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posted on 22 April 2017

NOAA and JAMSTEC Issue Seasonal Updates - Winter in Doubt

Written by Sig Silber

NOAA issued their Seasonal Outlook on April 20 and JAMSTEC issued theirs at least a week earlier than NOAA which is unusual.  Usually they follow pretty much the same schedule. Both forecasts assume an El Nino but with different timing. Here at GEI we think both Meteorological Agencies are incorrect on that forecast but we'll go over what they are presenting. December 2017 through February 2018 is where there is considerable disagreement or doubt regarding what we should expect for CONUS.

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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. Remember: these are forecasts not guarantees. But the differences between the NOAA and JAMSTEC forecasts are significant - especially in the further-out months - and are mostly related to the differing perspectives on the evolution of a possible ENSO into Summer and Fall. JAMSTEC in their further-out forecast (which is out to Dec 2017 - Feb 2018) is reflecting a higher probability of El Nino conditions this coming Winter.

Both the NOAA and ENSO forecasts are attempting to properly factor in the chances of an El Nino this Summer and into next winter. The difficulty with predicting an El Nino in April is discussed [click here ] This  makes all forecasts right now beyond the next three months somewhat of a WAG. We are also watching a possible Climate Shift in the Pacific to a period lasting two to three decades of PDO Positive.

Some Housekeeping Issues

This report will be posted late Saturday April 22 and will be referred to in the Weekly Report for reference until the Saturday after the next NOAA Update on May 20, 2017 which we will report on May 20. The Regular Weekly Report will be published on April 24. 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.


Below is a quick 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 Summer, Fall into Winter. 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 + CONUS JAMSTEC North America JAMSTEC Europe
JJA JJA US Temperature Issued on April 20, 2017, NOAA Forecast JJA Temperature Based on April 1, 2017 JAMSTEC Forecast JJA Europe Temperature JAMSTEC April 1, 2017 Forecast
SON SON US Temperature Issued by NOAA on April 20, 2017 SON NA Temperature based on JAMSTEC April 1, 2017 Forecast SON 2017 Europe Temperature based on JAMSTEC April 1, 2017 Forecast

DJF

2017/2018

DJF 2017-2018 Temperature Issued by NOAA on April 20, 2017 DJF NA Temperature based on April 1 JAMSTEC Forecast DJF Europe Temperature Based on April 1, 2017 Jamstec Forecast

 

Precipitation

  NOAA Alaska + CONUS JAMSTEC North America JAMSTEC Europe
JJA JJA US Precipitation Issued on April 20, 2017 NOAA Forecast JJA NA Precipitation Based on April 1, 2017 JAMSTEC Forecast JJA Europe JAMSTEC Precipitation April 1, 2017 Forecast
SON SON US Precipitation Based on April 20, 2017 Forecast SON NA Precipitation based on JAMSTEC April 1, 2017 Forecast SON 2017 Europe Precipitation based on JAMSTEC April 1, 2017 Forecast

DJF

2017/2018

DJF 2017 Precipitation based on April 20, 2017 NOAA forecast DJF US Precipitation based on April 1 JAMSTEC Forecast DJF Europe Precipitation Based on April 1, 2017 Jamstec Forecast

 

NOAA Updated Seasonal Outlook

NOAA issued their updated Seasonal Outlook on the third Thursday of the month i.e. April 20, 2017 as is their normal schedule. Let's first take a look at the NOAA maps. Then we will compare the NOAA Maps to those issued by JAMSTEC. A note about terminology; the deviations from climatology/normal are color coded but also labeled "A" for more than normal and "B" for less than 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.

First we will take a look at the Early Outlook for May 2017. It is called the Early Outlook because it will be updated at the end of April. Only the May Outlook will be updated at that time.

Temperature

May 2017 Early Temperature Report Issued on April 20, 2017

Precipitation

May 2017 Early Preciitation Outlook Issued on April 20, 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 May maps from the March 16, NOAA Report to compare against. And April is not over so we can not really compare the May forecast against April actual. It is probably best to just try to understand what NOAA is trying to convey about May which can be summarized as warm for Alaska, CONUS Southern Tier and East Coast and wet for Montana and Southeast Texas but cool for part of the Great Lakes and Northern Alaska and the Alaskan Panhandle.                                  .

Now we consider the three-month Outlook.

