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


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   CCA
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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 JUL 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 CLIMATOLOGICAL PERIOD (1981-2010).
3) THE MADDEN-JULIAN OSCILLATION (MJO) - AFFECTS CLIMATE VARIABILITY WITHIN
SEASONS.
4) THE NORTH ATLANTIC OSCILLATION (NAO) AND THE PACIFIC - NORTH AMERICAN (PNA)
PATTERNS - WHICH AFFECT ANOMALY PATTERNS ESPECIALLY DURING THE COLD SEASONS.
THESE PHENOMENA ARE CONSIDERABLY 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 TIMESCALE 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 OBSERVATIONS SUGGEST A TRANSITION FROM
ENSO-NEUTRAL TO EL NINO CONDITIONS IS UNDERWAY. EL NINO CONDITIONS ARE STILL
FAVORED TO BE IN PLACE BY EARLY FALL, HOWEVER, THE UNCERTAINTY ABOUT PACE OF
ONSET AND EVENTUAL INTENSITY HAVE INCREASED SLIGHTLY.  DISAGREEMENT BETWEEN THE
STATISTICAL AND DYNAMICAL MODEL ENSEMBLE MEAN FORECASTS HAVE SLIGHTLY DECREASED
FROM LAST MONTH, BUT THE STRENGTH AND DURATION OF THE EVENT IS STILL UNCERTAIN.
AT THIS POINT, AN EL NINO OF WEAK TO MODERATE STRENGTH IS MOST LIKELY.

THE TEMPERATURE OUTLOOK FOR AUGUST-SEPTEMBER-OCTOBER (ASO) 2014 INDICATES
ELEVATED ODDS OF ABOVE-NORMAL TEMPERATURES ACROSS THE WESTERN CONUS AND FOR
SOUTHERN TEXAS, THE SOUTHEAST U.S., AND PARTS OF THE MID-ATLANTIC STATES.
BELOW-NORMAL TEMPERATURES ARE FAVORED FROM THE NORTHERN ROCKIES TO THE MIDWEST.
THE CHANCES FOR ABOVE-NORMAL TEMPERATURES ARE ENHANCED FOR ALASKA.

THE ASO 2014 PRECIPITATION OUTLOOK CALLS FOR SLIGHTLY ENHANCED PROBABILITIES OF
BELOW-MEDIAN PRECIPITATION ALONG THE WESTERN GULF COAST.  ELEVATED CHANCES FOR
ABOVE-MEDIAN PRECIPITATION AMOUNTS ARE FORECAST FOR MUCH OF THE INTERIOR WEST
AND GREAT PLAINS, SPECIFICALLY FROM SOUTHERN CALIFORNIA, NORTHWARD TO WYOMING
AND EASTWARD TO MISSOURI.

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

ATMOSPHERIC AND OCEANIC CONDITIONS IN THE PACIFIC BASIN INDICATE THAT A
TRANSITION TO EL NINO CONDITIONS CONTINUES. THE LATEST WEEKLY OBSERVATIONS SHOW
SST ANOMALIES OF +0.5 DEGREES C ALONG THE EQUATOR FOR MUCH OF THE EQUATORIAL
PACIFIC BASIN EXCEPT FOR BETWEEN 150W AND THE DATE LINE, WHERE ANOMALIES ARE
LESS THAN +0.5C.  EAST OF ABOUT 130W, ANOMALIES EXCEED +1.0 C IN PLACES.
HOWEVER, SUBSEASONAL VARIABILITY ACROSS THE TROPICS HAS SLOWED THE TRANSITION
TO EL NINO IN RECENT WEEKS.. THE CURRENT SPATIAL DISTRIBUTION OF CONVECTION
ACROSS THE CENTRAL PACIFIC IS STILL CONSISTENT WITH A DEVELOPING EL NINO.
LOW-LEVEL WINDS ARE NEAR NORMAL ACROSS MOST OF THE PACIFIC, EXCEPT FROM
140W-120W, WHERE THERE WERE ANOMALOUS WESTERLY WINDS DURING THE PAST MONTH. THE
SOI REMAINED POSITIVE DURING THE PAST MONTH, ALTHOUGH IT DECREASED FROM MAY TO
JUNE.

THE EXTRATROPICAL PACIFIC (POLEWARD OF 20N) CURRENTLY PROJECTS STRONGLY ONTO A
POSITIVE PDO PATTERN, THE STRONGEST SUCH PROJECTION IN LATE SPRING IN MANY
YEARS. THE STATE OF THE NORTHERN ATLANTIC OCEAN IS ALSO A BIT DIFFERENT THAN IN
RECENT YEARS, WITH THE MOST RECENT INDEX VALUE OF THE AMO BEING JUST SLIGHTLY
POSITIVE, THE WEAKEST IN SEVERAL YEARS.

