PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD 830AM EST THURSDAY DEC 18 2014 SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS CURRENT ATMOSPHERIC AND OCEANIC OBSERVATIONS SHOW MIXED SIGNALS REGARDING THE ENSO STATE. SOME OBSERVATIONS, SUCH AS THE SEA SURFACE TEMPERATURES (SSTS) ALONG THE EQUATOR IN THE CENTRAL PACIFIC OCEAN ARE SUGGESTIVE OF EL NINO CONDITIONS, WHILE MANY OF THE ATMOSPHERIC CONDITIONS ASSOCIATED WITH EL NINO ARE ABSENT. MOST NOTABLY, THERE HAS NOT BEEN ANY ANOMALOUS CONVECTION OBSERVED IN THE CENTRAL EQUATORIAL PACIFIC. TAKEN IN COMBINATION, THE OBSERVATIONS CONTINUE TO SUGGEST ENSO-NEUTRAL CONDITIONS, THOUGH BIASED TOWARD A WARM ENSO STATE. BOTH STATISTICAL AND DYNAMICAL MODELS CONSISTENTLY FAVOR THE DEVELOPMENT OF WEAK EL NINO CONDITIONS. THE CHANCE OF EL NINO DEVELOPMENT IS ONLY ABOUT 60%, WITH A 40% CHANCE FOR A CONTINUATION OF ENSO-NEUTRAL CONDITIONS THROUGH THE WINTER. THE TEMPERATURE OUTLOOK FOR JANUARY-FEBRUARY-MARCH (JFM) 2015 INDICATES ELEVATED CHANCES OF ABOVE-NORMAL MEAN TEMPERATURES FOR ALASKA, THE WESTERN CONUS, AND IN PARTS OF NEW ENGLAND. THE CHANCES OF BELOW-NORMAL MEAN TEMPERATURES ARE ELEVATED ACROSS THE SOUTHEASTERN THIRD OF THE U.S.. THE JFM 2015 PRECIPITATION OUTLOOK INDICATES ENHANCED CHANCES OF BELOW-MEDIAN PRECIPITATION FOR PARTS OF THE PACIFIC NORTHWEST, NORTHERN ROCKIES, GREAT LAKES AND OHIO VALLEY. INCREASED PROBABILITIES FOR ABOVE-MEDIAN PRECIPITATION AMOUNTS ARE FORECAST FROM CALIFORNIA EASTWARD TO THE SOUTHERN PLAINS, AND AGAIN ACROSS THE SOUTHEAST COAST. THE PROBABILITIES FOR ABOVE-MEDIAN PRECIPITATION ARE ALSO ENHANCED OVER PARTS OF COASTAL SOUTHERN ALASKA. IN AREAS WHERE THE LIKELIHOODS OF SEASONAL MEAN TEMPERATURES AND SEASONAL ACCUMULATED PRECIPITATION AMOUNTS ARE SIMILAR TO CLIMATOLOGICAL PROBABILITIES, EQUAL CHANCES (EC) IS INDICATED. 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 ATMOSPHERIC AND OCEANIC CONDITIONS IN THE TROPICAL PACIFIC REMAIN MOST CONSISTENT WITH AN ENSO-NEUTRAL STATE. SST ANOMALIES REMAIN ABOVE +0.5 IN ALL THE ENSO CRITICAL REGIONS OF THE PACIFIC. SSTS ALONG THE EQUATOR ARE ABOVE +0.5 C EVERYWHERE FROM ABOUT 150 E TO JUST SHY OF THE SOUTH AMERICAN COAST, WITH SOME REGIONAL ANOMALIES IN EXCESS OF +1.0 C. OCEAN SUBSURFACE TEMPERATURE ANOMALIES REMAINED FAIRLY STEADY IN THE PAST MONTH, AND RANGE FROM +1.0 TO +4.0 C AT BETWEEN 50 AND 150 METERS DEPTH, EXCEPT NEAR SOUTH AMERICA WHERE ABOVE NORMAL OCEAN