Notice that the three-month periods are abbreviated e.g. May/June/July is shown as MJJ. You will see such abbreviations often in this report.

Prior Temperature Outlook for MJJ 2017

MJJ 2017 Temperature Outlook Issued March 16, 2017

New Temperature Outlook for MJJ 2017

MJJ 2017 Temperature Outlook Issued on April 20, 2017

There is not much change. The warm anomaly for the East and Gulf Coasts have higher probabilities of exceeding climatology (normal).

Prior Precipitation Outlook for MJJ 2017

MJJ 2017 Precipitation Outlook Issued on March 16, 2017

New Precipitation Outlook for MJJ 2017

MJJ 2017 Precipitation Outlook issued April 20, 2017

The significant change is he North Central wet anomaly narrows in longitude coverage but extends south to the Mexican Border.

Now let us focus on the long-term situation and compare the new set of maps with the maps issued on March 16, 2016.

Prior 14 Month Temperature Outlook: MJJ 2017 - AMJ 2018

14 month temperature Issued on March 16, 2017

New 14 Month Temperature Outlook: JJA 2017 - MJJ 2018

14 Month Temperature Issued April 20, 2017 by NOAA

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 so minor they are not worth commenting on. Basically in the early periods there are only slight changes in parts of each map in the probabilities of being warmer than climatology. In the later periods, it was strictly cut and paste.

Prior 14 Month Precipitation Outlook: MJJ 2017 - AMJ 2018

14 Month Precipitation Issue on March 16, 2017

New 14 Month Precipitation Outlook: JJA 2017 - MJJ 2018

14 Month Precipitation Issued by NOAA on April 20, 2017

For precipitation (unlike temperature) there have been some substantive changes. For JJA the changes are similar to those made for MJJ. For JAS the New England wet anomaly has been delayed until ASO. SON and OND were shown as EC in the Outlook issued last month but now SON shows a New England wet anomaly and both SON and OND show a Southwest wet anomaly with slight variations in size and location between the two three-month periods.

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           

May plus MJJ 2017 Issued on April 20, 2017

One can mentally subtract the May Outlook from the three-month Outlook and create the Outlook for the last two months in the three-month period namely June and July 2017. To  do that you need to take into account that:

For temperature there is much expanded coverage of the warm anomaly in the three-month period. Thus if you assume these colors are assigned correctly, it is a simple algebra equation to solve June/July probability for a given location = (3XThree-Month Probability - May Probability)/2*. So you can derive the June/July forecast this way. You can do that calculation easily for where you live.
Re precipitation, there is the extension to the south of what in May is a North Central wet anomaly. So if you assume these colors are assigned correctly, it is a simple algebra equation to solve June/July probability for a given location = (3XThree-Month Probability - May Probability)/2*. So you can derive the June/July forecast this way. You can do that calculation easily for where you live.

* 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 some of the redundancy removed) from the Discussion released by NOAA on April 20, 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

OCEANIC AND ATMOSPHERIC OBSERVATIONS ACROSS THE EQUATORIAL PACIFIC AS A WHOLE INDICATE ENSO-NEUTRAL CONDITIONS ARE CONTINUING. A RESIDUAL, SMALL AREA OF SLIGHTLY BELOW NORMAL SEA SURFACE TEMPERATURES (SSTS) REMAINS IN PROXIMITY TO THE DATE LINE, FROM LAST WINTER'S LA NINA, BUT IN AREAS TO THE WEST AND EAST ALONG THE EQUATOR, SSTS ARE NOW ABOVE AVERAGE. THE HEAT CONTENT ANOMALY OF THE UPPER-OCEAN LAYERS, TO A DEPTH OF 300 METERS, SUMMED ACROSS THE BASIN FROM THE DATE LINE TO 100W IS NOW NEAR ZERO AFTER DECREASING FROM POSITIVE HEAT CONTENT ANOMALIES DURING FEBRUARY AND MARCH.

IN THE ATMOSPHERE OVER THE PAST MONTH, EASTERLY WIND ANOMALIES CONTINUED TO BE OBSERVED OVER THE CENTRAL AND WESTERN TROPICAL PACIFIC. OVER THE SAME PERIOD, MEASUREMENTS OF TROPICAL CONVECTION INDICATED CONTINUED SUPPRESSED CONVECTION IN THE CENTRAL PACIFIC AND CONTINUING ENHANCED CONVECTION OVER MUCH OF THE MARITIME CONTINENT. THIS ANOMALOUS CONVECTION PATTERN APPEARS TO BE A RESIDUAL OF THE WEAK LA NINA EVENT THAT HAS OTHERWISE ENDED.

