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posted on 18 November 2017

November, 2017 Seasonal Outlook Update - NOAA and JAMSTEC

Written by Sig Silber

Updated on November 22, 2017 to incorporate JAMSTEC's discussion re their Nino 3.4 Forecast which had not been available at the time of publication.

Both NOAA and JAMSTEC believe that La Nina Conditions are present and may last through Winter and into Spring. This leads to similar but not identical forecasts for Alaska and CONUS. We compare these two forecasts and also discuss the JAMSTEC forecast for the rest of the World. The JAMSTEC Nino 3.4 forecast raises the possibility that this period of La Nina and near La Nina Conditions may continue for another year into 2019. The details on this are discussed in this report.

Seasonal Outlook Update


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There was a La Nina last winter and it looks like another one for this winter. It is too soon to tell for sure but there is a possibility that there will be a return visit the following summer.

Here is the current November 1, 2017 JAMSTEC forecast for the Nino 3.4 Index which is the primary forecast index for the phases of ENSO namely El Nino, Neutral, and La Nina all of which depend primarily on the Sea Surface Temperature in a particular part of the Eastern Equatorial Pacific Ocean.

November 1, 2017 JAMSTEC Forecast

NOAA has this week declared that La Nina Conditions currently apply. It is not certain that they will apply long enough for this winter to be declared an official La Nina but it may indeed happen but it may be close. Last winter was a La Nina Winter with a break in between the Nino 3.4 Index again declining to La Nina values. So this current La Nina Condition if it becomes recorded as a full La Nina would be a double dip and that has occurred just five times in modern history. But look at the JAMSTEC forecast for Spring the following year. As shown it is not quite at the La Nina level of -0.5C or less and it certainly is far too early to have any confidence in such a forecast but it is very interesting to be sure. 
The definition of a "double dip" is not real clear. A La Nina that lasts for two years is not a "double dip". It seems that there needs to be a break but the break may be a three-month period that just barely misses meeting the criteria for being a La Nina.  So there is a question for some of the double dips were they really a double dip or might the criteria or measurements turned what really was a continuous La Nina into two. Or alternatively might a continuous La Nina really have had a break if the criteria or measurements were more refined? But if you look at the JAMSTEC Nino 3.4 forecast, if their forecast for Jan 2019 and beyond were to turn into actuals that were just a bit cooler, and if the atmosphere confirmed that it was indeed La Nina Conditions, it would appear that it would be a separate event not a continuation of the possible La Nina for this Winter. So this is an interesting possibility.   

This report is organized into a summary that has two graphics that show the temperature and precipitation forecasts and then a lengthy discusion which is organized into three parts:

A. A full discussion of the recent NOAA Seasonal Outlook

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

C. A comparison between the NOAA and JAMSTEC Forecasts.

But 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 Winter, Spring and into Summer. 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

DJF

Winter

2017-2018

Temp

DJF 2017-2018  US Temperature Issued on November 16, 2017, NOAA Forecast DJF 2017 -2018 NA Temperature Based on Nov 1, 2017 JAMSTEC Forecast DJF 2017 - 2018 Europe Temperature JAMSTEC Nov 1, 2017 Forecast

MAM

Spring

2018

Temp

MAM 2018 US Temperature Issued by NOAA on November 16, 2017 MAM 2018  NA Temperature based on JAMSTEC Nov 1, 2017 Forecast MAM  - 2018 Europe Temperature based on JAMSTEC Nov 1 2017 Forecast

JJA 2018

Summer

Temp

JJA 2018 Temperature Issued by NOAA on November 16, 2017 JJA 2018 NA Temperature based on Nov 1 JAMSTEC Forecast JJA 2018 Europe Temperature Based on Nov 1, 2017 Jamstec Forecast

 

There are not a lot of changes by season in the NOAA or JAMSTEC forecasts for CONUS and Alaska but there is quite a bit by JAMSTEC for Europe with respect to Scandinavia and the British Isles with Spring being different from Winter and Summer.

Precipitation

  NOAA Alaska Plus CONUS JAMSTEC North America JAMSTEC Europe

DJF

Winter

2017/2018

Precip

DJF 2017 US Precipitation Issued by NOAA on November 16, 2017 DJF 2017-2018  NA Precipitation Based on Nov 1, 2017 JAMSTEC Forecast DJF 2017-2018 Europe JAMSTEC Precipitation Nov 1, 2017 Forecast

MAM

Spring

2018

Precip

NOAA MAM Precipitation Issued on November 16, 2017 MAM 2018 NA Precipitation based on JAMSTEC Nov 1, 2017 Forecast MAM- 2018 Europe Precipitation based on JAMSTEC Nov 1, 2017 Forecast

JJA

Summer

2018

Precip

JJA 2018 Precipitation issued by NOAA on November 16, 2017 JJA 2018 US Precipitation based on Nov 1, JAMSTEC Forecast JJA 2018 Europe Precipitation Based on Nov 1, 2017 Jamstec Forecast

 

For NOAA, there is a big change from Spring to Summer. JAMSTEC and NOAA  differ quite a bit with respect to next Summer. JAMSTEC tends to keep Southern Europe dry for Winter and Spring.

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 December 2017. It is called the Early Outlook because it will be updated at the end of November. Only the December Outlook will be updated at that time.

Temperature

December 2017 Early Temperature Report Issued on November 16, 2017

Precipitation

December 2017 Early Precipitation Outlook Issued on November 16, 2017

We have nothing to compare these maps with as NOAA does not in their Update provide a forecast for two months out separate from their three-month forecast. Thus I do not have December maps from the October 19, 2017 NOAA Report to compare against. And November is not over so we can not really compare the December forecast against November actual. It is probably best to just try to understand what NOAA is trying to convey about December which can be summarized as for temperature, the CONUS Southern Tier and Northern Alaska will be warm and Southern Alaska and the Panhandle and the extreme North of CONUS from the middle of Minnesota west will be cold with the rest of CONUS EC.  Re precipitation, the Southern Tier of CONUS except Western Arizona and California will be dry as will Southern Alaska and the Panhandle while Northern Alaska and the CONUS Northern Tier from the Great Lakes west will be wet.