TEMPERATURES ARE CONFINED TO THE UPPER 50 METERS OR SO. THE USUAL ATMOSPHERIC RESPONSE TO EL NINO ARE NOTABLY ABSENT FROM RECENT OBSERVATIONS. RECENT OLR ANOMALIES SUGGEST THAT CONVECTION IS NEAR TO BELOW NORMAL OVER THE CENTRAL EQUATORIAL PACIFIC IN AREAS THAT USUALLY SEE ABOVE-NORMAL CONVECTION DURING EL NINOS. BOTH LOWER AND UPPER LEVEL WIND ANOMALIES DURING THIS PERIOD ARE ONLY WEAKLY CONSISTENT WITH EL NINO. WITHOUT LARGE SCALE ATMOSPHERIC ANOMALIES NORMALLY ASSOCIATED WITH EL NINO PRESENT, ENSO-NEUTRAL STILL BEST DESCRIBES THE CURRENT CONDITIONS IN THE PACIFIC. SIGNIFICANT EXTRA-TROPICAL ANOMALIES THAT MAY HAVE AN IMPACT ON THE CLIMATE OVER NORTH AMERICA INCLUDE A DISTINCT POSITIVE PDO SIGNAL, WITH ABOVE-NORMAL SSTS FORMING A HORSESHOE FROM THE SUBTROPICS TO THE WEST COAST OF NORTH AMERICA, AND EXTENDING WESTWARD ACROSS THE FAR NORTHERN PACIFIC. PROGNOSTIC DISCUSSION OF SST FORECASTS THERE IS FAIRLY GOOD CONSENSUS AMONG BOTH STATISTICAL AND DYNAMICAL MODELS FOR ABOVE-NORMAL SSTS TO PERSIST IN THE NINO 3.4 REGION THROUGH THE BOREAL WINTER. MOST OF THE TROPICAL ATMOSPHERIC RESPONSE TO EL NINO IS USUALLY WELL ESTABLISHED BY THIS LATE IN THE YEAR, SO IN SPITE OF THE CONSENSUS OF PREDICTIONS, THE EL NINO IS EXPECTED TO BE WEAK, IF IT DEVELOPS AT ALL. THE CURRENT CONSENSUS OF OPINION AMONG FORECASTERS AT CPC AND IRI IS FOR A 60% CHANCE OF EL NINO DEVELOPMENT. THE MULTI-MODEL AVERAGE OF NINO 3.4 SSTS IS FOR ANOMALIES OF CLOSE TO +1.0 C LASTING INTO SUMMER 2015. IN FACT, THE LATEST DYNAMICAL MODELS SUGGEST A BETTER THAN NORMAL CHANCE AT A PROLONGED PERIOD OF ABOVE-NORMAL SSTS IN THE EQUATORIAL PACIFIC, PERHAPS LASTING THROUGH MOST OF 2015. HOWEVER, A CALIBRATED CONSENSUS OF BOTH STATISTICAL MODELS AND THE CFSV2 PREDICTIONS SUGGESTS AN EARLIER PEAK TO NINO 3.4 SSTS OF JUST OVER +0.7 C, IN NDJ 2014-15, DECREASING SLOWLY AFTERWARD AND REACHING +0.5 C BY JFM 2015 AND CONTINUING A SLOW DECREASE THROUGHOUT THE YEAR. MOST MODELS RUN AS PART OF THE NMME AND IMME PERSIST ABOVE-NORMAL SSTS ALONG THE WEST COAST OF NORTH AMERICA THROUGH AT LEAST LATE SPRING 2015. THE AREAL EXTENT AND MAGNITUDE OF THESE PREDICTED ANOMALIES PROJECT ONTO A POSITIVE PDO PATTERN AND ARE LARGE ENOUGH TO POTENTIALLY HAVE AN IMPACT ON CLIMATIC CONDITIONS OVER NORTH AMERICA IN THE NEXT SEVERAL SEASONS, IN AS MUCH AS THEY ARE FORCED BY A PERSISTENT ATMOSPHERIC STATE OVER THE NORTH PACIFIC. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS THE TEMPERATURE AND PRECIPITATION OUTLOOKS FROM JFM THROUGH MAM 2015 ARE INFLUENCED PARTLY BY THE POTENTIAL IMPACTS OF A WEAK EL NINO. THE LIKELY MARGINAL STRENGTH OF EL NINO RESULTS IN ONLY SLIGHTLY ENHANCED CHANCES OF CLIMATIC ANOMALIES IN THE REGIONS USUALLY INFLUENCED BY ENSO, AND IS WELL SHORT OF THE CONFIDENCE ASSOCIATED WITH EVEN A MODERATE EVENT. LARGE-SCALE INDICATORS, SUCH AS THE POSITIVE PDO, CURRENTLY ARE CONSISTENT WITH EL NINO CONDITIONS AND MAY INDICATE THE EVENTUAL ESTABLISHMENT OF THE USUAL TELECONNECTION PATTERNS ASSOCIATED WITH EL NINO IN SPITE OF THE CURRENTLY DISORGANIZED EQUATORIAL ATMOSPHERIC STATE. THAT SAID, THE OVERWHELMING SIGNAL FROM THE DYNAMICAL AND STATISTICAL MODELS IS THAT THE CONVECTIVE MAXIMUM IN THE EQUATORIAL PACIFIC IS LIKELY WEST OF THE DATE LINE, CASTING DOUBT ON THE DEVELOPMENT OF ANY ROBUST ENSO TELECONNECTIONS. THE CONSTRUCTED ANALOG FORECAST FOR TEMPERATURE AND PRECIPITATION BASED ON GLOBAL SST PATTERNS (CA-SST) WAS ALSO UTILIZED IN THE OUTLOOKS AS WAS INFORMATION FROM A LARGE VARIETY OF DYNAMICAL MODEL GUIDANCE, INCLUDING THE CFS, THE NMME AND IMME. OTHER GUIDANCE FROM INTERNATIONAL CENTERS WAS UTILIZED AS WELL. FOR OUTLOOKS FROM AMJ THROUGH JFM 2016, DECADAL TRENDS DUE TO CHANGES IN THE CLIMATE BASE STATE ARE WEIGHTED MORE HEAVILY, THOUGH DYNAMICAL AND STATISTICAL GUIDANCE IS ALSO APPLIED WHERE APPROPRIATE. PROGNOSTIC DISCUSSION OF OUTLOOKS - JFM 2015 TO JFM 2016 TEMPERATURE THE OUTLOOK FOR JFM 2015 INDICATES ELEVATED CHANCES FOR ABOVE-NORMAL TEMPERATURES IN ALASKA, MOST OF THE WESTERN CONUS, AND FOR PARTS OF NEW ENGLAND. THERE IS NOTABLY HIGH SPREAD AMONG TOOLS FOR TEMPERATURES IN THE CENTRAL AND EASTERN CONUS, WITH SOME TOOLS AND DYNAMICAL MODELS FAVORING BELOW NORMAL TEMPERATURES, WHILE OTHERS FAVOR ABOVE. THIS MAY, IN PART BE RELATED TO THE DIFFERING STRENGTHS OF THE EL NINO PREDICTIONS FROM THE MODELS. STRONGER EL NINO EVENTS TEND TO BE ASSOCIATED WITH ABOVE-NORMAL TEMPERATURES IN THE UPPER MID-WEST AND GREAT LAKES, WHILE WEAK EVENTS SHOW COOLER AND MORE VARIABLE TEMPERATURE CONDITIONS. GIVEN THE EXPECTED WEAK NATURE OF THIS EL NINO, THE WARMER SOLUTIONS AMONG THE TOOLS WERE LARGELY DISCOUNTED. STATISTICAL SIGNALS FROM BOTH THE CA-SST AND THE OCTOBER EURASIAN SNOWCOVER STILL FAVOR A -AO/NAO PATTERN FOR THE UPCOMING THREE MONTH SEASON. THIS INTRODUCES UNCERTAINTY ACROSS THE NORTH-CENTRAL CONUS, WHERE NMME PROBABILITIES INDICATE ELEVATED ODDS OF ABOVE-NORMAL