PROGNOSTIC DISCUSSION OF SST FORECASTS

THE CPC NINO 3.4 SST CONSOLIDATION FORECAST, WHICH INCLUDES CANONICAL CORRELATION ANALYSIS (CCA), CONSTRUCTED ANALOG (CA), AND MARKOV STATISTICAL FORECASTS, ALONG WITH THE CFS DYNAMICAL MODEL, PREDICTS A MEDIAN TEMPERATURE ANOMALY OF +0.4C FOR THE COMING SEASONS FROM APPROXIMATELY MJJ THROUGH OND 2017, WITH EL NINO AS MOST LIKELY FROM LATE SUMMER THROUGH AUTUMN. A CONSIDERABLE DIFFERENCE BETWEEN THE CFS AND THE STATISTICAL GUIDANCE APPEARS IN THE CONSOLIDATION, HOWEVER, WITH THE CFS FORECASTING A RAPID INCREASE IN SSTS EARLY IN THE OUTLOOK PERIOD AND EL NINO CONDITIONS BEGINNING WITH THE MJJ 2017 SEASON, WHILE THE CA STATISTICAL FORECAST EXCEEDS THE +0.5C THRESHOLD FOR EL NINO STARTING IN JAS 2017, AND THE CCA AND MARKOV MODELS REMAIN IN ENSO NEUTRAL THROUGHOUT THE FORECAST PERIOD.  THIS SEPARATION BETWEEN THE STATISTICAL AND DYNAMICAL MODELS IS ALSO DEPICTED BY THE LATEST IRI NINO3.4 SST FORECAST PLUME. MOREOVER, FORECASTS FROM THE DYNAMICAL SUITE OF MODELS FROM THE NMME ALSO INDICATE A MORE RAPID INCREASE IN NINO 3.4 SST DURING THE SPRING AND SUMMER MONTHS. THE LATEST OFFICIAL ENSO OUTLOOK FROM CPC/IRI INDICATES ENSO-NEUTRAL CONDITIONS ARE LIKELY TO CONTINUE THROUGH AT LEAST THE NORTHERN HEMISPHERE SPRING WITH INCREASING ODDS FOR THE DEVELOPMENT OF EL NINO CONDITIONS AS AUTUMN APPROACHES WITH PROBABILITIES FOR EL NINO OF ABOUT 50% FROM ASO 2017 CONTINUING THROUGH NDJ 2017. THE CONSENSUS FORECAST INDICATES THE LIKELIHOOD OF A REPEAT LA NINA EVENT TO BE VERY SMALL DURING THIS FORECAST PERIOD.

30-DAY OUTLOOK DISCUSSION FOR MAY 2017

ENSO NEUTRAL CONDITIONS ARE PRESENT ACROSS THE PACIFIC OCEAN.  SOME ATMOSPHERIC VARIABLES, SUCH AS LOW-LEVEL WINDS AND OUTGOING LONGWAVE RADIATION (OLR) STILL HAVE SOME RESEMBLANCE TO CANONICAL LA NINA PATTERNS, THOUGH OTHERS (UPPER-LEVEL WINDS) ARE LESS COHERENT. OLR STILL INDICATES SUPPRESSED (ENHANCED) CONVECTION NEAR THE DATE LINE (MARITIME CONTINENT). A KEY DIFFERENCE THIS MONTH, IS THAT THE SUPPRESSED CONVECTION EXTENDS NORTHEASTWARD, RATHER THAN BEING SYMMETRIC ALONG THE EQUATOR. THIS ASYMMETRY HAS ALLOWED SOME CONVECTION TO DEVELOP FROM 160W TO 120W, JUST SOUTH OF THE EQUATOR.

