815  
FXUS05 KWBC 181331  
PMD90D  
PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
830 AM EST THU JAN 18 2018  
 
SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS  
 
LA NINA CONDITIONS CONTINUE ACROSS THE EQUATORIAL PACIFIC OCEAN, AS REPRESENTED  
IN CURRENT OCEANIC AND ATMOSPHERIC OBSERVATIONS. THE OFFICIAL CPC ENSO FORECAST  
INDICATES THAT LA NINA IS LIKELY TO PERSIST THROUGH THE NORTHERN HEMISPHERE  
WINTER 2017-18, WITH A PREDICTED TRANSITION TO ENSO-NEUTRAL CONDITIONS DURING  
THE NORTHERN HEMISPHERE SPRING. ENSO-NEUTRAL CONDITIONS ARE FAVORED TO PERSIST  
THROUGH AT LEAST THE BOREAL SUMMER.  
 
THE FEBRUARY-MARCH-APRIL (FMA) 2018 TEMPERATURE OUTLOOK FAVORS ABOVE-NORMAL  
TEMPERATURES ACROSS THE SOUTHERN TIER OF THE CONUS, WITH THE HIGHEST ODDS  
(GREATER THAN 60 PERCENT) FORECAST ACROSS THE SOUTHWEST. A SLIGHT TILT IN THE  
ODDS TOWARD ABOVE-NORMAL TEMPERATURES IS FORECAST ALONG THE EAST COAST.  
ABOVE-NORMAL TEMPERATURES ARE ALSO FAVORED FOR THE NORTH SLOPE OF ALASKA, THE  
WESTERN COAST OF ALASKA, AND THE ALEUTIANS. INCREASED CHANCES FOR BELOW-NORMAL  
TEMPERATURES DURING FMA ARE FORECAST FROM PARTS OF THE PACIFIC NORTHWEST EAST  
TO THE NORTHERN GREAT PLAINS, UPPER AND MIDDLE MISSISSIPPI VALLEYS, AND GREAT  
LAKES. BELOW-NORMAL TEMPERATURES ARE ALSO FAVORED FOR SOUTHEAST MAINLAND ALASKA  
AND THE ALASKA PANHANDLE.  
 
THE FMA 2018 PRECIPITATION OUTLOOK INDICATES ENHANCED PROBABILITIES OF  
ABOVE-NORMAL PRECIPITATION AMOUNTS FOR PARTS OF THE PACIFIC NORTHWEST ALONG  
WITH NORTHERN AREAS OF THE GREAT BASIN, ROCKIES, AND GREAT PLAINS. INCREASED  
CHANCES OF ABOVE-NORMAL PRECIPITATION ARE ALSO FAVORED FROM THE GREAT LAKES  
SOUTH TO THE TENNESSEE VALLEY, ALONG WITH NORTHERN AND WESTERN MAINLAND ALASKA.  
BELOW-NORMAL PRECIPITATION IS FAVORED FOR PARTS OF THE SOUTHEAST, GULF COAST,  
CENTRAL AND SOUTHERN GREAT PLAINS, SOUTHWEST, AND SOUTHERN CALIFORNIA. THE MOST  
LIKELY AREA TO RECEIVE BELOW-NORMAL PRECIPITATION AMOUNTS IS SOUTHERN GEORGIA  
AND FLORIDA.  
 
