PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD 830AM EDT THURSDAY OCT 18 2012 SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS THE MAIN FACTORS WHICH USUALLY INFLUENCE THE SEASONAL CLIMATE OUTLOOK INCLUDE: 1) EL NINO AND LA NINA - WHICH TOGETHER COMPRISE EL NINO/SOUTHERN OSCILLATION OR ENSO. IMPACTS OF THESE EVENTS ARE SUMMARIZED BY SEPARATING 3-MONTH OBSERVATIONS FROM 3 OR MORE DECADES INTO EL NINO, NEUTRAL, AND LA NINA SETS, AVERAGING EACH SEPARATELY, AND THEN COMPUTING ANOMALIES. THESE ARE CALLED "ENSO COMPOSITES", WHICH ARE USED AT TIMES TO SUBJECTIVELY MODIFY THE FORECAST. 2) TRENDS - APPROXIMATED BY THE OCN TOOL AS THE DIFFERENCE BETWEEN THE MOST RECENT 10-YEAR MEAN OF TEMPERATURE OR 15-YEAR MEAN OF PRECIPITATION FOR A GIVEN LOCATION AND TIME OF YEAR AND THE 30-YEAR CLIMATOLOGY PERIOD (CURRENTLY 1981-2010). 3) THE TROPICAL 30-60 DAY OSCILLATION - SOMETIMES CALLED MADDEN JULIAN OSCILLATION (MJO) - AFFECTS CLIMATE VARIABILITY WITHIN SEASONS. 4) THE NORTH ATLANTIC OSCILLATION (NAO) AND THE PACIFIC NORTH AMERICAN (PNA) PATTERNS - WHICH AFFECT THE TEMPERATURE ANOMALY PATTERN ESPECIALLY DURING THE COLD SEASONS. THESE PHENOMENA ARE CONSIDERED LESS PREDICTABLE ON A SEASONAL TIMESCALE THAN ENSO. 5) THE PACIFIC DECADAL OSCILLATION (PDO) - AN ENSO-LIKE PATTERN OF CLIMATE VARIABILITY AFFECTING THE TROPICS AND THE NORTH PACIFIC AND NORTH AMERICAN REGIONS, BUT WHICH VARIES ON A MUCH LONGER TIME-SCALE THAN ENSO. 6) PERSISTENTLY DRY OR WET SOILS IN THE SPRING AND SUMMER AND SNOW AND ICE COVER ANOMALIES IN THE WINTER. THESE FACTORS TEND TO PERSIST FOR LONG PERIODS AND ACT AS A KIND OF MEMORY IN THE CLIMATE SYSTEM. 7) STATISTICAL FORECAST TOOLS - CANONICAL CORRELATION ANALYSIS (CCA), SCREENING MULTIPLE LINEAR REGRESSION (SMLR), CONSTRUCTED ANALOGUE (CA) AND ENSEMBLE CCA (ECCA). 8) DYNAMICAL FORECAST MODELS - INCLUDING THE NCEP CLIMATE FORECAST SYSTEM (CFS). THE UPGRADED PARALLEL VERSION OF THE CFS (CFSV2) BECAME OPERATIONAL IN LATE MARCH OF 2011. BOTH VERSIONS OF CFS ARE CURRENTLY RUN IN PARALLEL. AN EXPERIMENTAL MODEL FORECAST SYSTEM, THE NATIONAL MULTI-MODEL ENSEMBLE, COMPRISED OF SEVERAL MODELS AND DESIGNATED NMME, MAY ALSO BE USED EXPERIMENTALLY AND SUBJECTIVELY UNTIL IT IS INCLUDED INTO THE CONSOLIDATION. AN INTERNATIONAL MODEL ENSEMBLE DESIGNATED IMME IS ALSO AVAILABLE. 