PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD 830 AM EDT THU APR 20 2017 SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS THE MAY-JUNE-JULY (MJJ) 2017 TEMPERATURE OUTLOOK FAVORS ABOVE-NORMAL TEMPERATURES FOR MUCH OF THE FORECAST DOMAIN. FOR THE CONTIGUOUS U.S., ABOVE-NORMAL SEASONAL MEAN TEMPERATURES ARE MOST LIKELY FOR THE PACIFIC COASTAL STATES AND ACROSS THE SOUTHWEST REGION AND THE CENTRAL AND SOUTHERN PLAINS INTO THE EASTERN U.S., WITH THE GREATEST ODDS INDICATED FOR PARTS OF THE SOUTHWEST, THE GULF COAST AND ATLANTIC COASTAL REGIONS. ABOVE-NORMAL TEMPERATURES ARE ALSO FAVORED FOR MUCH OF ALASKA. THE MJJ 2017 PRECIPITATION OUTLOOK INDICATES ENHANCED PROBABILITIES OF ABOVE-MEDIAN PRECIPITATION FOR AREAS OF THE ROCKY MOUNTAINS AND JUST EAST, FROM CENTRAL MONTANA SOUTHWARD INCLUDING WYOMING, COLORADO AND NEW MEXICO, AS WELL AS FOR WESTERN AREAS OF THE GULF COAST, AND FOR EASTERN INTERIOR REGIONS OF ALASKA. BELOW-MEDIAN SEASONAL PRECIPITATION AMOUNTS ARE FAVORED FOR THE WESTERN AND CENTRAL GREAT LAKES REGION. 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 ACROSS THE EQUATORIAL PACIFIC AS A WHOLE INDICATE ENSO-NEUTRAL CONDITIONS ARE CONTINUING. A RESIDUAL, SMALL AREA OF SLIGHTLY BELOW NORMAL SEA SURFACE TEMPERATURES (SSTS) REMAINS IN PROXIMITY TO THE DATE LINE, FROM LAST WINTER'S LA NINA, BUT IN AREAS TO THE WEST AND EAST ALONG THE EQUATOR, SSTS ARE NOW ABOVE AVERAGE. THE HEAT CONTENT ANOMALY OF THE UPPER-OCEAN LAYERS, TO A DEPTH OF 300 METERS, SUMMED ACROSS THE BASIN FROM THE DATE LINE TO 100W IS NOW NEAR ZERO AFTER DECREASING FROM POSITIVE HEAT CONTENT ANOMALIES DURING FEBRUARY AND MARCH. IN THE ATMOSPHERE OVER THE PAST MONTH, EASTERLY WIND ANOMALIES CONTINUED TO BE OBSERVED OVER THE CENTRAL AND WESTERN TROPICAL PACIFIC. OVER THE SAME PERIOD, MEASUREMENTS OF TROPICAL CONVECTION INDICATED CONTINUED SUPPRESSED CONVECTION IN THE CENTRAL PACIFIC AND CONTINUING ENHANCED CONVECTION OVER MUCH OF THE MARITIME CONTINENT. THIS ANOMALOUS CONVECTION PATTERN APPEARS TO BE A RESIDUAL OF THE WEAK LA NINA EVENT THAT HAS OTHERWISE ENDED. PROGNOSTIC DISCUSSION OF SST FORECASTS THE CPC NINO 3.4 SST CONSOLIDATION FORECAST, WHICH INCLUDES CANONICAL CORRELATION ANALYSIS (CCA), CONSTRUCTED ANALOG (CA), AND MARKOV STATISTICAL FORECASTS, ALONG WITH THE CFS DYNAMICAL MODEL, PREDICTS A MEDIAN TEMPERATURE ANOMALY OF +0.4C FOR THE COMING SEASONS FROM APPROXIMATELY MJJ THROUGH OND 2017, WITH EL NINO AS MOST LIKELY FROM LATE SUMMER THROUGH AUTUMN. A CONSIDERABLE DIFFERENCE BETWEEN THE CFS AND THE STATISTICAL GUIDANCE APPEARS IN THE CONSOLIDATION, HOWEVER, WITH THE CFS FORECASTING A RAPID INCREASE IN SSTS EARLY IN THE OUTLOOK PERIOD AND EL NINO CONDITIONS BEGINNING WITH THE MJJ 2017 SEASON, WHILE THE CA STATISTICAL