TEMPERATURES. SOME OTHER NUMERICAL GUIDANCE, INCLUDING THE ECMWF AND UKMET, FAVOR BELOW-NORMAL TEMPERATURES ACROSS THE REGION. COMBINING THIS VARIOUS GUIDANCE WITH THE STATISTICAL TOOLS SUGGESTS THAT EC IS THE MOST APPROPRIATE FORECAST FOR PARTS OF THE NORTH-CENTRAL CONUS. ALSO ADDING TO THE UNCERTAINTY IS THE FACT THAT NEARLY ALL OF THE NUMERICAL GUIDANCE PLACES THE ANOMALOUS CONVECTION WEST OF THE DATE LINE IN THE EQUATORIAL PACIFIC. TELECONNECTIONS BASED ON ENHANCED CONVECTION IS THIS REGION ARE WEAK, BUT FAVOR ANOMALOUS RIDGING OVER ALASKA AND A TEMPERATURE SOLUTION MORE IN LINE WITH THE ECMWF AND UKMET SOLUTIONS. ALONG THE WEST COAST AND ALASKA, ALL TOOLS ARE IN REMARKABLE AGREEMENT, AND SO SOME AREAS EXCEEDING 60% PROBABILITY OF ABOVE-NORMAL TEMPERATURES ARE INDICATED. OVER THE SOUTHEASTERN CONUS, THERE IS REASONABLE AGREEMENT AMONG THE TOOLS FAVORING NEAR- TO BELOW-NORMAL TEMPERATURES. THERE IS SOME UNCERTAINTY, HOWEVER, IN THAT THE DYNAMICAL TOOLS THAT INDICATE COOLER SOLUTIONS ACROSS THE CENTRAL AND NORTHERN CONUS ARE LIKEWISE LESS COLD ACROSS THE FAR SOUTHEASTERN CONUS. THE COMBINATION OF +ENSO, A TILT TOWARD -AO/NAO, AND +PDO, LEAD TO A LARGE AREA FAVORING BELOW-NORMAL TEMPERATURES. HOWEVER, SINCE CONFIDENCE IN THOSE FIRST TWO INDICATORS IS LOW, PROBABILITIES REMAIN VERY MODEST. IT IS IMPORTANT TO NOTE THAT THE USE OF THE +PDO IN THIS CASE IS NOT SO MUCH BECAUSE WE EXPECT THE PATTERN OF SST ANOMALIES TO FORCE AN ATMOSPHERIC RESPONSE, BECAUSE THIS IS QUITE DEBATABLE. RATHER, DUE TO EXCEPTIONAL DYNAMICAL MODEL AGREEMENT, IT IS ASSUMED THAT THE ATMOSPHERIC CIRCULATION (+PNA) OVER THE NORTH PACIFIC IS CONSISTENT FROM MODEL TO MODEL, AND THUS CAN BE HARVESTED FOR PREDICTION. EVEN THIS ASSUMPTION IS NOT PARTICULARLY STRONG, THOUGH, SINCE IT HAS BEEN SHOWN RECENTLY THAT THE CFS HAS LITTLE SHILL IS PREDICTING PDO CHANGES ON MONTHLY TIMESCALES. THE PATTERN OF FORECAST TEMPERATURE PROBABILITIES FAVORED IN JFM 2015 EXTEND INTO FMA 2015 AND THEN DIMINISHES THEREAFTER. PREDICTED ANOMALIES FOR AMJ 2015 AND BEYOND ARE LARGELY DETERMINED BY RECENT TRENDS, THE CA-SST, DYNAMICAL GUIDANCE WHERE AVAILABLE, AND CONTEMPORANEOUS +PDO REGRESSIONS. SIGNALS FROM TRENDS AND THE CA-SST DOMINATE DURING THE SUMMER AND FALL MONTHS, RESULTING IN ELEVATED CHANCES FOR ABOVE-NORMAL TEMPERATURES FOR MUCH OF ALASKA, AND AS WELL AS MUCH OF THE CONUS EXCEPT FOR INTERIOR PORTIONS. BY NEXT WINTER, THE CON IS USED HEAVILY, WHICH