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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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    0.5mn MJJ 2014
    1.5mn JJA 2014
    2.5mn JAS 2014
    3.5mn ASO 2014
    4.5mn SON 2014
    5.5mn OND 2014
    6.5mn NDJ 2014
    7.5mn DJF 2014
    8.5mn JFM 2015
    9.5mn FMA 2015
   10.5mn MAM 2015
   11.5mn AMJ 2015
   12.5mn MJJ 2015
    0.5mn May 2014


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   CCA
   OCN
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HOME> Outlook Maps>Seasonal Forecast Discussion
 
PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS 
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830AM EDT THURSDAY APR 17 2014

SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS

THE MAIN FACTORS THAT USUALLY INFLUENCE THE SEASONAL CLIMATE OUTLOOK INCLUDE:
1) EL NINO AND LA NINA - WHICH TOGETHER COMPRISE EL NINO/SOUTHERN OSCILLATION
OR ENSO. IMPACTS OF THESE EVENTS ARE SUMMARIZED BY SEPARATING 3-MONTH
OBSERVATIONS FROM 3 OR MORE DECADES INTO EL NINO, NEUTRAL, AND LA NINA SETS,
AVERAGING EACH SEPARATELY, AND THEN COMPUTING ANOMALIES. THESE ARE CALLED "ENSO
COMPOSITES", WHICH ARE USED AT TIMES TO SUBJECTIVELY MODIFY THE FORECAST.
2) TRENDS - APPROXIMATED BY THE OCN TOOL AS THE DIFFERENCE BETWEEN THE MOST
RECENT 10-YEAR MEAN OF TEMPERATURE OR 15-YEAR MEAN OF PRECIPITATION FOR A GIVEN
LOCATION AND TIME OF YEAR AND THE 30-YEAR CLIMATOLOGY PERIOD (CURRENTLY
1981-2010).
3) THE TROPICAL 30-60 DAY OSCILLATION - SOMETIMES CALLED MADDEN JULIAN
OSCILLATION (MJO) - AFFECTS CLIMATE VARIABILITY WITHIN SEASONS.
4) THE NORTH ATLANTIC OSCILLATION (NAO) AND THE PACIFIC NORTH AMERICAN (PNA)
PATTERNS - WHICH AFFECT THE TEMPERATURE ANOMALY PATTERN ESPECIALLY DURING THE
COLD SEASONS. THESE PHENOMENA ARE CONSIDERED LESS PREDICTABLE ON A SEASONAL
TIMESCALE THAN ENSO.
5) THE PACIFIC DECADAL OSCILLATION (PDO) - AN ENSO-LIKE PATTERN OF CLIMATE
VARIABILITY AFFECTING THE TROPICS AND THE NORTH PACIFIC AND NORTH AMERICAN
REGIONS, BUT WHICH VARIES ON A MUCH LONGER TIME-SCALE THAN ENSO.
6) PERSISTENTLY DRY OR WET SOILS IN THE SPRING AND SUMMER AND SNOW AND ICE
COVER ANOMALIES IN THE WINTER. THESE FACTORS TEND TO PERSIST FOR LONG PERIODS
AND ACT AS A KIND OF MEMORY IN THE CLIMATE SYSTEM.
7) STATISTICAL FORECAST TOOLS - CANONICAL CORRELATION ANALYSIS (CCA), SCREENING
MULTIPLE LINEAR REGRESSION (SMLR), CONSTRUCTED ANALOGUE (CA) AND ENSEMBLE CCA
(ECCA).
8) DYNAMICAL FORECAST MODELS - INCLUDING THE NCEP CLIMATE FORECAST SYSTEM
(CFS). AN EXPERIMENTAL MODEL FORECAST SYSTEM, THE NATIONAL MULTI-MODEL
ENSEMBLE, COMPRISED OF SEVERAL MODELS AND DESIGNATED NMME, MAY ALSO BE USED
EXPERIMENTALLY AND SUBJECTIVELY UNTIL IT IS INCLUDED INTO THE CONSOLIDATION. AN
INTERNATIONAL MODEL ENSEMBLE DESIGNATED IMME IS ALSO AVAILABLE.
9) CONSOLIDATION (CON) - AN OBJECTIVE, SKILL-WEIGHTED COMBINATION OF THE OCN,
CCA, SMLR, ECCA, AND CFS FORECASTS IS USED AS A FIRST GUESS IN PREPARING THE
FORECAST MAPS. THIS TECHNIQUE MAKES OPTIMUM USE OF THE KNOWN SKILL OF FORECAST
TOOLS.

