PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD 830AM EDT THURSDAY JUN 19 2014 SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS THE MAIN FACTORS THAT USUALLY INFLUENCE THE SEASONAL CLIMATE OUTLOOK INCLUDE: 1) EL NINO AND LA NINA - WHICH TOGETHER COMPRISE EL NINO/SOUTHERN OSCILLATION OR ENSO. IMPACTS OF THESE EVENTS ARE SUMMARIZED BY SEPARATING 3-MONTH OBSERVATIONS FROM 3 OR MORE DECADES INTO EL NINO, NEUTRAL, AND LA NINA SETS, AVERAGING EACH SEPARATELY, AND THEN COMPUTING ANOMALIES. THESE ARE CALLED "ENSO COMPOSITES", WHICH ARE USED AT TIMES TO SUBJECTIVELY MODIFY THE FORECAST. 2) TRENDS - APPROXIMATED BY THE OCN TOOL AS THE DIFFERENCE BETWEEN THE MOST RECENT 10-YEAR MEAN OF TEMPERATURE OR 15-YEAR MEAN OF PRECIPITATION FOR A GIVEN LOCATION AND TIME OF YEAR AND THE 30-YEAR CLIMATOLOGY PERIOD (CURRENTLY 1981-2010). 3) THE TROPICAL 30-60 DAY OSCILLATION - SOMETIMES CALLED MADDEN JULIAN OSCILLATION (MJO) - AFFECTS CLIMATE VARIABILITY WITHIN SEASONS. 4) THE NORTH ATLANTIC OSCILLATION (NAO) AND THE PACIFIC NORTH AMERICAN (PNA) PATTERNS - WHICH AFFECT THE TEMPERATURE ANOMALY PATTERN ESPECIALLY DURING THE COLD SEASONS. THESE PHENOMENA ARE CONSIDERED LESS PREDICTABLE ON A SEASONAL TIMESCALE THAN ENSO. 5) THE PACIFIC DECADAL OSCILLATION (PDO) - AN ENSO-LIKE PATTERN OF CLIMATE VARIABILITY AFFECTING THE TROPICS AND THE NORTH PACIFIC AND NORTH AMERICAN REGIONS, BUT WHICH VARIES ON A MUCH LONGER TIME-SCALE THAN ENSO. 6) PERSISTENTLY DRY OR WET SOILS IN THE SPRING AND SUMMER AND SNOW AND ICE COVER ANOMALIES IN THE WINTER. THESE FACTORS TEND TO PERSIST FOR LONG PERIODS AND ACT AS A KIND OF MEMORY IN THE CLIMATE SYSTEM. 7) STATISTICAL FORECAST TOOLS - CANONICAL CORRELATION ANALYSIS (CCA), SCREENING MULTIPLE LINEAR REGRESSION (SMLR), CONSTRUCTED ANALOGUE (CA) AND ENSEMBLE CCA (ECCA). 8) DYNAMICAL FORECAST MODELS - INCLUDING THE NCEP CLIMATE FORECAST SYSTEM (CFS). AN EXPERIMENTAL MODEL FORECAST SYSTEM, THE NATIONAL MULTI-MODEL ENSEMBLE, COMPRISED OF SEVERAL MODELS AND DESIGNATED NMME, MAY ALSO BE USED EXPERIMENTALLY AND SUBJECTIVELY UNTIL IT IS INCLUDED INTO THE CONSOLIDATION. AN INTERNATIONAL MODEL ENSEMBLE DESIGNATED IMME IS ALSO AVAILABLE. 9) CONSOLIDATION (CON) - AN OBJECTIVE, SKILL-WEIGHTED COMBINATION OF THE OCN, CCA, SMLR, ECCA, AND CFS FORECASTS IS USED AS A FIRST GUESS IN PREPARING THE FORECAST MAPS. THIS TECHNIQUE MAKES OPTIMUM USE OF THE KNOWN SKILL OF FORECAST TOOLS. CURRENT ATMOSPHERIC AND OCEANIC OBSERVATIONS SUGGEST A TRANSITION FROM ENSO-NEUTRAL TO EL NINO CONDITIONS IS UNDERWAY. EL NINO CONDITIONS ARE STILL EXPECTED TO BE IN PLACE BY LATE SUMMER OR EARLY FALL, HOWEVER, AND THERE CONTINUES TO BE CONSIDERABLE DISAGREEMENT AMONG PREDICTIONS OF THE STRENGTH AND DURATION OF THE EVENT. AT THIS POINT, AN EL NINO OF MODERATE STRENGTH