months separate from their three-month forecast. Thus I do not have previously forecasted maps for February from the previous NOAA Report to compare against. And the current month is not over so we can not really compare the forecast for next month against the actual for this month. It is probably best to just try to understand what NOAA is trying to convey about February which can be summarized as for temperature we have a cool Northwest extending up into the Alaska Panhandle and a warm Southern Tier and East Coast. Re precipitation, for Alaska the precipitation is related to the temperature i.e. where warm it will be wet and where cool it will be dry. For CONUS the Southern Tier will be dry and there are two Northern Tier wet anomalies one in the North Central and the other covering the Great Lakes and New England.

Now we consider the three-month Outlook.

Notice that the three-month periods are abbreviated e.g. February/March/April is shown as FMA. You will see such abbreviations often in this report.

Prior Temperature Outlook for FMA 2018

FMA 2018 Temperature Outlook Issued December 21, 2017

New Temperature Outlook for FMA 2018

JFM 2018 Temperature Outlook Issued on January 18, 2018

It is hard to see much change other than somewhat changed probabilities of deviation from climatology in the warm Southern Tier and in the Northern Cool Tier which runs from the Mid-Great Lakes west and covers a bit larger area in the new forecast.

Prior Precipitation Outlook for FMA  2018

FMA 2018 Precipitation Outlook Issued on December 21, 2017

New Precipitation Outlook for FMA 2017 - 2918

JFM 2018 Precipitation Outlook issued January 18, 2018

There is again almost no change with some small changes of probabilities in the Southern Tier dry anomaly. Northeast Texas is one area where the change is most apparent. And Southern California is another.

Now let us focus on the long-term situation and compare the new set of maps with the maps issued on December 21, 2017.

Prior 14 Month Temperature Outlook: FMA 2018 - JFM 2019

14 month Temperature Issued December 21, 2017

New 14 Month Temperature Outlook: MAM 2018 - FMA 2019

14 Month Temperature Issued on January 18, 2018

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

The only discernable change in the temperature forecast is that the transition in the Northwest from warmer than climatology to climatology begins one month earlier in OND 2018 rather than NDJ 2018/2019.

Now Precipitation

Prior 14 Month Precipitation Outlook: FMA 2018 - JFM 2019

14 month Precipitation Issued on December 21

New 14 Month Precipitation Outlook: MAM 2018 - FMA 2019

14 Month Precipitation Issued on January 18, 2018

There is no discernable change in the precipitation forecast.

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

Sometimes it is useful to compare the three-month outlook to the forecast for the first of the three months. It shows how much the pattern changes over the three-month period.  

February Plus FMA 2018 Issued on January 18, 2018

One can mentally subtract the First-Month Outlook from the Three-month Outlook and create the Outlook for the last two months in the three-month period.

For both temperature and precipitation if you assume the colors in the maps are assigned correctly, it is a simple algebra equation to solve the month two/three forecast probability for a given location = (3XThree-Month Probability - Month One Probability)/2*. So you can derive the month two/three forecast this way. You can do that calculation easily for where you live or for the entire map.

*The concept is that the probabilities of a deviation from climatology in the First Month and the combined Month Two and Three forecast that one derives must average out to the probabilities shown in the three-month maps.

NOAA Discussion

Below are excerpts (significantly reorganized and with a lot of the redundancy and discussion of methodology removed) from the Discussion released by NOAA on January 18, 2018. Headings that are "Initial Cap" only rather than all caps were added by the Author of this Update Report for clarity. Also we have organized the sequence of the sections of NOAA Discussion to first present the Atmospheric and Oceanic Conditions and then the Initial Month, the Three or Four-month period, and finally the remainder of the 15 Month Forecast. We think that sequence with the three- to four-month period broken out separately, makes the discussion more useful for more readers.

CURRENT ATMOSPHERIC AND OCEANIC CONDITIONS

OCEANIC OBSERVATIONS INDICATE THAT LA NINA CONDITIONS CONTINUED DURING THE PAST MONTHS AS EQUATORIAL SSTS ANOMALIES REMAINED NEGATIVE, AT APPROXIMATELY THE SAME MAGNITUDE, FROM THE DATE LINE TO THE SOUTH AMERICAN COAST. THE LATEST WEEKLY NINO-3.4 INDEX VALUE WAS -0.8 DEG C, AND THE NINO-3 AND NINO-1+2 INDICES WERE AT OR BELOW -1.0 DEG C DURING MUCH OF THE MONTH. NEGATIVE SUB-SURFACE TEMPERATURE ANOMALIES IN THE CENTRAL AND EAST-CENTRAL EQUATORIAL PACIFIC WEAKENED AT THE END OF THE MONTH AS ANOMALOUSLY WARM WATERS IN THE WESTERN PACIFIC AT DEPTHS GREATER THAN 100 M PROPAGATED EASTWARD TO APPROXIMATELY 140W. THE MOST RECENT ONI VALUE (OCTOBER – DECEMBER 2017), BASED ON SST DEPARTURES FROM AVERAGE IN THE NINO 3.4 REGION, IS -0.9 DEGREES C.

THE ATMOSPHERIC CONDITIONS OVER THE TROPICAL PACIFIC OCEAN ALSO REFLECTED LA NINA, WITH SUPPRESSED CONVECTION NEAR AND EAST OF THE INTERNATIONAL DATE LINE AND ENHANCED CONVECTION TO THE NORTH OF INDONESIA. ALSO, THE LOW-LEVEL TRADE WINDS CONTINUED TO BE STRONGER THAN AVERAGE OVER THE WESTERN AND CENTRAL PACIFIC.

THE ENHANCED PHASE OF THE MJO IS FORECAST TO PROPAGATE EAST ACROSS THE MARITIME CONTINENT DURING THE NEXT TWO WEEKS AND MAY REEMERGE OVER THE PACIFIC DURING EARLY FEBRUARY 2018. THIS EVOLUTION OF THE MJO MAY PLAY A ROLE IN THE CIRCULATION PATTERN AND TEMPERATURES ACROSS THE MID-LATITUDES OF NORTH AMERICA LATER IN FEBRUARY 2018. LONGER-TERM IMPACTS OF THE MJO ARE UNCERTAIN.

