PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD 830 AM EST THU JAN 17 2019 SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS THE FEBRUARY-MARCH-APRIL (FMA) 2019 TEMPERATURE OUTLOOK FAVORS ABOVE NORMAL TEMPERATURES FOR APPROXIMATELY THE WESTERN HALF OF THE LOWER 48 STATES, FAR SOUTHERN FLORIDA, AND ALASKA. PROBABILITIES EXCEED 60% OVER THE PACIFIC NORTHWEST, THE ALASKA PANHANDLE, AND SOUTHEASTERN MAINLAND ALASKA. BELOW NORMAL TEMPERATURES ARE FAVORED OVER THE OHIO AND TENNESSEE VALLEYS, AND PARTS OF ADJACENT STATES. THIS TEMPERATURE OUTLOOK IS BASED LARGELY ON RECENT DYNAMICAL AND STATISTICAL MODEL OUTPUT, TEMPERATURE TRENDS, AND TO A DECREASING EXTENT, EFFECTS RELATED TO AN EL NINO. THE FMA 2019 PRECIPITATION OUTLOOK INDICATES ENHANCED ODDS OF ABOVE NORMAL PRECIPITATION AMOUNTS FROM SOUTH-CENTRAL ALASKA TO THE SOUTHERN ALASKA PANHANDLE, AND FOR THE SOUTHEASTERN CONUS. ABOVE NORMAL PRECIPITATION IS ALSO FAVORED FROM THE FOUR CORNERS REGION EASTWARD TO CENTRAL PORTIONS OF THE HIGH PLAINS. BELOW NORMAL PRECIPITATION IS FAVORED OVER NORTHERN CALIFORNIA, OREGON, AND PARTS OF ADJACENT STATES. ENHANCED ODDS OF LOWER TERCILE PRECIPITATION AMOUNTS ARE ALSO PREDICTED OVER THE MIDDLE AND UPPER MISSISSIPPI VALLEY, THE OHIO VALLEY, AND THE SOUTHERN GREAT LAKES REGION. THIS PRECIPITATION OUTLOOK IS BASED LARGELY ON RECENT DYNAMICAL AND STATISTICAL MODEL OUTPUT, HISTORICAL PRECIPITATION TRENDS, AND TO A DECREASING EXTENT, EFFECTS RELATED TO AN EL NINO. EQUAL CHANCES (EC) OF BELOW, NEAR, AND ABOVE NORMAL SEASONAL MEAN TEMPERATURES OR 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 RECENT OBSERVATIONS SHOW SEA-SURFACE TEMPERATURES (SST) AND SUBSURFACE TEMPERATURES ACROSS MOST OF THE EQUATORIAL PACIFIC CONTINUE TO BE ABOVE AVERAGE. DURING THE PAST MONTH, SST ANOMALIES RANGED FROM +0.5C TO +2.0C OVER MOST OF THIS REGION, AND SUBSURFACE ANOMALIES RANGED FROM +0.5C TO +4.0C FROM NEAR THE SURFACE TO A DEPTH OF 175 METERS. THE UPPER-OCEAN (TOP 300 METERS) HEAT CONTENT ACROSS THE NEAR-EQUATORIAL CENTRAL AND EASTERN PACIFIC PEAKED IN MID-OCTOBER 2018, AND HAS DECLINED FAIRLY RAPIDLY SINCE THEN. THE LATEST WEEKLY SST DEPARTURE FOR THE NINO 3.4 REGION DROPPED THIS PAST WEEK FROM +0.7C TO +0.4C . ENHANCED ATMOSPHERIC CONVECTION REMAINED RELATIVELY STATIONARY WEST OF THE DATE LINE DURING THE PAST 30-DAYS, AND CONCURRENTLY FLARED UP ALONG THE SOUTH PACIFIC CONVERGENCE ZONE. SUPPRESSED CONVECTION WAS OBSERVED EAST OF THE DATE LINE; AND NEAR TO BELOW NORMAL CONVECTION WAS NOTED OVER INDONESIA. LOW-LEVEL (850-HPA) AND UPPER-LEVEL (200-HPA) WINDS WERE GENERALLY CLOSE TO THE LONG-TERM AVERAGE OVER MUCH OF THE TROPICAL PACIFIC. DESPITE RELATIVELY WARM OCEAN TEMPERATURES OVER THE TROPICAL PACIFIC, THERE IS STILL NO CLEAR COUPLING BETWEEN THIS WARM WATER AND OVERLYING ATMOSPHERIC CONVECTION. THIS LACK OF COUPLING HAS INTERFERED WITH THE TYPICAL MATURATION PROCESS OF A DEVELOPING EL NINO. INSTEAD, SUBSEASONAL VARIABILITY ASSOCIATED WITH EPISODES OF ROBUST MJO ACTIVITY HAVE DOMINATED THE U.S. CLIMATE SINCE OCTOBER 2018. THE COMBINED EFFECT OF THE OCEAN-ATMOSPHERE SYSTEM IS MORE CONSISTENT WITH ENSO-NEUTRAL THAN IT IS WITH EL NINO. IN THE NEAR-TERM, THERE IS NO OBVIOUS INDICATION THAT THIS LONG-AWAITED OCEAN-ATMOSPHERE COUPLING WILL TAKE PLACE BEFORE THE END OF BOREAL WINTER. THE FMA 2019 SEASONAL OUTLOOK IS THEREFORE BASED PRIMARILY ON THE EXPECTATION OF CONTINUED ROBUST MJO ACTIVITY WITH LESS OF AN INFLUENCE ANTICIPATED FROM A WEAK (OR NOMINAL) EL NINO THAT MAY STILL FORM. ACCORDING TO THE LATEST ENSO DIAGNOSTIC DISCUSSION ISSUED BY CPC ON 10 JANUARY 2019, THERE IS A 65% CHANCE THAT EL NINO WILL FORM AND CONTINUE THROUGH THE NORTHERN HEMISPHERE SPRING 2019. HOWEVER, IT APPEARS THAT ANY EL NINO THAT DOES FORM WILL ONLY BE OF NOMINAL OR WEAK INTENSITY. PROGNOSTIC DISCUSSION OF SST FORECASTS THE CPC SST CONSOLIDATION TOOL FOR NINO 3.4 (WHICH INCLUDES THE CFS, CA, CCA, AND MARKOV SST PREDICTIONS) DEPICTS A MARGINAL EL NINO DURING FMA AND MAM 2019, BECOMING ENSO-NEUTRAL FOR THE REMAINDER OF 2019. THE CFS MODEL PRODUCES THE WARMEST SOLUTION OVERALL, WITH A PREDICTED NINO 3.4 SST ANOMALY CLOSE TO +1.0C (FMA), SLOWLY DROPPING TO ABOUT +0.7C BY JAS. HOWEVER, INDIVIDUAL ENSEMBLE MEMBERS FORECAST A LARGE SPREAD IN SOLUTIONS, FROM NEAR +2.3C DOWN TO -0.5C, WITH THE COOLEST OUTLYING MEMBER PREDICTING -1.5C. THE NMME AND IMME SST PLUMES FORECAST AN SST ANOMALY AT OR SOMEWHAT ABOVE +0.5C THROUGH JUNE 2019. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS THE TEMPERATURE AND PRECIPITATION OUTLOOKS WERE BASED ON DYNAMICAL MODEL GUIDANCE WHICH INCLUDED THE CFS ALONG WITH THE NMME AND ITS CALIBRATED PROBABILITIES THROUGH JJA 2019. THE IMME WAS USED THROUGH MJJ 2019. STATISTICAL FORECAST MODELS SUCH AS THE COMBINED ENSO-OCN TOOL, THE EXPERIMENTAL CBAM, SMLR, CCA, AND OCN WERE CONSIDERED. LONG-TERM TRENDS WERE WEIGHED MORE HEAVILY IN THE LATER OUTLOOKS, FROM ASO 2019 THROUGH FMA 2020. THE MJO IS EXPECTED TO REMAIN A MAJOR CONTRIBUTOR TO ANOMALOUS TROPICAL CONVECTION AND ITS ASSOCIATED INTERACTION WITH