EMPHASIZES TRENDS, ALONG WITH THE CA-SST. SOME THOUGHT WAS PUT INTO WHAT ENSO STATE IS MOST FAVORED FOR NEXT WINTER, AS CAN BE APPROPRIATE WHEN THERE IS A ROBUST ENSO ONGOING. FOR EXAMPLE, IF WE ARE CURRENTLY IN A MODERATE TO STRONG EL NINO, AN EL NINO THE FOLLOWING WINTER IS LESS LIKELY. HOWEVER, THERE ARE NOTABLE DISAGREEMENTS BETWEEN THE DYNAMICAL AND STATISTICAL TOOLS THROUGHOUT 2015 WHICH, COMBINED WITH OUR CURRENT WEAK/NEUTRAL ENSO STATE, YIELDS LITTLE SIGNAL FOR NEXT WINTER. SUBSTANTIALLY ENHANCED PROBABILITIES OF ABOVE-NORMAL TEMPERATURES ARE FORECAST FOR NORTHERN ALASKA FROM ASO 2015 THROUGH OND 2015 DUE TO THE LIKELY ANOMALOUS DELAY IN ARCTIC OCEAN AND BERING SEA SEA-ICE COVER FOR OCTOBER AND NOVEMBER IN THE LAST DECADE RELATIVE TO 1981-2010. PRECIPITATION THE ELEVATED CHANCES FOR A WEAK EL NINO EVENT INFLUENCES THE PRECIPITATION OUTLOOK MAPS THROUGH FMA 2015. DYNAMICAL MODEL FORECAST GUIDANCE FROM THE NMME AND IMME AND THEIR PARTICIPANT MODELS GENERALLY SUPPORT WARM EVENT COMPOSITES. PRECIPITATION FORECASTS FROM THE GLOBAL SST BASED CONSTRUCTED ANALOG TOOL WAS ALSO CONSIDERED. THE CHANCES FOR ABOVE-MEDIAN PRECIPITATION AMOUNTS ARE ELEVATED FOR CALIFORNIA, ACROSS THE SOUTHWEST, PARTS OF THE SOUTHERN GREAT BASIN, THE SOUTHERN PLAINS AND THE SOUTHEAST CONUS FROM JFM THROUGH FMA 2015. ENHANCED PROBABILITIES FOR BELOW-MEDIAN PRECIPITATION ARE INDICATED FOR THE PACIFIC NORTHWEST THROUGH FMA 2015, AND FROM THE CENTRAL MISSISSIPPI VALLEY INTO THE GREAT LAKES REGION FROM JFM THROUGH MAM 2015. PROBABILITIES OF ABOVE-MEDIAN PRECIPITATION ARE ENHANCED FOR PARTS OF SOUTHERN ALASKA THROUGH FMA 2015. ODDS OF ABOVE-MEDIAN PRECIPITATION ARE ENHANCED DURING AMJ AND MJJ 2015 FOR PARTS OF THE PACIFIC NORTHWEST AND CENTRAL ROCKIES BASED ON NMME, CA-SST, AND PDO REGRESSIONS. THE MODEL GUIDANCE FROM NMME HAS HIGH PROBABILITIES OF ABOVE-MEDIAN PRECIPITATION ACROSS PARTS OF THE SOUTHWEST DURING THIS PERIOD, WHICH CONTRADICTS GUIDANCE FROM THE CON BASED LARGELY ON TRENDS AS WELL AS THE CA-SST. THEREFORE, EC REMAINS FOR THE SOUTHWEST DURING THESE LEADS FOR THE TIME BEING, THOUGH THIS WILL BE MONITORED CLOSELY OVER THE NEXT COUPLE OF MONTHS. TRENDS IN PARTS OF THE SOUTHEAST CONUS INDICATE ELEVATED CHANCES FOR BELOW-MEDIAN PRECIPITATION AMOUNTS IN DJF 2015-16. 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 15 2015 1981-2010 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 19, 2011 FORECAST RELEASE. $$