Now we consider the three-month Outlook.

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

Prior Temperature Outlook for DJF 2017-2018

DJF 2017/2018 Temperature Outlook Issued October 19,  2017

New Temperature Outlook for DJF 2017-2018

DJF 2017 - 2018  Temperature Outlook Issued on November 16, 2017

The date of issue  has been changed on the new map but that is pretty much the extent of the change.

Prior Precipitation Outlook for DJF 2017 - 2018

DJF 2017/2018 Precipitation Outlook Issued on October 19, 2017

New Precipitation Outlook for DJF 2017 - 2918

DJF 2017 - 2018 Precipitation Outlook issued November 16, 2017

The new precipitation forecast has the wet anomaly in the north extending further west and reaching the West Coast. Southern Alaska including the Panhandle are now dry. That is about the extent of the changes.

Now let us focus on the long-term situation and compare the new set of maps with the maps issued on October 19, 2017.

Prior 14 Month Temperature Outlook: DJF 2017/2018 - NDJ 2018/2019

14 month Temperature Issued on October 19, 2017

New 14 Month Temperature Outlook: JFM 2018 - DJF 2018/2019

14 Month  Temperature  Issued on November 16,  2017

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 changes are minimal. The new three-month map added (each month to move forward by one month one three-month map is dropped and one later three-month map is added) namely DJF 2018 - 2019 looks a lot like AMJ 2018 for whatever that is worth and that may be important as it may relate to NOAA seeing something similar to JAMSTEC re the state of ENSO in 2019.

Now Precipitation

Prior 14 Month Precipitation Outlook: DJF 2017/2018 - NDJ 2018/2019

14 Month Precipitation Issued on October 19, 2017

New 14 Month Precipitation Outlook: JFM 2018 - DJF 2018/2019

14 month   precipitation  Issued on November 16, 2017

For precipitation, the changes are more numerous but not very dramatic. Of most interest perhaps is the addition of a small dry anomaly in the Northwest from MJJ 2018 through JAS 2018 and the larger Southwest Dry Anomaly which was also extended into Texas MAM 2018 and AMJ 2018 and the adding of the Northeast wet anomaly in AMJ 2018 keeping the Northern Alaska wet for MAM 2018 through MJJ 2018.

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 present month outlook to the three-month outlook 

December Plus DJF 2017 - 2018 Issued on November 16, 2017

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.

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 November 16, 2017. 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 Current Month, the Three or Four-month period, and finally the remainder of the 15 Month Forecast. We think that sequence with the three- to four-month period broken out separately, makes the discussion more useful for more readers.

CURRENT ATMOSPHERIC AND OCEANIC CONDITIONS

THE LATEST ENSO DIAGNOSTIC DISCUSSION UPDATED THE LA NINA WATCH TO A LA NINA ADVISORY, AS ATMOSPHERIC AND OCEANIC CONDITIONS, TAKEN IN TOTALITY, INDICATE ONGOING LA NINA CONDITIONS. THE LATEST WEEKLY NINO 3.4 VALUE IS -1.1 C, WHILE THE OCTOBER CONTRIBUTION TO THE ONI WAS -0.53 C. OCEANIC HEAT CONTENT (OCEAN TEMPERATURES ACROSS THE PACIFIC BASIN FROM THE SURFACE TO 300 METERS DEPTH) SHOW A CONSIDERABLE RESERVOIR OF COLDER THAN NORMAL WATER, OFTEN A PRECURSOR FOR THE DEVELOPMENT OF MORE ESTABLISHED LA NINA CONDITIONS.  

IN TERMS OF THE ATMOSPHERE, SUPPRESSED CONVECTION REMAINS OBSERVED ACROSS MUCH OF THE WEST-CENTRAL EQUATORIAL PACIFIC WHILE ENHANCED RAINFALL CONTINUES ACROSS THE MARITIME CONTINENT REGION. THE TRADE WINDS IN THE PACIFIC REMAIN ONLY WEAKLY ENHANCED OVER THE PAST 30 DAYS, THOUGH MORE ROBUST UPPER-LEVEL WESTERLY WIND ANOMALIES ARE CURRENTLY OBSERVED. THE MJO HAS RECENTLY WEAKENED AND IS NOT EXPECTED TO CONTRIBUTE TO STRONG FLUCTUATIONS IN WINDS AND SSTS OVER THE COMING WEEKS.

PROGNOSTIC DISCUSSION OF SST FORECASTS

THERE HAS NOT BEEN MUCH CHANGE TO PREDICTIONS OF EQUATORIAL PACIFIC SST ANOMALIES FROM LAST MONTH WITH MOST STATISTICAL AND DYNAMICAL MODEL SOLUTIONS INDICATING A WEAK LA NINA EVENT, THOUGH SOME DYNAMICAL MODEL SOLUTIONS FORECAST NINO 3.4 VALUES TO FALL BELOW -1.0 C. SPECIFICALLY, THE CPC NINO3.4 SST CONSOLIDATION, WHICH OBJECTIVELY WEIGHTS STATISTICAL GUIDANCE (CCA, CA AND MARKOV) AND THE CFS, FORECASTS THE NINO3.4 SST ANOMALY TO PEAK BETWEEN -0.6 AND -0.7 EARLY, BEFORE APPROACHING ZERO BY SPRING. RELATIVE TO LAST MONTH, THESE VARIOUS STATISTICAL AND DYNAMICAL FORECASTS ARE IN BETTER AGREEMENT WITH RESPECT TO THE OVERALL EVOLUTION, THOUGH THE SST-CA REMAINS A BIT OF AN OUTLIER IN COLD NEUTRAL TERRITORY.  

THE NMME SUITE OF MODELS FOLLOW THIS GENERAL THEME, ALTHOUGH THE PERIOD OF THE MOST NEGATIVE NINO3.4 SST ANOMALIES CONTINUES TO VARY FROM MODEL TO MODEL. THE ENSEMBLE MEAN PREDICTION IS QUITE CONSISTENT WITH THE CPC NINO3.4 SST CONSOLIDATED FORECAST, ALTHOUGH WITH SOMEWHAT MORE NEGATIVE TEMPERATURE DEPARTURES REACHING -0.9 DEGREES C DURING DECEMBER 2017 AND JANUARY 2018.