9) CONSOLIDATION (CON) - AN OBJECTIVE, SKILL WEIGHTED COMBINATION OF THE OCN, CCA, SMLR, ECCA, AND CFS FORECASTS IS USED AS A FIRST GUESS IN PREPARING THE FORECAST MAPS. THIS TECHNIQUE MAKES OPTIMUM USE OF THE KNOWN SKILL OF OUR FORECAST TOOLS. BORDERLINE ENSO-NEUTRAL-WEAK EL NINO CONDITIONS PREVAILED ACROSS THE EQUATORIAL PACIFIC OCEAN DURING SEPTEMBER. THE SEA SURFACE TEMPERATURE (SST) ANOMALY PATTERN, WHICH ONLY A MONTH EARLIER SHOWED MOSTLY ABOVE-NORMAL ALONG THE CENTRAL AND EASTERN EQUATORIAL PACIFIC, HAS WEAKENED CONSIDERABLY. BUOY DATA INDICATES NEAR TO ABOVE-NORMAL SSTS FROM 140W WESTWARD ACROSS THE DATE LINE, AND NEAR TO BELOW-NORMAL SSTS FROM 140W EASTWARD TO THE SOUTH AMERICAN COAST. SST ANOMALIES IN THE NINO 3.4 REGION ARE HOVERING NEAR THE POSITIVE 0.5 C THRESHOLD. DYNAMICAL AND STATISTICAL MODELS PREDICT SST ANOMALIES IN THIS REGION TO EITHER HOLD STEADY NEAR THE POSITIVE 0.5 C THRESHOLD, OR BRIEFLY EXCEED IT INTO WEAK EL NINO TERRITORY FOR NDJ 2012-13 AND DJF 2012-13, AFTER WHICH MOST MODELS GRADUALLY DECREASE THE REGIONAL SST ANOMALIES TOWARDS ZERO. THE LATEST OBSERVATIONS AND MODEL PREDICTIONS EMPHASIZE THE LARGE AMOUNT OF UNCERTAINTY ASSOCIATED WITH THE SURFACE TEMPERATURE AND PRECIPITATION OUTLOOKS FOR THE UNITED STATES DURING THIS UPCOMING WINTER SEASON. THE NDJ 2012-13 TEMPERATURE OUTLOOK INDICATES ENHANCED CHANCES FOR ABOVE NORMAL TEMPERATURES ACROSS MOST OF THE WESTERN HALF OF THE LOWER 48 STATES, AND FOR NORTHERN AND CENTRAL ALASKA, AND ENHANCED CHANCES FOR BELOW-NORMAL TEMPERATURES OVER THE FLORIDA PENINSULA. THIS IS SUPPORTED BY DYNAMICAL MODELS AND BY LOCAL SSTS ALONG THE SHORE OF NORTHERN ALASKA. THE NDJ 2012-13 PRECIPITATION OUTLOOK INDICATES AN INCREASED LIKELIHOOD FOR BELOW-MEDIAN PRECIPITATION FOR THE PACIFIC NORTHWEST, NORTHERN SECTIONS OF BOTH CALIFORNIA AND NEVADA, MOST OF THE ALASKA PANHANDLE, AND ACROSS MIDDLE AND UPPER PORTIONS OF THE MISSISSIPPI VALLEY AND ADJACENT EASTERN PLAINS BASED ON THE DYNAMICAL MODELS. THERE IS AN INCREASED LIKELIHOOD FOR ABOVE-MEDIAN PRECIPITATION ACROSS THE CENTRAL AND EASTERN GULF COAST REGION BASED ON THE POSSIBILITY THAT WEAK EL NINO CONDITIONS COULD HAVE AN EFFECT DURING THIS SEASON ACROSS THE GULF COAST REGION. ODDS ALSO FAVOR ABOVE-MEDIAN PRECIPITATION OVER NORTHWESTERN PORTIONS OF ALASKA BASED ON DYNAMICAL MODEL CONSIDERATIONS. IN LOCATIONS WHERE THE LIKELIHOODS OF SEASONAL MEAN TEMPERATURES AND SEASONAL PRECIPITATION AMOUNTS ARE SIMILAR TO THE CLIMATOLOGICAL PROBABILITIES, EQUAL CHANCES (EC) OF BELOW, NEAR, AND ABOVE-AVERAGE TEMPERATURE AND PRECIPITATION ARE 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 