PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD 830AM EST THURSDAY NOV 20 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 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. TAKEN IN COMBINATION, THE OBSERVATIONS CONTINUE TO SUGGEST ENSO-NEUTRAL CONDITIONS. BOTH STATISTICAL AND DYNAMICAL MODELS CONSISTENTLY FAVOR THE DEVELOPMENT OF EL NINO CONDITIONS, BUT THE CONTINUED WEAK ATMOSPHERIC RESPONSE SO LATE IN THE SEASON SUGGESTS THAT A WEAK EL NINO EVENT IS MOST PROBABLE. 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 DECEMBER-JANUARY-FEBRUARY (DJF) 2014-15 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 ALONG THE SOUTHERN PART OF THE COUNTRY FROM EASTERN NEW MEXICO TO THE SOUTHEASTERN ATLANTIC COAST AND FLORIDA. THE DJF 2014-15 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 SOUTHERN AND CENTRAL CALIFORNIA EASTWARD ACROSS THE SOUTHWEST, SOUTHERN PLAINS, AND ALONG THE GULF AND SOUTHERN ATLANTIC COASTS NORTHWARD TO INCLUDE THE EASTERN SEABOARD TO SOUTHERN NEW ENGLAND. THE PROBABILITIES FOR ABOVE-MEDIAN PRECIPITATION ARE ALSO ENHANCED OVER PARTS OF COASTAL SOUTHERN ALASKA, WHILE PARTS OF INTERIOR ALASKA HAVE ENHANCED CHANCES OF BELOW-MEDIAN PRECIPITATION AMOUNTS. 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 HAVE INCREASED IN RECENT WEEKS AND ARE NOW ABOVE +0.5 IN ALL THE ENSO CRITICAL REGIONS OF THE PACIFIC, WITH ANOMALIES OF +0.7C, +0.6C, +0.9C AND +0.6C IN THE NINO 4, 3.4, 3, AND 1+2 REGIONS RESPECTIVELY. SSTS ALONG THE EQUATOR ARE ABOVE +0.5 C EVERYWHERE FROM ABOUT 160 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 100 AND 200 METERS DEPTH, EXCEPT NEAR SOUTH AMERICA WHERE ABOVE NORMAL OCEAN TEMPERATURES ARE CONFINED TO THE UPPER 50 METERS OR SO. WITH THE EXCEPTION OF THE SOI, 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 REMAIN NEAR NORMAL. 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 LARGE AREA OF POSITIVE SST ANOMALIES IN THE WESTERN NORTH PACIFIC BASIN THAT PROJECTS ONTO A POSITIVE PDO, ALTHOUGH ANOMALIES HAVE WEAKENED CONSIDERABLY IN THE LAST MONTH. SST ANOMALIES ALONG THE ATLANTIC SEABOARD HAVE DECREASED CONSIDERABLY IN THE PAST MONTH, AND ARE NOW BELOW NORMAL FROM VIRGINIA SOUTHWARD, WITH POSITIVE SST ANOMALIES HOLDING ON IN THE NORTH. IMPRESSIVELY POSITIVE ANOMALIES IN THE AREAL EXTENT OF SNOW COVER WERE OBSERVED DURING THE MONTH OF OCTOBER IN BOTH NORTHERN EURASIA AND CANADA. THE AREAL EXTENT OF SNOW COVER IN LATE OCTOBER IS THE THIRD HIGHEST SINCE THE LATE 1960'S, ONLY EXCEEDED BY OCTOBER VALUES IN 1976 AND 2002. 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 BY EARLY 2015. 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 MAM 2015. 