THE STATUS OF ENSO DURING SUMMER 2018 AND BEYOND IS UNCERTAIN. THE OFFICIAL SST CONSOLIDATION FAVORS NEUTRAL ENSO CONDITIONS DURING SUMMER 2018, WITH A SLIGHT TILT TOWARD LA NINA IN LATE 2018.

30-DAY OUTLOOK DISCUSSION FOR DECEMBER 2017

THE DECEMBER 2017 TEMPERATURE AND PRECIPITATION OUTLOOKS ARE BASED ON DYNAMICAL MODEL GUIDANCE, THE TYPICAL INFLUENCE ASSOCIATED WITH LA NINA, AND LONG-TERM TRENDS. DURING THE PAST MONTH, LA NINA CONDITIONS DEVELOPED AS NEGATIVE SEA  SURFACE TEMPERATURE ANOMALIES CONTINUED ACROSS THE EASTERN AND CENTRAL EQUATORIAL PACIFIC ALONG WITH SUPPRESSED (ENHANCED) CONVECTION ACROSS THE CENTRAL TROPICAL PACIFIC (MARITIME CONTINENT AND PHILIPPINES). CLIMATE SIGNALS TYPICALLY ASSOCIATED WITH LA NINA WERE CONSIDERED IN MAKING THE DECEMBER 2017 OUTLOOK, GIVEN THESE CURRENT ATMOSPHERIC AND OCEANIC STATES.  

A ROBUST MJO OCCURRED DURING OCTOBER, BUT IT WEAKENED SINCE THE BEGINNING OF NOVEMBER.  THE DYNAMICAL MODELS INDICATE A CONTINUED WEAK OR INCOHERENT SIGNAL DURING THE NEXT TWO WEEKS. THEREFORE, THE MJO IS NOT EXPECTED TO PROVIDE ANY FORCING TO THE EXTRATROPICS. ALTHOUGH THE MJO DID NOT FACTOR INTO THE DECEMBER OUTLOOK, ITS EVOLUTION WILL BE CLOSELY MONITORED FOR THE REVISED OUTLOOK AT THE END OF THE MONTH.

THE ARCTIC OSCILLATION (AO) INDEX IS FORECAST TO BECOME LARGELY NEGATIVE DURING MID-NOVEMBER AS A BLOCKING RIDGE PERSISTS OVER THE BERING SEA WITH ANOTHER UPPER-LEVEL RIDGE BUILDING OVER THE DAVIS STRAIT. THE DURATION OF THIS NEGATIVE AO INDEX IS UNCERTAIN AND COULD BE TRANSIENT WITH MANY GFS ENSEMBLE MEMBERS INDICATING THAT THE AO INDEX BECOMES MORE NEUTRAL BY THE END OF NOVEMBER. MOST INPUTS TO THE NMME AGREE ON ENHANCED ODDS FOR ABOVE-NORMAL TEMPERATURES ACROSS THE EASTERN CONUS. SINCE THE ECMWF MODEL AT WEEKS 3-4 (WHICH INCLUDES DEC 1-12) INDICATES INCREASED CHANCES FOR BELOW-NORMAL TEMPERATURES ACROSS MUCH OF THE EASTERN CONUS AND GREAT LAKES, EQUAL CHANCES OF BELOW, NEAR, OR ABOVE  NORMAL TEMPERATURES ARE NECESSARY FOR THESE AREAS AT THIS TIME LEAD. THE SPATIAL PATTERN OF THE TEMPERATURE FORECAST ACROSS THE WESTERN AND SOUTH-CENTRAL CONUS IS SIMILAR TO THE SEASONAL OUTLOOK SINCE LA NINA WAS A MAJOR FACTOR IN CREATING THE DECEMBER OUTLOOK, BUT THE COVERAGE OF AREAS WHERE BELOW- AND ABOVE-NORMAL TEMPERATURES ARE FAVORED IS SMALLER DUE TO UNCERTAINTY. DYNAMICAL MODELS, INCLUDING WEEKS 3-4, AND LONG-TERM TRENDS SUPPORT THE RELATIVELY HIGH ODDS FOR ABOVE-NORMAL TEMPERATURES ACROSS THE SOUTHWESTERN CONUS.

THE PRECIPITATION OUTLOOK FOR DECEMBER IS BASED PRIMARILY ON THE CALIBRATED NMME AND IS CONSISTENT WITH LA NINA CONDITIONS AND THE DJF OUTLOOK. THE HIGHEST PROBABILITIES FOR BELOW-NORMAL PRECIPITATION ARE FORECAST ACROSS PARTS OF THE GULF COAST AND SOUTHEAST WHERE A DRY SIGNAL IS STRONG IN LA NINA COMPOSITES FOR NDJ AND PROBABILITIES ARE RELATIVELY HIGH IN THE CALIBRATED NMME. THE BROAD AREA OF ENHANCED ODDS FOR ABOVE-NORMAL PRECIPITATION FROM THE PACIFIC NORTHWEST EAST TO THE GREAT LAKES IS EITHER SUPPORTED BY LA NINA COMPOSITES OR THE CALIBRATED NMME.  PROBABILITIES FOR BELOW- AND ABOVE-NORMAL PRECIPITATION ARE MODEST DUE TO LIMITED SKILL INHERENT IN A MONTHLY OUTLOOK AT THIS TIME LEAD.  

