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Official 90-day Outlooks are issued once each month near mid-month at 8:30am Eastern Time. Please consult the schedule of 30 & 90-day outlooks for exact release dates.

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More Outlooks
    0.5mn NDJ 2017
    1.5mn DJF 2017
    2.5mn JFM 2018
    3.5mn FMA 2018
    4.5mn MAM 2018
    5.5mn AMJ 2018
    6.5mn MJJ 2018
    7.5mn JJA 2018
    8.5mn JAS 2018
    9.5mn ASO 2018
   10.5mn SON 2018
   11.5mn OND 2018
   12.5mn NDJ 2018
    0.5mn Nov 2017


Tools Used (see Discussion for explanation)
   CCA
   OCN
   CMP
   SMT
   POE
 
HOME> Outlook Maps>Seasonal Forecast Discussion
 
PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS 
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830 AM EDT THU OCT 19 2017

SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS

THE NOVEMBER-DECEMBER-JANUARY (NDJ) 2017-18 OUTLOOK FAVORS ABOVE NORMAL
TEMPERATURES FOR THE MAJORITY OF THE FORECAST DOMAIN, INCLUDING MUCH OF ALASKA.
THE HIGHEST PROBABILITIES FOR ELEVATED ODDS OF WARMER THAN NORMAL TEMPERATURES
ARE LOCATED ACROSS PORTIONS OF THE SOUTHWEST AND TEXAS. DURING THE WINTER
MONTHS THROUGH FEBRUARY-MARCH-APRIL (FMA) 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.

THE NDJ 2017-18 PRECIPITATION OUTLOOK INDICATES INCREASED CHANCES OF ABOVE
NORMAL PRECIPITATION FOR WESTERN AND NORTHERN ALASKA, AS WELL AS AREAS OF THE
NORTHERN AND CENTRAL ROCKIES. DURING NDJ 2017-18, BELOW NORMAL PRECIPITATION IS
FAVORED ALONG THE SOUTHERN TIER OF THE CONUS, EXCLUDING SOUTHERN CALIFORNIA. AS
WE MOVE THROUGH THE WINTER SEASON, ELEVATED ODDS FOR ABOVE NORMAL PRECIPITATION
INCREASE IN COVERAGE FOR AREAS OF THE NORTHERN PLAINS, GREAT LAKES AND OHIO
VALLEY THROUGH JANUARY-FEBRUARY-MARCH (JFM) 2018 AND THEN SLOWLY DECREASE
ENTERING THE CORE SPRING MONTHS.

EQUAL CHANCES (EC) ARE FORECAST OVER AREAS WHERE PROBABILITIES OF ABOVE, BELOW,
OR NEAR NORMAL SEASONAL MEAN TEMPERATURES AND SEASONAL ACCUMULATED
PRECIPITATION AMOUNTS ARE FAVORED TO BE SIMILAR TO CLIMATOLOGICAL PROBABILITIES.

BASIS AND SUMMARY OF THE CURRENT LONG-LEAD OUTLOOKS
NOTE: FOR GRAPHICAL DISPLAYS OF THE FORECAST TOOLS DISCUSSED BELOW SEE:
HTTP://WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/PREDICTIONS/90DAY/TOOLS/BRIEFING

CURRENT ATMOSPHERIC AND OCEANIC CONDITIONS

A LA NINA WATCH CONTINUES, AS ATMOSPHERIC AND OCEANIC CONDITIONS, TAKEN IN
TOTALITY, REMAIN CLOSEST TO ENSO-NEUTRAL CONDITIONS THROUGH EARLY OCTOBER.
OCEANIC CONDITIONS CONTINUE TO MOVE QUITE CLOSE TO THE LA NINA STATE AS
EQUATORIAL SEA SURFACE TEMPERATURE (SST) DEPARTURES FROM NORMAL ARE NEGATIVE TO
A MAGNITUDE OF -0.5 DEGREES C FROM ABOUT 150W TO THE SOUTH AMERICAN COAST WITH
A HORSESHOE OF ABOVE NORMAL SSTS TO THE NORTH AND SOUTH OF THIS REGION AND
ACROSS THE FAR WESTERN PACIFIC (TYPICAL OF DEVELOPING/ESTABLISHED LA NINA
CONDITIONS). 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 CENTRAL EQUATORIAL PACIFIC WHILE ENHANCED RAINFALL CONTINUES ACROSS THE
MARITIME CONTINENT REGION. ALTHOUGH GENERALLY WEAK OVERALL, THE TRADE WINDS IN
THE PACIFIC HAVE BEEN ENHANCED AND UPPER-LEVEL WESTERLY WIND ANOMALIES ARE
CURRENTLY OBSERVED IN THE REGION AS WELL. AN ADDITIONAL FACTOR TO BE COGNIZANT
OF IN THE COMING MONTH IS THE CURRENT DEVELOPING MJO WHICH HAS, AND WILL LIKELY
CONTINUE TO, MODULATE SST, WINDS AND CONVECTION ON THE SUBSEASONAL TIME SCALE
ACROSS THE PACIFIC BASIN AS IT PROGRESSES ACROSS THE PACIFIC TO THE WESTERN
HEMISPHERE, AS CURRENTLY PREDICTED.