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. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS THE TEMPERATURE AND PRECIPITATION OUTLOOKS FROM DJF 2014-15 THROUGH MAM 2015 ARE INFLUENCED 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 A STRONGER EVENT. LARGE-SCALE INDICATORS, SUCH AS THE POSITIVE PDO AND NEGATIVE SOI 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. 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. THE PREDICTIVE SIGNALS FROM THESE MODELS ARE IN GENERAL AGREEMENT WITH EL NINO COMPOSITES. FOR OUTLOOKS FROM AMJ THROUGH DJF 2015-16, DECADAL TRENDS DUE TO CHANGES IN THE CLIMATE BASE STATE AND THE CON (HEAVILY INFLUENCED BY TRENDS) ARE THE PRIMARY SOURCE OF TEMPERATURE AND PRECIPITATION SIGNALS. PROGNOSTIC DISCUSSION OF OUTLOOKS - DJF 2014 TO DJF 2015 TEMPERATURE THE OUTLOOK FOR DJF 2014-15 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 DYNAMIC 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. SNOW COVER THROUGHOUT THE NORTHERN HEMISPHERE WAS WELL ABOVE THE LONG-TERM NORMALS IN OCTOBER, AND SOME RECENT RESEARCH SUGGESTS THAT THIS MAY INCREASE LIKELIHOOD OF BELOW-NORMAL TEMPERATURES IN EASTERN NORTH AMERICA. THE CA-SST TOOL SUGGESTS A NEGATIVE AO/NAO WHICH IS ALSO ASSOCIATED WITH BELOW-NORMAL TEMPERATURES IN THE EASTERN CONUS. CONSIDERING THESE FACTORS, THE REGION FAVORING BELOW-NORMAL TEMPERATURES WAS EXPANDED SOMEWHAT FROM WHAT WAS INDICATED ON LAST MONTH'S OUTLOOK, AND THE CHANCES FOR ABOVE-NORMAL TEMPERATURES IN THE NORTHERN GREAT PLAINS HAVE DIMINISHED TO NO HIGHER THAN LONG TERM CLIMATOLOGY. BELOW-NORMAL TEMPERATURES ARE NOW FAVORED THROUGHOUT MUCH OF THE SOUTHERN HALF OF THE CONUS FROM THE SOUTHERN ROCKIES EASTWARD, WHERE WEAK EL NINO COMPOSITES ALSO LEND SUPPORT. THE PATTERN OF FORECAST TEMPERATURE PROBABILITIES FAVORED IN DJF EXTENDS TO THE LATE WINTER MONTHS AND THEN GRADUALLY DIMINISHES INTO SPRING, 2015. BEFORE LARGELY VANISHING BY AMJ 2015. PREDICTED ANOMALIES FOR MJJ AND BEYOND ARE LARGELY DETERMINED BY RECENT TRENDS, ALTHOUGH SOME REVISIONS WERE MADE TO THE FORECAST IN THE WESTERN CONUS. THE REGION OF ENHANCED CHANCES FOR ABOVE-NORMAL TEMPERATURES WAS EXPANDED IN THE LATE SPRING TO REFLECT NORTH PACIFIC SSTS PREDICTED BY THE MOST DYNAMIC MODELS AS WELL AS THE CA-SST WHICH FAVOR WARM CONDITIONS. THE PREDICTED SSTS PROJECTS ON TO THE POSITIVE PDO INDEX, AND CORRELATES WEAKLY WITH ABOVE-NORMAL TEMPERATURES IN THE WESTERN CONUS, SO THE REGION OF ENHANCED CHANCES OF ABOVE-NORMAL TEMPERATURES WAS EXPANDED IN PARTS OF THE WEST RELATIVE TO PREVIOUS OUTLOOKS IN AMJ AND MJJ 2015. SIGNALS FROM TRENDS PREDOMINATE DURING THE SUMMER 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. TREND-RELATED SIGNALS GRADUALLY DIMINISH INTO THE FALL AND WINTER SEASONS, UNTIL BY DJF 2015-16 ELEVATED CHANCES FOR ABOVE-NORMAL TEMPERATURES ARE RESTRICTED ONLY TO REGIONS IN THE SOUTHWEST, SOUTHERN ROCKIES, AND TEXAS AS WELL AS NEAR NEW ENGLAND, AND IN NORTHERN ALASKA. 