THE HIGHEST ODDS FOR ABOVE-NORMAL TEMPERATURES ACROSS ALASKA ARE FORECAST FOR AREAS OF THE STATE ADJACENT TO THE BERING AND CHUKCHI SEAS WHERE SEA SURFACE TEMPERATURE ANOMALIES ARE AVERAGING AS MUCH AS 1.5 DEGREES C ABOVE NORMAL. ENHANCED ODDS FOR BELOW-NORMAL TEMPERATURES FORECAST ACROSS PARTS OF SOUTHEAST MAINLAND ALASKA AND THE ALASKA PANHANDLE ARE BASED ON THE MONTHLY CFS TEMPERATURE FORECAST. THE FAVORED AREAS OF BELOW- AND ABOVE-NORMAL PRECIPITATION ACROSS ALASKA ARE CONSISTENT WITH THE TEMPERATURE OUTLOOK AND SUPPORTED BY THE WEEKS 3-4 CFS AND ECMWF PRECIPITATION FORECASTS ALONG WITH  SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS

Three Months: December 2017, January and February 2018

THE DECEMBER-JANUARY-FEBRUARY (DJF) 2017-18 OUTLOOK AND SUBSEQUENT OUTLOOKS ARE HEAVILY INFLUENCED BY ONGOING LA NINA CONDITIONS THAT ARE FORECAST TO CONTINUE THROUGH LATE WINTER.

Temperature

THE DJF OUTLOOK FAVORS ABOVE-NORMAL TEMPERATURES FOR THE MAJORITY OF THE FORECAST DOMAIN, INCLUDING MUCH OF ALASKA. THE HIGHEST PROBABILITIES OF WARMER-THAN-NORMAL TEMPERATURES ARE LOCATED ACROSS PORTIONS OF THE SOUTHWEST AND TEXAS.

THE DJF 2017-18 TEMPERATURE OUTLOOK IS LARGELY UNCHANGED FROM THE OUTLOOK RELEASED LAST MONTH. THE MAIN CHANGE WAS A DECREASE IN COVERAGE IN FAVORED ABOVE-NORMAL TEMPERATURES FOR PORTIONS OF THE SOUTH-CENTRAL U.S. AND A SLIGHT ENHANCEMENT OF PROBABILITIES FAVORING BELOW-NORMAL TEMPERATURES OVER THE NORTHERN PLAINS AND UPPER MIDWEST. THIS CHANGE IS BASED LARGELY ON STATISTICAL GUIDANCE THAT SUGGESTS THE CURRENT SST CONDITIONS OVER THE TROPICS AND NORTHERN HEMISPHERE ARE SLIGHTLY CLOSER TO THOSE PRECEDING WINTERS WITH COLDER OUTCOMES ACROSS THE NORTHERN CONUS.

Precipitation

THE DJF 2017-18 PRECIPITATION OUTLOOK INDICATES INCREASED CHANCES OF ABOVE-NORMAL PRECIPITATION FOR WESTERN AND NORTHERN ALASKA, AS WELL AS MUCH OF THE NORTHERN CONUS, CONSISTENT WITH LA NINA. THIS FOOTPRINT SLOWLY DECREASES ENTERING THE CORE SPRING MONTHS BEFORE LONG-TERM TRENDS BECOME DOMINANT DURING THE WARM SEASON.

PROGNOSTIC DISCUSSION OF OUTLOOKS - DJF 2017 TO DJF 2018 (With a focus on months beyond DJF 2017/2018)

THE OFFICIAL TEMPERATURE AND PRECIPITATION OUTLOOKS FOR THE SEASONS FROM DJF 2017-18 THROUGH FMA 2018 TOOK INTO CONSIDERATION IMPACTS OFTEN OBSERVED DURING LA NINA EVENTS AS THE LATEST OFFICIAL ENSO OUTLOOK FORECASTS LA NINA CONDITIONS TO CONTINUE THROUGH THE UPCOMING COLD SEASON. STATISTICAL FORECAST TOOLS, SUCH AS REGRESSIONS ANCHORED TO THE CPC NINO3.4 SST CONSOLIDATION FORECAST AND THE CCA, ALONG WITH DYNAMICAL MODEL GUIDANCE FROM THE NMME SUITE OF MODELS, BOTH IN DETERMINISTIC AND CALIBRATED PROBABILISTIC FORM, CONTRIBUTED HEAVILY TO THE OUTLOOK. LONG TERM TRENDS IN BOTH TEMPERATURE AND PRECIPITATION WERE ALSO UTILIZED QUITE STRONGLY IN SOME AREAS IN THE OUTLOOKS, THOUGH THESE TRENDS ARE NOT INDEPENDENT OF THE AFOREMENTIONED FORECAST TOOLS. INTERNATIONAL MODEL GUIDANCE FROM THE ECMWF, UKMET, AND JMA, ARE ALL BROADLY CONSISTENT WITH THE OFFICIAL OUTLOOKS. THE SST-CA IS UTILIZED THIS MONTH SINCE IT IS LESS OF AN OUTLIER WITH RESPECT TO ONGOING AND FORECAST TROPICAL PACIFIC SSTS.

TEMPERATURE

THE UPDATED SET OF TEMPERATURE OUTLOOKS THIS MONTH KEEP NEAR PERFECT CONTINUITY WITH THOSE ISSUED LAST MONTH, AS ONLY MINOR CHANGES WERE NEEDED. STATISTICAL AND DYNAMICAL FORECAST TOOLS THAT IN LARGE PART ARE CONSISTENT WITH TYPICAL LA NINA IMPACTS, ESPECIALLY THOSE OBSERVED IN THE MORE RECENT PORTION OF THE AVAILABLE RECORD, ARE A STRONG CONTRIBUTION TO THE TEMPERATURE OUTLOOK EVOLUTION FROM DJF 2017-18 THROUGH FMA 2018. LONG-TERM TRENDS IN MANY AREAS ALSO PLAYED A CONSIDERABLE ROLE IN THE OUTLOOK EVOLUTION AT NEARLY ALL FORECAST LEADS. OUTLOOKS FROM SUMMER 2018 WERE PRIMARILY DRIVEN BY LONG TERM TRENDS AND THE SST-CA STATISTICAL TOOL AFTER ANY CONSIDERATIONS FOR RESIDUAL LA NINA IMPACTS ARE ANTICIPATED TO END.