IS MOST LIKELY. THE TEMPERATURE OUTLOOK FOR JULY-AUGUST-SEPTEMBER (JAS) 2014 INDICATES ELEVATED ODDS OF ABOVE-NORMAL TEMPERATURES IN MOST AREAS ALONG THE WEST COAST. ABOVE-NORMAL TEMPERATURES ARE ALSO FAVORED FOR THE SOUTHERN GREAT PLAINS, THE SOUTHEAST U.S., AND PARTS OF THE MID-ATLANTIC STATES. BELOW-NORMAL TEMPERATURES ARE FAVORED FROM THE NORTHERN ROCKIES TO THE WESTERN GREAT LAKES AND UPPER MIDWEST. THE CHANCES FOR ABOVE-NORMAL TEMPERATURES ARE ENHANCED FOR ALASKA. THE JAS 2014 PRECIPITATION OUTLOOK CALLS FOR ENHANCED PROBABILITIES OF BELOW-MEDIAN PRECIPITATION ALONG THE WESTERN COAST OF THE GULF OF MEXICO. THERE IS A FAIRLY LARGE REGION OF ELEVATED CHANCES FOR ABOVE-MEDIAN PRECIPITATION AMOUNTS FOR MUCH OF THE INTERIOR WEST, FROM PARTS OF THE SOUTHERN ROCKIES NORTHWARD TO IDAHO AND SOUTHERN MONTANA. IN AREAS WHERE THE LIKELIHOODS OF SEASONAL MEAN TEMPERATURES AND SEASONAL ACCUMULATED PRECIPITATION AMOUNTS ARE SIMILAR TO CLIMATOLOGICAL PROBABILITIES, EQUAL CHANCES (EC) IS SHOWN. 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 ATMOSPHERIC AND OCEANIC CONDITIONS IN THE PACIFIC BASIN INDICATE THAT A TRANSITION TO EL NINO CONDITIONS CONTINUES. THE LATEST WEEKLY OBSERVATIONS SHOW SST ANOMALIES OF +0.5 DEGREES C ALONG THE EQUATOR THROUGHOUT THE PACIFIC BASIN, WITH ANOMALIES EXCEEDING +1.0 C IN PLACES. POSITIVE SST ANOMALIES HAVE RECENTLY INCREASED NEAR THE EQUATOR ALONG THE SOUTH AMERICAN COAST. HOWEVER, SUBSEASONAL VARIABILITY ACROSS THE TROPICS HAS SLOWED THE TRANSITION TO EL NINO IN RECENT WEEKS, WITH A RECENT SURGE IN TRADE WINDS ACROSS THE PACIFIC RESULTING IN SOMEWHAT WEAKER UPPER-OCEAN EQUATORIAL HEAT ANOMALIES. THE CURRENT SPATIAL DISTRIBUTION OF CONVECTION ACROSS THE CENTRAL PACIFIC IS STILL CONSISTENT WITH A DEVELOPING EL NINO, BUT NOT NEARLY AS AMPLIFIED AS WHAT WAS OBSERVED IN APRIL AND EARLY MAY. THE SOUTHERN OSCILLATION INDEX (SOI) HAS BEEN PERSISTENTLY POSITIVE FOR THE PAST 30 DAYS, CONSISTENT WITH A PAUSE IN THE DEVELOPMENT OF ROBUST EL NINO CONDITIONS. THE EXTRATROPICAL PACIFIC (POLEWARD OF 20N) CURRENTLY PROJECTS STRONGLY ONTO A POSITIVE PDO PATTERN, THE STRONGEST SUCH PROJECTION IN LATE SPRING IN MANY YEARS. THE STATE OF THE NORTHERN ATLANTIC OCEAN IS ALSO A BIT DIFFERENT THAN IN RECENT YEARS, WITH THE MOST RECENT INDEX VALUE OF THE AMO BEING JUST SLIGHTLY POSITIVE, THE WEAKEST IN SEVERAL YEARS. PROGNOSTIC DISCUSSION OF SST FORECASTS MOST STATISTICAL AND DYNAMICAL MODELS CONTINUE TO SUGGEST THAT EL NINO CONDITIONS WILL EMERGE IN THE NEXT COUPLE OF MONTHS. THE CFS PREDICTS NINO 3.4 SST ANOMALIES TO INCREASE TO AROUND +1.0 C BY LATE FALL. MOST STATISTICAL MODELS PREDICT SSTS ONLY SLIGHTLY ABOVE THE +0.5 DEGREE C ANOMALY THRESHOLD ASSOCIATED WITH EL NINO CONDITIONS. THE CPC SST CONSOLIDATION FORECAST PREDICTS THE