PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS 
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD 
830AM EDT THURSDAY MAY 16 2013 
 
SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS 
 
THE MAIN FACTORS WHICH 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 OUR 
FORECAST TOOLS. 
 
RECENT ATMOSPHERIC AND OCEANIC OBSERVATIONS CONTINUE TO INDICATE ENSO-NEUTRAL 
CONDITIONS. PREDICTIONS OF SEA SURFACE TEMPERATURE (SST) IN THE NINO 3.4 REGION 
OF THE PACIFIC OCEAN FROM DYNAMICAL AND STATISTICAL MODELS INDICATE THAT SST 
WILL BE CLOSE TO THE CLIMATOLOGICAL MEAN THROUGH NORTHERN HEMISPHERE SUMMER. 
THE OFFICIAL ENSO OUTLOOK IS FOR A CONTINUATION OF ENSO-NEUTRAL CONDITIONS 
THROUGH ASO 2013.  CONFIDENCE IN PREDICTIONS FOR THE STATE OF ENSO FROM LATE 
2013 AND BEYOND IS LOW AT THIS TIME. 
 
THE SEASONAL TEMPERATURE OUTLOOK FOR JJA 2013 INDICATES ENHANCED CHANCES FOR 
ABOVE NORMAL TEMPERATURES FOR MUCH OF THE NATION EXCEPT FOR ALONG COASTAL 
CALIFORNIA, AND ALONG THE NORTHERN PORTION OF THE LOWER 48 STATES FROM THE 
PACIFIC NORTHWEST THROUGH THE WESTERN GREAT LAKES.  ABOVE NORMAL TEMPERATURES 
ARE ALSO EXPECTED IN NORTHERN SECTIONS OF ALASKA.  THIS IS PRIMARILY A 
REFLECTION OF RECENT TEMPERATURE TRENDS TOWARD ABOVE NORMAL TEMPERATURES. 
CONFIDENCE IN THE FORECAST IS HIGHEST FOR PORTIONS OF THE SOUTHERN ROCKIES AND 
SOUTHERN GREAT PLAINS WHERE DRY INITIAL SOIL MOISTURE CONDITIONS ALSO FAVOR 
ABOVE NORMAL TEMPERATURES. 
 
THE JJA 2013 PRECIPITATION OUTLOOK INDICATES THAT PROBABILITIES OF BELOW MEDIAN 
PRECIPITATION ARE ENHANCED FOR SECTIONS OF THE NORTHWESTERN CONUS AND ALSO FOR 
PARTS OF THE SOUTHERN ROCKIES AND WESTERN PORTIONS OF THE SOUTHERN AND CENTRAL 
GREAT PLAINS.  THE CHANCES FOR BELOW MEDIAN RAINFALL ARE ENHANCED FOR HAWAII. 
ABOVE MEDIAN PRECIPITATION AMOUNTS ARE FAVORED FOR PORTIONS OF THE GULF COAST 
AND ALSO FOR THE SOUTHERN ALASKA PANHANDLE. 
 