THE MJO PLAYED A SMALL ROLE IN THE TROPICAL PACIFIC DURING MARCH. SOME SHORTER PERIOD VARIABILITY WAS EVIDENT ACROSS THE EASTERN PACIFIC, BUT THE PATTERN OVER THE CENTRAL PACIFIC WAS HIGHLY LINKED TO THE LONG-TERM PATTERN. FORECASTS OF THE MJO INDICATE AN AMPLIFICATION OVER THE WESTERN PACIFIC, THOUGH THE INCOHERENCE OF THE OBSERVED SIGNAL INCREASES UNCERTAINTY. THE MJO IS NOT LIKELY TO PLAY A LARGE ROLE IN THE MONTHLY VARIABILITY OVER NORTH AMERICA DURING MAY.

OTHER FACTORS, SUCH AS ANTECEDENT SOIL MOISTURE AND SNOW PACK, WERE CONSIDERED. SOIL MOISTURE IS ANOMALOUSLY HIGH OVER PORTIONS OF THE MIDWEST, WHICH HAS A LAGGED RELATIONSHIP WITH BELOW NORMAL TEMPERATURES. ABOVE NORMAL SNOW PACK OVER THE CENTRAL AND NORTHERN ROCKIES WAS ALSO CONSIDERED IN THE TEMPERATURE OUTLOOK.

Temperature

DYNAMIC MODELS FROM THE NMME SUITE GENERALLY INDICATED ABOVE NORMAL TEMPERATURES FOR MOST OF THE CONUS AND ALASKA. PROBABILITIES WERE WEAKEST FROM CALIFORNIA TO THE PACIFIC NORTHWEST AND NORTHERN ROCKIES. MORE RECENT TRENDS IN MODEL GUIDANCE (CFS FOR THE MONTH OF MAY, GUIDANCE FOR THE WEEK 3-4 PERIOD, AND THE LAST FEW DAYS OF THE 8-14 DAY PERIOD) INDICATE A COOL START TO THE MONTH OVER THE NORTHERN ROCKIES AND GREAT PLAINS. THE OUTLOOK REFLECTS THE COMBINATION OF NMME MODELS AND MORE RECENT MODEL INPUTS, AS WELL AS THE ANTECEDENT CONDITIONS MENTIONED ABOVE. THE OUTLOOK INDICATES ABOVE NORMAL TEMPERATURES ARE FAVORED FOR THE SOUTHWEST, TEXAS, AND FROM THE SOUTHEAST TO THE GREAT LAKES AND NORTHEAST.

Precipitation

SIGNALS FOR PRECIPITATION ANOMALIES IN THE INDIVIDUAL NMME MODELS ARE QUITE STRONG, BUT SIGNALS IN THE MEAN ARE QUITE A BIT WEAKER AS THE MODELS EXHIBIT POOR AGREEMENT IN THE OVERALL PATTERN. AFTER CALIBRATION, WEAK SIGNALS REMAIN OVER WESTERN ALASKA, THE NORTHERN HIGH PLAINS, THE GREAT LAKES, AND NORTHEAST.

SOME OF THE MODELS IN THE NMME SUITE INDICATED EXTREME ANOMALIES (IN BOTH TEMPERATURE AND PRECIPITATION), SO THOSE MODELS WERE CONSIDERED OUTLIERS. TO BROADEN THE MODEL INPUTS AND LESSEN THE IMPACT OF THE EXTREME ANOMALIES, THE IMME WAS ALSO USED AS AN INPUT FOR THE PRECIPITATION OUTLOOK. THE OFFICIAL OUTLOOK INDICATES BELOW MEDIAN PRECIPITATION IS FAVORED FOR WESTERN ALASKA, THE ALASKA PANHANDLE, AND THE GREAT LAKES, ALL CONSISTENT WITH MODEL OUTPUT. ABOVE MEDIAN PRECIPITATION IS FAVORED OVER THE NORTHERN HIGH PLAINS AND ALONG THE GULF COAST, CONSISTENT WITH MODEL OUTPUT AND IN SOME CASES, TRENDS.