PROGNOSTIC DISCUSSION OF SST FORECASTS

MOST STATISTICAL AND DYNAMICAL MODELS CONTINUE TO SUGGEST THAT EL NINO
CONDITIONS WILL EMERGE IN THE NEXT COUPLE OF MONTHS. THE CFS PREDICTS NINO 3.4
SST ANOMALIES TO INCREASE TO AROUND +1.0 C BY LATE FALL. THE MEAN OF THE
STATISTICAL TOOLS IS JUST SLIGHTLY BELOW THE DYNAMICAL TOOL MEAN THROUGH THE
FALL, WITH BOTH PEAKING JUST BELOW +1.0C DURING THE WINTER. THE CPC SST
CONSOLIDATION FORECAST PREDICTS THE SST ANOMALY FOR NINO 3.4 TO INCREASE TO
+0.9 C BY THE TURN OF THE CALENDAR YEAR.  THE LATEST ENSEMBLE MEAN FORECASTS
FROM THE IMME AND NMME ALSO PREDICT SST ANOMALIES INCREASING FROM NEAR +0.5 C
IN JUNE TO NEAR +1.0 BY OCTOBER, WITH THE IMME SLIGHTLY COLDER THROUGH
SEPTEMBER, THEN SLIGHTLY WARMER THEREAFTER. ALTHOUGH THE SPREAD AMONG THE
MODELS IN THE NMME AND IMME HAS TIGHTENED, THERE IS STILL UNCERTAINTY IN THE
PREDICTION OF THE STRENGTH OF THE POSSIBLE EVENT. ALTOGETHER, ODDS OF AN EL
NINO EVENT OF ANY STRENGTH PEAK AT 78% BY LATE FALL.  THE COMBINATION OF
STATISTICAL AND DYNAMICAL SST PREDICTION METHODS SUGGESTS A BORDERLINE MODERATE
EVENT, ALTHOUGH THE POSSIBILITY OF A STRONG EVENT, OR A RETURN TO ENSO NEUTRAL
CONDITIONS, THOUGH LESS LIKELY, CANNOT BE RULED OUT AT THIS POINT. IT IS WORTH
NOTING, HOWEVER, THAT THE LIKELIHOOD OF A STRONG EVENT IS LOWER COMPARED TO
LAST MONTH.

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

THE TEMPERATURE AND PRECIPITATION OUTLOOKS WERE MADE CONSIDERING EL NINO
CONDITIONS TO BE A FACTOR IN LATE SUMMER AND EARLY FALL. GUIDANCE FROM THE CFS
AS WELL AS THE NMME AND IMME AND THEIR ASSOCIATED COMPONENTS CONTRIBUTED TO THE
OUTLOOKS FROM ASO THROUGH NDJ 2014, ESPECIALLY WHERE THEIR ANOMALIES AGREED
WITH COMPOSITES FROM DEVELOPING WARM ENSO EVENTS. THE OUTLOOKS FROM DJF 2014-15
THROUGH FMA 2015 WERE PRIMARILY DETERMINED FROM EL NINO COMPOSITES AND
REGRESSIONS OF TEMPERATURE AND PRECIPITATION ON THE NINO3.4 INDEX, WITH
PROBABILITIES REDUCED TO ACCOUNT FOR UNCERTAINTY IN THE ENSO FORECAST AND
VARIABILITY IN DOWNSTREAM PATTERNS ASSOCIATED WITH MODERATE STRENGTH WARM
EVENTS. THE BACKGROUND CLIMATE SIGNAL FROM RECENT TRENDS AND THE CPC CON WERE
PRIMARILY USED IN CONSTRUCTING OUTLOOKS FROM MAM THROUGH ASO 2015. LITTLE TO NO
SIGNAL WAS DISCERNIBLE FOR PRECIPITATION AFTER MAM 2015.

ADDITIONALLY, ANALOG TOOLS TAKING INTO ACCOUNT THE CURRENT STATE OF SSTS WERE
UTILIZED, AS WERE SOIL MOISTURE ANOMALIES WHERE APPROPRIATE DURING THE WARM
SEASON.

