PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD 830 AM EDT THU APR 21 2016 SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS BOTH OCEAN AND ATMOSPHERIC CONDITIONS ACROSS THE EQUATORIAL PACIFIC OCEAN INDICATE A CONTINUED WEAKENING EL NINO STATE OVER THE PAST MONTH, WITH A TRANSITION TO ENSO-NEUTRAL FAVORED DURING THE LATE SPRING OR EARLY SUMMER 2016. THE LIKELIHOOD OF LA NINA DEVELOPING THEREAFTER INCREASES QUITE RAPIDLY WITH THE CHANCES EXCEEDING 50 PERCENT BY LATE SUMMER 2016, EARLIER THAN THE PREVIOUS OFFICIAL ASSESSMENT. THE MAY-JUNE-JULY (MJJ) 2016 TEMPERATURE OUTLOOK INDICATES INCREASED PROBABILITIES OF ABOVE-NORMAL TEMPERATURES ACROSS MUCH OF THE CONTINENTAL U.S. AND ALL OF ALASKA, WITH THE ONLY EXCEPTION BEING AN AREA ACROSS THE CENTRAL AND SOUTHERN PLAINS. THE CHANCES OF ABOVE-NORMAL TEMPERATURES ARE HIGHEST FOR SOUTHERN ALASKA, THE FAR WEST AND THE NORTHEAST WHERE ODDS EXCEED 50 PERCENT. THE MJJ 2016 PRECIPITATION OUTLOOK FAVORS ABOVE-MEDIAN PRECIPITATION FOR PARTS OF WESTERN AND NORTHERN ALASKA AND A REGION IN THE CONTIGUOUS U.S. THAT STRETCHES FROM NORTHERN CALIFORNIA ACROSS THE INTERIOR WEST SOUTHWARD AND THEN EASTWARD TO INCLUDE THE SOUTHERN PLAINS, GULF COAST AND PARTS OF THE SOUTHEAST. THE GREATEST ODDS FOR ABOVE-MEDIAN SEASONAL PRECIPITATION AMOUNTS ARE FOR NORTHERN ALASKA AND PARTS OF THE CENTRAL ROCKIES, ALTHOUGH ELEVATED CHANCES ARE VERY MODEST. BELOW-MEDIAN PRECIPITATION IS FAVORED FOR PARTS OF THE UPPER GREAT LAKES REGION. EQUAL CHANCES (EC) ARE FORECAST IN AREAS WHERE THE LIKELIHOOD OF 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 EQUATORIAL PACIFIC SSTS REMAIN ABOVE CLIMATOLOGICAL MEANS WITH THE LAST FOUR WEEK AVERAGE DEPICTING DEPARTURES FROM NORMAL OF +1.0C OVER THE ENTIRE EQUATORIAL PACIFIC BASIN WITH A FEW AREAS NEAR +1.5C. THE NINO3.4 REGION THREE-MONTH MEAN SST ANOMALY PEAKED AT +2.3C DURING NDJ 2015-2016, BUT HAS DECREASED TO +2.0C FOR THE MOST RECENT THREE MONTH SEASON OF JFM 2016. THE LATEST WEEKLY NINO3.4 REGION ANOMALY IS NOW +1.3C. IMPORTANT AND RAPID CHANGES CONTINUE TO BE INDICATED IN SUBSURFACE OCEAN TEMPERATURES. ALTHOUGH OCEAN SURFACE TEMPERATURES REMAIN ABOVE AVERAGE ACROSS THE EQUATORIAL PACIFIC AS NOTED ABOVE, THIS LAYER IS SHALLOW AND ONLY EXTENDS DOWNWARD A FEW TENS OF METERS IN DEPTH, ESPECIALLY ACROSS THE EASTERN PORTION OF THE BASIN. BELOW AVERAGE OCEAN TEMPERATURES (MAGNITUDE OF GREATER THAN 2 