Three Months May-June-July and to some extent August

Temperature

THE LATEST MJJ AND JJA 2017 TEMPERATURE OUTLOOKS INDICATE ABOVE-NORMAL TEMPERATURES ARE MOST LIKELY FOR MUCH OF THE FORECAST DOMAIN, WITH THE EXCEPTION OF PARTS OF THE NORTHERN ROCKIES AND NORTHERN PLAINS. THE CHANCES OF ABOVE-NORMAL SEASONAL MEAN TEMPERATURES ARE SLIGHTLY ENHANCED FOR MUCH OF THE PACIFIC NORTHWEST, BUT THE PROBABILITY OF ABOVE-NORMAL TEMPERATURES IS MODERATED BY RECENT POSITIVE SNOW AND SOIL MOISTURE ANOMALIES. ABOVE-NORMAL TEMPERATURES ARE PARTICULARLY ENHANCED FOR A REGION STRETCHING FROM THE SOUTHWEST, EASTWARD ACROSS THE CENTRAL AND SOUTHERN PLAINS INTO THE EASTERN U.S. THE GREATEST PROBABILITIES EXCEED 50% FOR PARTS OF THE SOUTHWEST AND ALONG THE GULF AND ATLANTIC COASTS, FOLLOWING THE CALIBRATED PROBABILISTIC GUIDANCE FROM THE NMME. NEGATIVE SOIL MOISTURE ANOMALIES IN THE SOUTHEAST REGION ALSO CONTRIBUTE TO THE LIKELIHOOD OF ANOMALOUS WARMTH. DECADAL CLIMATE TRENDS ALSO SUPPORT THE OUTLOOK AND ARE A COMPONENT OF THE DYNAMICAL MODEL GUIDANCE. THESE FORECAST TOOLS ALSO SUPPORT ENHANCED PROBABILITIES OF ABOVE-NORMAL TEMPERATURES FOR ALASKA.

Precipitation

FOR PRECIPITATION, THE MJJ AND JJA 2017 OUTLOOKS INDICATE ABOVE-MEDIAN PRECIPITATION FOR AREAS OF THE ROCKY MOUNTAINS AND JUST TO THE EAST, FROM CENTRAL MONTANA SOUTHWARD INCLUDING PARTS OF WYOMING, UTAH, COLORADO AND NEW MEXICO, AS WELL AS FOR WESTERN AREAS OF THE GULF COAST, AND FOR EASTERN INTERIOR REGIONS OF ALASKA. BELOW-MEDIAN SEASONAL PRECIPITATION AMOUNTS ARE FAVORED FOR THE WESTERN AND CENTRAL GREAT LAKES REGION.

PROGNOSTIC DISCUSSION OF OUTLOOKS - MJJ 2017 TO MJJ 2018 (Focus on August and Beyond)

TEMPERATURE

LITTLE CHANGE WAS MADE TO PREVIOUS OUTLOOKS FOR REMAINING SEASONS THROUGH 2017 INTO THE FIRST HALF OF 2018. ENHANCED PROBABILITIES OF ABOVE-NORMAL TEMPERATURES ARE INDICATED THROUGHOUT THE FORECAST DOMAIN THROUGH DJF 2017-2018. FROM THE JFM THROUGH MJJ 2018 SEASONS, REGIONS OF ENHANCED PROBABILITIES OF ABOVE-NORMAL TEMPERATURES FOLLOW STATISTICAL GUIDANCE, PRIMARILY RESULTING FROM DECADAL CLIMATE TRENDS.

HIGH PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ARE INDICATED FOR THE NORTH SLOPE OF ALASKA DURING SON AND OND 2017 DUE TO DECADAL TRENDS IN THE SEASONAL CYCLE OF SEA ICE.

PRECIPITATION

THE OUTLOOKS FOR THE MJJ THROUGH SON 2017 SEASONS ARE PRIMARILY BASED ON WEAK SIGNALS THAT APPEAR IN CALIBRATED PROBABILISTIC GUIDANCE FROM THE NMME. ELEVATED CHANCES FOR ABOVE-MEDIAN PRECIPITATION CONTINUE FOR AREAS IN THE CENTRAL AND NORTHERN ROCKIES AND NORTHERN HIGH PLAINS FOR JJA AND JAS 2017, AND FOR THE CENTRAL ROCKIES FOR ASO AND SON 2017. FROM ASO THROUGH OND 2017, INCREASING CHANCES FOR EL NINO CONDITIONS AND DYNAMICAL MODEL FORECASTS OF GREATER THAN AVERAGE SSTS IN THE EASTERN TROPICAL PACIFIC LEAD TO A SOUTHWARD SHIFT OF THIS REGION OF LIKELY ABOVE-MEDIAN PRECIPITATION INTO THE SOUTHWEST CONUS INCLUDING SOUTHERN CALIFORNIA AND ARIZONA IN OND 2017.

