PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD 830 AM EST THU JAN 19 2017 SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS WEAK LA NINA CONDITIONS CONTINUE ACROSS THE EQUATORIAL PACIFIC OCEAN, AS REPRESENTED IN CURRENT OCEANIC AND ATMOSPHERIC OBSERVATIONS. THE OFFICIAL CPC ENSO FORECAST INDICATES A TRANSITION TO ENSO-NEUTRAL CONDITIONS DURING FEBRUARY 2017. ENSO-NEUTRAL CONDITIONS ARE FAVORED TO PERSIST THROUGH AT LEAST THE BOREAL SUMMER. THE FEBRUARY-MARCH-APRIL (FMA) 2017 TEMPERATURE OUTLOOK FAVORS ABOVE-NORMAL TEMPERATURES FROM THE NORTHEAST TO THE GULF COAST, AND WESTWARD ACROSS THE SOUTHERN PLAINS TO THE FOUR CORNERS REGION. THE HIGHEST ODDS (GREATER THAN 50 PERCENT) FOR ABOVE-NORMAL TEMPERATURES ARE INDICATED OVER NEW MEXICO AND TEXAS. ABOVE-NORMAL TEMPERATURES ARE ALSO FAVORED FOR WESTERN AND NORTHERN ALASKA. ELEVATED ODDS FOR BELOW-NORMAL TEMPERATURES ARE PREDICTED FROM THE PACIFIC NORTHWEST TO THE NORTHERN GREAT PLAINS AND UPPER MISSISSIPPI VALLEY. THE FMA 2017 PRECIPITATION OUTLOOK INDICATES ENHANCED PROBABILITIES OF ABOVE-MEDIAN PRECIPITATION FROM THE PACIFIC NORTHWEST, ACROSS THE NORTHERN GREAT PLAINS, TO THE GREAT LAKES AND OHIO VALLEY. BELOW-MEDIAN PRECIPITATION AMOUNTS ARE MOST LIKELY FOR THE SOUTHWEST AND WESTERN TEXAS, AS WELL AS FROM THE CENTRAL GULF COAST TO THE SOUTHEAST AND THE MID-ATLANTIC. 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 INDICATE THAT LA NINA CONDITIONS ARE PRESENT. DURING THE PAST FOUR WEEKS, EQUATORIAL SSTS IN THE NINO INDEX REGIONS REMAINED BELOW (ABOVE)-AVERAGE ACROSS THE CENTRAL AND EASTERN PACIFIC OCEAN (NEAR THE MARITIME CONTINENT). NEGATIVE ANOMALIES REMAINED IN PLACE FROM THE DATE LINE TO 80W. ANOMALIES WERE AS LARGE -1.0 DEGREE C, THOUGH THE NINO REGION INDEX VALUES HOVERED NEAR -0.5 DEGREE C AS THE LARGER MAGNITUDE ANOMALY VALUES EXTENDED OVER RELATIVELY SMALL AREAS. NEGATIVE SUBSURFACE TEMPERATURE ANOMALIES PERSISTED, SINCE APRIL 2016, ACROSS THE CENTRAL AND EASTERN PACIFIC. HOWEVER, THESE ANOMALIES WEAKENED DURING DECEMBER. THE ONI VALUE (OCTOBER - NOVEMBER - DECEMBER 2016), BASED ON SST DEPARTURES FROM AVERAGE IN THE NINO 3.4 REGION, WAS -0.8 DEGREES C. ENHANCED CONVECTION REMAINED CENTERED OVER THE MARITIME CONTINENT, WITH SUPPRESSED CONVECTION EXTENDING EASTWARD FROM 160E ACROSS MUCH OF THE EQUATORIAL PACIFIC. DURING THE PAST COUPLE OF MONTHS, SUBSEASONAL VARIABILITY HAS DISRUPTED THIS PATTERN AND LED TO PERIODIC DRYING ACROSS PARTS OF THE MARITIME CONTINENT AND EASTERN INDIAN OCEAN. TRADE WINDS