CURRENT ATMOSPHERIC AND OCEANIC CONDITIONS ARE ENSO-NEUTRAL BUT THE LATEST ENSO
OUTLOOK FAVORS WARM-ENSO CONDITIONS, ALSO CALLED EL NINO, TO DEVELOP IN EITHER
LATE SPRING OR SUMMER 2014 WITH PROBABILITIES OF AN EL NINO IN PLACE IN EARLY
FALL ASSESSED AT 60%. A LA NINA IN 2014 CAN BE VIRTUALLY RULED OUT.

THE TEMPERATURE OUTLOOK FOR MAY-JUNE-JULY (MJJ) 2014 INDICATES ELEVATED ODDS OF
ABOVE NORMAL TEMPERATURES FOR ALASKA AND A REGION FROM THE PACIFIC NORTHWEST TO
CALIFORNIA AND NEVADA, EASTWARD ALONG THE SOUTHERN TIER OF THE CONTINENTAL U.S.
AND ALSO ALONG THE EAST COAST TO INCLUDE MUCH OF NEW ENGLAND. THERE ARE
ELEVATED CHANCES OF BELOW NORMAL TEMPERATURES MAINLY IN MONTANA AND NORTH
DAKOTA.

THE MJJ 2014 PRECIPITATION OUTLOOK CALLS FOR ENHANCED PROBABILITIES OF
BELOW-MEDIAN PRECIPITATION FOR SOUTHEAST ALASKA ALONG THE WEST COAST TO
NORTHERN CALIFORNIA. ENHANCED PROBABILITIES OF ABOVE-MEDIAN PRECIPITATION ARE
INDICATED FOR THE FOUR CORNERS REGION OF NEW MEXICO, COLORADO, UTAH AND ARIZONA.

IN AREAS WHERE THE LIKELIHOODS OF SEASONAL MEAN TEMPERATURES AND SEASONAL
ACCUMULATED PRECIPITATION AMOUNTS ARE SIMILAR TO CLIMATOLOGICAL PROBABILITIES,
EQUAL CHANCES (EC) IS SHOWN.

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

OVER THE LAST FEW MONTHS, CONSIDERABLE CHANGES HAVE OCCURRED ACROSS THE
EQUATORIAL PACIFIC OCEAN, BOTH IN THE ATMOSPHERE AND IN THE OCEAN THAT HAVE
INCREASED PROBABILITIES FOR THE DEVELOPMENT OF EL NINO LATER IN 2014.  THERE
HAS BEEN TWO STRONG WESTERLY WIND BURSTS OVER THE WESTERN PACIFIC, ONE
OCCURRING DURING LATE JANUARY AND ANOTHER SPANNING LATE FEBRUARY AND EARLY
MARCH. A THIRD ONE MAY BE DEVELOPING RIGHT NOW. THE FIRST WESTERLY WIND EVENT
INITIATED A STRONG OCEANIC DOWN-WELLING KELVIN WAVE WHICH TRAVERSED MUCH OF THE
PACIFIC OCEAN AND MIGHT IMPACT SEA SURFACE TEMPERATURE IN THE EAST PACIFIC
SOON. THE SUB-SURFACE HEAT CONTENT HAS INCREASED DRAMATICALLY IN THE LAST
MONTH. AT DEPTH, POSITIVE OCEAN TEMPERATURES ARE EVIDENT FROM 180W TO 90W AT
DEPTHS RANGING FROM LESS THAN 50 M TO 200 M. THE GREATEST POSITIVE ANOMALIES
REACH +6.0 DEGREES C.

ANOMALOUS EQUATORIAL CONVECTION HAS ALSO CHANGED MARKEDLY IN RECENT MONTHS. THE
SUPPRESSED CONVECTION THAT HAD BEEN SURPRISINGLY DOMINANT NEAR THE DATE LINE
DURING LATE 2013 AND EARLY 2014 HAS DISAPPEARED ENTIRELY AND HAS NOW SEEN
TRANSIENTS OF STRONGER THAN NORMAL CONVECTION.

PROGNOSTIC DISCUSSION OF SST FORECASTS

IN THE PAST MONTH THERE HAS BEEN A FURTHER INCREASE IN CHANCES FOR EL NINO
LATER THIS YEAR. THE CPC SST CONSOLIDATION FORECAST NOW HAS THE SST ANOMALY FOR
NINO3.4 GROWING ABOVE POSITIVE 0.5C IN JJA 2014. THE LATEST CFS NINO3.4
FORECAST INDICATES ITS ENSEMBLE MEAN CROSSING ABOVE +0.5 DEGREES C IN MJJ 2014
AND INCREASING TO MORE THAN +1.5 DEGREES C BY OND 2014. ENSEMBLE MEAN FORECASTS
FROM THE IMME AND NMME INDICATE CROSSING THE 0.5 AND 1.5 THRESHOLDS IN JUNE AND
OCTOBER RESPECTIVELY.

