PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD 830 AM EDT THU JUN 15 2017 SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS THE JULY-AUGUST-SEPTEMBER (JAS) 2017 TEMPERATURE OUTLOOK FAVORS ABOVE-NORMAL TEMPERATURES ACROSS ALASKA AND MUCH OF THE CONTINENTAL U.S., ALTHOUGH PROBABILITIES ARE REDUCED ACROSS THE CENTRAL U.S. THE HIGHEST PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ARE FORECAST ACROSS THE NORTHEAST, PARTS OF THE GULF COAST AND FLORIDA, THE SOUTHWEST, AND SOUTHWEST ALASKA AND THE ALEUTIANS. THE JAS 2017 PRECIPITATION OUTLOOK INDICATES A SLIGHT TILT IN THE ODDS FOR ABOVE-MEDIAN PRECIPITATION FOR THE NORTHERN GREAT PLAINS, WESTERN GULF COAST, SOUTHWEST ALASKA, AND THE ALEUTIANS. DURING THE FALL AND WINTER 2017-18, CHANCES OF EL NINO DEVELOPMENT HAVE DECREASED COMPARED TO THE PREVIOUS MONTH. SINCE ENSO-NEUTRAL CONDITIONS ARE MOST LIKELY TO PERSIST, THE TEMPERATURE AND PRECIPITATION OUTLOOKS DURING THE COLD SEASON ARE BASED PRIMARILY ON DYNAMICAL MODEL GUIDANCE AND DECADAL TRENDS. 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 INDICATE ENSO-NEUTRAL CONDITIONS PERSIST, ALTHOUGH SEA SURFACE TEMPERATURES (SSTS) ARE ABOVE AVERAGE IN THE EAST-CENTRAL PACIFIC OCEAN. THE OBSERVED WEEKLY SSTS ACROSS THIS REGION, CENTERED ON JUNE 7, FEATURE SMALL POSITIVE SST ANOMALIES OF 0.5 TO 1 DEGREE C FROM THE DATE LINE TO 130 DEGREES W. THE UPPER-OCEAN HEAT CONTENT ANOMALY FROM THE DATE LINE TO 100 DEGREES W REMAINS ABOVE AVERAGE BUT THE MAGNITUDE OF THIS ANOMALY DECREASED SINCE EARLY MAY. DESPITE WARMER-THAN-AVERAGE OCEAN TEMPERATURES ACROSS THE CENTRAL AND EASTERN PACIFIC SINCE MARCH, ATMOSPHERIC CONVECTIVE ANOMALIES CONTINUE TO REMAIN NEAR AVERAGE OVER THE EASTERN TROPICAL PACIFIC AND SLIGHTLY SUPPRESSED TO THE WEST OF THE DATE LINE FROM MAY 13 TO JUNE 7. ENHANCED CONVECTION WAS OBSERVED ACROSS INDONESIA DURING THIS TIME PERIOD. THE WIND ANOMALIES AT THE LOWER AND UPPER-LEVELS WERE NEAR AVERAGE DURING THE PAST MONTH. THESE ATMOSPHERIC INDICATORS ARE CONSISTENT WITH ENSO NEUTRAL CONDITIONS. PROGNOSTIC DISCUSSION OF SST FORECASTS THE LATEST NCEP CFSV2 AND MOST OF THE MODELS OF THE NORTH AMERICAN MULTI-MODEL ENSEMBLE (NMME) ARE FAVORING A CONTINUATION OF ENSO-NEUTRAL CONDITIONS THROUGH THE FALL. THE CPC NINO 3.4 SST INDEX CONSOLIDATION FORECAST INDICATES A POSITIVE ANOMALY AT OR SLIGHTLY BELOW 0.5 DEGREES C THROUGH NDJ. DUE TO THESE LATEST MODEL PREDICTIONS ALONG WITH NEAR-AVERAGE ATMOSPHERIC CONDITIONS OVER THE PACIFIC, THE CPC/IRI CONSENSUS FORECAST INDICATES SLIGHTLY MORE CONFIDENCE (50 TO 55 PERCENT CHANCE) IN THE PERSISTENCE OF ENSO-NEUTRAL CONDITIONS THROUGH JFM 2018. THE CHANCES FOR EL NINO (AROUND 35 PERCENT) DURING THE UPCOMING FALL AND WINTER ARE SIMILAR TO THE CLIMATOLOGICAL PROBABILITY. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS THE PRIMARY TOOLS USED FOR THE SEASONAL OUTLOOKS INCLUDED STATISTICAL AND DYNAMICAL MODEL FORECAST GUIDANCE, AND IN PARTICULAR AT LONGER LEADS, DECADAL TEMPERATURE AND PRECIPITATION TRENDS. THE CALIBRATED DYNAMICAL MODEL GUIDANCE FROM THE NORTH AMERICAN MULTI-MODEL ENSEMBLE (NMME) AND, TO LESSER EXTENT, ITS INDIVIDUAL MODELS, INCLUDING THE NCEP CFS, WERE IMPORTANT CONTRIBUTORS TO THE OUTLOOKS THROUGH NDJ 2017. ANTECEDENT SOIL MOISTURE WAS CONSIDERED, ALTHOUGH IT WILL PLAY A DIMINISHING ROLE LATER IN