AVERAGED NEAR NORMAL ACROSS THE CENTRAL AND EASTERN EQUATORIAL PACIFIC FROM NOVEMBER 10 TO DECEMBER 9, 2016. AS OF EARLY JANUARY, NEGATIVE SST ANOMALIES WERE PRESENT OVER THE NORTH PACIFIC ALONG 45N. POSITIVE SST ANOMALIES WERE MEASURED OVER THE BERING SEA AND NEAR THE COAST OF ALASKA, AS WELL AS OVER THE CENTRAL PACIFIC ALONG 30N. THE ABOVE-NORMAL SSTS NEAR ALASKA, COMBINED WITH THE RECENT ATMOSPHERIC CIRCULATION, HAVE RESULTED IN SEA ICE COVERAGE THAT IS MUCH BELOW-NORMAL AND LATE TO ARRIVE AT POINTS ALONG THE WEST COAST OF ALASKA. PROGNOSTIC DISCUSSION OF SST FORECASTS THE CPC SST CONSOLIDATION FORECAST, WHICH INCLUDES THREE STATISTICAL FORECASTS ALONG WITH THE CFS, PREDICTS ENSO-NEUTRAL CONDITIONS DURING FMA 2017 AND BEYOND. THERE IS A SLIGHT TILT TOWARD BELOW-AVERAGE SSTS DURING NEXT WINTER, BUT THE UNCERTAINTY IS TOO LARGE TO MAKE ANY DEFINITIVE STATEMENT ABOUT TROPICAL PACIFIC SSTS NEXT WINTER. THE NORTH AMERICAN MULTI-MODEL ENSEMBLE (NMME) ENSEMBLE MEAN FORECAST FOR THE NINO-3.4 SST ANOMALY IS SLIGHTLY WARMER THAN LAST MONTH, WITH ENSO-NEUTRAL FAVORED EARLY IN OUTLOOK PERIOD. BASED ON THE LATEST OBSERVATIONAL AND MODEL FORECAST INDICATORS, THE OFFICIAL CPC/IRI ENSO OUTLOOK FAVORS ENSO-NEUTRAL CONDITIONS AT 70% DURING FMA 2017. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS THE OUTLOOKS FOR FMA 2017 THROUGH JJA 2017 ARE BASED ON DYNAMICAL MODEL OUTPUTS FROM THE NMME AND IMME (INTERNATIONAL MULTI-MODEL ENSEMBLE) BALANCED WITH INPUT FROM THE CPC CONSOLIDATION AND CONSTRUCTED ANALOG BASED ON SSTS (CA-SST). BEYOND THE SUMMER (JJA) OF 2017, THE OUTLOOKS ARE BASED ON TRENDS, THE CPC CONSOLIDATION, AND CA-SST. PROGNOSTIC DISCUSSION OF OUTLOOKS - FMA 2017 TO FMA 2018 TEMPERATURE THE OUTLOOK FOR FMA 2017 WAS CHANGED LITTLE FROM LAST MONTH. PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES FROM THE OHIO VALLEY TO THE SOUTHEAST WERE REDUCED DUE TO UNCERTAINTY IMPLIED BY MODEL OUTLOOKS AND STATISTICAL TOOLS (CCA AND CA-SST) INDICATING THE POTENTIAL FOR COLDER AIR TO SPILL ACROSS THE GREAT LAKES REGION. THE DECREASED ODDS RESULTED IN EC NOW INDICATED OVER THE OHIO VALLEY, WHILE A SLIGHT TILT TOWARD ABOVE-NORMAL TEMPERATURES REMAINED OVER THE TENNESSEE VALLEY, MID-ATLANTIC, AND THE SOUTHEAST. RECENT HEAVY SNOWS AND THE LAGGED IMPACT TO TEMPERATURES ACROSS THE GREAT BASIN AND CENTRAL ROCKIES ALSO RESULTED IN A SHIFT AWAY FROM FAVORING ABOVE-NORMAL TEMPERATURES IN THOSE REGIONS. SUBSEASONAL TROPICAL VARIABILITY SUCH AS THE MADDEN-JULIAN OSCILLATION, ESPECIALLY DURING