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
HOVERING AROUND THE -0.5 DEGREES C THRESHOLD, GENERALLY TAKEN AS THE BOUNDARY
FOR WEAK LA NINA CONDITIONS. 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 HOVER AT THE -0.5 DEGREES C VALUE
THROUGH JFM 2018 BEFORE GRADUALLY REDUCING TOWARD AN ANOMALY NEAR ZERO BY AMJ
2018. THERE ARE CONSIDERABLE DIFFERENCES IN THE EVOLUTION OVER TIME OF THESE
FORECASTS THIS MONTH, WITH THE CA, AS AN EXAMPLE, PREDICTING NEAR ZERO ANOMALY
THROUGHOUT THE FORECAST PERIOD.

THE NMME SUITE OF MODELS FOLLOW THIS GENERAL THEME, ALTHOUGH THE PERIOD OF THE
MOST NEGATIVE NINO3.4 SST ANOMALIES VARIES SOMEWHAT AS THE CFS REACHES THIS
POINT DURING DJF 2017-18 WHILE THE GFDL MODEL DOES SO DURING OND 2017. THE
ENSEMBLE MEAN PREDICTION IS QUITE CONSISTENT WITH THE CPC NINO3.4 SST
CONSOLIDATED FORECAST, ALTHOUGH WITH SOMEWHAT MORE NEGATIVE TEMPERATURE
DEPARTURES - REACHING -0.7 DEGREES C DURING DECEMBER 2017 AND JANUARY 2018. THE
VARIATION AND IN SOME CASES THE INCREASE IN NINO3.4 SST ANOMALIES AT THE START
OF THE PREDICTIONS IS RELATED SUBSEASONAL NOISE ASSOCIATED WITH THE ONGOING MJO
EVENT.

PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS

THE OFFICIAL TEMPERATURE AND PRECIPITATION OUTLOOKS FOR THE SEASONS FROM NDJ
2017-18 THROUGH FMA 2018 TOOK INTO CONSIDERATION IMPACTS OFTEN OBSERVED DURING
LA NINA EVENTS AS THE LATEST OFFICIAL ENSO OUTLOOK AND NINO3.4 SST MODEL
GUIDANCE CONTINUES TO INDICATE ELEVATED PROBABILITIES AS COMPARED TO
CLIMATOLOGY FOR LA NINA CONDITIONS DURING THIS PERIOD. STATISTICAL MODEL
FORECAST TOOLS SUCH AS REGRESSIONS ANCHORED TO THE CPC NINO3.4 SST
CONSOLIDATION FORECAST AND THE CCA U.S. TEMPERATURE AND PRECIPITATION
PREDICTIONS 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. THE CA U.S. TEMPERATURE
AND PRECIPITATION PREDICTIONS WERE ONLY USED AT INTERMEDIATE AND LATER LEADS AS
ITS ENSO FORECAST WAS VIEWED AS SOMEWHAT OF AN OUTLIER AS COMPARED TO THE
REMAINING NINO3.4 SST GUIDANCE EARLY IN THE PERIOD.

PROGNOSTIC DISCUSSION OF OUTLOOKS - NDJ 2017 TO NDJ 2018

TEMPERATURE

THE UPDATED SET OF TEMPERATURE OUTLOOKS THIS MONTH DO INDICATE SOME SUBSTANTIAL
CHANGES FROM THE PRECEDING SET OF OUTLOOKS DURING THE WINTER SEASONS PRIMARILY
ACROSS THE NORTHERN CONUS AND SOUTHEAST AREAS OF ALASKA INCLUDING THE ALASKA
PANHANDLE. INCREASING PROBABILITIES FOR LA NINA (AS INDICATED IN OBSERVATIONAL
DATA AND THE MOST RECENT SET OF MODEL FORECASTS) AS WELL AS 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 NDJ
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
CONSTRUCTED ANALOGUE STATISTICAL TOOL AFTER ANY CONSIDERATIONS FOR RESIDUAL LA
NINA IMPACTS ARE ANTICIPATED TO END.