FORECAST EXCEEDS THE +0.5C THRESHOLD FOR EL NINO STARTING IN JAS 2017, AND THE CCA AND MARKOV MODELS REMAIN IN ENSO NEUTRAL THROUGHOUT THE FORECAST PERIOD. THIS SEPARATION BETWEEN THE STATISTICAL AND DYNAMICAL MODELS IS ALSO DEPICTED BY THE LATEST IRI NINO3.4 SST FORECAST PLUME. MOREOVER, FORECASTS FROM THE DYNAMICAL SUITE OF MODELS FROM THE NMME ALSO INDICATE A MORE RAPID INCREASE IN NINO 3.4 SST DURING THE SPRING AND SUMMER MONTHS. THE LATEST OFFICIAL ENSO OUTLOOK FROM CPC/IRI INDICATES ENSO-NEUTRAL CONDITIONS ARE LIKELY TO CONTINUE THROUGH AT LEAST THE NORTHERN HEMISPHERE SPRING WITH INCREASING ODDS FOR THE DEVELOPMENT OF EL NINO CONDITIONS AS AUTUMN APPROACHES WITH PROBABILITIES FOR EL NINO OF ABOUT 50% FROM ASO 2017 CONTINUING THROUGH NDJ 2017. THE CONSENSUS FORECAST INDICATES THE LIKELIHOOD OF A REPEAT LA NINA EVENT TO BE VERY SMALL DURING THIS FORECAST PERIOD. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS THE PRIMARY TOOLS USED FOR THIS SET OF SEASONAL OUTLOOKS INCLUDED BOTH STATISTICAL AND DYNAMICAL MODEL FORECAST GUIDANCE, AND IN PARTICULAR AT LONGER LEADS, DECADAL TEMPERATURE AND PRECIPITATION TRENDS. THE DYNAMICAL MODEL GUIDANCE FROM THE NORTH AMERICAN MULTI-MODEL ENSEMBLE (NMME) AND ITS INDIVIDUAL MODELS, INCLUDING THE NCEP CFS, WERE IMPORTANT CONTRIBUTORS TO THE OUTLOOKS THROUGH SON 2017. ANTECEDENT SOIL MOISTURE AND SNOWPACK ANOMALIES IN CERTAIN REGIONS ALSO IMPACTED THE OUTLOOKS, PRIMARILY AT EARLY LEADS. LIKELY ENSO-NEUTRAL CONDITIONS IN EARLY SEASONS, LEADS TO RELIANCE PRIMARILY ON THE DYNAMICAL MODEL FORECASTS, WHILE THE INCREASING CHANCE OF EL NINO IN LATE SUMMER AND AUTUMN WAS CONSIDERED IN THE TEMPERATURE AND PRECIPITATION OUTLOOKS INTO WINTER SEASONS. PROGNOSTIC DISCUSSION OF OUTLOOKS - MJJ 2017 TO MJJ 2018 TEMPERATURE THE LATEST MJJ AND JJA 2017 TEMPERATURE OUTLOOKS INDICATE ABOVE-NORMAL TEMPERATURES ARE MOST LIKELY FOR MUCH OF THE FORECAST DOMAIN, WITH THE EXCEPTION OF PARTS OF THE NORTHERN ROCKIES AND NORTHERN PLAINS. THE CHANCES OF ABOVE-NORMAL SEASONAL MEAN TEMPERATURES ARE SLIGHTLY ENHANCED FOR MUCH OF THE PACIFIC NORTHWEST, BUT THE PROBABILITY OF ABOVE-NORMAL TEMPERATURES IS MODERATED BY RECENT POSITIVE SNOW AND SOIL MOISTURE ANOMALIES. ABOVE-NORMAL TEMPERATURES ARE PARTICULARLY ENHANCED FOR A REGION STRETCHING FROM THE SOUTHWEST, EASTWARD ACROSS THE CENTRAL AND SOUTHERN PLAINS INTO THE EASTERN U.S. THE GREATEST PROBABILITIES EXCEED 50% FOR PARTS OF THE SOUTHWEST AND ALONG THE GULF AND ATLANTIC COASTS, FOLLOWING THE CALIBRATED PROBABILISTIC GUIDANCE FROM THE NMME. NEGATIVE SOIL MOISTURE ANOMALIES IN THE SOUTHEAST REGION ALSO CONTRIBUTE TO THE LIKELIHOOD OF ANOMALOUS WARMTH. DECADAL CLIMATE TRENDS ALSO SUPPORT THE OUTLOOK AND ARE A COMPONENT OF THE DYNAMICAL MODEL