EQUAL CHANCES (EC) ARE FORECAST AMONG AREAS WHERE 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 OBSERVATIONS INDICATE THAT LA NINA CONDITIONS CONTINUED DURING THE PAST  
MONTHS AS EQUATORIAL SSTS ANOMALIES REMAINED NEGATIVE, AT APPROXIMATELY THE  
SAME MAGNITUDE, FROM THE DATE LINE TO THE SOUTH AMERICAN COAST. THE LATEST  
WEEKLY NINO-3.4 INDEX VALUE WAS -0.8 DEG C, AND THE NINO-3 AND NINO-1+2 INDICES  
WERE AT OR BELOW -1.0 DEG C DURING MUCH OF THE MONTH. NEGATIVE SUB-SURFACE  
TEMPERATURE ANOMALIES IN THE CENTRAL AND EAST-CENTRAL EQUATORIAL PACIFIC  
WEAKENED AT THE END OF THE MONTH AS ANOMALOUSLY WARM WATERS IN THE WESTERN  
PACIFIC AT DEPTHS GREATER THAN 100 M PROPAGATED EASTWARD TO APPROXIMATELY 140W.  
THE MOST RECENT ONI VALUE (OCTOBER DECEMBER 2017), BASED ON SST DEPARTURES  
FROM AVERAGE IN THE NINO 3.4 REGION, IS -0.9 DEGREES C.  
 
THE ATMOSPHERIC CONDITIONS OVER THE TROPICAL PACIFIC OCEAN ALSO REFLECTED LA  
NINA, WITH SUPPRESSED CONVECTION NEAR AND EAST OF THE INTERNATIONAL DATE LINE  
AND ENHANCED CONVECTION TO THE NORTH OF INDONESIA. ALSO, THE LOW-LEVEL TRADE  
WINDS CONTINUED TO BE STRONGER THAN AVERAGE OVER THE WESTERN AND CENTRAL  
PACIFIC.  
 
THE ENHANCED PHASE OF THE MJO IS FORECAST TO PROPAGATE EAST ACROSS THE MARITIME  
CONTINENT DURING THE NEXT TWO WEEKS AND MAY REEMERGE OVER THE PACIFIC DURING  
EARLY FEBRUARY 2018. THIS EVOLUTION OF THE MJO MAY PLAY A ROLE IN THE  
CIRCULATION PATTERN AND TEMPERATURES ACROSS THE MID-LATITUDES OF NORTH AMERICA  
LATER IN FEBRUARY 2018. LONGER-TERM IMPACTS OF THE MJO ARE UNCERTAIN.  
 
PROGNOSTIC DISCUSSION OF SST FORECASTS  
 
THE CPC SST CONSOLIDATION FORECAST, WHICH INCLUDES THREE STATISTICAL FORECASTS  
ALONG WITH THE CFS, PREDICTS A TRANSITION FROM LA NINA TO ENSO-NEUTRAL  
CONDITIONS DURING SPRING 2018 WITH ENSO-NEUTRAL CONDITIONS FAVORED THEREAFTER.  
THE NORTH AMERICAN MULTI MODEL ENSEMBLE (NMME) ENSEMBLE MEAN FORECAST FOR THE  
NINO-3.4 SST ANOMALY IS SIMILAR TO THE PREVIOUS MONTH, THOUGH A LITTLE COOLER  
THROUGH APRIL, WITH A GRADUAL TRANSITION TO ENSO-NEUTRAL CONDITIONS AFTER THE  
NORTHERN HEMISPHERE WINTER. BASED ON THE LATEST OBSERVATIONS AND MODEL  
FORECASTS, THE OFFICIAL CPC/IRI ENSO OUTLOOK FAVORS ENSO-NEUTRAL CONDITIONS BY  
AMJ 2018.  
 
PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS  
 
THE TEMPERATURE AND PRECIPITATION OUTLOOKS FOR FMA 2018 WERE BASED ON DYNAMICAL  
MODEL GUIDANCE AND STATISTICAL TOOLS THAT INCLUDE A CONSTRUCTED ANALOG BASED ON  
GLOBAL SST ANOMALY PATTERNS AND REGRESSIONS OF TEMPERATURE/PRECIPITATION ON THE  
CPC CONSOLIDATED NINO3.4 OUTLOOKS. DURING THE NEXT FOUR LEADS (MAM THROUGH JJA  
2018), THE FACTORS IN CREATING THE SUBSEQUENT OUTLOOKS WERE THE CALIBRATED  
PROBABILISTIC FORECASTS FROM THE NMME, TRENDS, THE CPC CONSOLIDATION, AND  
REGRESSIONS OF TEMPERATURE/PRECIPITATION ON THE CPC CONSOLIDATED NINO3.4  
OUTLOOKS. THE LATER OUTLOOKS THROUGH NEXT WINTER 2018-19 WERE BASED ON TRENDS  
AND THE CPC CONSOLIDATION FORECAST.  
 