THE UPCOMING SEASON OF JAS. THE DECREASING LIKELIHOOD OF EL NINO DEVELOPMENT, COMPARED TO PREVIOUS OUTLOOKS, WAS A FACTOR IN LATER LEADS. PROGNOSTIC DISCUSSION OF OUTLOOKS - JAS 2017 TO JAS 2018 TEMPERATURE ABOVE-NORMAL TEMPERATURES ARE FAVORED ACROSS NEARLY ALL OF THE FORECAST DOMAIN FOR THE JAS OUTLOOK, AS THE TEMPERATURE TOOLS ARE IN GOOD AGREEMENT AND THE MOST RECENT NMME INCREASED COVERAGE OF ENHANCED ODDS FOR ABOVE-NORMAL TEMPERATURES. THE LOWEST PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ARE FORECAST ACROSS PARTS OF THE CENTRAL U.S. IN PART DUE TO INITIALLY HIGH SOIL MOISTURE ACROSS THE CENTRAL/SOUTHERN GREAT PLAINS AND UPPER MIDWEST, BUT THIS REDUCED AREA OF PROBABILITIES IS ALSO CONSISTENT WITH A CONSENSUS FROM THE VARIOUS TOOLS. EQUAL CHANCES OF BELOW-, NEAR-, OR ABOVE-NORMAL TEMPERATURES ARE LIMITED TO PARTS OF MONTANA BASED ON DYNAMICAL MODEL GUIDANCE AND THE CFS MODEL INDICATING A SMALL AREA OF BELOW-NORMAL TEMPERATURES. PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES DURING JAS ARE HIGHEST OVER THE NORTHEAST, PARTS OF THE GULF COAST AND FLORIDA, AND THE SOUTHWEST DUE TO DECADAL TRENDS AND CALIBRATED PROBABILITIES FROM THE NMME. THIS TOOL INDICATES INCREASED CHANCES FOR ABOVE-NORMAL TEMPERATURES ACROSS MUCH OF ALASKA WITH THE HIGHEST CHANCES (50 AND ABOVE) OVER SOUTHWEST ALASKA AND THE ALEUTIANS. THE TEMPERATURE OUTLOOKS FROM ASO 2017 TO NDJ 2017-18 ARE BASED PRIMARILY ON THE NMME CALIBRATED PROBABILITIES SINCE THE MOST LIKELY OUTCOME IS FOR ENSO-NEUTRAL CONDITIONS DURING THESE SEASONAL PERIODS. AN EXPECTED LACK OF SEA ICE ELEVATES CHANCES FOR ABOVE-NORMAL TEMPERATURES ACROSS NORTHERN ALASKA DURING THE FALL SEASON. DECADAL TRENDS ARE USED IN CREATING THE TEMPERATURE OUTLOOKS AT THE LONGER LEAD TIMES DURING THE SPRING AND SUMMER OF 2018. PRECIPITATION ENHANCED ODDS FOR ABOVE-MEDIAN PRECIPITATION DURING JAS ARE MAINTAINED FROM ONE MONTH AGO ACROSS THE NORTH-CENTRAL U.S. AND PARTS OF ALASKA, BASED ON THE MOST RECENT DYNAMICAL MODEL GUIDANCE. PRECIPITATION TOOLS FEATURE A WET SIGNAL ACROSS THE WESTERN GULF COAST REGION AND INCREASED CHANCES FOR ABOVE-MEDIAN PRECIPITATION DURING JAS IS INTRODUCED TO THIS REGION. THE SIGNAL IS GENERALLY WEAK AMONG PRECIPITATION TOOLS WITH MONSOON RAINFALL ACROSS THE SOUTHWEST DURING JAS 2017. THEREFORE, EQUAL CHANCES OF BELOW-, NEAR-, OR ABOVE-MEDIAN PRECIPITATION ARE FORECAST FOR THE SOUTHWEST DURING JAS. SINCE THE PREVIOUS OUTLOOK, THE CHANCES FOR EL NINO DEVELOPMENT DURING THE NEXT SIX MONTHS HAVE DECREASED. GIVEN THE LATEST CPC/IRI CONSENSUS FORECAST FAVORING A CONTINUATION OF ENSO-NEUTRAL CONDITIONS THROUGH THE WINTER 2017-18, IT WAS NECESSARY TO REMOVE THE INCREASED CHANCES FOR ABOVE-MEDIAN PRECIPITATION OVER THE GULF COAST REGION AND SOUTHEAST DURING THE UPCOMING FALL AND WINTER. PRECIPITATION OUTLOOKS (THROUGH NDJ 2017-18) ARE BASED PRIMARILY ON GUIDANCE FROM THE CALIBRATED PROBABILITIES FROM THE NMME WHICH DEPICTS INCREASED CHANCES FOR ABOVE-MEDIAN PRECIPITATION FROM THE FOUR CORNERS REGION EXTENDING INTO THE NORTH-CENTRAL U.S. PRECIPITATION OUTLOOKS AT LATER LEADS ARE BASED ON THE CONSOLIDATION AND DECADAL TRENDS. FORECASTER: BRAD PUGH 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 JUL 20 2017 1981-2010 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 19, 2011 FORECAST RELEASE. $$