PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD 830 AM EST THU DEC 17 2015 SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS STRONG EL NINO CONDITIONS PERSIST ACROSS THE EQUATORIAL PACIFIC OCEAN WHICH IS EVIDENT IN BOTH OCEANIC AND ATMOSPHERIC DATA. THE ONGOING EL NINO IS LIKELY AT ITS PEAK, WITH A TRANSITION TO ENSO-NEUTRAL EXPECTED DURING THE LATE SPRING OR EARLY SUMMER 2016. ODDS OF LA NINA DEVELOPING BY NEXT WINTER ARE ELEVATED COMPARED TO LAST MONTH. THE JANUARY-FEBRUARY-MARCH (JFM) 2016 TEMPERATURE OUTLOOK FAVORS ABOVE-NORMAL TEMPERATURES ACROSS THE CONTINENTAL U.S., NORTH OF THE 40TH PARALLEL, ALONG WITH MUCH OF THE WESTERN U.S. ABOVE-NORMAL TEMPERATURES ARE ALSO FAVORED FOR MOST OF ALASKA. THE ODDS OF ABOVE-NORMAL TEMPERATURES ARE HIGHEST ACROSS THE PACIFIC NORTHWEST AND UPPER GREAT LAKES WHERE PROBABILITIES OF ABOVE-NORMAL TEMPERATURES EXCEED 60 PERCENT. INCREASED CHANCES FOR BELOW-NORMAL TEMPERATURES DURING JFM ARE FORECAST ACROSS PARTS OF THE SOUTH-CENTRAL AND SOUTHEASTERN U.S. THE JFM 2016 PRECIPITATION OUTLOOK INDICATES ENHANCED PROBABILITIES OF ABOVE-MEDIAN PRECIPITATION FOR CALIFORNIA, THE SOUTHWEST, THE CENTRAL AND SOUTHERN GREAT PLAINS, THE LOWER MISSISSIPPI VALLEY, AND FROM THE SOUTHEAST NORTH TO SOUTHERN NEW ENGLAND. THE PROBABILITIES ARE HIGHEST FOR ABOVE-MEDIAN PRECIPITATION ACROSS SOUTHERN CALIFORNIA, THE DESERT SOUTHWEST, WEST TEXAS, AND FLORIDA. BELOW-MEDIAN PRECIPITATION AMOUNTS ARE MOST LIKELY FOR PARTS OF THE PACIFIC NORTHWEST, NORTHERN ROCKIES, AND GREAT LAKES. A SLIGHT TILT IN THE ODDS FOR ABOVE (BELOW)-MEDIAN PRECIPITATION IS FORECAST ACROSS SOUTHERN COASTAL (WESTERN) ALASKA. 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 EQUATORIAL PACIFIC SST ANOMALIES REMAIN EXCEPTIONALLY HIGH, WITH NINO3.4 VALUES PEAKING AT 3.1 DEGREES C IN WEEKLY OI DATA DURING NOVEMBER. THE OFFICIAL MONTHLY NINO3.4 VALUE FROM ERSSTV4 FOR NOVEMBER IS 2.35 DEGREES C, RIGHT IN LINE WITH THE BENCHMARK 1997 EVENT. SUBSURFACE OCEAN TEMPERATURES FROM NEAR THE DATE LINE EASTWARD TO THE SOUTH AMERICAN COAST ARE AT LEAST 2.0 DEGREES C ABOVE AVERAGE TO DEPTHS OF 100 TO 150 METERS, EXCEEDING 6.0 DEGREES C ABOVE AVERAGE IN PARTS OF THE EASTERN BASIN. THIS SUBSURFACE VOLUME OF ANOMALOUSLY WARM WATER PROVIDES A RESERVOIR OF HEAT TO HELP SUSTAIN CURRENT POSITIVE SEA SURFACE TEMPERATURES. NEGATIVE ANOMALIES AT DEPTH (NEAR 150 METERS) HAVE CONTINUED TO SHIFT SLIGHTLY EASTWARD ACROSS THE WESTERN AND CENTRAL PACIFIC DURING THE PAST MONTH. ENHANCED CONVECTION RETURNED TO THE EQUATORIAL CENTRAL PACIFIC DURING MID-NOVEMBER. NEGATIVE OUTGOING LONGWAVE RADIATION (OLR) ANOMALIES INDICATING ENHANCED CONVECTION EXTEND FROM THE DATE LINE ACROSS THE EASTERN TROPICAL PACIFIC TOWARD CENTRAL AMERICA DURING THE PAST MONTH. POSITIVE OLR ANOMALIES WERE OBSERVED OVER THE MARITIME CONTINENT. LOW-LEVEL (850-HPA) WESTERLY WIND ANOMALIES WERE OBSERVED FROM THE DATE LINE EASTWARD, WHILE UPPER-LEVEL (200-HPA) EASTERLY WIND ANOMALIES ARE PRESENT OVER THE CENTRAL EQUATORIAL PACIFIC. WELL DEFINED ANTI-CYCLONIC CIRCULATIONS BOTH NORTH AND SOUTH OF THE EQUATOR IN THE EAST-CENTRAL PACIFIC ARE ALSO EVIDENT. IN JUST THE PAST SEVERAL DAYS, SUBSEASONAL TROPICAL CONVECTIVE VARIABILITY ASSOCIATED WITH THE MADDEN-JULIAN OSCILLATION (MJO) HAS BEGUN TO DESTRUCTIVELY INTERFERE WITH THE ENSO BASE STATE. SEE THE MONTHLY FORECAST DISCUSSION FOR MORE INFORMATION ON HOW THIS COULD IMPACT THE JANUARY OUTLOOK. THE EXTRA-TROPICAL PACIFIC OCEAN REMAINS CONSISTENT WITH THE POSITIVE PHASE OF THE PACIFIC DECADAL OSCILLATION WITH ABOVE AVERAGE SSTS SOUTH OF ALASKA AND ALONG THE WEST COAST. PROGNOSTIC DISCUSSION OF SST FORECASTS SINCE WE ARE NOW AT THE PEAK OF THE EL NINO EVENT IN TERMS OF SST ANOMALIES, THE RELEVANT QUESTIONS RELATE TO HOW QUICKLY THE EVENT DECAYS AND WHETHER WE SEE A TRANSITION TO LA NINA, WHICH FREQUENTLY FOLLOWS ON THE HEELS OF EL NINO EVENTS. THE CPC SST CONSOLIDATION FORECASTS A RETURN TO NEUTRAL CONDITIONS BY MJJ AND A 79% CHANCE OF LA NINA BY NEXT WINTER. THERE IS A LARGE SPREAD AMONG THE NMME CONSTITUENT MEMBERS IN TERMS OF HOW QUICKLY A TRANSITION TO NEUTRAL CONDITIONS OCCURS. THE CFSV2 MAINTAINS ANOMALOUSLY WARM SSTS MUCH LONGER THAN THE OTHER GUIDANCE, WHILE THE GFDL AND CANADIAN MODELS ARE ON THE FASTER SIDE OF THE GUIDANCE. THE CPC/IRI CONSENSUS FORECAST INDICATES THAT THE TRANSITION TO ENSO NEUTRAL IS MOST LIKELY BY EARLY SUMMER, AND ODDS OF LA NINA DEVELOPING BY JAS EXCEED 30%. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS THE SEASONAL OUTLOOKS FROM JFM 2016 THROUGH AMJ 2016 ARE BASED PRIMARILY ON THE TYPICAL CIRCULATION RESPONSE TO EL NINO CONDITIONS AND THE ASSOCIATED TEMPERATURE AND PRECIPITATION IMPACTS AS DETERMINED BY REGRESSION-BASED STATISTICAL MODELS AS WELL AS EL NINO COMPOSITES. THE NORTH AMERICAN MULTI-MODEL ENSEMBLE (NMME) AND THE INTERNATIONAL MULTI-MODEL ENSEMBLE (IMME), WHICH INCLUDE THE NCEP CLIMATE FORECAST SYSTEM (CFS), ALSO PLAYED A LARGE ROLE THROUGH EARLY SUMMER. OUTLOOKS FOR MJJ 2016 THROUGH ASO 2016 RELY PRIMARILY ON LAGGED ENSO REGRESSIONS AND OTHER STATISTICAL GUIDANCE INCLUDING TRENDS AND THE SST CONSTRUCTED ANALOG. SOME THOUGHT IS GIVEN TO COMPOSITES OF EL NINO TO LA NINA TRANSITION PERIODS. THESE GENERALLY SUPPORT