PROGNOSTIC DISCUSSION OF SST FORECASTS

THE CPC SST CONSOLIDATION FORECAST, WHICH INCLUDES THREE STATISTICAL FORECASTS ALONG WITH THE CFS, PREDICTS A TRANSITION FROM LA NINA TO ENSO-NEUTRAL CONDITIONS DURING SPRING 2018 WITH ENSO-NEUTRAL CONDITIONS FAVORED THEREAFTER. THE NORTH AMERICAN MULTI MODEL ENSEMBLE (NMME) ENSEMBLE MEAN FORECAST FOR THE NINO-3.4 SST ANOMALY IS SIMILAR TO THE PREVIOUS MONTH, THOUGH A LITTLE COOLER THROUGH APRIL, WITH A GRADUAL TRANSITION TO ENSO-NEUTRAL CONDITIONS AFTER THE NORTHERN HEMISPHERE WINTER. BASED ON THE LATEST OBSERVATIONS AND MODEL FORECASTS, THE OFFICIAL CPC/IRI ENSO OUTLOOK FAVORS ENSO-NEUTRAL CONDITIONS BY AMJ 2018. [Editor's Note: The latest CPC/IRI Report suggests that it will happen a month earlier]

30-DAY OUTLOOK DISCUSSION FOR FEBRUARY 2018  

LA NINA CONDITIONS CONTINUED INTO MID-JANUARY, WITH NEGATIVE SEA SURFACE TEMPERATURE (SST) ANOMALIES OBSERVED ACROSS THE CENTRAL AND EASTERN PACIFIC OCEAN FROM NEAR THE DATE LINE TO THE COAST OF SOUTH AMERICA. THE COUPLED ATMOSPHERIC RESPONSE TO LA NINA WAS OBSERVED AS WELL, WITH POSITIVE OUTGOING LONGWAVE RADIATION (OLR) ANOMALIES DUE TO REDUCED CONVECTION NEAR THE DATE LINE AND NEGATIVE OLR ANOMALIES DUE TO ENHANCED CONVECTION OVER PARTS OF THE MARITIME CONTINENT. THE LOW-LEVEL EASTERLIES OBSERVED AT THE 850-HPA LEVEL WERE ENHANCED OVER THE WESTERN PACIFIC. LA NINA IS EXPECTED TO IMPACT THE TEMPERATURE AND PRECIPITATION PATTERNS IN FEBRUARY OVER NORTH AMERICA. TROPICAL CONDITIONS PROJECT ONTO THE MADDEN-JULIAN OSCILLATION (MJO) PHASE 4, WITH ENHANCED CONVECTION OVER THE MARITIME CONTINENT. DYNAMICAL MODELS PREDICT PROPAGATION OF THE ACTIVE MJO INTO THE WESTERN PACIFIC IN EARLY FEBRUARY. A PREDICTED ACTIVE MJO, WITH THE ONGOING LA NINA BASE STATE, COULD IMPACT CLIMATE VARIABILITY IN FEBRUARY, INCREASING THE UNCERTAINTY IN THE AVERAGE FEBRUARY FORECAST. THE CURRENT MJO PHASE AND FORECAST INCREASE THE LIKELIHOOD OF ABOVE NORMAL TEMPERATURES OVER THE EASTERN CONUS AND BELOW NORMAL TEMPERATURES IN THE NORTHWEST EARLY IN THE MONTH.

Temperature

THE FEBRUARY TEMPERATURE OUTLOOK RELIES PRIMARILY ON CALIBRATED PROBABILITIES OF ABOVE AND BELOW NORMAL TEMPERATURES FROM THE NORTH AMERICAN MULTI-MODEL ENSEMBLE (NMME), WITH CONSIDERATION OF THE IMPACTS OF AN ONGOING LA NINA, AS EXPRESSED THROUGH BRIDGING OF PREDICTED NINO 3.4 REGION SST ANOMALIES AND CALIBRATED TEMPERATURE PROBABILITIES, USING STATISTICAL FORECASTS OF ENSO IMPACTS. ADDITIONAL CONSIDERATION WAS GIVEN TO DYNAMICAL MODEL FORECASTS FOR THE BEGINNING OF FEBRUARY THAT ARE IMPACTED BY AN ACTIVE MJO.  

THE FEBRUARY TEMPERATURE OUTLOOK INDICATES INCREASES IN THE PROBABILITIES OF ABOVE NORMAL TEMPERATURES FOR THE U.S. SOUTHWEST, NORTHWARD TO SOUTHERN WYOMING. INCREASED PROBABILITIES OF ABOVE NORMAL TEMPERATURES EXTEND EASTWARD TO THE SOUTHERN GREAT PLAINS, THE GULF COAST, AND THE SOUTHEAST REGION, AND EXTEND NORTHWARD ALONG THE EAST COAST TO NEW ENGLAND. PROBABILITIES ARE HIGHEST FOR PARTS OF THE SOUTHWEST AND SOUTHERN TEXAS AND LOUISIANA, CONSISTENT WITH DECADAL TEMPERATURE TRENDS AND LA NINA IMPACTS. THE LIKELIHOOD OF ABOVE NORMAL TEMPERATURES ARE REDUCED OVER NEW ENGLAND AND EQUAL CHANCES IS INDICATED OVER THE MIDWEST, AS WELL AS MUCH OF SOUTHERN CALIFORNIA AND NEVADA, WHERE VARIABILITY RELATED TO MJO AND LA NINA INCREASE UNCERTAINTY IN THE NMME PREDICTED FEBRUARY MEAN TEMPERATURES. BELOW NORMAL TEMPERATURES ARE MOST LIKELY FOR SOUTHEASTERN REGIONS OF ALASKA AND PARTS OF THE PACIFIC NORTHWEST, FROM NORTHERN CALIFORNIA INTO OREGON AND WASHINGTON, AND EASTWARD INTO MONTANA, ASSOCIATED WITH PREDICTED TEMPERATURE PROBABILITIES FOR EARLY FEBRUARY RESULTING LARGELY FROM THE COMBINED IMPACTS OF LA NINA AND THE MJO. ABOVE NORMAL TEMPERATURES ARE MOST LIKELY FOR WESTERN AND NORTHERN ALASKA, AS INDICATED BY NMME DYNAMICAL MODEL FORECASTS AND DECADAL TRENDS.  