AN EL NINO WATCH WAS ISSUED EARLIER IN MARCH INDICATING THAT CONDITIONS ARE
FAVORABLE FOR THE DEVELOPMENT OF EL NINO SOMETIME IN THE NEXT SIX MONTHS.
ACCORDING TO THE IRI/CPC CONSENSUS THE GREATEST ODDS FOR EL NINO DEVELOPMENT
GENERALLY BEGIN FROM JJA 2014 ONWARDS, WITH PROBABILITIES FOR EL NINO SLIGHTLY
OVER 50% AND 65% IN SUMMER AND FALL OF 2014 RESPECTIVELY.

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

THE TEMPERATURE AND PRECIPITATION OUTLOOKS WERE MADE CONSIDERING ENSO
CONDITIONS TO BE A MINOR FACTOR IN EARLY SUMMER. THEREAFTER, INCREASING CHANCES
FOR EL NINO AND ASSOCIATED POTENTIAL IMPACTS WERE INCORPORATED AT LONGER LEADS
ESPECIALLY FOR THE CORE WINTER 2014/15 SEASONS. GUIDANCE FROM THE CFS AS WELL
AS THE NMME AND IMME AND THEIR ASSOCIATED COMPONENTS CONTRIBUTED TO THE
OUTLOOKS FROM MJJ THROUGH SON 2014. IN PARTICULAR AT THE EARLY LEADS MJJ, JJA
AND ASO THE NMME PROBABILITY EXPRESSION WAS USED HEAVILY. THE CON TOOL WAS THE
PRIMARY DRIVER FOR THE OUTLOOKS FROM SON 2014 ONWARDS, WITH ENSO COMPOSITES AT
LEAST EQUALLY CONSIDERED IMPORTANT FROM NDJ THROUGH FMA.

PROGNOSTIC DISCUSSION OF OUTLOOKS - MJJ 2014 TO MJJ 2015

TEMPERATURE

THE MJJ 2014 TEMPERATURE OUTLOOK INDICATES ELEVATED PROBABILITIES OF ABOVE-
NORMAL SEASONAL MEAN TEMPERATURES FOR ALL OF ALASKA, WESTERN AREAS OF THE
PACIFIC NORTHWEST, CALIFORNIA AND NEVADA AND EASTWARD ALONG THE SOUTHERN TIER
OF THE CONUS AND ALSO ALONG THE EAST COAST TO INCLUDE MUCH OF NEW ENGLAND. THE
PROBABILITIES OF BELOW-NORMAL TEMPERATURES ARE ELEVATED FOR MOST OF MONTANA AND
NORTH DAKOTA. STATISTICAL TOOLS, DYNAMICAL MODEL GUIDANCE FROM THE CFS, NMME
AND IMME, OCN AND THE CON ALL POINTED TO ABOVE-NORMAL TEMPERATURES FOR MANY
AREAS IN THE HIGHLIGHTED REGION. IN ADDITION, DRY SOIL MOISTURE CONSIDERATIONS
PLAYED A ROLE AS WELL, ESPECIALLY FOR CALIFORNIA AND PARTS OF THE SOUTHWEST.

OUTLOOKS FROM JJA THROUGH SON 2014 WERE LARGELY UNCHANGED FROM THE PREVIOUS
OUTLOOK AND INDICATE ELEVATED PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES FOR
THE WESTERN AND SOUTHERN CONUS, ALONG THE EASTERN SEABOARD AND FOR ALASKA,
SUPPORTED BY THE CON AND DYNAMICAL MODEL GUIDANCE.

INCREASING CHANCES FOR EL NINO HAVE RESULTED IN SOME ADJUSTMENTS ESPECIALLY AT
LONGER LEADS, PRIMARILY BASED ON EL NINO COMPOSITES DURING WINTER SEASONS DJF,
JFM AND FMA. ABOVE-NORMAL TEMPERATURES FAVORED DURING THE LATE AUTUMN AND
WINTER SEASONS WERE FURTHER REDUCED OR REMOVED ACROSS THE SOUTH AND REPLACED
WITH EQUAL CHANCES, AS EL NINO TYPICALLY FAVORS BELOW-NORMAL TEMPERATURES IN
THESE AREAS. WE INTRODUCED MODEST PROBABILITIES FOR BELOW-NORMAL TEMPERATURES
IN THE SOUTHEAST ONLY FOR DJF, JFM AND FMA. ALSO, DURING THE LATE AUTUMN AND
WINTER SEASONS THROUGH JFM 2015, THE AREA OF ELEVATED ABOVE-NORMAL TEMPERATURES
WAS EXTENDED WESTWARD TO THE NORTHERN ROCKIES.

