679  
FXUS05 KWBC 161231  
PMD90D  
PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
830 AM EDT THU MAR 16 2017  
 
SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS  
 
THE APRIL-MAY-JUNE (AMJ) 2017 TEMPERATURE OUTLOOK FAVORS ABOVE-NORMAL  
TEMPERATURES FOR MUCH OF THE U.S. FOR THE CONTIGUOUS U.S., ABOVE-NORMAL  
SEASONAL MEAN TEMPERATURES ARE MOST LIKELY FOR AN AREA STRETCHING EASTWARD FROM  
THE SOUTHWEST TO MUCH OF THE CENTRAL AND EASTERN U.S. WITH THE GREATEST ODDS  
INDICATED FOR THE SOUTH-CENTRAL PLAINS AND EASTERN U.S. ABOVE-NORMAL  
TEMPERATURES ARE ALSO FAVORED FOR MUCH OF ALASKA.  
 
THE AMJ 2017 PRECIPITATION OUTLOOK INDICATES ENHANCED PROBABILITIES OF  
ABOVE-MEDIAN PRECIPITATION FOR AREAS OF THE NORTHERN ROCKIES, NORTHERN PLAINS  
AND WESTERN AREAS OF THE GULF COAST. IN ALASKA, BELOW-MEDIAN SEASONAL  
PRECIPITATION AMOUNTS ARE FAVORED FOR WESTERN ALASKA.  
 
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 THAT ENSO-NEUTRAL CONDITIONS ARE NOW IN PLACE. A RESIDUAL, GENERALLY  
SMALL, AREA OF BELOW NORMAL SEA SURFACE TEMPERATURES (SSTS) PERSISTS IN  
PROXIMITY TO THE DATE LINE, BUT IN MOST AREAS ALONG THE EQUATOR, OCEAN SURFACE  
TEMPERATURES ARE NOW ABOVE AVERAGE, ESPECIALLY FOR THE EASTERN AREAS OF THE  
BASIN WHERE THE LATEST WEEKLY VALUE OF THE NINO1+2 INDEX WAS +2.1 DEGREES C.  
 
AT DEPTH, THE UPPER-OCEAN (TOP 300 METERS) HEAT CONTENT ANOMALY SUMMED ACROSS  
THE BASIN FROM THE DATE LINE TO 100W BECAME POSITIVE DURING JANUARY AND  
CONTINUED TO INCREASE DURING FEBRUARY INTO EARLY MARCH. IT NOW REFLECTS A VALUE  
OF +0.4 DEGREES C INDICATING CONSIDERABLE AREAS OF ABOVE-AVERAGE OCEAN  
TEMPERATURES BELOW THE SURFACE.  
 
IN THE ATMOSPHERE OVER THE PAST MONTH, EASTERLY WIND ANOMALIES CONTINUED TO BE  
OBSERVED OVER THE WESTERN TROPICAL PACIFIC. OVER THE SAME PERIOD, ANOMALOUS  
TROPICAL CONVECTION INDICATED CONTINUED SUPPRESSED CONVECTION IN THE CENTRAL  
PACIFIC BUT CONTINUING ENHANCED CONVECTION IN THE FAR WESTERN PACIFIC PRIMARILY  
NORTH OF THE EQUATOR. THE REMAINING DIPOLE IN ANOMALOUS CONVECTION INDICATES  
SOME SIGNATURES OF THE PAST WEAK LA NINA EVENT HAVE BEEN SLOW TO FADE.  
 
PROGNOSTIC DISCUSSION OF SST FORECASTS  
 
THE CPC SST CONSOLIDATION FORECAST, WHICH INCLUDES THREE STATISTICAL FORECASTS  
ALONG WITH THE CFS, PREDICTS ENSO-NEUTRAL CONDITIONS WILL PERSIST FROM NOW  
UNTIL THE UPCOMING WINTER SEASON. THERE IS A CONSIDERABLE DIFFERENCE, HOWEVER,  
BETWEEN THE CFS AND THE STATISTICAL GUIDANCE AS THE CFS FAVORS AN INCREASE IN  
SST QUITE EARLY IN THE OUTLOOK PERIOD ENTERING EL NINO CONDITIONS DURING THE  
AMJ 2017 SEASON WHILE THE AFOREMENTIONED STATISTICAL TOOLS FAVOR ENSO-NEUTRAL  
CONDITIONS. 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 INDICATES A MORE ROBUST  
AND EARLIER INCREASE IN NINO3.4 SST DURING THE SPRING AND SUMMER MONTHS. THE  
LATEST OFFICIAL ENSO OUTLOOK FROM CPC/IRI FAVORS ENSO-NEUTRAL CONDITIONS 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 REACHING NEAR 50% BY JAS 2017 AND APPROXIMATELY  
REMAINING AT THESE ODDS THROUGH OND 2017. AT THE CURRENT TIME, THE  
PROSPECTS FOR A ENSO COLD EVENT ARE SMALL (UNDER 10%) FOR MUCH OF THE OUTLOOK  
PERIOD.  
 
PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS  
 
THE PRIMARY TOOLS USED FOR THIS SET OF OUTLOOKS INCLUDED BOTH STATISTICAL AND  
DYNAMICAL MODEL FORECAST INFORMATION AND WHERE APPROPRIATE LONG TERM TRENDS.  
THE DYNAMICAL MODEL GUIDANCE FROM CFS, NMME AND IMME (AND THEIR PARTICIPANT  
INDIVIDUAL MODELS) WERE IMPORTANT CONTRIBUTORS TO THE OUTLOOKS THROUGH ASO  
2017. ANTECEDENT SOIL MOISTURE AND SNOWPACK ANOMALIES IN CERTAIN REGIONS WERE  
ALSO INCLUDED IN THE OUTLOOKS WHERE APPROPRIATE, PRIMARILY AT EARLY LEADS. THE  
FAVORED ENSO-NEUTRAL CONDITIONS EARLY IN THE OUTLOOK PERIOD UNDERPINNED THE SET  
OF OUTLOOKS, ALTHOUGH THE LOW THREAT OF LA NINA CONDITIONS THROUGHOUT MUCH OF  
THE OUTLOOK PERIOD AS WELL AS INCREASING CHANCES (ALBEIT WITH HIGH UNCERTAINTY)  
FOR EL NINO WAS CONSIDERED IN MAKING SMALL CHANGES IN SOME OF THE OUTLOOKS AT  
MIDDLE AND LATER LEADS.  
 
PROGNOSTIC DISCUSSION OF OUTLOOKS - AMJ 2017 TO AMJ 2018  
 
TEMPERATURE  
 
THE LATEST AMJ 2017 TEMPERATURE OUTLOOK INDICATES GENERALLY MINOR CHANGES FROM  
THE PREVIOUS OUTLOOK. AS SHOWN, ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR MUCH  
OF THE FORECAST DOMAIN. FOR THE CONTIGUOUS U.S., THERE IS AN ENHANCED  
LIKELIHOOD OF ABOVE-NORMAL SEASONAL MEAN TEMPERATURES FOR A REGION STRETCHING  
FROM THE SOUTHWEST, EASTWARD TO INCLUDE MUCH OF THE CENTRAL AND EASTERN U.S.  
THE GREATEST ODDS (EXCEEDING 50% PROBABILITY) ARE LOCATED ACROSS THE  
SOUTH-CENTRAL PLAINS AND EASTERN CONUS. SHORT TERM CLIMATE PREDICTION MODELS  
(CFS, ECMWF, NMME SUITE AND IMME SUITE) OVERWHELMINGLY SUPPORTED THE  
CONTINUATION OF THIS SOLUTION INTO AND THROUGH THE SPRING WITH THE CALIBRATED  
PROBABILISTIC GUIDANCE FROM THE NMME INDICATING 50% OR GREATER ODDS FOR  
RELATIVE WARMTH IN THE AREAS HIGHLIGHTED WITH THE LARGEST OUTLOOK  
PROBABILITIES. NEGATIVE SOIL MOISTURE DEPARTURES IN SOME AREAS OF THIS  
DESIGNATED REGION ALSO CONTRIBUTED TO THE FAVORED ANOMALOUS WARMTH. SOME  
STATISTICAL FORECAST TOOLS AND LONG TERM TRENDS FURTHER SUPPORTED THE OUTLOOK.  
 
POSITIVE SOIL MOISTURE DEPARTURES AND ELEVATED SNOWPACK IN SOME AREAS ACROSS  
THE NORTHERN TIER OF THE U.S. FROM THE NORTHERN HIGH PLAINS WESTWARD TO INCLUDE  
MUCH OF THE WEST, ALONG WITH WEAK SHORT TERM CLIMATE PREDICTION MODEL SIGNALS  
IN THESE AREAS RESULTED IN A DESIGNATION OF EQUAL CHANCES (EC) OR A REDUCTION  
IN PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES FROM THE PREVIOUS OUTLOOK IN  
THESE REGIONS.  
 