PROGNOSTIC DISCUSSION OF OUTLOOKS - ASO 2014 TO ASO 2015

TEMPERATURE

THE ASO THROUGH NDJ 2014-15 TEMPERATURE OUTLOOKS INDICATE ELEVATED
PROBABILITIES OF ABOVE-NORMAL SEASONAL MEAN TEMPERATURES FOR ALL OF ALASKA.
ABOVE-NORMAL SSTS ACROSS THE NORTH PACIFIC WERE A FACTOR IN THE ALASKA
OUTLOOKS. ELEVATED PROBABILITIES OF ABOVE-NORMAL SEASONAL MEAN TEMPERATURES ARE
ALSO FORECAST FOR MOST OF THE AREA TO THE WEST OF THE ROCKY MOUNTAINS DURING
ASO AND SON 2014, WHICH IS CONSISTENT WITH CON, NMME, AND IMME OUTPUTS.
ABOVE-NORMAL TEMPERATURES ARE ALSO FAVORED IN PARTS OF THE SOUTHEASTERN CONUS
THROUGH OND 2014. THESE SIGNALS ARE SUPPORTED BY A BROAD RANGE OF TOOLS AND
DYNAMICAL CLIMATE MODELS.

COMPOSITES BASED ON THE CURRENT PHASE OF THE PDO AND DEVELOPING ENSO WARM
EVENTS FAVOR BELOW-NORMAL TEMPERATURES ACROSS THE CENTRAL PORTIONS OF THE
COUNTRY THROUGH THE AUTUMN. FROM NDJ 2014-15 THROUGH MAM 2015, BELOW-NORMAL
TEMPERATURES ARE FAVORED ACROSS MUCH OF THE SOUTHERN TIER OF THE CONUS,
SUPPORTED BY DYNAMICAL MODEL OUTPUT, CPC EL NINO COMPOSITES, AND REGRESSIONS OF
TEMPERATURE ONTO THE NINO3.4 AND MULTIVARIATE ENSO INDICES.

THE OUTLOOKS FROM AMJ TO ASO 2015 SHOW A COMBINATION OF RECENT TRENDS AND
TYPICAL EVOLUTION FOLLOWING EL NINO EVENTS AS WELL AS THE CPC CON. ENHANCED
PROBABILITIES OF ABOVE-NORMAL TEMPERATURES COVERED MOST OF THE MAPS, CONSISTENT
WITH THE CPC CON, WITH THE PROBABILITY VALUES CHANGED LITTLE FROM LAST MONTH.

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

PRECIPITATION

THROUGH AUTUMN 2014, THERE ARE FAIRLY STRONG AND CONSISTENT INDICATIONS FROM
MOST MODELS RUN AS PART OF THE NMME AND IMME FOR ABOVE-MEDIAN PRECIPITATION
AMOUNTS THROUGHOUT MUCH OF THE SOUTHWEST, SOUTHERN AND CENTRAL ROCKY MOUNTAINS
AND THE INTERMOUNTAIN WEST. THE MODEL SOLUTIONS DO CONTRADICT COMPOSITES AND
CORRELATIONS BASED ON NINO3.4 INDEX VALUES OVER THE EXTREME SOUTHWEST, SO THE
PROBABILITIES FOR ABOVE-MEDIAN PRECIPITATION ARE REDUCED WHERE THE COMPOSITES
MOST STRONGLY DISAGREE.

AS SEASONS PROGRESS INTO WINTER THE OUTLOOKS REFLECT THE PRECIPITATION PATTERN
ASSOCIATED WITH EL NINO EVENTS, WITH ABOVE-MEDIAN PRECIPITATION AMOUNTS FAVORED
THROUGHOUT MUCH OF THE SOUTHERN CONUS IN ASSOCIATION WITH AN EXPECTED ACTIVE
SOUTHERN STREAM, AND A TENDENCY FOR BELOW-MEDIAN AMOUNTS NEAR THE OHIO RIVER
VALLEY AND ALSO IN PARTS OF THE NORTHERN ROCKIES.  AT THIS POINT PROBABILITIES
ARE ONLY MARGINALLY DIFFERENT FROM CLIMATOLOGICAL VALUES IN MOST AREAS DUE TO
UNCERTAINTIES IN THE EVENTUAL STRENGTH OF EL NINO.

THE PRECIPITATION OUTLOOK FOR MAM 2015 AND BEYOND SHOW EQUAL CHANCES FOR
BELOW-, NEAR- AND ABOVE-MEDIAN SEASONAL ACCUMULATED PRECIPITATION THROUGHOUT
THE CONUS AND ALASKA.  STATISTICAL MODELS SHOW THE NINO 3.4 SSTS WEAKENING TO
NEAR NORMAL BY LATE SPRING 2015, LEAVING LITTLE PREDICTABLE SIGNAL FOR
PRECIPITATION ANOMALIES.

FORECASTER: MATTHEW ROSENCRANS

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 AUG 21 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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