DURING THE WINTER MONTHS THROUGH THE MARCH-APRIL-MAY (MAM) 2018 SEASON, ENHANCED ODDS FOR BELOW-NORMAL TEMPERATURES ARE HIGHLIGHTED IN VARYING AREAS OF THE NORTHERN CONUS, SOUTHEAST ALASKA AND THE ALASKA PANHANDLE, WHILE ABOVE-NORMAL TEMPERATURES REMAIN FAVORED FOR MUCH OF THE WESTERN AND SOUTHERN CONUS, AND NORTHERN ALASKA.

AS WE EVOLVE FROM THE WINTER SEASON THROUGH MAM 2018, AN ENHANCED LIKELIHOOD OF BELOW-NORMAL TEMPERATURES REMAINS HIGHLIGHTED  FOR PORTIONS OF SOUTHEAST ALASKA INCLUDING THE PANHANDLE, THE PACIFIC NORTHWEST, AND THE NORTHERN PLAINS. RECENT TEMPERATURE TRENDS IN THE GREAT LAKES REGION AND MIDWEST, AS CHARACTERIZED BY 15 YEAR OCN METHODOLOGY, ARE VERY SLIGHTLY NEGATIVE AND CONTRIBUTE TO AN OUTLOOK THAT IS COOLER THAN THE NMME ANOMALY FORECAST (AND UNCALIBRATED PROBABILITIES) FOR THAT REGION.

THE REMAINING OUTLOOKS FROM AMJ 2018 ONWARD THROUGH DJF 2018-19 ARE PRIMARILY BASED ON LONGER TERM TEMPERATURE TRENDS THAT CAN BE STRONG AND REASONABLY PREDICTABLE IN MANY AREAS OF THE CONTIGUOUS U.S. AND ALASKA. ALONG WITH TRENDS, PREDICTIONS FROM THE SST-CA ALSO CONTRIBUTED TO THE OUTLOOKS.  

PRECIPITATION

FOR PRECIPITATION, THE OUTLOOKS ARE AGAIN VERY SIMILAR TO THE SET OF OUTLOOKS RELEASED LAST MONTH. IN DJF THE MINOR CHANGES INCLUDE SUBTLE INCREASES IN THE PROBABILITIES FOR ABOVE-(BELOW-)NORMAL PRECIPITATION ACROSS THE NORTHWEST (CALIFORNIA). PROBABILITIES ARE INCREASED OVER ALASKA AS WELL, WITH BELOW-NORMAL PRECIPITATION NOW FAVORED OVER THE SOUTH COAST AND PANHANDLE. INTERESTINGLY, THE CALIBRATED NMME PROBABILITIES INDICATED ENHANCED ODDS OF ABOVE-NORMAL PRECIPITATION OVER TEXAS DURING DJF, WHICH IS AT ODDS WITH STATISTICAL GUIDANCE AND THE ECMWF SEASONAL FORECAST. A SMALL REDUCTION IN PROBABILITIES FAVORING BELOW-NORMAL PRECIPITATION WAS MADE IN THAT AREA AS A RESULT OF SOMEWHAT INCREASED UNCERTAINTY. PROGRESSING FROM THE DJF 2017-18 PERIOD THROUGH THE SPRING, ELEVATED ODDS FOR ABOVE-NORMAL PRECIPITATION ACROSS THE NORTHERN CONUS, DIPPING DOWN INTO THE OHIO AND TENNESSEE VALLEYS AT TIMES, REMAIN INTACT. BELOW-NORMAL PRECIPITATION OVER THE SOUTHERN TIER OF THE U.S. IS ALSO FAVORED INTO SPRING. OVER WESTERN AND CENTRAL MAINLAND ALASKA, ABOVE-NORMAL PRECIPITATION IS NOW FAVORED THROUGH MJJ 2018 BASED ON THE LATEST DYNAMICAL AND STATISTICAL GUIDANCE.

THE PRECIPITATION OUTLOOKS FROM AMJ 2018 ONWARD THROUGH OND 2018 WERE SIMILAR FROM THE OUTLOOKS PREPARED LAST MONTH. THESE FORECASTS ARE HIGHLIGHTING GENERALLY SMALL REGIONS WHERE LONG-TERM PRECIPITATION TRENDS ARE EVIDENT AND WHERE HISTORICAL CROSS VALIDATED PREDICTION SKILL HAS BEEN SHOWN TO BE POSITIVE. PROBABILITIES FAVORING BELOW-NORMAL PRECIPITATION WERE INTRODUCED OVER PARTS OF THE INTERIOR NORTHWEST FROM MJJ THROUGH JAS 2018 BASED ON LONG-TERM TRENDS.

I have not done this before but the discussion that was issued Friday with the Week 3 and Week 4 forecast (Operational for temperature and experimental for precipitation) is quite interesting so here it is.

Week 3-4 Forecast Discussion Valid Sat Dec 02 2017-Fri Dec 15 2017

The Week 3-4 outlook this week takes place within a backdrop of ongoing La Nina conditions and after the demise of a rather substantial MJO event during October into November. La Nina ocean and atmospheric conditions serve as the low frequency base state for this outlook with no predictions of revitalized, organized MJO activity anticipated over the next 1-2 weeks. The forecast temperature and precipitation outlooks are based on low frequency La Nina background conditions, in some areas local sea surface temperature anomalies, statistical model guidance and long term trends. Dynamical model guidance also played a substantial role in the outlooks, but primarily from the ECMWF system.

The dynamical model guidance had large spread this week with all three utilized operational center model systems offering varying depictions of some of the large scale features over the Pacific Ocean and North America region. There were large changes in Week-3 forecasts from the CFS and JMA solutions across the Pacific sector than that most likely to arise out of the Week-2 period at the moment. It was viewed that the ECMWF solution for Week-3 to be the most consistent and representative with the anticipated eventual evolution over the Week 2-4 time period. Therefore, its temperature and precipitation forecast was considerably more heavily weighted in the final outlook maps.