 FOR LATE AUTUMN AND WINTER, FROM NDJ 2017-2018 THROUGH JFM 2018, THE LOW PROBABILITY OF A LA NINA AND ELEVATED CHANCES FOR A POSSIBLE EL NINO RESULT IN REMOVAL OF A SIGNAL FOR DRIER THAN NORMAL CONDITIONS FROM THE DECADAL CLIMATE TRENDS FOR THE SOUTHWEST. FOLLOWING FMA 2018, WEAK SIGNALS DUE TO DECADAL TRENDS IN PRECIPITATION ARE INDICATED, INCLUDING BELOW-MEDIAN PRECIPITATION FOR PARTS OF THE SOUTHWEST BEGINNING WITH THE FMA 2018 SEASON AND ABOVE-MEDIAN PRECIPITATION IN THE NORTHERN-CENTRAL CONTIGUOUS U.S. BEGINNING WITH MAM 2018.

Forecasting the Evolution of ENSO

Here 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.

We are beyond wondering if the Cool Event will meet La Nina Standards (it did not but that did not stop NOAA from declaring it to have been a reportable La Nina). Now we are wondering if the forecasted Warm Event will meet El Nino Standards.

 CFS.V2 SST Forecast April 21, 2017

Note that the forecast is showing two peaks in the Nino 3.4 Index: one in MJJ and JJA and a second peak this winter. At GEI we still believe the conditions do not exist to have a significant El Nino but the World's forecasters are forecasting just that so we will have to wait and see. For this report, the NOAA and JAMSTEC Nino 3.4 forecasts are what is important.

SOI values as of April 21, 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 are clearly in the ENSO Neutral phase of ENSO.

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

And now we have the IRI/CPC April 20, 2017 fully model-based report. This (click to read) is the discussion that was issued with the April 20 Report.

April 20, 2017 IRI/CPC ENSO Model Based Report.

As you can see, II and CPC are bullish re the probabilities for an El Nino very soon and lasting quite long.

Here is the most recent Nino 3.4 report from the Australian BOM.

Australia POAMA ENSO model run April 17, 2017

This is basically the same forecast as other agencies but with a different threshold for considering a SSTA to be either La Nina or El Nino. Note their forecast is showing borderline El Nino levels starting in July and gradually moving higher through Jan 2018 which is the limit of what is shown on the map.

Here is the recently released JAMSTEC forecast of the Nino 3.4 values. Notice they are forecasting a fairly high level for the Nino 3.4 Index (higher than the other Meteorological Agencies) but a rapid decline starting in January. That is very significant relative to their DJF 2017 - 2018 forecast. Their forecast for the Nino 3.4 Index is of course subject to change next month.

JAMSTEC April 1, 2017 ENSO Forecast.

The ENSO forecasts are not the only factor that is considered when making these fairly long term forecasts but it is a very major factor so that ENSO forecast strongly influences the Temperature and Precipitation forecasts.

Now the Comparison of the NOAA and JAMSTEC Forecasts. I am only discussing the differences for Alaska and CONUS since NOAA does not cover the World in this set of forecasts. But the JAMSTEC World forecast is here for you to see and I comment on the highlights of that forecast also. I should note that JAMSTEC believes their model is most accurate at low latitudes. This makes sense as they would reasonably focus on Japan which is at about the same latitude as CONUS (the contiguous part of the United States in North America).

JAMSTEC works in three-month intervals and does not change the selection of months each time they update. So we have  JJA, SON and DJF 2018, to work with from JAMSTEC. May is not in one of the JAMSTEC three-month maps so our comparisons begin with the JJA three-month period.

JJA

Temperature

NOAA

JJA 2017 Temperature Issued by NOAA on April 20, 2017

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

JJA JAMSTEC extracted from April 1, 2017 World Forecast

NOAA shows a North Central area that is EC. For JAMSTEC, almost everything is warm except for part of Florida

And Now the JAMSTEC WORLD FORECAST

JJA Temperature Forecast from JAMSTEC April 1, 2017 forecast.

For the World, JAMSTEC sees very little that is cool other than Northern Australia and Northeast China which is a bit of a surprise as summer is the warm season for the Ice Province of China.