MANY OF THE REMAINING TEMPERATURE OUTLOOK MAPS SAW LITTLE CHANGE FROM THE  
PREVIOUS SET OF OUTLOOKS AS STATISTICAL AND DYNAMICAL FORECAST TOOL INDICATORS  
DID NOT VARY STRONGLY. SOME EXCEPTIONS INCLUDE THE FOLLOWING. SLIGHTLY LOWER  
PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ARE NOW INDICATED FOR AREAS OF THE  
WEST DURING MJJ 2017 DUE TO PREVIOUSLY MENTIONED INITIAL LAND SURFACE  
CONDITIONS. WARMER GUIDANCE SUPPORTED AN INCREASE IN PROBABILITIES FOR ABOVE  
NORMAL TEMPERATURES FOR THE EASTERN U.S. DURING JJA, JAS AND ASO 2017. LOW  
PROBABILITIES FOR LA NINA CONDITIONS AND CONSEQUENTLY ELEVATED ODDS FOR EL NINO  
CONDITIONS POTENTIALLY ENTERING THE AUTUMN FAVORED A SLIGHT INCREASE IN  
PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ALONG THE NORTHERN TIER IN THE  
CENTRAL AND EASTERN CONUS FOR SON, OND 2017 AND NDJ 2017-2018.  
 
FOR ALASKA, HIGH PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ARE INDICATED FOR  
THE NORTH SLOPE DUE TO RECENT TRENDS IN SEA ICE COVERAGE AND TIMING DURING SON  
AND OND 2017.  
 
PRECIPITATION  
 
FOR PRECIPITATION, THE AMJ 2017 OUTLOOK FAVORS ABOVE-MEDIAN PRECIPITATION FOR A  
REGION ACROSS THE NORTHERN ROCKIES AND NORTHERN HIGH PLAINS AS WELL AS ALONG  
THE WESTERN GULF COAST. BELOW-MEDIAN PRECIPITATION IS MOST LIKELY FOR AREAS OF  
WESTERN ALASKA INCLUDING THE ALEUTIANS. THE OUTLOOK IS PRIMARILY BASED ON  
AVAILABLE DYNAMICAL MODEL GUIDANCE AND LONG TERM TRENDS IN LOCATIONS WHERE THEY  
ARE DEEMED SOMEWHAT RELIABLE (I.E., NORTHERN ROCKIES, NORTHERN PLAINS).  
HIGHLIGHTED AREAS FOR THE MJJ THROUGH ASO 2017 SEASONS ARE IN AREAS WHERE THERE  
WAS CONSISTENT, ALBEIT OFTEN WEAK, SIGNATURES INDICATED BY CALIBRATED  
PROBABILISTIC GUIDANCE FROM THE NMME SUITE OF MODELS. THIS INCLUDES A  
CONTINUATION OF ELEVATED ODDS FOR ABOVE-MEDIAN PRECIPITATION FOR AREAS IN THE  
NORTHERN ROCKIES AND NORTHERN HIGH PLAINS. BY ASO 2017, CONSIDERATIONS AS NOTED  
ABOVE REGARDING INCREASING ODDS FOR EL NINO ALLOW A SLIGHT SOUTHWARD SHIFT OF  
THIS REGION. BELOW-MEDIAN PRECIPITATION CONTINUES FOR PARTS OF WESTERN ALASKA  
IN MJJ 2017 AND IS INTRODUCED IN MJJ AND JJA 2017 NEAR THE OHIO VALLEY. THERE  
IS A SLIGHT TILT IN THE ODDS FOR ABOVE MEDIAN PRECIPITATION FOR PORTIONS OF  
EASTERN MAINLAND ALASKA FROM MJJ TO JAS 2017.  
 
FOR LATER LEADS, THE LOW PROBABILITIES FOR LA NINA AT THE CURRENT TIME AND  
CONSEQUENTLY ELEVATED ODDS FOR POTENTIAL EL NINO CONDITIONS RESULTED IN REMOVAL  
OF SOME DRY SIGNALS IN PREVIOUS OUTLOOKS ACROSS THE SOUTHERN TIER OF THE U.S.,  
IN PARTICULAR THE SOUTHEAST CONUS BEGINNING IN NDJ 2017-2018.  
 
FORECASTER: JON GOTTSCHALCK  
 
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 APR 20 2017  
 
1981-2010 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 19, 2011  
FORECAST RELEASE.  

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page