The temperature outlook depicts elevated probabilities for above normal temperatures for northern and western areas of Alaska supported by continuing above normal sea surface temperatures, long term trends and the majority of bias corrected, calibrated dynamical model guidance. Statistical model forecast guidance incorporating information from ENSO, the MJO and long term trends favors above normal temperatures for areas across the southwest corner of the CONUS with the primary drivers being La Nina and long term trends, rather than the MJO. Dynamical model guidance especially from the ECMWF and JMA further support this area of elevated odds of anomalous warmth so probabilities are highest in this region. The enhanced likelihood of above normal temperatures extends to the north to include much of the remainder of the West as well as much of the Great Plains. This is supported by the expectation of considerable Pacific air entering the CONUS consistent with the preferred ECMWF solution and so its calibrated dynamical model guidance, but also to a lesser degree from the CFS and JMA solutions. The probabilities are lessened for the northern Plains in deference to statistical model guidance favoring below normal temperatures related to a potential La Nina influence. There exists considerable uncertainty in both statistical and dynamical model guidance across the eastern CONUS as even model output from the ECMWF is quite muted as well as in contradiction to solutions from the CFS and JMA systems. Equal chances (EC) is forecast in the eastern CONUS.

The precipitation outlook utilized a mixture of statistical model forecast guidance, some commonly observed La Nina impacts and bias corrected, calibrated dynamical model guidance. Even though at odds with typical La Nina impacts, above normal precipitation is favored for parts of the South Coast of Alaska and the Alaska Panhandle as the preferred dynamical model guidance (i.e., ECMWF), supports wetter than normal conditions in this region. The North Slope of Alaska also has an enhanced likelihood of above normal precipitation as indicated by all bias corrected, calibrated dynamical model guidance. The strong trough and somewhat zonal flow across the Pacific to the West coast of North America predicted by the ECMWF solution favors above normal precipitation for areas of the Pacific Northwest. Statistical model guidance (mainly from long term trends) favors an extension of this area to the east to include parts of the northern Rockies. A rather large area of marginally elevated probabilities for below normal precipitation is shown from the Southwest CONUS, east and north to include much of the interior portion of the country, to the Gulf Coast and Florida. A combination of factors, the La Nina low frequency base state, long term trends and the anticipated upper-level height pattern (ridge-trough) over the period across the CONUS favors in the mean an area of upper-level convergence and so generally fair surface conditions.

For Hawaii, above normal ocean surface temperatures favor elevated odds for above normal temperatures for all areas. Dynamical model guidance quite marginally favors above normal precipitation for eastern areas of the Hawaiian Islands while uncertainty in the forecast tools results in an outlook of EC for western areas.

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

El Nino Probabilities used by NOAA in Their Forecast (The forecast for the value of the Nino 3.4 Index receives the most attention).

Below is the latest NOAA forecast of Nino 3.4 temperature anomalies.  You can see the "blue" newer model runs and the "red" older model runs. The Oceanic Niño Index (ONI) which is the three-month rolling average of the Nino 3.4 values is NOAA's primary indicator for monitoring El Niño and La Niña. The secondary indicator is the Southern Oscillation Index (SOI) which is based on the extent that the air pressure anomaly in Tahiti exceeds the air pressure anomaly in Darwin Australia.  It is a complicated formula and is intended to assess the response of the atmosphere to the changes in the pattern of warm and cool sea surface temperatures.

Here is the NOAA forecast for the Nino 3.4 Index.

CFSv2 Forecast as of November 16, 2017

I have added a blue line at -0.5C which is the level that defines La Nina Sea Surface Temperature in the Nino 3.4 Measurement Area. This level needs to be maintained or exceeded on the downside for five consecutive overlapping three-month periods to constitute a La Nina not just a period of La Nina Conditions. In the above graphic, the required duration may be barely met over the period from mid October through MAM 2018. But it does not last that long in some other models that NOAA uses. It does not last that long in many International forecasting models. So it is a judgment call at this point in time re this La Nina Condition recently declared (click here to read the Advisory) will eventually be recorded as a full La Nina.

I am using the below NOAA image in addition to the image that updates daily because it also shows the sea surface temperature forecast for the entire Equatorial Pacific. Red is a warm anomaly. For an El Nino forecast the model would be showing red along the Equator in the Eastern Pacific and the model is not projecting that but instead we see what is called a cold tongue in blue extending from Ecuador. Those images are a bit small I agree. But the Equator is marked and so is the Coast of South America. It is a little tricky but you can find larger images here. Track across the top row labeled SST Normalized with Skill Mask and click on the E3 which is the latest forecast. Each of the images can also be clicked on to enlarge.

 CFS.V2 SST Forecast November 13, 2017

It is now showing a La Nina for Winter and Spring. You can see the cold tongue extending from Ecuador in the maps on the right.

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. Below is the October 12 and October 19 CPC/IRI ENSO Forecasts

CPC/IRI October 19, 2017 ENSO Forecast

And here is the most recent set of graphics. We had anticipated that this would have been updated last Thursday but it was not and we doubt that it would have changed very much.

November 9, 2017 CPC/IRI ENSO 3.4 forecast.

You might notice the pattern here that the early month forecasts that are partly based on a survey have meteorologists has not changed. In between the October and recent forecast there was the second week model based forecast. So my conclusion is that there has been no change.

Published: November 09, 2017

El Niño/Southern Oscillation (ENSO) Diagnostic Discussion issued jointly by the Climate Prediction Center/NCEP/NWS and the International Research Institute for Climate and Society

ENSO Alert System Status: La Niña Advisory

Synopsis: La Niña conditions are predicted to continue (~65-75% chance) at least through the Northern Hemisphere winter 2017-18.

During October, weak La Niña conditions emerged as reflected by below-average sea surface temperatures (SSTs) across most of the central and eastern equatorial Pacific Ocean. The weekly Niño indices were variable during the month, with values near -0.5° C during the past week in the Niño-3.4 and Niño-3 regions.  Sub-surface temperatures remained below average during October reflecting the anomalously shallow depth of the thermocline across the central and eastern Pacific. Also, convection was suppressed near the International Date Line and slightly enhanced over parts of the Maritime Continent and the Philippines. Over the equatorial Pacific Ocean, low-level trade winds were mainly near average, but the upper-level winds were strongly anomalously westerly and the Southern Oscillation Index was positive.  Overall, the ocean and atmosphere system reflects the onset of La Niña conditions.