THE AFOREMENTIONED STATISTICAL GUIDANCE, BUT THEIR PHYSICAL BASIS IS NOT CLEAR AND SO THE OBJECTIVE SST CA AND TRENDS ARE WEIGHTED MORE HEAVILY. THE EXPECTATION IS FOR ENSO NEUTRAL CONDITIONS DURING THIS PERIOD. BASED ON THE BEHAVIOR OF SST ANOMALIES AFTER MANY PAST EL NINO EVENTS AND THE CPC CONSOLIDATION NINO3.4 SST FORECAST, EFFECTS FROM POTENTIAL LA NINA CONDITIONS WERE CONSIDERED BEGINNING IN SON 2016 THROUGH JFM 2017. PROGNOSTIC DISCUSSION OF OUTLOOKS - JFM 2016 TO JFM 2017 TEMPERATURE THERE ARE VERY FEW CHANGES TO THE EARLY LEAD TEMPERATURE OUTLOOKS, WHICH LARGELY HARVEST THE LOW-FREQUENCY ENSO RESPONSE, EVIDENT AMONG ALL THE CURRENT DYNAMICAL AND STATISTICAL GUIDANCE. STATISTICAL GUIDANCE IS GENERALLY COLDER THAN THE DYNAMICAL GUIDANCE ACROSS THE SOUTHEAST, WHERE A VERY SLIGHT SHIFT TOWARD COLDER TEMPERATURES IS INDICATED NEAR THE GULF COAST. DYNAMICAL GUIDANCE INDICATES A SLIGHT COOLING TREND OVER THAT REGION COMPARED TO LAST MONTH. IN SPITE OF THE NEAR-RECORD WARM DECEMBER UNDERWAY ACROSS MUCH OF THE EASTERN TWO-THIRD OF THE CONUS, THE LOW-FREQUENCY CLIMATE SIGNALS STILL POINT TOWARD A COLDER SOLUTION FOR THE FAR SOUTHEASTERN CONUS. ALL TEMPERATURE TOOLS CONTINUE TO STRONGLY FAVOR ABOVE-NORMAL TEMPERATURES ACROSS THE NORTHERN HALF OF THE CONTINENTAL U.S. THROUGH THE EARLY SPRING WHICH IS CONSISTENT WITH A STRONG EL NINO. ALSO, ABOVE-NORMAL SSTS ALONG THE WEST COAST CONTRIBUTE TO THE ENHANCED ODDS FOR ABOVE-NORMAL TEMPERATURES IN EARLY LEADS. BELOW-NORMAL TEMPERATURES FAVORED FOR THE SOUTHERN HIGH PLAINS DURING THE 2016 SPRING ARE PARTLY RELATED TO THE EXPECTATION OF ABNORMALLY MOIST TOPSOIL AT THAT LEAD TIME. A TRANSITION TO ENSO NEUTRAL CONDITIONS IS FAVORED DURING THE LATE SPRING AND SUMMER 2016 SO THE OUTLOOKS FROM MJJ THROUGH ASO 2016 FOLLOW A BLEND OF TREND, DYNAMICAL GUIDANCE WHERE AVAILABLE, AND OTHER STATISTICAL GUIDANCE. ENHANCED ODDS OF ABOVE-NORMAL TEMPERATURES ARE FORECAST FOR THE ENTIRE CONUS AT TIMES DURING THIS PERIOD, BUT AT LOW PROBABILITIES. INCREASED ODDS FOR ABOVE-NORMAL TEMPERATURES OVER THE EASTERN CONUS COMPARED TO LAST MONTH ARE BASED ON THE LATEST MODEL GUIDANCE, LAGGED ENSO REGRESSIONS, AND THE SST CONSTRUCTED ANALOG. OVER TIME, ODDS OF ABOVE-NORMAL TEMPERATURES INCREASE OVER THE SOUTHWESTERN AND SOUTH-CENTRAL CONUS WHERE TRENDS ARE STRONG. PROBABILITIES THERE ARE SOMEWHAT RESTRAINED BY THE EXPECTATION OF ABOVE-NORMAL SOIL MOISTURE, ESPECIALLY EARLY IN THE WARM SEASON. INCREASED CHANCES FOR ABOVE-NORMAL TEMPERATURES FORECAST ACROSS THE SOUTHERN TIER OF THE CONUS FROM SON 2016 THROUGH JFM 2017 ARE BASED LARGELY ON THE ENHANCED