Precipitation

THE FEBRUARY PRECIPITATION OUTLOOK, RELYING PRIMARILY ON THE PROBABILITY-ANOMALY-CORRELATION CALIBRATED PROBABILITIES FROM THE NMME, RESEMBLES THE CANONICAL IMPACTS DUE TO LA NINA, WITH GREATER UNCERTAINTY RELATED TO ADDITIONAL CLIMATE FORCING SUCH AS THE MJO. ABOVE NORMAL PRECIPITATION IS MOST LIKELY FOR PARTS OF THE NORTHERN ROCKY MOUNTAINS, FROM NORTHERN UTAH INTO EASTERN OREGON AND WASHINGTON, AS WELL AS IDAHO, MONTANA AND WESTERN WYOMING. MONTHLY AVERAGE PRECIPITATION IS MOST LIKELY TO BE ABOVE NORMAL FOR THE MIDWEST FROM THE CENTRAL AND UPPER MISSISSIPPI VALLEY INTO THE OHIO VALLEY AND GREAT LAKES REGION. ABOVE NORMAL PRECIPITATION IS ALSO MOST LIKELY TO THE EAST IN NEW ENGLAND, HOWEVER WITH GREATER UNCERTAINTY. BELOW NORMAL PRECIPITATION IS MOST LIKELY ACROSS THE SOUTHERN CONUS FROM NEW MEXICO ACROSS TEXAS AND THE GULF COAST TO THE SOUTHERN ATLANTIC COAST, FOLLOWING CANONICAL IMPACTS OF LA NINA AS PREDICTED BY CALIBRATED PROBABILITY FORECASTS FROM THE NMME. EQUAL CHANCES OF ABOVE, NEAR OR BELOW NORMAL PRECIPITATION IS INDICATED FOR THE WEST COAST OF THE CONUS AND WESTERN AREAS OF THE SOUTHWEST, WHERE UNCERTAINTY IS GREATER DUE TO VARIABILITY IN DYNAMICAL MODEL FORECASTS. THE INCREASED LIKELIHOOD OF BELOW NORMAL PRECIPITATION INDICATED FOR SOUTHEASTERN ALASKA INCLUDING THE PANHANDLE IS A CANONICAL IMPACT OF AN ONGOING LA NINA. ABOVE NORMAL PRECIPITATION IS MOST LIKELY FOR WESTERN AND NORTHERN ALASKA, AS INDICATED BY NMME FORECAST PROBABILITIES.

BASIS AND SUMMARY OF THE CURRENT LONG-LEAD OUTLOOKS

PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS THE TEMPERATURE AND PRECIPITATION OUTLOOKS FOR FMA 2018 WERE BASED ON DYNAMICAL MODEL GUIDANCE AND STATISTICAL TOOLS THAT INCLUDE A CONSTRUCTED ANALOG BASED ON GLOBAL SST ANOMALY PATTERNS AND REGRESSIONS OF TEMPERATURE/PRECIPITATION ON THE CPC CONSOLIDATED NINO3.4 OUTLOOKS. DURING THE NEXT FOUR LEADS (MAM THROUGH JJA 2018), THE FACTORS IN CREATING THE SUBSEQUENT OUTLOOKS WERE THE CALIBRATED PROBABILISTIC FORECASTS FROM THE NMME, TRENDS, THE CPC CONSOLIDATION, AND REGRESSIONS OF TEMPERATURE/PRECIPITATION ON THE CPC CONSOLIDATED NINO3.4 OUTLOOKS. THE LATER OUTLOOKS THROUGH NEXT WINTER 2018-19 WERE BASED ON TRENDS AND THE CPC CONSOLIDATION FORECAST.

Three Month FMA 2018

Temperature

ABOVE-NORMAL TEMPERATURES DURING FMA 2018 ARE MOST LIKELY, WITH A GREATER THAN 60 PERCENT CHANCE, TO BE OBSERVED ACROSS THE SOUTHWESTERN CONUS, WHICH IS CONSISTENT WITH REGRESSIONS OF TEMPERATURE ON LA NINA RELATED OCEANIC CONDITIONS, VARIOUS STATISTICAL TOOLS, DYNAMICAL MODEL FORECASTS, AND TRENDS. ABOVE-NORMAL TEMPERATURES, ALBEIT WITH LOWER PROBABILITIES, ARE ALSO FAVORED FOR THE GULF COAST STATES AND ALONG THE EAST COAST, BASED ON GOOD AGREEMENT AMONG THE DYNAMICAL MODELS. THE ODDS FOR ABOVE-NORMAL TEMPERATURES FOR THE AREAS FROM THE TENNESSEE VALLEY TO THE MID-ATLANTIC COAST, AND FOR THE CENTRAL CALIFORNIA COAST, ARE SLIGHTLY LOWER THAN WHAT WAS INDICATED FOR FMA 2018 FROM THE DEC 2017 RELEASE. MODELS OUTPUT AND CONSTRUCTED ANALOGS BASED ON SST PATTERNS INDICATE A SLIGHTLY COOLER PATTERN FOR SOME AREAS EAST OF THE ROCKIES, WHEN COMPARED TO LAST MONTH, SO THAT NEWER INFORMATION WAS INCORPORATED. LA NINA TEMPERATURE COMPOSITES DURING FMA SUPPORT BELOW-NORMAL TEMPERATURES ACROSS THE PACIFIC NORTHWEST, NORTHERN ROCKIES, NORTHERN GREAT PLAINS, AND UPPER MISSISSIPPI VALLEY. SOME STATISTICAL METHODS CONTINUE TO OFFER A COLDER SOLUTION ACROSS THESE AREAS COMPARED TO THE DYNAMICAL MODELS. BELOW-NORMAL TEMPERATURES ARE SLIGHTLY FAVORED FROM THE PACIFIC NORTHWEST TO THE GREAT LAKES REGION, GIVEN THE WELL-ESTABLISHED LA NINA CONDITIONS AND ASSOCIATED TELECONNECTIONS.  BELOW-NORMAL TEMPERATURES ARE ALSO FAVORED OVER SOUTHERN ALASKA, SUPPORTED BY MODEL OUTPUTS AND STATISTICALLY BASED RELATIONSHIPS WITH LA NINA.