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 
 
EQUATORIAL SST ANOMALIES HAVE BEEN QUITE STEADY THROUGH THE WESTERN AND CENTRAL 
PACIFIC OCEAN AND REMAIN CLOSE TO THEIR LONG TERM AVERAGES.  SST ANOMALIES 
ALONG THE EQUATOR FROM ABOUT 120 W TO NEAR THE SOUTH AMERICAN COAST HAVE 
DECREASED AND ARE NOW BETWEEN -0.5 AND -1.0 DEGREES C.  HEAT CONTENT IN THE 
UPPER 300 METERS OF THE EQUATORIAL PACIFIC OCEAN IS CLOSE TO LONG-TERM AVERAGE 
VALUES.  LOW LEVEL EASTERLY WINDS AT 850 HPA WERE SLIGHTLY ENHANCED OVER THE 
WESTERN HALF OF THE TROPICAL PACIFIC BASIN IN THE LAST FEW WEEKS. POSITIVE 
ANOMALIES IN MONTHLY MEAN OUTGOING LONG-WAVE RADIATION (OLR) CONTINUE TO 
SUGGEST SUPPRESSED CONVECTION OVER THE CENTRAL PACIFIC NEAR THE DATE LINE. 
NEGATIVE OLR ANOMALIES, INDICATIVE OF ENHANCED CONVECTION, WERE OBSERVED NEAR 
INDONESIA AND OVER THE WESTERN PACIFIC.  IN EARLY MAY, THE MJO BECAME MUCH MORE 
ACTIVE THAN IT HAD BEEN IN APRIL, WITH THE REGION OF ACTIVE CONVECTION 
CURRENTLY LOCATED OVER THE CENTRAL INDIAN OCEAN.  MOST MODELS CURRENTLY SHOW 
THE MJO WEAKENING AS ITS CONVECTIVE PHASE PASSES INDONESIA IN THE LATER HALF OF 
MAY. 
 
PROGNOSTIC DISCUSSION OF SST FORECASTS 
 
ENSO-NEUTRAL CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THE NORTHERN 
HEMISPHERE SUMMER 2013. THE NINO 3.4 SST ANOMALY FORECAST FROM THE CFSV2 IS IN 
LINE WITH THE FORECAST FROM THE MAJORITY OF OTHER MODELS RUN AS PART OF THE 
NMME IN ITS FORECAST OF VERY WEAK POSITIVE ANOMALIES THROUGH THE LATER PART OF 
THE YEAR.  THE CONSENSUS OF STATISTICAL MODELS CONTINUE TO FAVOR BELOW NORMAL 
SST'S IN NINO 3.4, WITH MOST PREDICTING ANOMALIES NEAR -0.5 C.  THE 
CONSOLIDATION FORECAST BASED ON THE CFSV2, CA, MARKOV AND CCA MODELS INDICATES 
NINO 3.4 SST ANOMALIES OF BETWEEN -0.2 AND -0.4 C BETWEEN NOW AND NDJ 2013/14. 
FACTORING IN THE ADDITIONAL SUPPORT FOR SLIGHTLY POSITIVE ANOMALIES FROM MOST 
OTHER DYNAMICAL SST FORECASTS, SST ANOMALIES ARE EXPECTED TO REMAIN NEAR ZERO, 
INDICATING BEST CHANCES FOR NEUTRAL ENSO CONDITIONS THROUGH THE REMAINDER OF 
THE YEAR.  MOST DYNAMICAL MODELS PREDICT ONLY THROUGH THE END OF 2013, HOWEVER 
THE DISTRIBUTION OF PREDICTED SST'S AT THE END OF 2013 FROM INDIVIDUAL ENSEMBLE 
MEMBERS OF THE NMME SHOW CONTINUED SUPPORT FOR NEAR NORMAL NINO 3.4 SST'S. 
THERE IS ABOUT AN EVEN SPLIT BETWEEN ENSEMBLE MEMBERS FAVORING ABOVE OR BELOW 
NORMAL NINO 3.4 SST ANOMALIES AMONG THE MEMBERS THAT STRAY FROM NEUTRAL VALUES. 
 STATISTICAL MODELS FAVOR SST ANOMALIES OF AROUND -0.5 C FOR THE EARLY PART OF 
2014.  WHEN DYNAMICAL AND STATISTICAL FORECASTS ARE TAKEN TOGETHER, AND 
CONSIDERING NONE OF THE TOOLS PREDICT PARTICULARLY STRONG ANOMALIES FOR NEXT 
WINTER, NEUTRAL ENSO CONDITIONS ARE SLIGHTLY FAVORED FOR THE COOL SEASON 
2013-2014. 
 
PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS 
 
THE TEMPERATURE AND PRECIPITATION OUTLOOKS WERE MADE CONSIDERING ENSO-NEUTRAL 
CONDITIONS TO BE MOST LIKELY THROUGH EARLY 2014.  THE FORECASTS WERE BASED 
PRIMARILY ON DYNAMICAL MODEL OUTPUT FROM THE NMME AND IMME FOR JJA THROUGH OND 
2013, WITH SOME ADDITIONAL CONSIDERATION FROM THE LIKELY INFLUENCE OF INITIAL 
SOIL MOISTURE CONDITIONS ON THE JJA AND JAS OUTLOOKS.  WITH NEUTRAL ENSO 
CONDITIONS EXPECTED FOR NEXT WINTER, THE OUTLOOKS BEYOND OND PRIMARILY REFLECT 
AN ESTIMATE OF DECADAL TRENDS REFLECTED IN THE CONSOLIDATION AND OCN. 
 
PROGNOSTIC DISCUSSION OF OUTLOOKS - JJA 2013 TO JJA 2014 
 
TEMPERATURE 
 
THE TEMPERATURE OUTLOOKS FOR JJA THROUGH ASO 2013 INDICATE ENHANCED CHANCES FOR 
ABOVE NORMAL TEMPERATURES FOR NORTHERN ALASKA, THE SOUTHWEST, THE SOUTHERN AND 
CENTRAL PLAINS, AND MUCH OF THE EASTERN HALF OF THE CONUS.  ENHANCED 
PROBABILITIES OF BELOW NORMAL TEMPERATURES ARE NOT INDICATED ANYWHERE AT ANY 
TIME.  THESE FORECASTS ARE SUPPORTED BY THE MODELS OF THE NMME AND IMME, AND 
ALSO LARGELY CONSISTENT WITH DECADAL TRENDS.  SUBSTANTIAL SOIL MOISTURE 
DEFICITS OVER MUCH OF THE WESTERN AND CENTRAL CONUS ARE ALSO CONSISTENT WITH AN 
INCREASED LIKELIHOOD OF ABOVE NORMAL TEMPERATURES DURING THE WARM SEASON. 
NORTHERN ALASKA IS MORE LIKELY TO EXPERIENCE ABOVE NORMAL TEMPERATURES FOR JJA 
THROUGH OND 2013 AS INDICATED BY THE DECADAL TEMPERATURE TRENDS.  THESE 
TEMPERATURE TRENDS ARE DUE IN PART TO REDUCED ARCTIC OCEAN SEA ICE COVER IN 
THIS REGION DURING RECENT YEARS FOR THE SPRING THROUGH AUTUMN SEASONS.  THE 
CONFIDENCE IN THE FORECAST FOR EAST-CENTRAL CONUS IS SOMEWHAT LOWER FOR JJA 
THAN ON LAST MONTH'S OUTLOOK DUE TO THE CONTINUED COOL CONDITIONS IN THE 
NORTHERN GREAT PLAINS AND RECENT RAINS IN THE CENTRAL MISSISSIPPI VALLEY THAT 
HELP REDUCE THE CHANCES OF ABOVE NORMAL TEMPERATURES.  WHILE THE SKILL OF 
MONTH-TO-MONTH PERSISTENCE IN ANOMALIES IS LOW, THE MEAN ANOMALIES FROM THE 
CFSV2 FOR JJA ARE SOMEWHAT LOWER THAN THEY WERE LAST MONTH LENDING FURTHER 
SUPPORT TO THE REDUCTION OF CONFIDENCE IN THE FORECAST FOR THE EAST CENTRAL 
CONUS. 
 
FOR SON 2013 AND BEYOND, TEMPERATURE OUTLOOKS ARE PRIMARILY A RESULT OF SIGNALS 
RELATED TO DECADAL VARIABILITY AS DETERMINED BY THE CONSOLIDATION FORECAST AND 
OCN.  OUTLOOKS ARE VERY SIMILAR TO THOSE ISSUED LAST MONTH.  ENHANCED 
PROBABILITIES OF ABOVE NORMAL TEMPERATURES CONTINUE FOR PORTIONS OF THE GREAT 
LAKES REGION, THE NORTHEAST, THE SOUTH AND THE SOUTHWEST THROUGHOUT THE YEAR 
INTO AMJ 2014.  ENHANCED CHANCES FOR ABOVE NORMAL TEMPERATURES FOR NORTHERN 
ALASKA REAPPEAR FROM FMA 2014 FORWARD. 
 