DEGREES C) ENCOMPASS A LARGE VOLUME OF WATER FROM 130E TO 90W WITH A THICKNESS RANGING FROM 150 METERS IN THE WESTERN PACIFIC TO 50 METERS IN THE EAST-CENTRAL PACIFIC. ANOMALOUS INTEGRATED (0-300 METERS DEPTH) EQUATORIAL PACIFIC OCEAN HEAT CONTENT BECAME NEGATIVE IN MARCH AND CONTINUES TO DECREASE THROUGH APRIL. THIS EXPANSE OF NEGATIVE HEAT CONTENT ANOMALIES AT DEPTH MAY BE AN INDICATOR OF A POTENTIAL RAPID TRANSITION TO LA NINA CONDITIONS DURING 2016. WITH RESPECT TO THE TROPICAL PACIFIC ATMOSPHERE, ENHANCED CONVECTION CONTINUED ACROSS THE CENTRAL PACIFIC BUT WEAKENED EAST OF THE DATE LINE, AND LOW-LEVEL WIND ANOMALIES WERE CLOSE TO AVERAGE OVER THE PAST MONTH. ALTHOUGH THE UPPER-LEVEL ANOMALOUS CIRCULATION REMAINS CONSISTENT WITH EL NINO IT ALSO HAS WEAKENED AS COMPARED TO FEBRUARY AND MARCH 2016. THE EXTRA-TROPICAL PACIFIC OCEAN REMAINS CONSISTENT WITH THE POSITIVE PHASE OF THE PACIFIC DECADAL OSCILLATION WITH ABOVE AVERAGE SSTS SOUTH OF ALASKA AND ALONG THE WEST COAST. POSITIVE SST ANOMALIES IN THE WESTERN ATLANTIC NEAR THE EAST COAST CONTINUE TO PERSIST AS WELL ESPECIALLY OFF THE NEW ENGLAND COAST. PROGNOSTIC DISCUSSION OF SST FORECASTS AS THE CURRENT EL NINO EVENT WEAKENS, SOME CHALLENGES MOVING FORWARD INCLUDE HOW QUICKLY ANY RELATED EL NINO IMPACTS DISSIPATE AS WE MOVE TOWARD ENSO-NEUTRAL CONDITIONS AND WHEN A POTENTIAL TRANSITION TO A LA NINA EVENT MAY OCCUR. THE CPC SST CONSOLIDATION CONTINUES TO FORECAST A RETURN TO ENSO-NEUTRAL CONDITIONS BY MJJ AND WEAK LA NINA CONDITIONS BY OND, ALTHOUGH THIS IS INFLUENCED STRONGLY BY ONE STATISTICAL FORECAST WHICH MAINTAINS ENSO-NEUTRAL CONDITIONS THROUGHOUT THIS PERIOD INTO THE WINTER MONTHS. IT SHOULD BE NOTED THAT THE CFS AND CA PREDICTIONS INDICATE A TRANSITION TO LA NINA BY ASO 2016. PREDICTIONS FROM THE NORTH AMERICAN MULTI-MODEL ENSEMBLE (NMME) MEMBERS ARE IN BETTER AGREEMENT THIS MONTH AS COMPARED TO LAST MONTH AND EXHIBIT GENERALLY TIGHT CLUSTERING WITH THE ENSEMBLE MEAN ENTERING LA NINA TERRITORY (NINO3.4 ANOMALY AT OR LESS THAN -0.5) BY JULY 2016 AND ALL INDIVIDUAL MODELS BY AUGUST. THE CPC/IRI CONSENSUS FORECAST INDICATES THAT THE TRANSITION TO ENSO-NEUTRAL IS MOST LIKELY BY EARLY SUMMER, AND THE PROBABILITY OF LA NINA DEVELOPING FIRST EXCEEDS 50% IN JAS 2016, TWO OVERLAPPING SEASONS EARLIER THAN FORECAST IN THE OFFICIAL OUTLOOK LAST MONTH. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS ALTHOUGH EL NINO CONDITIONS CONTINUE TO WEAKEN, IMPACTS ASSOCIATED WITH EL NINO WERE CONSIDERED EARLY IN THE OUTLOOK PERIOD WITH DECREASED INFLUENCE AS COMPARED TO EARLIER IN THE SPRING. SOIL MOISTURE CONDITIONS WERE ALSO CONSIDERED IN EARLY OUTLOOKS WHERE SOME REGIONS CURRENTLY HAVE SUBSTANTIAL DEPARTURES FROM NORMAL. PROSPECTS FOR A TRANSITION TO LA NINA CONDITIONS WERE CONSIDERED PRIMARILY BEGINNING IN ASO 2016 AND THROUGHOUT THE AUTUMN AND WINTER MONTHS AT THE CURRENT TIME. IN ADDITION TO THE ABOVE FACTORS, DYNAMICAL MODEL GUIDANCE FROM THE NMME, AND THE INTERNATIONAL MULTI-MODEL ENSEMBLE (IMME) AND THEIR INDIVIDUAL MODEL COMPONENTS CONTRIBUTE TO THE SEASONAL OUTLOOKS THROUGH SON 2016. THE OUTLOOKS ALSO UTILIZED QUITE HEAVILY THE SST BASED CONSTRUCTED ANALOGUE TEMPERATURE/PRECIPITATION FORECAST TOOL FOR MUCH OF THE OUTLOOK PERIOD. PROGNOSTIC DISCUSSION OF OUTLOOKS - MJJ 2016 TO MJJ 2017 TEMPERATURE THE SUITE OF TEMPERATURE OUTLOOKS THIS MONTH ARE SIMILAR TO THOSE RELEASED LAST MONTH AS THE GENERAL THINKING OVER THE OUTLOOK PERIOD REMAINS GENERALLY UNCHANGED, ALTHOUGH POTENTIAL LA NINA IMPACTS WERE CONSIDERED EARLIER THAN IN PREVIOUS SETS OF OUTLOOKS. OVERALL FOR TEMPERATURE, CHANGES WERE PRIMARILY MINOR ADJUSTMENTS FOR THE FIRST SEVERAL LEADS WHERE PROBABILITIES ARE MODIFIED SOMEWHAT IN SOME AREAS BASED ON THE LATEST CALIBRATED DYNAMICAL MODEL GUIDANCE AND CURRENT SOIL MOISTURE CONDITIONS. FOR MJJ 2016, CALIBRATED MODEL GUIDANCE AND IN SOME AREAS POSITIVE DEPARTURES IN SOIL MOISTURE SUPPORT A SLIGHTLY ADJUSTED REGION OF EQUAL CHANCES (EC) AND A SLIGHT DECREASE IN PROBABILITIES FOR ABOVE NORMAL TEMPERATURES FOR SOME LOCATIONS IN THE NORTHERN PLAINS, UPPER MISSISSIPPI VALLEY AND GREAT LAKES. PROBABILITIES FOR ABOVE NORMAL TEMPERATURES WERE INCREASED FOR PARTS OF THE FAR WEST AND SOUTHWEST CONUS BASED ON DYNAMICAL MODEL GUIDANCE, LONG TERM TRENDS AND BELOW AVERAGE WINTER AND EARLY SPRING PRECIPITATION. FOR JJA AND JAS 2016, SIMILAR ADJUSTMENTS WERE MADE, AND PROBABILITIES WERE SLIGHTLY INCREASED ACROSS THE INTERIOR OF THE CONUS DURING ASO 2016 DUE TO POTENTIAL LA NINA CONSIDERATIONS. IN ADDITION TO CALIBRATED DYNAMICAL MODEL GUIDANCE, STATISTICAL GUIDANCE FROM THE SST BASED CONSTRUCTED ANALOGUE TOOL FURTHER SUPPORTS FAVORED ABOVE NORMAL TEMPERATURES FOR MOST OF THE FORECAST DOMAIN FROM JJA 2016 THROUGH SON 2016. INCREASED CHANCES FOR ABOVE-NORMAL TEMPERATURES FORECAST ACROSS