Precipitation

THE FMA 2018 PRECIPITATION OUTLOOK IS BASED ON PRECIPITATION SIGNALS ASSOCIATED WITH LA NINA AND INPUT FROM THE SUITE OF NMME DYNAMICAL MODELS. PRECIPITATION TOOLS FAVOR A TIGHT GRADIENT BETWEEN AREAS FAVORED TO RECEIVE BELOW- AND ABOVE-NORMAL PRECIPITATION ACROSS THE SOUTHERN TO NORTHERN TIER OF THE CONUS, RESPECTIVELY. BASED ON GOOD AGREEMENT AMONG MOST OF THE DYNAMICAL MODEL FORECASTS INCLUDING THE NMME AND IMME, A SLIGHT TILT IN THE ODDS FOR BELOW-NORMAL PRECIPITATION COVERS PORTIONS OF CENTRAL CALIFORNIA AND ALL OF SOUTHERN CALIFORNIA. THIS FAVORED AREA FOR BELOW-NORMAL PRECIPITATION IS ALSO CONSISTENT WITH PRECIPITATION COMPOSITES FROM BACK-TO-BACK LA NINA WINTERS. THE AREA WHERE BELOW-NORMAL PRECIPITATION IS FAVORED DURING FMA 2018 IS SLIGHTLY SMALLER THAN THE AREA DEPICTED IN LAST MONTH'S FMA OUTLOOK, REFLECTING NEWER MODEL OUTPUT. THE HIGHEST PROBABILITIES (EXCEEDING 50 PERCENT CHANCE FOR BELOW-NORMAL PRECIPITATION) IN THE PRECIPITATION OUTLOOK FOR FMA ARE FORECAST ACROSS SOUTHERN GEORGIA AND FLORIDA, AND PORTIONS OF THE SOUTHWEST.

PROGNOSTIC DISCUSSION OF OUTLOOKS - FMA 2018 TO FMA 2019 (with a focus on periods beyond FMA)

TEMPERATURE

THE TEMPERATURE OUTLOOK FOR MAM 2018 HAS MORE COVERAGE FOR ABOVE-NORMAL TEMPERATURES AND LESS FOR BELOW-NORMAL TEMPERATURES THAN FOR FMA. AREAS WHERE BELOW-NORMAL TEMPERATURES ARE NOW FAVORED ARE RESTRICTED TO THE PACIFIC NORTHWEST AND NORTHERN ROCKIES. TELECONNECTIONS FROM LA NINA TYPICALLY WEAKEN DURING THE SPRING AND A SHIFT TO ENSO-NEUTRAL CONDITIONS IS LIKELY TO OCCUR DURING THE SPRING. THE COOLER SHIFT, RELATIVE TO THE LAST RELEASE AS MENTIONED ABOVE, IS CONTINUED IN THE OUTLOOKS THROUGH AMJ 2018. THE TEMPERATURE OUTLOOKS FROM AMJ THROUGH JJA 2018 ARE BASED LARGELY ON THE CALIBRATED PROBABILITY FORECASTS FROM THE NMME ALONG WITH TRENDS. AN INCREASING CHANCE OF DROUGHT BECOMING ENTRENCHED OVER THE SOUTHWEST AND SOUTHERN PLAINS CONTRIBUTES TO ELEVATED ODDS FOR ABOVE NORMAL TEMPERATURES ELEVATED OVER THOSE REGIONS THROUGH JJA 2018. THE IMPACT OF SOIL MOISTURE ON TEMPERATURE IS MOST PRONOUNCED DURING THE WARM SEASON.

PRECIPITATION

BASED ON THE LATEST NMME CALIBRATED PROBABILITY FORECAST, BELOW-NORMAL PRECIPITATION IS FAVORED ACROSS THE SOUTHERN HIGH PLAINS THROUGH MJJ 2018.

COVERAGE OF FAVORED AREAS FOR ANOMALOUS PRECIPITATION DECREASE DURING THE SUMMER AS FORECAST CONFIDENCE DIMINISHES WITH A WEAKENING SIGNAL AMONG TOOLS AND CONVECTIVE PRECIPITATION BECOMES MORE DOMINANT. DURING JJA AND JAS 2017, BELOW (ABOVE)-NORMAL PRECIPITATION IS FAVORED FOR THE PACIFIC NORTHWEST (NORTHEAST), RELATED TO HISTORICAL TRENDS AND SIGNALS IN THE CPC CON.

B. Now we begin our comparison of the NOAA and JAMSTEC Forecasts (Focus on next nine months i.e. three seasons)

In this Update, we compare the JAMSTEC temperature and precipitation forecast maps, which are for the World, with the NOAA temperature and precipitation forecast maps that cover only CONUS and Alaska. We do this primarily for educational purposes.

JAMSTEC works in three-month intervals which correspond to seasons and does not change the selection of months each time they update but does so every three months. At that time they drop one season and add another season further in the future. So for JAMSTEC we now have Spring (MAM 2018), Summer (JJA), and Fall (SON)  to work with and we have the corresponding maps from NOAA (except that for NOAA we also have FMA 2018 maps but we are not using them in this comparison in order to match the time periods that are provided by JAMSTEC. Earlier we did show the new maps for FMA compared to the maps issued  on December 21, 2018

I show the NOAA Maps first followed by the JAMSTEC maps. I extract North America from the Worldwide JAMSTEC map and use that to compare with the NOAA Maps. I also extract Europe including parts of North Africa and Western Asia from the Worldwide JAMSTEC maps and include it in the summary table at the beginning of this article.