GUIDANCE. THESE FORECAST TOOLS ALSO SUPPORT ENHANCED PROBABILITIES OF ABOVE-NORMAL TEMPERATURES FOR ALASKA. SHORT TERM CLIMATE MODEL FORECASTS FOR THE BEGINNING OF MAY AND WEAKER SIGNALS IN THE SEASONAL MODEL GUIDANCE FOR PARTS OF THE NORTHERN ROCKIES INTO THE NORTHERN PLAINS RESULTS IN AN AREA OF EQUAL CHANCES (EC) OVER THESE REGIONS. LITTLE CHANGE WAS MADE TO PREVIOUS OUTLOOKS FOR REMAINING SEASONS THROUGH 2017 INTO THE FIRST HALF OF 2018. ENHANCED PROBABILITIES OF ABOVE-NORMAL TEMPERATURES ARE INDICATED THROUGHOUT THE FORECAST DOMAIN THROUGH DJF 2017-2018. FROM THE JFM THROUGH MJJ 2018 SEASONS, REGIONS OF ENHANCED PROBABILITIES OF ABOVE-NORMAL TEMPERATURES FOLLOW STATISTICAL GUIDANCE, PRIMARILY RESULTING FROM DECADAL CLIMATE TRENDS. HIGH PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ARE INDICATED FOR THE NORTH SLOPE OF ALASKA DURING SON AND OND 2017 DUE TO DECADAL TRENDS IN THE SEASONAL CYCLE OF SEA ICE. PRECIPITATION FOR PRECIPITATION, THE MJJ AND JJA 2017 OUTLOOKS INDICATE ABOVE-MEDIAN PRECIPITATION FOR AREAS OF THE ROCKY MOUNTAINS AND JUST TO THE EAST, FROM CENTRAL MONTANA SOUTHWARD INCLUDING PARTS OF WYOMING, UTAH, COLORADO AND NEW MEXICO, AS WELL AS FOR WESTERN AREAS OF THE GULF COAST, AND FOR EASTERN INTERIOR REGIONS OF ALASKA. BELOW-MEDIAN SEASONAL PRECIPITATION AMOUNTS ARE FAVORED FOR THE WESTERN AND CENTRAL GREAT LAKES REGION. THE OUTLOOKS FOR THE MJJ THROUGH SON 2017 SEASONS ARE PRIMARILY BASED ON WEAK SIGNALS THAT APPEAR IN CALIBRATED PROBABILISTIC GUIDANCE FROM THE NMME. ELEVATED CHANCES FOR ABOVE-MEDIAN PRECIPITATION CONTINUE FOR AREAS IN THE CENTRAL AND NORTHERN ROCKIES AND NORTHERN HIGH PLAINS FOR JJA AND JAS 2017, AND FOR THE CENTRAL ROCKIES FOR ASO AND SON 2017. FROM ASO THROUGH OND 2017, INCREASING CHANCES FOR EL NINO CONDITIONS AND DYNAMICAL MODEL FORECASTS OF GREATER THAN AVERAGE SSTS IN THE EASTERN TROPICAL PACIFIC LEAD TO A SOUTHWARD SHIFT OF THIS REGION OF LIKELY ABOVE-MEDIAN PRECIPITATION INTO THE SOUTHWEST CONUS INCLUDING SOUTHERN CALIFORNIA AND ARIZONA IN OND 2017. FOR LATE AUTUMN AND WINTER, FROM NDJ 2017-2018 THROUGH JFM 2018, THE LOW PROBABILITY OF A LA NINA AND ELEVATED CHANCES FOR A POSSIBLE EL NINO RESULT IN REMOVAL OF A SIGNAL FOR DRIER THAN NORMAL CONDITIONS FROM THE DECADAL CLIMATE TRENDS FOR THE SOUTHWEST. FOLLOWING FMA 2018, WEAK SIGNALS DUE TO DECADAL TRENDS IN PRECIPITATION ARE INDICATED, INCLUDING BELOW-MEDIAN PRECIPITATION FOR PARTS OF THE SOUTHWEST BEGINNING WITH THE FMA 2018 SEASON AND ABOVE-MEDIAN PRECIPITATION IN THE NORTHERN-CENTRAL CONTIGUOUS U.S. BEGINNING WITH MAM 2018. FORECASTER: DAN COLLINS 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 MAY 18 2017 1981-2010 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 19, 2011 FORECAST RELEASE. $$