PARTS OF THE SOUTHERN CONTIGUOUS U.S. AND A SLIGHT INCREASE IN THE PROBABILITY FOR BELOW-NORMAL TEMPERATURES ACROSS THE NORTHERN U.S. FROM NDJ 2016-17 THROUGH AMJ 2017 ARE BASED LARGELY ON THE IMPACTS FROM POTENTIAL LA NINA CONDITIONS. AN INCREASED PROBABILITY OF ABOVE-NORMAL TEMPERATURES FOR THE NORTH SLOPE OF ALASKA DURING THE AUTUMN AND AGAIN IN THE SPRING IS DUE TO THE LIKELIHOOD OF ANOMALOUSLY OPEN SEA ICE AND THE FEEDBACK BETWEEN SEA ICE COVERAGE AND CHANGES IN THE CLIMATE STATE. PRECIPITATION THE MJJ 2016 PRECIPITATION OUTLOOK FAVORS ABOVE-MEDIAN PRECIPITATION FOR A REGION STRETCHING FROM NORTHERN CALIFORNIA EASTWARD TO INCLUDE MUCH OF THE INTERIOR WEST, PARTS OF THE SOUTHWEST, SOUTHERN PLAINS AND SOUTHEAST. RESIDUAL EL NINO IMPACTS SUPPORT THE HIGHLIGHTED AREA ACROSS MUCH OF THE WEST AND SOUTHERN PLAINS WHILE DYNAMICAL AND STATISTICAL MODEL GUIDANCE FAVOR AREAS IN THE SOUTHEAST. IT IS IMPORTANT TO NOTE THAT THESE PROBABILITIES ARE QUITE MODEST AND REPRESENT ONLY A SLIGHT TILT TO THE ABOVE-MEDIAN CATEGORY, ESPECIALLY ACROSS THE SOUTHEAST CONUS. BELOW-MEDIAN PRECIPITATION IS MOST LIKELY FOR NORTHERN REGIONS OF THE PACIFIC NORTHWEST AND THE WESTERN GREAT LAKES CONSISTENT WITH ANY REMAINING EL NINO INFLUENCE AND DYNAMICAL MODEL GUIDANCE. AN INCREASED CHANCE OF ABOVE-MEDIAN PRECIPITATION IS ALSO FORECAST FOR WESTERN AND NORTHERN ALASKA THROUGH JJA 2016 BY DYNAMICAL MODELS, RESULTING FROM ANOMALOUSLY OPEN SEA ICE AND WARM OPEN OCEAN TEMPERATURES. POTENTIAL LA NINA INFLUENCE AND STATISTICAL FORECAST GUIDANCE SUPPORT A SLIGHT TILT IN THE ODDS TO ABOVE-MEDIAN SEASONAL TOTAL PRECIPITATION AMOUNTS FOR COASTAL AREAS OF THE SOUTHEAST DURING JAS AND ASO 2016. POTENTIAL LA NINA CONDITIONS ALSO SUPPORT FAVORED BELOW MEDIAN PRECIPITATION ACROSS PORTIONS OF CENTRAL PLAINS WESTWARD TO THE CENTRAL ROCKIES DURING ASO 2016. DURING AUTUMN OF 2016 AND WINTER OF 2016-17, THE POTENTIAL FOR ONGOING LA NINA CONDITIONS IS THE PRIMARY FACTOR FOR INCREASED PROBABILITIES OF BELOW-MEDIAN PRECIPITATION ACROSS THE SOUTHERN TIER OF THE CONTIGUOUS U.S. AND THE SOUTHERN COAST OF ALASKA, AND INCREASED PROBABILITIES OF ABOVE-MEDIAN PRECIPITATION FOR THE PACIFIC NORTHWEST AND OHIO VALLEY AND CENTRAL GREAT LAKES. FORECASTER: JON GOTTSCHALCK 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 MAY 19 2016 1981-2010 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 19, 2011 FORECAST RELEASE. $$