MAM 2018 (Spring)

Temperature

NOAA (we use their MAM 2018 map)

MAM 2018 US Temperature Issued on January 18, 2018, NOAA Forecast

And here is the MAM 2018  temperature forecast for North America that I extracted from the JAMSTEC World Forecast

MAM 2018 NA Temperature Based on Jan 1, 2018 JAMSTEC Forecast

They are similar but JAMSTEC shows a much cooler Northern Tier which extends to the East Coast.

And now the JAMSTEC WORLD FORECAST (for this graphic my comments are mostly related to areas other than Alaska and CONUS as those comments appear with the larger graphics above)

MAM 2018 World Temperature Forecast from JAMSTEC Jan 1, 2018 forecast.

For the World, JAMSTEC shows a cool Europe and Northern CONUS, Northern South America, Equatorial Africa, Southern Africa, Northern Australia and India as well as most of Eastern Siberia.  There is a very warm area shown around the Caspian Sea. .

Precipitation

NOAA (and again we use their MAM 2018 map)

MAM 2018 US Precipitation Issued by NOAA on January 18, 2018

And here is the MAM 2018 Precipitation Forecast for North America that I extracted from the JAMSTEC World Forecast.

MAM 2018 NA Precipitation Based on Jan 1, 2018 JAMSTEC Forecast

These are quite similar except for East Texas and some states east of Texas where JAMSTEC shows things to be a bit wetter than NOAA.

JAMSTEC WORLD FORECAST

MAM 2018 Jamstec Precipitation Forecast From Jan 1, 2018

Of interest is the wet British Isles. Southeast Asia is dry.

Here is the precipitation forecast from Queensland Australia: Notice it covers JFM 2018. A FMA 2018 forecast will be available on February 1.

Rapidly falling SOI  forecast for January to March 2018

It is kind of amazing that you can make a worldwide forecast based on just one parameter the SOI and changes in the SOI. In this graphic, CONUS precipitation looks more like an El Nino pattern with a dry Northwest. Southern Africa is wet. Eastern Australia is wet, Europe is dry and parts of Eastern Siberia are dry. There is quite a bit of resemblance to the JAMSTEC forecast.

JJA  (Summer)

Temperature

NOAA

xJJA 2018 US Temperature Issued by NOAA on January 18, 2018

And here is the JJA  2018 Temperature Forecast for North America that I extracted from the JAMSTEC World Forecast

JJA 2018 NA Temperature based on JAMSTEC Jan 1, 2018 Forecast

There is a lot of difference here with JAMSTEC showing much more cool area both in Alaska and CONUS.

JAMSTEC WORLD FORECAST

JJA 2018 JAMSTEC Temp from Jan 1, 2018

For JAMSTEC we see a big change for the area around the Caspian Sea. India is now warm in this season. Eastern Siberia is cold.

Precipitation

NOAA

NOAA JJA Precipitation Issued on January 18, 2018

And here is the JJA 2018 Precipitation Forecast for North America that I extracted from the JAMSTEC World Forecast

JJA 2018 NA Precipitation based on JAMSTEC Jan 1, 2018 Forecast

Almost opposites. Of special importance is the Northeast which NOAA shows as wet and JAMSTEC shows as dry. JAMSTEC  also shows Arizona having a poor Monsoon.

JAMSTEC WORLD FORECAST

JJA 2018 JAMSTEC Precipitation Forecast from Jan 1, 2018

For JAMSTEC we see a wet West Africa near the Equator and a dry India and Southeast Asia. Europe remains dry.

SON 2018 (Fall)

Temperature

NOAA

SON 2018 Temperature Issued by NOAA on January 18, 2018

And here is the SON 2018 Temperature Forecast for North America that I extracted from the JAMSTEC World Forecast

SON 2018 NA Temperature based on Jan 1, 2018 JAMSTEC Forecast

The pattern is somewhat similar. NOAA shows warm all over. JAMSTEC shows a cool Southern Alaska and the Panhandle and a cool area for a number of Gulf States.

JAMSTEC WORLD FORECAST

SON 2018 JAMSTEC Temperature from Jan 1, 2018

The cool areas are far Western Europe, North Africa, east of the Caspian Sea, extreme South America, Greenland and far Eastern Siberia. Australia and much of Siberia and India are forecast to be warm.

Precipitation

NOAA

SON 2018 Precipitation issued by NOAA on January 18, 2018

And here is the SON 2018 Precipitation Forecast for North America that I extracted from the JAMSTEC World Forecast

SON 2018 US Precipitation based on Jan 1, 2018  JAMSTEC Forecast

NOAA does not go out on a limb that far out and shows Alaska and CONUS as EC. JAMSTEC shows somewhat of a west to east split with the West mostly dry and the East mostly wet.

JAMSTEC WORLD FORECAST

JAMSTEC SON 2018. Precipitation from 1 Jan 2018

Europe again is dry especially to the south. Same for Southeast Asia. Australia is moderately dry. Overall it is a more moderate pattern than the earlier seasons.

Conclusion

For Alaska and CONUS, we have substantial agreement on how Spring will unfold but beyond Spring, there is a lack of agreement. The JAMSTEC maps also provides a worldview that NOAA does not.       

One value of doing this sort of analysis is that as the projected value of Nino 3.4 changes, we have the basis for extrapolating between these two sets of forecast maps if the Nino 3.4 forecasts come closer together. If they become farther apart, it may still be possible to make some reasonable guesses as to how this will impact weather. This approach may be very useful this month since NOAA and JAMSTEC have somewhat different forecasts for Nino 3.4 for the Summer and Fall Seasons.

C. An analysis of the forecasts for ENSO by NOAA and JAMSTEC and others including the Australian Bureau of Meteorology

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 in order to follow the discussion below, but here is a link to TAO/TRITON terminology.

And here is the current version of the TAO/TRITON Graphic. The top part shows the actual temperatures, the bottom part shows the anomalies i.e. the deviation from normal.Current SST and wind anomalies January 18, 2018

Location Bar for Nino 3.4 Area Above and Below

------------------------------------------------ A B C D E -----------------

 

The cool anomaly (cooler than -0.5C) barely exists in the Nino 3.4 Measurement Area. The cool water is further east. The Nino 3.4 Measurement area extends from 170W to 120W and five degrees north and south of the Equator.