PACIFIC SST ANOMALIES ALONG THE EQUATOR ARE NEAR TO SLIGHTLY ABOVE-AVERAGE WEST OF ABOUT 140W, AND NEAR TO SLIGHTLY BELOW-AVERAGE EAST OF 140W. THE AVERAGE HEAT CONTENT IN THE UPPER OCEAN NEAR THE EQUATOR HAS SUBSTANTIALLY DECLINED DURING THE PAST MONTH. THE LARGE POOL OF SUBSURFACE WARMTH IN THE CENTRAL AND EASTERN EQUATORIAL PACIFIC OCEAN JUST ONE MONTH EARLIER HAS MOSTLY DISAPPEARED. THE SUB-SURFACE THERMAL PROFILE IN THIS REGION IS NOW ILL-DEFINED WITH WEAK ANOMALIES. FARTHER WEST, FROM 160W WESTWARD ACROSS THE DATE LINE TO 150E LONGITUDE, ABOVE-AVERAGE TEMPERATURES ARE OBSERVED AT A DEPTH OF 50-200 METERS, WITH THE LARGEST ANOMALIES RANGING BETWEEN +2.0C AND +3.0C. THE TROPICAL ATMOSPHERIC CIRCULATION IS APPARENTLY HAVING A DIFFICULT TIME IN TRANSITIONING FROM ENSO-NEUTRAL TO WEAK EL NINO CONDITIONS. THIS IS REVEALED BY AN INCREASE IN LOW-LEVEL WESTERLY WIND ANOMALIES IN THE FAR WESTERN PACIFIC (TYPICAL OF A WARM EVENT), AND ENHANCED TROPICAL CONVECTION OVER BOTH THE DATE LINE (AGAIN TYPICAL OF A WARM EVENT) AND THE MARITIME CONTINENT (NOT TYPICAL). THESE MIXED SIGNALS ONLY COMPLICATE THIS SET OF SEASONAL TEMPERATURE AND PRECIPITATION OUTLOOKS FOR THE UNITED STATES, ESPECIALLY FOR THE FIRST FEW LEADS. PROGNOSTIC DISCUSSION OF SST FORECASTS LATEST WEEKLY OBSERVATIONS PLACE THE NINO 3.4 INDEX AT ABOUT 0.1C. THE CPC SST CONSOLIDATION FORECAST FOR THE NINO 3.4 REGION STARTS OFF WITH BORDERLINE NEUTRAL-WEAK EL NINO OCEANIC NINO INDEX (ONI) VALUES NEAR +0.5C, THEN GRADUALLY DECLINES TO NEAR ZERO BY JFM 2013, AND REMAINING NEAR ZERO THROUGHOUT THE NEXT SEVERAL SEASONS INTO AMJ 2013. THIS SKILL-WEIGHTED SST CONSOLIDATION FORECAST USES THE CONSTRUCTED ANALOG, CANONICAL CORRELATION ANALYSIS, MARKOV MODEL, AND CFSV2 AS INPUTS. THE CFSV2 ENSEMBLE PLUME FORECAST FOR THE NINO 3.4 REGION SHOWS CONSIDERABLE VARIATION OF SST ANOMALIES (AS MUCH AS ONE FULL DEGREE C ON EITHER SIDE OF ZERO) THROUGHOUT THE WINTER AND EARLY SPRING. HOWEVER, THE ENSEMBLE MEAN DEPICTS A VERY SLOW DECLINE FROM INITIAL CONDITIONS (NEAR +0.5C) TO ZERO BY FEBRUARY 2013, AND THEN SLOWLY CLIMBING FOR SEVERAL MONTHS THEREAFTER. AN SST PLUME DIAGRAM FOR THE NINO 3.4 REGION SHOWING THE AVERAGE OF 17 DYNAMICAL MODELS AND 8 STATISTICAL MODELS DEPICTS THE DYNAMICAL AVERAGE BRIEFLY EXCEEDING +0.5C FOR BOTH NDJ 2012-13 AND DJF 2012-13 WHICH VERY SLOWLY TAPERS OFF TO ABOUT +0.25C BY SUMMER, WITH THE STATISTICAL AVERAGE PARALLELING THE DYNAMICAL MODEL CURVE BUT REMAINING SEVERAL TENTHS OF A DEGREE C COOLER. BASED ON THESE FORECAST TOOLS, IT IS POSSIBLE THAT AN EL NINO EVENT OF WEAK AMPLITUDE WILL OCCUR LATER THIS FALL AND INTO WINTER. FOR THE PHYSICAL IMPACT, THE THRESHOLD DEFINITION OF HALF A DEGREE IS SOMEWHAT ARBITRARY. SO A NON-EVENT OF 0.49 C MAY BE AS IMPORTANT FOR THE NORTH AMERICAN CLIMATE AS A WEAK EVENT OF 0.51. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS WITH THE ADVANCE OF COUPLED ATMOSPHERE OCEAN MODELS WE NOW HAVE A SET OF ABOUT 10 MODELS, EACH WITH MANY RUNS, THAT IN GENERAL REFLECT SST ANOMALIES THAT ARE WEAKER THAN EXPECTED A MONTH AGO. WE DO MAINTAIN CONTINUITY AS MUCH AS IS REASONABLE WITH FORECASTS RELEASED LAST MONTH. ENSO COMPOSITES HAVE BEEN CONSIDERED BUT DOWNPLAYED. THE FORECAST WAS ADJUSTED TO REFLECT THE NMME AND IMME, AS WELL AS THE CONSOLIDATION WHERE AND WHEN DEEMED HELPFUL. A SIGNIFICANT WILDCARD IN THE UPCOMING WINTER OUTLOOK IS THE UNCERTAINTY ASSOCIATED WITH THE PHASE OF THE ARCTIC OSCILLATION (AO). UNFORTUNATELY, IT IS VERY DIFFICULT TO PREDICT THE PHASE OF THE AO MORE THAN A FEW WEEKS INTO THE FUTURE. THE OUTLOOKS FOR NDJ 2012-13 THUS PRIMARILY REFLECT DYNAMICAL MODEL FORECASTS INCLUDING THE CFSV2 AND IMME AND NMME FORECASTS, AS WELL AS DECADAL TIMESCALE TRENDS. THE CONSOLIDATION OF (MOSTLY) STATISTICAL TOOLS IS THE ONLY BASIS FOR FORECASTS FROM AMJ 2013 ONWARD. PROGNOSTIC DISCUSSION OF OUTLOOKS - NDJ 2012 TO NDJ 2013 TEMPERATURE THE NDJ 2012-13 TEMPERATURE OUTLOOK INDICATES ENHANCED CHANCES FOR ABOVE-NORMAL TEMPERATURES ACROSS MOST OF THE WESTERN HALF OF THE LOWER 48 STATES, AND FOR NORTHERN AND CENTRAL ALASKA, AND ENHANCED CHANCES FOR BELOW-NORMAL TEMPERATURES OVER THE FLORIDA PENINSULA. THIS IS SUPPORTED BY DYNAMICAL MODELS AND BY LOCAL SSTS ALONG THE SHORE OF NORTHERN ALASKA. TEMPERATURE OUTLOOKS FROM DJF 2012-13 THROUGH FMA 2013 SHOW INCREASED CHANCES OF ABOVE-NORMAL TEMPERATURES ACROSS MUCH OF THE WESTERN AND CENTRAL CONUS AND NORTHERN PORTIONS OF ALASKA, MOSTLY DUE TO DYNAMICAL MODEL INPUT (CFSV2, NMME, IMME) AND THE CON TOOL. PROBABILITIES ARE HIGHEST IN NORTHERN ALASKA, REACHING 50 PERCENT IN NDJ AND DJF. THE ELEVATED ODDS FOR BELOW-NORMAL TEMPERATURES IN FLORIDA IN NDJ AND DJF ARE DUE TO THE POSSIBLE EARLY-SEASON INFLUENCE OF WEAK EL NINO CONDITIONS, AS SEEN IN EMPIRICAL COMPOSITES AND THE CON. THE OUTLOOKS FROM MAM AND AMJ 2013 ONWARD ARE BASED ON DECADAL TRENDS AS INDICATED BY THE CONSOLIDATION TOOL. IN AREAS WITHOUT STRONG CLIMATE