Precipitation

NOAA

NOAA SON 2017 Precipitation Issued April 20, 2017

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

CONUS JJA Precipitation Extracted from April 1, JAMSTEC Forecast

For CONUS, NOAA shows Alaska EC but wet to the east and JAMSTEC is showing Alaska dry. For CONUS NOAA shows mostly EC with a small Great Lakes dry anomaly and a small Western Gulf of Mexico wet anomaly and a Rocky Mountains wet anomaly. Neither CONUS nor JAMSTEC is showing a Southwest Monsoon that differs significantly from climatology (normal) but JAMSTEC is a bit more wet in Southern Arizona and NOAA shows the wet area strangely north of the usual Southwest Monsoon location. JAMSTEC is showing a wet North Central extending into the Midwest and a slightly dry East Coast.

JAMSTEC WORLD FORECAST

JJA 2017 Jamstec Precipitation Forecast From April 1, 2017

Of interest is the dry Europe. Southeast Asia is wet but part of the Maritime Continent is dry. Just north of the Equator, Africa is wet. Australia is dry.

SON 2017

Temperature

NOAA

SON Temperature NOAA Issued on April 20, 2017

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

SON North American Temperature extracted from JAMSTEC April 1 Forecast

NOAA shows all of Alaska and CONUS warm. For JAMSTEC, not much change from JJA other than the odd cool anomaly in Eastern Arizona and Northern New Mexico with a small cool anomaly in Northern Florida. Quite a feat if their models can pin things down this well.

JAMSTEC WORLD FORECAST

SON 2017 JAMSTEC Temp from March 1, 2017

For JAMSTEC we see a few cool areas including Southern South America, Greenland, and quite a bit of Asia above 30N plus Somalia and Western Sahara. One has to search for cool areas these days.

Precipitation

NOAA

NOAA SON 2017 Precipitation Issued on April 20, 2017

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

SON JAMSTEC Precipitation for CONUS based on April 1 forecast

One difference is that JAMSTEC shows Alaska wet while NOAA is showing Alaska EC. For CONUS there is some similarity but JAMSTEC shows more wet area especially the Plains States but Texas dry. Both NOAA and JAMSTEC show the Southwest wet which is kind of like a late Southwest Monsoon.

JAMSTEC WORLD FORECAST

SON 2017 JAMSTEC Precipitation Forecast from April 1, 2017

Northern Europe is dry. Australia and more intensely the island nations north of Australia are dry. Part of India is dry. Equatorial and much of southern Africa is wet. Most of South America is wet.

DJF 2017-2018

Temperature

NOAA

NOAA DJF 2017- 2018 Temperature Issued April 20, 2017

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

DJF 2017-2018 North America Temperature Forcast Extracted from the April 1 JAMSTEC Forecast

NOAA has both Alaska and CONUS warm. For JAMSTEC, Alaska and Canada are warm and CONUS is cool except for a sliver along the West Coast and Minnesota and the Eastern Dakotas which are being influenced by Canada. It is kind of shocking to see the difference between NOAA and JAMSTEC re the temperature anomaly in CONUS.

JAMSTEC WORLD FORECAST

SON 2017 JAMSTEC Temperature from April 1,  2017

The major cool area is CONUS but there are other cool areas such as the southern tip of South America, The U.K., Greenland, Iran, and parts of Central Asia.

Precipitation

NOAA

DJF 2017 Precipitation Issued April 20, 2017

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

JAMSTEC DJF precipitation extracted from their April 1 2017 Forecast

CONUS is not ready to forecast precipitation this far out. JAMSTEC has Alaska slightly wet and the northern tier of CONUS very dry with a very wet Southeast a typical El Nino Pattern.

JAMSTEC WORLD FORECAST

DJF 2017-2018 JAMSTEC Precipitation Forecas from April 1, 2017

South Africa is wet, Australia is dry. Much of South America is wet but not northern South America which is important due to the unrest in Venezuela. Much of southern Asia is wet.

Conclusion

Both forecasts are based on an El Nino arriving. JAMSTEC assumes a stronger El Nino than NOAA and their forecast reflects this. In general an El Nino is a drought pattern for most of the World but not the U.S. The JAMSTEC forecast is not as drought oriented as we might have expected but both JAMSTEC and NOAA are oriented towards warm conditions except JAMSTEC for December - February 2018 for CONUS. If they are correct about a cool CONUS in December 2017 through February 2018, this has many implications for energy use in CONUS and raises questions about the Citrus Crops in the Southeast.  

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

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