FEBRUARY WHEN VARIANCE IS HIGHEST, MAY PLAY A ROLE IN DETERMINING THE OBSERVED TEMPERATURE FIELD DURING FMA 2017 ACROSS THE CENTRAL AND EASTERN U.S. IF ENHANCED CONVECTION REMAINS CENTERED OVER THE MARITIME CONTINENT AND FAR WESTERN PACIFIC, THE COLDER OUTCOME INDICATED BY STATISTICAL GUIDANCE IS MORE LIKELY ACROSS THE NORTHERN CONUS. THE ARCTIC OSCILLATION (AO) HAS BEEN POSITIVE FOR THE PAST 45 DAYS. THE GFS MODEL INDICATES THAT A POSITIVE AO INDEX WILL PERSIST INTO THE LATTER HALF OF JANUARY AND INTO EARLY FEBRUARY. THE AO INDEX HAS VERIFIED OUTSIDE OF THE MODEL ENVELOPE A FEW TIMES DURING THE PAST 60 DAYS, SO THERE IS UNCERTAINTY WITH THE AO OUTLOOK GOING FORWARD. THROUGH THE SPRING AND SUMMER, THE OUTLOOK TOOLS INDICATE THAT ABOVE-NORMAL TEMPERATURES ARE MOST FAVORED FOR MOST OF THE CONUS AND ALASKA. THE CPC CONSOLIDATION INDICATES A WEAKNESS IN THE SIGNAL FOR ABOVE-NORMAL TEMPERATURES OVER THE CENTRAL PORTIONS OF THE CONUS, WHICH IS REFLECTED IN THE OUTLOOKS. BY AUTUMN, ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR THE ENTIRE FORECAST DOMAIN. PRECIPITATION THE FMA 2017 PRECIPITATION OUTLOOK REFLECTS THE WEAK LA NINA WITH A GENERALLY DRY PATTERN ACROSS THE SOUTHERN TIER AND AN ACTIVE STORM TRACK OVER THE NORTHERN CONUS. MODEL OUTPUTS REFLECTED THAT SAME PATTERN, ALTHOUGH SIGNALS IN THE MODEL OUTLOOKS WERE VERY WEAK, WITH MANY SMALL SCALE ANOMALIES AND LOW PROBABILITIES. COMPARED TO THE FMA OUTLOOK FROM LAST MONTH, THE NEW OUTLOOK REFLECTS A WEAKER LA NINA SIGNAL WHILE INCORPORATING THE LATEST MODEL GUIDANCE AND STATISTICAL TOOLS. THE RESULTING OUTLOOK FAVORS BELOW-MEDIAN PRECIPITATION OVER THE MID-ATLANTIC, SOUTHEAST, AND SOUTHWEST, WHILE SLIGHTLY INCREASING ODDS FOR ABOVE-MEDIAN PRECIPITATION OVER THE NORTHERN GREAT PLAINS. THROUGH MAM 2017, ABOVE- (BELOW-) MEDIAN PRECIPITATION IS FAVORED OVER THE NORTHERN (SOUTHERN) CONUS, BUT THAT SIGNAL FADES THROUGH THE SPRING. BY NEXT SUMMER, ABOVE-MEDIAN PRECIPITATION IS MORE LIKELY OVER THE SOUTHWEST CONUS, CONSISTENT WITH MODEL OUTPUTS, AND THE NORTHEAST, CONSISTENT WITH TRENDS AS INTEGRATED INTO THE CPC CON. BY AUTUMN OF 2017, NO SIGNIFICANT SIGNALS ARE EVIDENT. TRENDS FAVOR BELOW-MEDIAN PRECIPITATION OVER THE SOUTHEAST AND PORTIONS OF NORTHERN CALIFORNIA, SO THOSE SIGNALS ARE INDICATED IN THE OUTLOOKS FOR LATER IN 2017 AND EARLY 2018. FORECASTER: MATTHEW ROSENCRANS 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 FEB 16 2017 1981-2010 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 19, 2011 FORECAST RELEASE. $$