PROBABILITIES OF LA NINA BY THAT TIME. A SLIGHT TILT IN THE ODDS FOR BELOW-NORMAL TEMPERATURES ACROSS THE NORTH-CENTRAL CONUS BEGINNING IN NDJ 2016-17 IS RELATED TO THE POTENTIAL FOR LA NINA INFLUENCES AT THAT LEAD TIME. A VERY HIGH PROBABILITY OF ABOVE-NORMAL TEMPERATURES INDICATED FOR THE NORTH SLOPE OF ALASKA DURING THE AUTUMN IS DUE TO THE LIKELIHOOD OF ANOMALOUSLY OPEN SEA ICE DURING THAT TIME OF YEAR AND STRONG TRENDS. PRECIPITATION THE JFM 2016 PRECIPITATION OUTLOOK THROUGH THE EARLY SPRING CONTINUES TO FAVOR A PATTERN THAT IS TYPICALLY ASSOCIATED WITH EL NINO. ENHANCED ODDS FOR ABOVE-MEDIAN PRECIPITATION ARE FORECAST ACROSS CALIFORNIA, THE SOUTHWEST, CENTRAL/SOUTHERN GREAT PLAINS, GULF COAST STATES, AND PARTS OF THE EAST COAST. THE HIGHEST PROBABILITIES (ABOVE 70 PERCENT) FOR ABOVE-MEDIAN PRECIPITATION ARE FORECAST ACROSS THE FLORIDA PENINSULA FOR JFM 2016 WHICH TYPICALLY HAS THE STRONGEST WET SIGNAL DURING EL NINO. BELOW-MEDIAN PRECIPITATION IS FAVORED THROUGH THE EARLY SPRING ACROSS THE NORTHERN ROCKIES, PARTS OF THE NORTHERN GREAT PLAINS, GREAT LAKES, AND THE OHIO VALLEY. THE DRY SIGNAL ACROSS THE OHIO VALLEY PEAKS DURING THE JFM 2016 SEASON DURING EL NINO. THIS DRY SIGNAL SLOWLY WEAKENS WITH TIME THROUGH LATE SPRING AND EARLY SUMMER. CONSISTENT WITH A SOUTHWARD AND EASTWARD SHIFTED STORM TRACK DURING EL NINO AND CONSISTENT WITH THE NMME DYNAMICAL MODEL GUIDANCE, BELOW MEDIAN PRECIPITATION IS FAVORED FOR WEST-CENTRAL MAINLAND ALASKA FROM JFM 2016 THROUGH MAM 2016. A SLIGHT TILT IN THE ODDS FOR ABOVE-MEDIAN PRECIPITATION ALONG SOUTHERN COASTAL ALASKA IS BASED ON EL NINO PRECIPITATION COMPOSITES AND ENSO REGRESSIONS. LAGGED ENSO REGRESSIONS AND ENSO TRANSITION COMPOSITES SUGGEST ENHANCED ODDS OF BELOW-(ABOVE-) MEDIAN PRECIPITATION ACROSS PARTS OF THE NORTHEAST/MID-ATLANTIC (GULF COAST) FROM JJA THROUGH ASO. HOWEVER, THE PHYSICAL BASIS FOR THESE SIGNALS IS A LITTLE SUSPECT. THERE IS SUPPORT FROM THE SST CA ACROSS THE GULF COAST REGION, BUT NOT FARTHER NORTH. THIS IS AN ISSUE THAT WILL BE DISCUSSED FURTHER IN FUTURE OUTLOOKS, BUT AT THIS TIME NO CHANGES ARE MADE TO THE PREVIOUS OUTLOOK IN THIS REGARD. DURING THE FALL SEASON OF 2016 AND WINTER 2016-17, THE POTENTIAL FOR LA NINA CONDITIONS IS THE PRIMARY REASON FOR THE FAVORED AREAS OF BELOW- (ABOVE-) MEDIAN PRECIPITATION ACROSS THE SOUTHERN TIER OF THE CONUS AND SOUTHERN COAST OF ALASKA (PACIFIC NORTHWEST AND OHIO VALLEY/GREAT LAKES). FORECASTER: STEPHEN BAXTER 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 JAN 21 2016 1981-2010 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 19, 2011 FORECAST RELEASE. $$