SIGNALS, EQUAL CHANCES FOR BELOW-NORMAL, NEAR- NORMAL, OR ABOVE-NORMAL SEASONAL MEAN TEMPERATURES IS PREDICTED. PRECIPITATION THE NDJ 2012-13 PRECIPITATION OUTLOOK INDICATES AN INCREASED LIKELIHOOD FOR BELOW-MEDIAN PRECIPITATION FOR THE PACIFIC NORTHWEST, NORTHERN SECTIONS OF BOTH CALIFORNIA AND NEVADA, MOST OF THE ALASKA PANHANDLE, AND ACROSS MIDDLE AND UPPER PORTIONS OF THE MISSISSIPPI VALLEY AND ADJACENT EASTERN PLAINS BASED ON THE DYNAMICAL MODELS. THERE IS AN INCREASED LIKELIHOOD FOR ABOVE-MEDIAN PRECIPITATION ACROSS THE CENTRAL AND EASTERN GULF COAST REGION BASED ON THE POSSIBILITY THAT WEAK EL NINO CONDITIONS COULD HAVE AN EFFECT DURING THIS SEASON ACROSS THE GULF COAST REGION. ODDS ALSO FAVOR ABOVE-MEDIAN PRECIPITATION OVER NORTHWESTERN PORTIONS OF ALASKA BASED ON DYNAMICAL MODEL CONSIDERATIONS. IT IS UNCLEAR AT THIS TIME WHETHER OR NOT WEAK EL NINO CONDITIONS WILL BECOME ESTABLISHED THIS WINTER ACROSS THE U.S., AND TO WHAT DEGREE AN EXTENDED SUBTROPICAL JET STREAM MAY INFLUENCE PRECIPITATION PATTERNS ACROSS THE SOUTHEAST. THEREFORE, LAST MONTH'S PREDICTED AREA OF ABOVE-MEDIAN PRECIPITATION HAS BEEN SIGNIFICANTLY REDUCED IN COVERAGE THIS MONTH ACROSS THE SOUTH. IN ADDITION, THE PREDICTED AREA OF BELOW-MEDIAN PRECIPITATION OVER THE OHIO VALLEY (A FEATURE CONSISTENT WITH EL NINO WINTERS) FOR THE DJF, JFM AND FMA SEASONS LAST MONTH HAS BEEN REPLACED WITH EC. SOME CLIMATE MODELS TILT THE ODDS TOWARDS THE INTRODUCTION OF A NEW AREA OF BELOW-MEDIAN PRECIPITATION OVER THE UPPER AND MIDDLE MISSISSIPPI VALLEY FOR BOTH NDJ AND DJF. THE PREDICTED BELOW-MEDIAN PRECIPITATION AMOUNTS OVER THE PACIFIC NORTHWEST ARE STRONGLY INDICATED BY VARIOUS DYNAMICAL MODELS. IN NORTHERN ALASKA, THE ENHANCED ODDS OF ABOVE-MEDIAN PRECIPITATION IN NDJ 2012-13 ARE BASED ON NMME PROBABILISTIC FORECASTS, AND TO SOME EXTENT THE CFSV2 MODEL. FOR DJF 2012-13 THROUGH MAM 2013, DYNAMICAL MODELS SUPPORT ELEVATED ODDS OF ABOVE-MEDIAN PRECIPITATION AMOUNTS ACROSS PORTIONS OF THE GULF COAST REGION. BEYOND MAM, THERE ARE PRACTICALLY NO SIGNALS FROM DECADAL TRENDS, EXCEPT FOR BELOW-MEDIAN PRECIPITATION IN THE PACIFIC NORTHWEST FOR JJA AND JAS 2013. IN AREAS WITHOUT STRONG CLIMATE SIGNALS, EQUAL CHANCES FOR BELOW, NEAR, OR ABOVE-MEDIAN SEASONAL PRECIPITATION AMOUNTS IS PREDICTED. FORECASTER: ANTHONY ARTUSA 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 NOV 15 2012 1981-2010 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 19, 2011 FORECAST RELEASE. $$