Now we look at the current reported values of the various Nino Indices. 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 graphic form but going back a couple of more years can be found here.  The full table of values can be found here.

January 15, 2018 Nino Readings

This graphic brings the Nino 3.4 up to date and is easy to read.

BOM Nino 3.4 January 19, 2018

You can see that this is a double dip La Nina. It appears to have bottomed out.

This is probably the best place to AGAIN express the thought that this way of measuring an ENSO event leaves a lot to be desired. Only the surface interacts with the atmosphere and is able to influence weather. The subsurface tells us how long the surface will remain cool (or warm). Anomalies are deviations from "Normal". NOAA calculates and determines what is "Normal" which changes due to long ocean cycles and Global Warming. So to some extent, the system is "rigged". Hopefully it is rigged to assist in providing improved weather forecasts. But to assume that any numbers reported can be assumed to be accurate to a high level of precision is foolhardy.

This overlaps with the next topic but I will show it here.

January 15, 2018 Upper Ocean Heat anamaly

The discussion in this slide says it better than I could.

A side by side comparison can be useful. I saved the graphic on the left from the third week of December 2017.

Comparison Week Probably Third Week of December 2017 Current Week

Equatorial (0 - 300) meter heat content As reported December 18, 2017

January 15, 2018 Upper Ocean Heat anamaly

 

You can see the relentless decline in the Eastern Pacific cool-water anomaly. We believe the forecast models are not giving sufficient weight to this data.

Anomalies are strange. You can not really tell for sure if the blue area is colder or warmer than the water above or below. All you know is that it is cooler than usual for this time of the year. A later graphic will provide more information. Aside from buoyancy the currents and easterly winds tend to bring water from that depth up to the surface mostly farther east.

Now for a more detailed look. Below is the pair of graphics that I regularly provide. The date shown is the midpoint of a five-day period with that date as the center of the five-day period. 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 I have discussed the difference between the actual values and the deviation of the actual values from what is defined as current climatology (which adjusts every ten years except along the Equator where it is adjusted every five years) and how both measures are useful for other purposes.

There is cool water at the surface from 170W to Land. At  the west end of the cool anomaly it is not consistently even 100 meters deep (it was once over 200 meters deep). We now have warm water developing west of the Dateline and crossing the Dateline at depth all the way to 140W and beyond. Thus it is now intruding far into the Eastern Pacific Nino 3.4 Measurement Area but at depth not at the surface. La Nina's days are numbered but in terms of a month or two not weeks or days but probably not three or four months as some models are suggesting.
Subsurface temperature Anomalies January 13, 2018
The 28C Isotherm is at the Dateline, the 27C Isotherm is at the 170W, the 25C Isotherm is now all the way to 150W and the 20C Isotherm is barely reaching the surface. The pattern has recently shifted a bit further to the east but the Active Phase of the MJO has passed where it has the most effect and the pattern farthest east has shifted back signifying a more rapid decline in the La Nina as the cooler water is now being brought to the surface where it will warm or be dispersed.

 

The flattening of the Isotherm Pattern is an indication of ENSO Neutral just as the steepening of the pattern indicates La Nina or El Nino depending on where the slope shows the warm or cool pool to be. That flattening has occurred and we have gone to a weak La Nina thermocline.

Tracking the change.

Sepember 15, 2017 Subsurface Water Temperatures Equatorial Ocean Subsurface as of January 13, 2018

 

I have "frozen" the graphic on the left side above which shows the situation as reported for September 15, 2017. The one on the right is the current situation. The situation with the cool anomaly is not much different east of the Dateline from the situation as reported for September 15, 2017 but it is a little different. West of the Dateline it looks a lot different  i.e. warmer. We use the graphic on the left as a reference to see how the current situation changes over time. The subsurface warm anomaly has progressed to the east and strengthened substantially. It is not ready to displace or dilute the Eastern Pacific Cool Anomaly just yet but it will not be long. We now see the warm anomaly appearing below the cool anomaly.

But What about the Forecast of the Nino 3.4 Index?

The CFS.v2 is not the only forecast tool used by NOAA. The CPC/IRI Analysis which is produced out of The International Research Institute (IRI) for Climate and Society at Columbia University is also very important to NOAA.

This was just released on January 19, 2018

january 19, 2018 CPC/IRI ENSO Analysis.

If you scrutinized the latest analysis from the earlier, what you see is that in the earlier analysis the time when the probability of La Nina versus Neutral was FMA and now it is MAM one month later so that is the difference in the forecasts. As an aside, we think it may happen even sooner.

January 19, 2018 CPC/IRI ENSO Analysis

This is the discussion

IRI ENSO Forecast

IRI Technical ENSO Update Published: January 19, 2018

Note: The SST anomalies cited below refer to the OISSTv2 SST data set, and not ERSSTv4. OISSTv2 is often used for real-time analysis and model initialization, while ERSSTv4 is used for retrospective official ENSO diagnosis because it is more homogeneous over time, allowing for more accurate comparisons among ENSO events that are years apart. During ENSO events, OISSTv2 often shows stronger anomalies than ERSSTv4, and during very strong events the two datasets may differ by as much as 0.5 C. Additionally, the ERSSTv4 may tend to be cooler than OISSTv2, because ERSSTv4 is expressed relative to a base period that is updated every 5 years, while the base period of OISSTv2 is updated every 10 years and so, half of the time, is based on a slightly older period and does not account as much for the slow warming trend in the tropical Pacific SST.

Recent and Current Conditions

In mid-January 2018, the NINO3.4 SST anomaly was in the upper portion of the weak La Niña range. For December the SST anomaly was -0.79 C, indicating weak La Niña, and for October-December it was -0.70 C, also in that range. The IRI’s definition of El Niño, like NOAA/Climate Prediction Center’s, requires that the SST anomaly in the Nino3.4 region (5S-5N; 170W-120W) exceed 0.5 C. Similarly, for La Niña, the anomaly must be -0.5 C or less. The climatological probabilities for La Niña, neutral, and El Niño conditions vary seasonally, and are shown in a table at the bottom of this page for each 3-month season. The most recent weekly anomaly in the Nino3.4 region was -0.9, showing weak La Niña. The pertinent atmospheric variables, including the lower level zonal wind anomalies, the Southern Oscillation Index and the anomalies of outgoing longwave radiation (convection), have been showing patterns suggestive of La Niña, although the Southern Oscillation has been weak recently. Subsurface temperature anomalies across the eastern equatorial Pacific, while recently weakening significantly, are also still consistent with La Niña. Given the current and recent SST anomalies, the subsurface profile and the La Niña patterns in most key atmospheric variables, it appears we are in the later stage of a weak La Niña.