THE NDJ 2017-18 TEMPERATURE OUTLOOK IS LARGELY UNCHANGED FROM THE OUTLOOK
RELEASED LAST MONTH AND DEPICTS ELEVATED ODDS FOR ABOVE NORMAL TEMPERATURES FOR
MOST OF THE FORECAST DOMAIN. THE MAIN CHANGE WAS A DECREASE IN COVERAGE IN
FAVORED ABOVE NORMAL TEMPERATURES FOR PORTIONS OF SOUTHERN ALASKA. AS WE EVOLVE
THROUGH THE WINTER SEASON THROUGH FMA 2018, HOWEVER, AN ENHANCED LIKELIHOOD OF
BELOW NORMAL TEMPERATURES IS HIGHLIGHTED FIRST FOR PORTIONS OF SOUTHEAST AREAS
OF ALASKA INCLUDING THE PANHANDLE, THE FAR PACIFIC NORTHWEST TO THE FAR
NORTHERN PLAINS. DURING JFM AND FMA 2018, BELOW NORMAL TEMPERATURES ARE FAVORED
FOR AN AREA IN THE MIDWEST AND WESTERN GREAT LAKES. THE ADDITIONS ARE BASED AS
A RESULT OF A CONVERGENCE OF TOOL SUPPORT FROM TYPICAL LA NINA IMPACTS,
TEMPERATURE PREDICTIONS BASED ON REGRESSION WITH THE CPC NINO3.4 SST
CONSOLIDATION PREDICTION AND LONG TERM TRENDS AS PREDICTORS AND CONSISTENT, TO
FIRST ORDER, FORECASTS FROM SEVERAL SHORT TERM CLIMATE DYNAMICAL MODEL GUIDANCE
FROM THE NMME PARTICIPANT MODELS AND ITS ENSEMBLE MEAN IN BOTH DETERMINISTIC
AND CALIBRATED PROBABILISTIC FORMATS. ALSO, RECENT LONGER TERM TEMPERATURE
TRENDS IN THE GREAT LAKES REGION AND MIDWEST, AS CHARACTERIZED BY 15 YEAR OCN
METHODOLOGY, ARE NEGATIVE AND CONTRIBUTE TO THE OUTLOOK AS WELL.

THE REMAINING OUTLOOKS FROM MJJ 2018 ONWARD THROUGH NDJ 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 NEAR GLOBAL SST BASED CONSTRUCTED ANALOGUE TOOL ALSO
CONTRIBUTED TO THE OUTLOOKS.

PRECIPITATION

FOR PRECIPITATION, THE OUTLOOKS ARE TO FIRST ORDER SIMILAR TO THE SET OF
OUTLOOKS RELEASED LAST MONTH WITH THE PRIMARY DIFFERENCE IN MOST CASES, AN
INCREASE IN FORECAST COVERAGE AND IN SOME CASES AN INCREASE IN FORECAST
PROBABILITIES. PROGRESSING FROM THE NDJ 2017-18 PERIOD THROUGH THE WINTER,
ELEVATED ODDS FOR ABOVE NORMAL PRECIPITATION, INITIALLY HIGHLIGHTED IN THE
NORTHERN ROCKIES, EXPAND IN COVERAGE TO INCLUDE PARTS OF THE NORTHERN PLAINS,
MIDWEST, GREAT LAKES AND OHIO VALLEY. DRIER THAN AVERAGE CONDITIONS ARE FAVORED
ACROSS THE SOUTHERN TIER OF THE CONUS WITH THE GREATEST PROBABILITIES IN DJF
2017-18 AND JFM 2018 IN SOME AREAS OF THE SOUTHEAST. AGAIN, IN MOST PARTS OF
THE REGIONS DEPICTED, ALTHOUGH THE PROBABILITIES ARE MODEST, FORECASTS REFLECT
WHERE THERE IS A PREPONDERANCE OF EVIDENCE FROM BOTH STATISTICAL FORECAST
TOOLS, DYNAMICAL MODEL OUTPUT AND IN SOME REGIONS NON-TRIVIAL LONG TERM, BOTH
POSITIVE AND NEGATIVE, PRECIPITATION TRENDS.

THE PRECIPITATION OUTLOOKS FROM AMJ 2018 ONWARD THROUGH OND 2018 WERE GENERALLY
UNCHANGED 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.

FORECASTER: JON GOTTSCHALCK

THE CLIMATIC NORMALS ARE BASED ON CONDITIONS BETWEEN 1981 AND 2010, FOLLOWING
THE WORLD METEROLOGICAL ORGANIZATION CONVENTION OF USING THE MOST RECENT 3
COMPLETE DECADES AS THE CLIMATIC REFERENCE PERIOD.  THE PROBABILITY ANOMALIES
FOR TEMPERATURE AND PRECIPITATION BASED ON THESE NEW NORMALS BETTER REPRESENT
SHORTER TERM CLIMATIC ANOMALIES THAN THE FORECASTS BASED ON OLDER NORMALS.

FOR A DESCRIPTION OF OF THE STANDARD FORECAST TOOLS - THEIR SKILL- AND THE
FORECAST FORMAT PLEASE SEE OUR WEB PAGE AT
HTTP://WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/PREDICTIONS/LONG_RANGE/TOOLS.HTML
(USE LOWER CASE LETTERS)
INFORMATION ON THE FORMATION OF SKILL OF THE CAS FORECASTS MAY BE FOUND AT:
HTTP://WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/SOILMST_MONITORING/US/OUTLOOK/OUTLOOK.SHTM
L
(USE LOWERCASE LETTERS)
NOTES - THESE CLIMATE OUTLOOKS ARE INTENDED FOR USE PRIOR TO THE START OF THEIR
VALID PERIOD.  WITHIN ANY GIVEN VALID PERIOD OBSERVATIONS AND SHORT AND MEDIUM
RANGE FORECASTS SHOULD BE CONSULTED.

THIS SET OF OUTLOOKS WILL BE SUPERSEDED BY THE ISSUANCE OF THE NEW SET NEXT
MONTH ON NOV 16 2017


1981-2010 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 19, 2011
FORECAST RELEASE.
$$

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Page last modified: January 17, 2006
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