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 CENTRAL CALIFORNIA, ACROSS THE SOUTHWEST, PARTS OF THE SOUTHERN GREAT BASIN, THE SOUTHERN PLAINS AND THE SOUTHEAST CONUS FROM DJF 2014-15 THROUGH FMA 2015. THE NMME SUGGESTS WETTER CONDITIONS FOR CENTRAL CALIFORNIA ON THE MOST RECENT RUNS THAN RUNS FOR THE SAME SEASON ISSUED LAST MONTH. THE PRECIPITATION FORECAST FOR CENTRAL CALIFORNIA WAS REVISED TO REFLECT THIS INFORMATION. EL NINO COMPOSITES ALSO WEAKLY SUPPORT AN INCREASE IN THE ODDS FOR ABOVE AVERAGE PRECIPITATION NORTHWARD ALONG THE EASTERN SEABOARD TO SOUTHERN NEW ENGLAND WITH LIMITED SUPPORT FROM THE NMME AND IMME MODEL GUIDANCE. ENHANCED PROBABILITIES FOR BELOW-MEDIAN PRECIPITATION ARE INDICATED FOR THE PACIFIC NORTHWEST THROUGH MAM 2015, AND FROM THE CENTRAL MISSISSIPPI VALLEY INTO THE GREAT LAKES REGION FROM DJF 2014-15 THROUGH MAM 2015. THE AREA AND CONFIDENCE IN THE FORECAST FAVORING BELOW-MEDIAN PRECIPITATION IS REDUCED SOMEWHAT IN RELATION TO THE OUTLOOKS ISSUED A MONTH AGO IN THE PACIFIC NORTHWEST DUE TO WEAK SUPPORT FROM THIS MONTHS NMME AND IMME. PROBABILITIES OF ABOVE-MEDIAN PRECIPITATION ARE ENHANCED FOR PARTS OF SOUTHERN ALASKA THROUGH FMA 2015, ALTHOUGH THIS AREA IS SOMEWHAT SMALLER THAN IN PREVIOUS OUTLOOKS FOR THE SAME SEASON DUE TO THE LACK OF SUPPORT FROM RECENT MODEL RUNS. SOME RECENT EXAMINATION OF PRECIPITATION IN PAST INSTANCES OF WEAK EL NINO CONDITIONS SUPPORT ENHANCED CHANCES OF BELOW-MEDIAN PRECIPITATION AMOUNTS IN PARTS OF CENTRAL ALASKA IN DJF AND JFM. RECENT DYNAMIC FORECASTS FROM THE NMME SUGGEST ABOVE-MEDIAN PRECIPITAITON FOR THE SOUTHERN ROCKY MOUNTAINS AND PARTS OF THE SOUTHERN GREAT PLAINS IN THE LATE SPRING, CONTRADICTING THE FORECAST ISSUED LAST MONTH, WHICH WERE PRIMARILY BASED ON TREND AND BEYOND THE LAST LEAD OF THE DYNAMIC MODELS INITIALIZED LAST MONTH. IN VIEW OF THIS NEW INFORMATION, THE FORECAST FOR AMJ AND MJJ 2015 WAS REVISED TO EQUAL CHANCES FOR PRECIPITATION TERCILES FOR THE SOUTHERN HIGH PLAINS. DECADAL TRENDS POINT TO ELEVATED CHANCES FOR BELOW-MEDIAN PRECIPITATION IN THE PACIFIC NORTHWEST DURING THE JAS AND ASO 2015 SEASONS. TRENDS IN PARTS OF THE SOUTHEAST CONUS INDICATE ELEVATED CHANCES FOR BELOW-MEDIAN PRECIPITATION AMOUNTS IN DJF 2015-16. FORECASTER: DAVID UNGER 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 DEC 18 2014 1981-2010 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 19, 2011 FORECAST RELEASE. $$