Expected Conditions

What is the outlook for the ENSO status going forward? The most recent official diagnosis and outlook was issued approximately one week ago in the NOAA/Climate Prediction Center ENSO Diagnostic Discussion, produced jointly by CPC and IRI; it stated that La Niña is strongly favored for the remainder of winter, with a likely transition to ENSO-neutral during spring. A La Niña Advisory was once again issued with that Discussion. The latest set of model ENSO predictions, from mid-January, now available in the IRI/CPC ENSO prediction plume, is discussed below. Those predictions suggest that the SST is most likely to stay in the weak La Niña range for January-March, followed by increasing chances for neutral during spring.

As of mid-December, 80% of the dynamical or statistical models predicts La Niña conditions for the initial Jan-Mar 2018 season, dropping to 48% for Feb-Apr and 28% for Mar-May. For these seasons, no model predicts El Niño conditions, so that the remaining probability is only for neutral conditions. At lead times of 3 or more months into the future, statistical and dynamical models that incorporate information about the ocean’s observed subsurface thermal structure generally exhibit higher predictive skill than those that do not. For the Apr-Jun 2018 season, among models that do use subsurface temperature information, 76% of models predicts neutral conditions and 19% predicts La Niña conditions. For all models, at longer lead times beginning with Feb-Apr 2018, predictions for ENSO-neutral conditions have more than a 50% probability, with probabilities of 75% or more for Apr-Jun to May-Jul. At the end of the forecast range, Aug-Oct and Sep-Nov, the probability for El Niño rises to near 40% and La Niña probabilities decrease to about 5-11%, leaving about 50-55% for neutral.

Note  – Only models that produce a new ENSO prediction every month are included in the above statement.

Caution is advised in interpreting the distribution of model predictions as the actual probabilities. At longer leads, the skill of the models degrades, and skill uncertainty must be convolved with the uncertainties from initial conditions and differing model physics, leading to more climatological probabilities in the long-lead ENSO Outlook than might be suggested by the suite of models. Furthermore, the expected skill of one model versus another has not been established using uniform validation procedures, which may cause a difference in the true probability distribution from that taken verbatim from the raw model predictions.

An alternative way to assess the probabilities of the three possible ENSO conditions is more quantitatively precise and less vulnerable to sampling errors than the categorical tallying method used above. This alternative method uses the mean of the predictions of all models on the plume, equally weighted, and constructs a standard error function centered on that mean. The standard error is Gaussian in shape, and has its width determined by an estimate of overall expected model skill for the season of the year and the lead time. Higher skill results in a relatively narrower error distribution, while low skill results in an error distribution with width approaching that of the historical observed distribution. This method shows probabilities for La Niña at 69% for Jan-Mar, 50% for Feb-Apr, 30% for Mar-May, and decreasing thereafter to 15-20% for Apr-Jun through Sep-Nov. Probabilities for neutral conditions begin at 31% for Jan-Mar, 50% for Feb-Apr, peak at 79% in Apr-Jun, after which they drop to less than 50% for Jul-Sep through Sep-Nov as El Niño probabilities rise, reaching 48% by Sep-Nov.  A plot of the probabilities generated from this most recent IRI/CPC ENSO prediction plume using the multi-model mean and the Gaussian standard error method summarizes the model consensus out to about 10 months into the future. The same cautions mentioned above for the distributional count of model predictions apply to this Gaussian standard error method of inferring probabilities, due to differing model biases and skills. In particular, this approach considers only the mean of the predictions, and not the total range across the models, nor the ensemble range within individual models.

In summary, the probabilities derived from the models on the IRI/CPC plume describe, on average, a preference for weak La Niña conditions for Jan-Mar 2018, a 50% chance for each of La Niña or neutral for Feb-Apr, and neutral having highest probability status from Mar-May through Jul-Sep. Chances for El Niño are small through Apr-Jun 2018, rising to 31% for Jun-Aug and up to 48% by Sep-Nov. A caution regarding this latest set of model-based ENSO plume predictions, is that factors such as known specific model biases and recent changes that the models may have missed will be taken into account in the next official outlook to be generated and issued early next month by CPC and IRI, which will include some human judgment in combination with the model guidance.

The above is based on looking at a variety of models and other information but we should not forget that NOAA has their own model.

CFSv2 spread and bias correct ENSO forecast January 19, 2018

Here is a another view of the same model with on the right the forecasts of the sea surface temperatures that result from the forecast. It is the model as of January 14 and is frozen i.e. will not update.

January 15, 2018 SST Outlook and CSFv2

And here is what is called the plume of a varied of forecast models.

January 19, 2018 Plume of ENSO Forecast Models.

It may not have been available to NOAA when they prepared their January 18 Report as it was released on January 19.

It is not in extreme disagreement with the MAM assessment but suggests there is not much difference in weather impacts from ENSO after JFM as the estimate of the NINO 3.4 Index does not change very much through the end of the forecast period shown in the CFSv2 Model. If you look at the spread among different model runs which are shown on the graphic, does the mean of the model runs mean anything? I think not.

Forecasts from Other Meteorological Agencies.

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

Australia POAMA ENSO model run

And the ENSO Outlook Discussion Issued on January 16, 2018:

Weak La Niña continues over the Pacific

International climate models surveyed by the Bureau indicate that it is likely the event has reached, or will soon reach, its peak. Most of the models indicate that equatorial Pacific sea surface temperatures are likely to warm over the coming months, returning to neutral values between late in the austral summer and mid-autumn. However, three of the eight models maintain temperatures near La Niña thresholds well into the austral autumn. Only one out of the eight models maintains La Niña levels into winter (July).