For the remainder of the Northern Hemisphere fall and winter 2017-18, a weak La Niña is favored in the model averages of the IRI/CPC plume and also in the North American Multi-Model Ensemble (NMME). The consensus of forecasters is for the event to continue through approximately February-April 2018.  In summary, La Niña conditions are predicted to continue (~65-75% chance) at least through the Northern Hemisphere winter.

La Niña is likely to affect temperature and precipitation across the United States during the upcoming months (the 3-month seasonal temperature and precipitation outlooks will be updated on Thursday November 16th). The outlooks generally favor above-average temperatures and below-median precipitation across the southern tier of the United States, and below-average temperatures and above-median precipitation across the northern tier of the United States.

As you can see there has been some recent change to limit the period where La Nina is favored to just the Fall and Winter. The CFS.v2 model holds the La Nina conditions for perhaps an additional two months.

Now for a more detailed look. Below is the pair of graphics that I regularly provide in my Monday night Weather and Climate Report. 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 cold water from 170W to Land. To the west, the cool pool is no longer quite 200 meters deep. We now have warm water developing west of the Dateline and starting to cross the Dateline. Soon it will be intruding into the Eastern Pacific Nino 3.4 Measurement Area. La Nina's days are numbered. But that process takes a few to several months to play out.
Subsurface temperature Anomalies November 14, 2017
The 28C Isotherm is at 175W, the 27C Isotherm is at 170W, the 25C Isotherm is at 145W.

 

A flattening of the Isotherm Pattern is an indication of ENSO Neutral just as a 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 occurred to some extent after last year's La Nina and now we have returned to a steeper pattern consistent with a weak La Nina thermocline.

Tracking the change.

Sepember 15, 2017 Subsurface Water Temperatures Equatorial Ocean Subsurface as of November 14, 2017

 

I have "frozen" these two charts. The one on the left shows the situation as reported for September 15, 2017. The one on the right shows the situation now.  The situation is not much different east of the Dateline from the situation as reported for September 15, 2017. But west of the Dateline is looks a lot different. We will use the graphic on the left as a reference and see how the current situation changes over time.
 The below graphic essentially integrates the information shown above for the area between the Dateline and 100W, So it converts a graphic showing warm and cool anomalies at different depths into an average for the top 300 meters.

Upper Ocean heat Content November 13, 2017

This pretty much integrates the temperature of the water in the area of measurement across the various pods of warmer and cooler water...we are talking about anomalies not absolute temperatures. It may be that the overall negative temperature anomaly has peaked and is starting to moderate. That is a natural process and suggests that the life of this cool event is limited.

It could well be that the every ten year adjustment mechanism NOAA uses for the base climatology of the Tropical Pacific for real time analysis (OISSTv2 data set) is not able to keep up with Ocean Warming which may slightly overstate warm anomalies. Even the five year adjustment they use to review the data for historical analysis (ERSSTv4) really does not help very much when there is a trend that is either a secular trend due to Global Warming or part of a sixty-year low-frequency cycle such as the PDO. Current values tend to be higher than the average.

Here is the current November 1, 2017 JAMSTEC forecast for the Nino 3.4 Index.

November 1, 2017 JAMSTEC Forecast

There has since last month been a significant change in the JAMSTEC forecast of the Nino 3.4 Index  It is now fairly consistent with the NOAA forecast but the NOAA forecast is more suggestive that this cool event will have sufficient duration to be declared a La Nina and will reach a lower level of the Nino 3.4 index. The JAMSTEC forecasted Index may not be low enough for long enough to be declared an official La Nina (-0.5C or lower) but it is close and it continues to be a negative or neutral value through the forecast period way into 2019. The fairly minor differences between the various Nino 3.4 forecasts have an impact on the seasonal outlooks of the two Agencies. 

Here is the discussion from JAMSTEC: [We updated this article on November 22 with the short JAMSTEC Discussion when it was posted]

Nov. 22, 2017 Prediction from 1st Nov., 2017

ENSO forecast:

The weak La Niña-like condition will persist until boreal spring of next year. 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 spring of next year. Then we expect a positive Indian Ocean Dipole in summer of 2018. 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 Africa and Brazil will experience a colder-than-normal condition in boreal winter.

As regards to the seasonally averaged rainfall, a wetter-than-normal condition is predicted for some parts of East Africa, eastern Southern Africa, Philippine, East Australia, and northern Brazil during boreal winter, whereas most parts of Indonesia, West Australia, West Africa, southern Europe, western U.S, eastern China and southern Brazil will experience a drier condition during boreal winter. Those are partly due to the weak La Niña-like condition.

In winter, most parts of Japan will experience warmer- and drier-than-normal conditions.

Forecasts from Other Meteorological Agencies.

Australia POAMA ENSO model run

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

POAMA, run at the Bureau of Meteorology, generates a nine-month forecast each fortnight. The most recent model run (generated 5 November) indicates NINO3.4 will just touch on La Niña thresholds during the austral summer before warming again and returning to near average values by autumn 2018.

The Australian BOM employs a different threshold for considering a SSTA to be either La Nina or El Nino. Note their forecast is showing ENSO Neutral based on their criteria through their forecast period. But it would meet the NOAA criteria for La Nina Conditions but it is marginal for having sufficient duration. 

Thus the NOAA and Australian BOM forecasts are signaling the cool phase of ENSO with NOAA declaring La Nina Conditions in place and the BOM indicating that the Nino 3.4 Index will not exceed their more strict criteria and the November 1 JAMSTEC forecast shows La Nina conditions (at least in terms of the Nino 3.4 Index for the Winter and Summer.

Indian Ocean IOD (It updates every two weeks)

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

IOD POAMA Model Run

Discussion Issued November 5

The IOD is currently neutral with the weekly IOD index value (to 5 November) at –0.1 °C.

All six models favour a neutral IOD for the rest of 2017 and early 2018.

Indian Ocean Dipole events are typically unable to form between 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. It has little effect on Australian climate at this time of year.

Does the Atmosphere as measured by the SOI Index confirm that we have La Nina Conditions?