AFTER FMA THE FORECAST IS BASED ON CON, WHICH REFLECTS MAINLY LONG TERM TRENDS
AT THESE LEADS.

IN AREAS WITHOUT SUBSTANTIAL AND RELIABLE CLIMATE SIGNALS, EQUAL CHANCES OF
BELOW, NEAR AND ABOVE-NORMAL SEASONAL MEAN TEMPERATURES ARE INDICATED.

PRECIPITATION

CLIMATE SIGNALS FOR PRECIPITATION ARE OFTEN QUITE WEAK AND WHAT SIGNALS ARE
INDICATED FROM VARIOUS FORECAST TOOLS OFTEN CONFLICT, EVEN AT THE EARLIEST
LEAD. BUT ON THIS OCCASION WE INTRODUCED TWO SETS OF NON-EC PROBABILITIES
RELATIVE TO THE PREVIOUS RELEASE. THE FIRST IS ELEVATED PROBABILITIES OF ABOVE
MEDIAN PRECIPITATION IN THE INTERIOR SOUTHWEST FOR MJJ-JAS AS INDICATED
STRONGLY BY THE NMME PROBABILITIES OF BOTH THE CURRENT AND THE PREVIOUS MONTH.
THE SECOND SET, FOR NDJ TO FMA ARE BASED ON EL NINO COMPOSITES WHICH TYPICALLY
SHOW WETNESS IN THE SOUTHEAST AND A DRY AREA IN THE OHIO VALLEY. PROBABILITIES
ASSIGNED TO THESE ARE MODEST AT THIS TIME BECAUSE OF THE LONG LEAD AND EL NINO
NEXT WINTER IS NOT CERTAIN BY ANY MEANS.

THE MJJ 2014 PRECIPITATION OUTLOOK INDICATES ENHANCED PROBABILITIES OF
BELOW-MEDIAN SEASONAL ACCUMULATED PRECIPITATION FOR THE WEST COAST FROM
NORTHERN CALIFORNIA NORTHWARD TO INCLUDE THE ALASKA PANHANDLE AND PARTS OF
SOUTHEAST ALASKA. ENHANCED PROBABILITIES OF ABOVE-MEDIAN PRECIPITATION ARE
INDICATED FOR THE FOUR CORNERS REGION OF NEW MEXICO, COLORADO, UTAH AND ARIZONA.
MOST OF THE OUTLOOK IS DESIGNATED AS EQUAL CHANCES, OR CLIMATOLOGICAL
PROBABILITIES OF BELOW, NEAR AND ABOVE-MEDIAN SEASONAL ACCUMULATED
PRECIPITATION. THE PRIMARY DRIVER FOR THE MJJ OUTLOOK WAS DYNAMICAL MODEL
GUIDANCE FROM THE CFS, NMME AND IMME. SIMILAR SUPPORT AND RATIONALE IS USED FOR
JJA AND JAS 2014.

BEYOND JAS 2014, THE UNCERTAINTY OF PRECIPITATION GUIDANCE INCREASES AND FEW
CLEAR SIGNALS ARE INDICATED UNTIL WE COME TO NDJ. FOR NDJ THROUGH FMA EL NINO
CONDITIONS FAVOR ABOVE-MEDIAN PRECIPITATION ACROSS THE SOUTHEAST AND BELOW
MEDIAN PRECIPITATION IN THE OHIO VALLEY. SMALL SEASON TO SEASON DIFFERENCES
WERE BASED ON THE ENSO COMPOSITES. IF PROSPECTS FOR EL NINO CONTINUE TO
INCREASE, ABOVE-MEDIAN PRECIPITATION MAY BEGIN TO BE NOTED WITH HIGHER
PROBABILITIES AND SOMEWHAT LARGER AREAS.

BEYOND FMA 2014 ALL MAPS ARE EC.

IN AREAS WHERE CLIMATE SIGNALS FOR PRECIPITATION ARE WEAK OR UNRELIABLE, EQUAL
CHANCES OF BELOW, NEAR AND ABOVE MEDIAN SEASONAL ACCUMULATED PRECIPITATION ARE
INDICATED.

FORECASTER: HUUG VAN DEN DOOL

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/90DAY/DISC.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/SOILMST/FORECASTS.HTML (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 MAY 15 2014


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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