Sea surface temperatures currently show a clear La Niña pattern, with coolest waters concentrated in the eastern Pacific Ocean. Likewise, some atmospheric indicators such as trade winds and cloudiness also show a clear La Niña signal. However, a continuing build-up of warmer water beneath the surface of the western Pacific is a likely precursor to the end of this event.

In order for 2017–18 to be classed as a La Niña year, thresholds need to be exceeded for at least three months. Most climate models surveyed by the Bureau suggest this event is likely to last through the southern summer, and decay in the early southern autumn of 2018, so these thresholds are likely to be met.

La Niña typically brings above average rainfall to eastern Australia during summer, particularly in northern New South Wales and Queensland. However, a weak La Niña will have less influence on Australian rainfall than a strong event. La Niña events can also increase the likelihood of prolonged warm spells for southeast Australia.

In order for 2017–18 to be considered a La Niña year, NINO3 or NINO3.4 values cooler than −0.8 °C need to be observed for at least three months.

Here is the most recent JAMSTEC forecast issued on January 1, 2018

January 1, 2018 JAMSTEC Forecast

And here is the short discussion issued with the January forecast.

January 18, 2018

Prediction from 1st Jan., 2018

ENSO forecast:

The weak La Niña-like condition will persist until late spring. Then the tropical Pacific will return to a normal state by summer.

Indian Ocean forecast:

A normal state in the tropical Indian Ocean will persist until late spring. Then we expect evolution of a moderately positive Indian Ocean Dipole in summer. However, there is a large uncertainty in the prediction at present because of the large spread in the prediction plumes of the dipole mode index.

Regional forecast:

On a seasonal scale, most part of the globe will experience a warmer-than-normal condition, while some parts of northern/eastern U.S., northwestern Canada, Europe, India, northern Brazil, central and southern Africa, and northern Australia will experience a colder-than-normal condition in boreal spring. As regards to the seasonally averaged rainfall, a wetter-than-normal condition is predicted for some parts of the Philippines, East Australia, and northern Brazil during boreal spring, whereas most parts of Indonesia, Indo-China, Southeast Asia, eastern/southern U.S, and southern Brazil will experience a drier condition during boreal spring.

In spring, most parts of Japan will experience somewhat warmer-than-normal conditions. The southern part will experience drier-than-normal conditions.

Indian Ocean IOD (It is updated every two weeks)

BOM IOD Forecast.

Indian Ocean Dipole Outlook  Discussion Issued January 16, 2018

The Indian Ocean Dipole (IOD) is neutral. The weekly index value to 14 January was −0.33 °C. All six of the climate models surveyed by the Bureau indicate that the IOD will remain neutral into the southern hemisphere winter of 2018.

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

The IOD Forecast is indirectly related to ENSO but in a complex way. It is important to understand how and where the IOD is measured.

IOD Measurement Regions

IOD Positive is the West Area being warmer than the East Area (with of course many adjustments/normalizations). IOD Negative is the East Area being warmer than the West Area. Notice that the Latitudinal extent of the western box is greater than that of the eastern box. This type of index is based on observing how these patterns impact weather and represent the best efforts of meteorological agencies to figure these things out. Global Warming may change the formulas probably slightly over time but it is costly and difficult to redo this sort of work because of long weather cycles.

And Now the Air Pressure to Confirm that the Atmosphere is Reacting to the Sea Surface Temperature Pattern.

The most common way to do that is to use an Index called the SOI. Does the Atmosphere as measured by the SOI Index confirm that we have La Nina Conditions?

SOI values as of January 19, 2018

Normally La Nina Conditions are confirmed by SOI 30 day values that are greater than or equal to +7.0.  El Nino Conditions are confirmed by SOI 30 day values that are less than or equal to -7.0. So right now the 30 Day value is not at all a LA Nina value. What is up with that?

Some believe the rate of change of the SOI Index is as important as the absolute value so notice the change from July through September and month to date in October.

SOI = 10 X [ Pdiff - Pdiffav ]/ SD(Pdiff) where Pdiff = (average Tahiti MSLP for the month) - (average Darwin MSLP for the month), Pdiffav = long term average of Pdiff for the month in question, and SD(Pdiff) = long term standard deviation of Pdiff for the month in question. So really it is comparing the extent to which Tahiti is more cloudy than Darwin, Australia. During El Nino we expect Darwin Australia to have lower air pressure and more convection than Tahiti (Negative SOI especially lower than -7 correlates with El Nino Conditions). During La Nina we expect the Warm Pool to be further east resulting in Positive SOI values greater than +7).

To some extent it is the change in the SOI that is of most importance. The MJO or Madden Julian Oscillation is an important factor in regulating the SOI and Ocean Equatorial Kelvin Waves and other tropical weather characteristics. More information on the MJO can be found here. Here is another good resource.

The SOI Index is quite volatile. So even + or - 7.0 is not that significant. +  or - 20 means something.

SOI Index History

The Nino 3.4 Index and other information is used to forecast Sea Surface Temperatures SSTs around the World. This in turn is used to forecast climate. In the short term, the SST's and other information such as the pattern of Highs and Lows is used to forecast weather. 

The below graphic shows the NOAA and JAMSTEC Sea Surface Temperature (SST) Anomaly forecasts. This is important because weather is determined by patterns of sea surface temperature (SST) variances from normal.  Updates from JAMSTEC can be found here. Updates from NOAA can be found here. You have to look for the SST row and go to the right where it says "normalized with mask" and click on E3 which provides the latest model run..
NOAA SST MAM 2018
Projected JAMSTEC SST DJF 2017/2018

 

The key is the so-called cold tongue (shown in blue) extending west from Ecuador. Do not be fooled by the differences in how the two agencies use color to show the Sea Surface Temperature Anomalies. So we would expect that the two Agencies would be viewing SSTA in a very similar way and in general they are. But JAMSTEC is showing a much less intense cold tongue (remember this is a forecast for MAM not the current conditions) and there are other important differences including the Northern Pacific, the Maritime Continent, the North Atlantic and west of Africa.

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

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