THE MID-LATITUDE CIRCULATION PATTERN, ESPECIALLY IN FEBRUARY 2019. UNCERTAINTY REMAINS ON HOW MUCH BLOCKING AT THE HIGH LATITUDES DEVELOPS BY FEBRUARY AND ITS LONGEVITY WITH LIMITED CONFIDENCE ON THE FUTURE EVOLUTION OF THE ARCTIC OSCILLATION (AO) AND NORTH ATLANTIC OSCILLATION (NAO). CLIMATE EFFECTS TYPICALLY ASSOCIATED WITH EL NINO DURING THE WINTER AND SPRING WERE CONSIDERED, BUT DOWNPLAYED SIGNIFICANTLY. PROGNOSTIC DISCUSSION OF OUTLOOKS - FMA 2019 TO FMA 2020 TEMPERATURE THE GREATEST UNCERTAINTY WITH THE FMA 2019 SEASONAL TEMPERATURE OUTLOOK IS IN THE PREDICTED COVERAGE OF FAVORED BELOW NORMAL TEMPERATURES IN THE EAST. THIS IS BASED ON SEVERAL CONSIDERATIONS WHICH INCLUDE: THE EXPERIMENTAL CBAM TOOL, LAGGED MJO COMPOSITES BASED ON THE EXPECTATION OF ENHANCED TROPICAL CONVECTION PROPAGATING ACROSS THE WESTERN PACIFIC (RMM PHASES 6 AND 7), AND THE GEFS CONSISTENTLY FORECASTING AN IMPRESSIVELY NEGATIVE AO AT LEAST FOR THE START OF FEBRUARY. AS MENTIONED EARLIER, THE LACK OF CLEAR OCEAN-ATMOSPHERE COUPLING MAKES SIGNIFICANT ENSO-RELATED IMPACTS MUCH LESS LIKELY ACROSS THE U.S. AS IS OFTEN THE CASE, WHEN ENSO IS WEAK, OTHER CONTRIBUTORS SUCH AS THE AO AND MJO CAN PLAY A LARGER ROLE IN U.S. WINTER CLIMATE VARIABILITY. THE EXPECTATION OF A HIGHLY VARIABLE TEMPERATURE PATTERN DURING THE 3-MONTH PERIOD RESULTS IN A FORECAST OF EC ACROSS MOST OF THE REMAINDER OF THE EASTERN CONUS. THE WIDESPREAD AREA OF FAVORED ABOVE NORMAL TEMPERATURES, WHICH INCLUDES MOST OF THE WESTERN CONUS AND ALASKA, IS SUPPORTED BY MANY OF THE TOOLS, SUCH AS THE CFS, THE CALIBRATED NMME (PAC) AND MOST OF ITS INPUT MODELS, ENSO-OCN, SMLR, CCA, AND OCN, AND TO A LESSER EXTENT, THE EXPERIMENTAL CBAM TOOL. IN MAM AND AMJ 2019, THE OUTLOOKS DEPICT THE EXPANSION OF FAVORED ABOVE NORMAL TEMPERATURES ACROSS THE EASTERN CONUS, AS PREDICTED BY ENSO-OCN, CBAM, THE NMME PAC, AND THE IMME. IN AMJ AND MJJ, PROBABILITIES FOR ABOVE NORMAL TEMPERATURES REACH A MAXIMUM ACROSS NORTHERN ALASKA, IN PART DUE TO THE EARLIER BREAKUP OF ICE IN RECENT DECADES AND WARMING TEMPERATURE TRENDS. BY JJA AND JAS, ABOVE NORMAL TEMPERATURES ARE FAVORED ACROSS MUCH OF THE LOWER 48 STATES AND ALASKA, PRIMARILY RELATED TO HISTORICAL TEMPERATURE TRENDS, BUT ALSO SUPPORTED BY CBAM. TRENDS FOR WARMTH ARE PROMINENT ACROSS THE NORTHEAST DURING THE SUMMER AND EARLY AUTUMN (JJA THROUGH OND). FOR JJA AND JAS, EC IS FAVORED ACROSS THE NORTH-CENTRAL CONUS, SUPPORTED BY CBAM (WHICH ALSO PREDICTS BELOW NORMAL TEMPERATURES ACROSS PART OF THIS REGION), NMME (PAC) TO SOME