IN AREAS WITHOUT SUBSTANTIAL AND RELIABLE CLIMATE SIGNALS, EQUAL CHANCES OF 
BELOW, NEAR AND ABOVE NORMAL SEASONAL MEAN TEMPERATURES IS INDICATED. 
 
PRECIPITATION 
 
THE PRECIPITATION OUTLOOK FOR JJA THROUGH ASO 2013 INDICATES ELEVATED CHANCES 
FOR BELOW MEDIAN PRECIPITATION AMOUNTS FOR SECTIONS OF THE SOUTHERN ROCKIES AND 
THE SOUTHERN AND CENTRAL GREAT PLAINS, AND ALSO FOR MUCH OF THE PACIFIC 
NORTHWEST.  THESE AREAS ARE FROM A CONSENSUS OF STATISTICAL TOOLS AND DYNAMICAL 
MODEL FORECASTS FROM THE NMME AND IMME.  THE REGION IN THE PACIFIC NORTHWEST IS 
DUE MAINLY TO DECADAL TRENDS TOWARD BELOW MEDIAN PRECIPITATION, WITH SOME 
SUPPORT FROM DYNAMICAL MODELS.  THERE IS NOTABLY LITTLE CONSENSUS TOWARD THE 
PREDICTED STRENGTH OF THE SOUTHWESTERN MONSOON, SO THE REGION OF ENHANCED 
CHANCES FOR BELOW NORMAL PRECIPITATION WAS ADJUSTED SOMEWHAT EASTWARD FROM ITS 
POSITION IN LAST MONTH'S OUTLOOK NEAR WHERE INITIAL DRY SOIL MOISTURE 
CONDITIONS MAY PLAY A ROLE IN ENHANCING CHANCES FOR BELOW MEDIAN PRECIPITATION. 
 THE CHANCES FOR ABOVE MEDIAN PRECIPITATION AMOUNTS ARE SLIGHTLY ELEVATED FOR 
THE SOUTHERN ALASKA PANHANDLE AND ALSO FOR PORTIONS OF THE GULF COAST.  THIS IS 
FROM A WEAK CONSENSUS AMONG THE NMME.  WHILE MOST OF THE DYNAMIC CLIMATE MODELS 
INDICATE ABOVE MEDIAN PRECIPITATION AMOUNTS FOR VARIOUS PLACES IN THE 
SOUTHEASTERN U.S., THERE IS LITTLE CONSISTENCY ON THE LOCATION OF THE AREAS. 
THE INDICATED LOCATION IS CENTERED NEAR ELEVATED CHANCES FOR ABOVE MEDIAN 
PRECIPITATION AMOUNTS HIGHLIGHTED BY THE CONSOLIDATION FORECAST.  BELOW MEDIAN 
PRECIPITATION IN THE SOUTHERN ROCKIES IN SON IS MAINLY DUE TO DECADAL TRENDS. 
DECADAL TRENDS FOR BELOW MEDIAN PRECIPITATION ALSO EMERGE IN THE SOUTHEAST FOR 
NDJ 2013 THROUGH FMA 2014. 
 
IN AREAS WITHOUT SUBSTANTIAL AND RELIABLE CLIMATE SIGNALS, EQUAL CHANCES OF 
BELOW, NEAR AND ABOVE MEDIAN SEASONAL PRECIPITATION AMOUNTS IS INDICATED. 
 
FORECASTER: DAVID UNGER 
 
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 JUN 20 2013 
 
 
1981-2010 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 19, 2011 
FORECAST RELEASE. 
$$