SOI values as of November 18, 2017

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 both the Nino 3.4 Index and the SOI suggest that we are entering La Nina "Conditions". NOAA has declared that La Nina Conditions currently exist.

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.

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

SOI Index History November 17, 2017

The below graphic often very clearly shows the difference in the forecasts between NOAA and JAMSTEC because weather is determined by patterns of sea surface temperature (SST) variances from normal. These two graphics show the two forecasts for SST's for DJF 2017/2018
NOAA SST DJF 2017/2018
Projected JAMSTEC SST DJF 2017/2018

 

They are almost identical. The key is the so-called cold tongue 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 DJF 2017/2018 in a very similar way and in general they are. But there are some differences.

C. 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 have Winter (DJF 2017-2018) Spring (MAM 2018) and Summer (JJA) to work with and we have the corresponding maps from NOAA so that we can compare the two. 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.

DJF 2017/2018 (Winter)

Temperature

NOAA

DJF 2017-2018 Temperature Issued by NOAA on November 16, 2017

And here is the DJF 2017/2018  temperature forecast for North America that I extracted from the JAMSTEC World Forecast

DJF 2017/2018 JAMSTEC Temperature extracted from Nov1, 2017 World Forecast

JAMSTEC does not extend the Canadian cool anomaly into the Northern Tier of CONUS but shows some cooler areas in CONUS Southeast.

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 graphics above)

DJF 2017/2018 World Temperature Forecast from JAMSTEC Nov 1, 2017 forecast.

For the World, JAMSTEC shows much of the Northern Hemisphere other than Scandinavia and Eastern Siberia warm but shows much of the Southern Hemisphere other than Southern Australia and Southern South America cool.

Precipitation

NOAA

NOAA DJF 2017/2018 Precipitation Issued November 16, 2017

And here is the DJF 2017/2018 Precipitation Forecast for North America that I extracted from the JAMSTEC World Forecast.

North America DJF 2017/2018 Precipitation Extracted from Nov 1, JAMSTEC Forecast

For Alaska the pattern is sort of reversed for JAMSTEC versus NOAA. For CONUS, NOAA is wetter in the Northern Tier but in the Southern Tier NOAA is solidly dry while JAMSTEC for the Southern Tier is mostly dry only in the extreme Southwest.

JAMSTEC WORLD FORECAST

DJF 2017/2018 Jamstec Precipitation Forecast From Nov 1, 2017

Of interest is the dry Southern Europe and generally wet Southern Hemisphere. The dry Japan and Maritime Continent are also of interest.

Here is the precipitation forecast from Queensland Australia. It does not cover the same months but rather NDJ 2017-2018:

Consistently Positive SOI  forecast for November 2017 to January 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 looks like a north south divide with the southern tier dry which pretty much agrees with both NOAA and JAMSTEC. Southern Africa is wet. Eastern Australia is wet, Europe is dry. This forecast will be updated on December 1 when the monthly average of the SOI for November becomes available. .

MAM  (Spring)

Temperature

NOAA

MAM  2018 Temperature NOAA Issued on November 16, 2017

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

MAM  2018 North American Temperature extracted from JAMSTEC Nov 1 Forecast

Fairly similar and the view of Canada helps to put it in perspective. But NOAA sees the cool anomaly extending into North Central CONUS but JAMSTEC  limits the cool area to further west.

JAMSTEC WORLD FORECAST

MAM  2018 JAMSTEC Temp from Nov 1, 2017

For JAMSTEC we see a lot more cool areas in this season. Northern South America is cool plus much of Central America as is Northern Australia, Northern Africa, Eastern India, Western Canada and Greenland. 

Precipitation

NOAA

NOAA AM  2018 Precipitation Issued on November 16, 2017

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

MAM  2018 JAMSTEC Precipitation for CONUS based on Nov 1 forecast

NOAA shows Northern Alaska wet but for JAMSTEC it is mostly EC. NOAA shows the Northern Tier of CONUS wet but for JAMSTEC it is mixed to dry. JAMSTEC shows the extreme Southwest dry while NOAA shows a more consistent dry pattern for the Southern Tier of CONUS but not extending as far west but also less intense for the Southeast than JAMSTEC.

JAMSTEC WORLD FORECAST

MAM 2018 JAMSTEC Precipitation Forecast from Nov 1, 2017

Much of Southern Africa is wet as is Southern South America. Southeast Asia is Dry. So is Southern Europe.

JJA 2018 (Summer)

Temperature

NOAA

NOAA JJA 2018 Temperature Issued November 16, 2017

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

JJA 2018 North America Temperature Forcast Extracted from the Nov 1 JAMSTEC Forecast

The pattern is similar but JAMSTEC shows Northern Alaska cool not warm as NOAA and JAMSTEC shows the Great Lakes Area cool rather than EC as does NOAA. .

JAMSTEC WORLD FORECAST

JJA 2018 JAMSTEC Temperature from Nov 1, 2017

The cool areas are Scandinavia, Northern Australia, Northern Canada, east of the Caspian Sea Central America and Greenland.

Precipitation

NOAA

JJA 2018 Precipitation Issued November 16, 2017

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

JAMSTEC JJA 2018 precipitation extracted from their Nov 1 2017 Forecast

NOAA shows the Northwest dry and the Northeast wet. JAMSTEC agrees on the Northeast but sees the entire Southern Tier dry but the Northwest EC.

JAMSTEC WORLD FORECAST

JAMSTEC JJA 2018. Precipitation from 1 Nov 2017

Australia and India are a bit dry.

Conclusion

Both forecasts are based on ENSO being primarily negative with NOAA going all the way to a weak but short La Nina and JAMSTEC not quite as convinced that this will be a full La Nina. The differences in the forecast maps are again less than last month. Aside from the comparison of NOAA and JAMSTEC for Alaska and CONUS, JAMSTEC 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 not be as useful this month since both NOAA and JAMSTEC  have similar forecasts for Nino 3.4

Some Housekeeping Issues.

The next Regular Weekly Weather and Climate Report will be published on November 20, 2017. 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.

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

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