EXTENT, ENSO-OCN, AND CCA. FOR THE REMAINING SEASONS, ASO 2019 THROUGH FMA 2020, THE OUTLOOKS ARE BASED PRIMARILY ON HISTORICAL TEMPERATURE TRENDS AS EXPRESSED IN THE ENSO-OCN TOOL. PRECIPITATION THE FMA 2019 SEASONAL PRECIPITATION OUTLOOK FAVORS ABOVE NORMAL (UPPER TERCILE) PRECIPITATION FROM SOUTH-CENTRAL ALASKA TO THE SOUTHERN ALASKA PANHANDLE, AND CENTRAL AND SOUTHERN PORTIONS OF BOTH THE ROCKIES AND HIGH PLAINS. ABOVE NORMAL PRECIPITATION IS ALSO FAVORED ACROSS THE SOUTHEAST AND EAST GULF REGIONS. THESE AREAS ARE SUPPORTED BY THE NMME (PAC), CBAM, AND TO SOME EXTENT THE IMME AND CFS. THE GFDL FLOR AND NCAR MODELS ALSO LEND SOME SUPPORT FOR THESE PREDICTED REGIONS OF FAVORED ABOVE NORMAL PRECIPITATION. BELOW NORMAL (LOWER TERCILE) PRECIPITATION IS FAVORED OVER OREGON, NORTHERN CALIFORNIA, AND PARTS OF NEIGHBORING STATES, AND THE MID-UPPER MISSISSIPPI VALLEY, SOUTHERN GREAT LAKES REGION, AND OHIO AND TENNESSEE VALLEYS. THE UN-CALIBRATED NMME AND SOME OF ITS INPUTS PREDICT THESE TWO DRY SIGNALS. THE IMME, CBAM, AND CFS ALSO CONTRIBUTE TOWARD THESE PREDICTED PRECIPITATION ANOMALIES. THE FMA 2019 PRECIPITATION OUTLOOK ACKNOWLEDGES THE DECREASING CHANCES OF SIGNIFICANT ENSO-RELATED ANOMALIES, AND THESE DEPARTURES HAVE BEEN SUBSTANTIALLY SCALED BACK IN SPATIAL COVERAGE. STILL, THERE REMAINS AN OUTSIDE CHANCE THAT THE OCEAN-ATMOSPHERE SYSTEM COULD COUPLE LATE THIS WINTER, SO EL NINO EFFECTS CAN NOT BE RULED OUT ENTIRELY AT THIS TIME FOR THE U.S. IN MAM, THE PRECIPITATION OUTLOOK RETAINS THE WET SIGNAL OVER SOUTHERN PORTIONS OF ALASKA, THOUGH THE COVERAGE DIMINISHES. FROM MAM THROUGH MJJ 2019, VARIOUS STATISTICAL AND DYNAMICAL MODELS, AND HISTORICAL PRECIPITATION TRENDS, TEND TO SLOWLY DECREASE THE COVERAGE OF FAVORED ABOVE NORMAL PRECIPITATION OVER THE SOUTHEAST, WHILE INCREASING IT OVER THE WEST-CENTRAL CONUS, AND THEN INTO THE MIDDLE AND UPPER MISSISSIPPI VALLEY AND OHIO VALLEY. BY JJA AND JAS, LONG-TERM TRENDS (AND THE CBAM TOOL TO SOME DEGREE) FAVOR DRYNESS IN THE NORTHERN ROCKIES AND NORTHERN INTERMOUNTAIN REGION, AND WETNESS IN MUCH OF ALASKA AND FROM THE MIDDLE MISSISSIPPI VALLEY EASTWARD TOWARDS THE MID-ATLANTIC AND NORTHEAST. FOR THE REMAINING SEASONS ASO 2019 THROUGH FMA 2020, THE SEASONAL PRECIPITATION OUTLOOKS ARE ALMOST EXCLUSIVELY BASED ON LONG-TERM PRECIPITATION TRENDS. 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/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 21 2019 1981-2010 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 19, 2011 FORECAST RELEASE. $$