PROGNOSTIC DISCUSSION OF OUTLOOKS - FMA 2018 TO FMA 2019  
 
TEMPERATURE  
 
ABOVE-NORMAL TEMPERATURES DURING FMA 2018 ARE MOST LIKELY, WITH A GREATER THAN  
60 PERCENT CHANCE, TO BE OBSERVED ACROSS THE SOUTHWESTERN CONUS, WHICH IS  
CONSISTENT WITH REGRESSIONS OF TEMPERATURE ON LA NINA RELATED OCEANIC  
CONDITIONS, VARIOUS STATISTICAL TOOLS, DYNAMICAL MODEL FORECASTS, AND TRENDS.  
ABOVE-NORMAL TEMPERATURES, ALBEIT WITH LOWER PROBABILITIES, ARE ALSO FAVORED  
FOR THE GULF COAST STATES AND ALONG THE EAST COAST, BASED ON GOOD AGREEMENT  
AMONG THE DYNAMICAL MODELS. THE ODDS FOR ABOVE-NORMAL TEMPERATURES FOR THE  
AREAS FROM THE TENNESSEE VALLEY TO THE MID-ATLANTIC COAST, AND FOR THE CENTRAL  
CALIFORNIA COAST, ARE SLIGHTLY LOWER THAN WHAT WAS INDICATED FOR FMA 2018 FROM  
THE DEC 2017 RELEASE. MODELS OUTPUT AND CONSTRUCTED ANALOGS BASED ON SST  
PATTERNS INDICATE A SLIGHTLY COOLER PATTERN FOR SOME AREAS EAST OF THE ROCKIES,  
WHEN COMPARED TO LAST MONTH, SO THAT NEWER INFORMATION WAS INCORPORATED. LA  
NINA TEMPERATURE COMPOSITES DURING FMA SUPPORT BELOW-NORMAL TEMPERATURES ACROSS  
THE PACIFIC NORTHWEST, NORTHERN ROCKIES, NORTHERN GREAT PLAINS, AND UPPER  
MISSISSIPPI VALLEY. SOME STATISTICAL METHODS CONTINUE TO OFFER A COLDER  
SOLUTION ACROSS THESE AREAS COMPARED TO THE DYNAMICAL MODELS. BELOW-NORMAL  
TEMPERATURES ARE SLIGHTLY FAVORED FROM THE PACIFIC NORTHWEST TO THE GREAT LAKES  
REGION, GIVEN THE WELL-ESTABLISHED LA NINA CONDITIONS AND ASSOCIATED  
TELECONNECTIONS. BELOW-NORMAL TEMPERATURES ARE ALSO FAVORED OVER SOUTHERN  
ALASKA, SUPPORTED BY MODEL OUTPUTS AND STATISTICALLY BASED RELATIONSHIPS WITH  
LA NINA.  
 
