401  
FXUS05 KWBC 201230  
PMD90D  
PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
830 AM EDT THU APR 20 2017  
 
SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS  
 
THE MAY-JUNE-JULY (MJJ) 2017 TEMPERATURE OUTLOOK FAVORS ABOVE-NORMAL  
TEMPERATURES FOR MUCH OF THE FORECAST DOMAIN. FOR THE CONTIGUOUS U.S.,  
ABOVE-NORMAL SEASONAL MEAN TEMPERATURES ARE MOST LIKELY FOR THE PACIFIC COASTAL  
STATES AND ACROSS THE SOUTHWEST REGION AND THE CENTRAL AND SOUTHERN PLAINS INTO  
THE EASTERN U.S., WITH THE GREATEST ODDS INDICATED FOR PARTS OF THE SOUTHWEST,  
THE GULF COAST AND ATLANTIC COASTAL REGIONS. ABOVE-NORMAL TEMPERATURES ARE ALSO  
FAVORED FOR MUCH OF ALASKA.  
 
THE MJJ 2017 PRECIPITATION OUTLOOK INDICATES ENHANCED PROBABILITIES OF  
ABOVE-MEDIAN PRECIPITATION FOR AREAS OF THE ROCKY MOUNTAINS AND JUST EAST, FROM  
CENTRAL MONTANA SOUTHWARD INCLUDING WYOMING, 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.  
 
EQUAL CHANCES (EC) ARE FORECAST OVER AREAS WHERE ODDS OF ABOVE-, BELOW-, OR  
NEAR-NORMAL SEASONAL MEAN TEMPERATURES AND SEASONAL ACCUMULATED PRECIPITATION  
AMOUNTS ARE EXPECTED 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  
 
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.  
 
PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS  
 
THE PRIMARY TOOLS USED FOR THIS SET OF SEASONAL OUTLOOKS INCLUDED BOTH  
STATISTICAL AND DYNAMICAL MODEL FORECAST GUIDANCE, AND IN PARTICULAR AT LONGER  
LEADS, DECADAL TEMPERATURE AND PRECIPITATION TRENDS. THE DYNAMICAL MODEL  
GUIDANCE FROM THE NORTH AMERICAN MULTI-MODEL ENSEMBLE (NMME) AND ITS INDIVIDUAL  
MODELS, INCLUDING THE NCEP CFS, WERE IMPORTANT CONTRIBUTORS TO THE OUTLOOKS  
THROUGH SON 2017. ANTECEDENT SOIL MOISTURE AND SNOWPACK ANOMALIES IN CERTAIN  
REGIONS ALSO IMPACTED THE OUTLOOKS, PRIMARILY AT EARLY LEADS. LIKELY  
ENSO-NEUTRAL CONDITIONS IN EARLY SEASONS, LEADS TO RELIANCE PRIMARILY ON THE  
DYNAMICAL MODEL FORECASTS, WHILE THE INCREASING CHANCE OF EL NINO IN LATE  
SUMMER AND AUTUMN WAS CONSIDERED IN THE TEMPERATURE AND PRECIPITATION OUTLOOKS  
INTO WINTER SEASONS.  
 
PROGNOSTIC DISCUSSION OF OUTLOOKS - MJJ 2017 TO MJJ 2018  
 
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.  
 
SHORT TERM CLIMATE MODEL FORECASTS FOR THE BEGINNING OF MAY AND WEAKER SIGNALS  
IN THE SEASONAL MODEL GUIDANCE FOR PARTS OF THE NORTHERN ROCKIES INTO THE  
NORTHERN PLAINS RESULTS IN AN AREA OF EQUAL CHANCES (EC) OVER THESE REGIONS.  
 
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  
 
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. 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.  
 
FORECASTER: DAN COLLINS  
 
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 MAY 18 2017  
 
1981-2010 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 19, 2011  
FORECAST RELEASE.  

 
 
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