THE TEMPERATURE OUTLOOK FOR MAM 2018 HAS MORE COVERAGE FOR ABOVE-NORMAL  
TEMPERATURES AND LESS FOR BELOW-NORMAL TEMPERATURES THAN FOR FMA. AREAS WHERE  
BELOW-NORMAL TEMPERATURES ARE NOW FAVORED ARE RESTRICTED TO THE PACIFIC  
NORTHWEST AND NORTHERN ROCKIES. TELECONNECTIONS FROM LA NINA TYPICALLY WEAKEN  
DURING THE SPRING AND A SHIFT TO ENSO-NEUTRAL CONDITIONS IS LIKELY TO OCCUR  
DURING THE SPRING. THE COOLER SHIFT, RELATIVE TO THE LAST RELEASE AS MENTIONED  
ABOVE, IS CONTINUED IN THE OUTLOOKS THROUGH AMJ 2018. THE TEMPERATURE OUTLOOKS  
FROM AMJ THROUGH JJA 2018 ARE BASED LARGELY ON THE CALIBRATED PROBABILITY  
FORECASTS FROM THE NMME ALONG WITH TRENDS. AN INCREASING CHANCE OF DROUGHT  
BECOMING ENTRENCHED OVER THE SOUTHWEST AND SOUTHERN PLAINS CONTRIBUTES TO  
ELEVATED ODDS FOR ABOVE NORMAL TEMPERATURES ELEVATED OVER THOSE REGIONS THROUGH  
JJA 2018. THE IMPACT OF SOIL MOISTURE ON TEMPERATURE IS MOST PRONOUNCED DURING  
THE WARM SEASON.  
 
PRECIPITATION  
 
THE FMA 2018 PRECIPITATION OUTLOOK IS BASED ON PRECIPITATION SIGNALS ASSOCIATED  
WITH LA NINA AND INPUT FROM THE SUITE OF NMME DYNAMICAL MODELS. PRECIPITATION  
TOOLS FAVOR A TIGHT GRADIENT BETWEEN AREAS FAVORED TO RECEIVE BELOW- AND  
ABOVE-NORMAL PRECIPITATION ACROSS THE SOUTHERN TO NORTHERN TIER OF THE CONUS,  
RESPECTIVELY. BASED ON GOOD AGREEMENT AMONG MOST OF THE DYNAMICAL MODEL  
FORECASTS INCLUDING THE NMME AND IMME, A SLIGHT TILT IN THE ODDS FOR  
BELOW-NORMAL PRECIPITATION COVERS PORTIONS OF CENTRAL CALIFORNIA AND ALL OF  
SOUTHERN CALIFORNIA. THIS FAVORED AREA FOR BELOW-NORMAL PRECIPITATION IS ALSO  
CONSISTENT WITH PRECIPITATION COMPOSITES FROM BACK-TO-BACK LA NINA WINTERS. THE  
AREA WHERE BELOW-NORMAL PRECIPITATION IS FAVORED DURING FMA 2018 IS SLIGHTLY  
SMALLER THAN THE AREA DEPICTED IN LAST MONTH'S FMA OUTLOOK, REFLECTING NEWER  
MODEL OUTPUT. THE HIGHEST PROBABILITIES (EXCEEDING 50 PERCENT CHANCE FOR  
BELOW-NORMAL PRECIPITATION) IN THE PRECIPITATION OUTLOOK FOR FMAARE FORECAST  
ACROSS SOUTHERN GEORGIA AND FLORIDA, AND PORTIONS OF THE SOUTHWEST. BASED ON  
THE LATEST NMME CALIBRATED PROBABILITY FORECAST, BELOW-NORMAL PRECIPITATION IS  
FAVORED ACROSS THE SOUTHERN HIGH PLAINS THROUGH MJJ 2018.  
 
COVERAGE OF FAVORED AREAS FOR ANOMALOUS PRECIPITATION DECREASE DURING THE  
SUMMER AS FORECAST CONFIDENCE DIMINISHES WITH A WEAKENING SIGNAL AMONG TOOLS  
AND CONVECTIVE PRECIPITATION BECOMES MORE DOMINANT. DURING JJA AND JAS 2017,  
BELOW (ABOVE)-NORMAL PRECIPITATION IS FAVORED FOR THE PACIFIC NORTHWEST  
(NORTHEAST), RELATED TO HISTORICAL TRENDS AND SIGNALS IN THE CPC CON.  
 
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/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 FEB 15 2018  
 
1981-2010 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 19, 2011  
FORECAST RELEASE.  

 
 
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