SST ANOMALY FOR NINO 3.4 TO INCREASE TO +1.0 C BY LATE FALL. THE LATEST ENSEMBLE MEAN FORECASTS FROM THE IMME AND NMME ALSO PREDICT SST ANOMALIES INCREASING FROM NEAR +0.5 C IN JUNE TO NEAR +1.0 BY OCTOBER. THERE IS STILL UNCERTAINTY IN THE PREDICTION OF THE STRENGTH OF THE POSSIBLE EVENT. THE CFS AND UKMET MODELS SUGGEST A WEAKER EVENT COMPARED TO FORECASTS FROM ONE MONTH AGO, WHILE THE ECMWF FORECAST IS NOW THE STRONGEST AMONG THE DYNAMICAL MODELS, WITH ITS PEAK AMPLITUDE ONLY SLIGHTLY REDUCED FROM LAST MONTH'S FORECAST. ALTOGETHER, ODDS OF AN EL NINO EVENT OF ANY STRENGTH PEAK AT ABOUT 80% BY LATE FALL. THE COMBINATION OF STATISTICAL AND DYNAMICAL SST PREDICTION METHODS SUGGESTS A BORDERLINE MODERATE EVENT, ALTHOUGH THE POSSIBILITY OF A STRONG EVENT, OR A RETURN TO ENSO NEUTRAL CONDITIONS, THOUGH LESS LIKELY, CANNOT BE RULED OUT AT THIS POINT. IT IS WORTH NOTING, HOWEVER, THAT THE LIKELIHOOD OF A STRONG EVENT IS LOWER COMPARED TO LAST MONTH'S THINKING. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS THE TEMPERATURE AND PRECIPITATION OUTLOOKS WERE MADE CONSIDERING EL NINO CONDITIONS TO BE A FACTOR IN LATE SUMMER AND EARLY FALL. GUIDANCE FROM THE CFS AS WELL AS THE NMME AND IMME AND THEIR ASSOCIATED COMPONENTS CONTRIBUTED TO THE OUTLOOKS FROM JAS THROUGH OND 2014, ESPECIALLY WHERE THEIR ANOMALIES AGREED WITH COMPOSITES FROM DEVELOPING EL NINOS. OUTPUT FROM THE JMA AND UKMET SEASONAL FORECAST MODELS WAS ALSO TAKEN INTO ACCOUNT. THE OUTLOOKS FROM NDJ 2014 THROUGH MAM 2015 WERE PRIMARILY DETERMINED FROM EL NINO COMPOSITES, WITH PROBABILITIES REDUCED FROM THOSE ASSOCIATED WITH A MODERATE ENSO EVENT TO REFLECT THAT EL NINO CONDITIONS HAVE NOT YET FULLY DEVELOPED, AND GENERAL UNCERTAINTY IN THE ENSO FORECAST. ADDITIONALLY, THE MODEL CONSENSUS FOR THE STRENGTH OF EL NINO IS NO STRONGER THAN IT WAS A MONTH AGO, SUGGESTING A WEAK OR MODERATE EVENT LATE IN THE YEAR IS STILL THE BEST ESTIMATE OF ITS INTENSITY AT THIS TIME. THE POST-EL NINO COMPOSITES WERE BLENDED WITH THE BACKGROUND CLIMATE SIGNAL FROM RECENT TRENDS IN OUTLOOKS FROM AMJ THROUGH JAS 2015. ADDITIONALLY, ANALOG TOOLS TAKING INTO ACCOUNT THE CURRENT STATE OF SSTS WERE UTILIZED, AS WERE SOIL MOISTURE ANOMALIES WHERE APPROPRIATE DURING THE WARM SEASON. PROGNOSTIC DISCUSSION OF OUTLOOKS - JAS 2014 TO JAS 2015 TEMPERATURE THE JAS AND ASO 2014 TEMPERATURE OUTLOOKS INDICATE ELEVATED PROBABILITIES OF ABOVE-NORMAL SEASONAL MEAN TEMPERATURES FOR ALL OF ALASKA, AND ALSO MOST OF THE AREA TO THE WEST OF THE ROCKY MOUNTAINS IN THE CONUS. ABOVE-NORMAL TEMPERATURES ARE ALSO FAVORED IN PARTS OF THE SOUTHEASTERN AND SOUTH-CENTRAL CONUS. THESE SIGNALS ARE SUPPORTED BY A BROAD RANGE OF TOOLS AND DYNAMICAL CLIMATE MODELS. THE PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ARE REDUCED ALONG PARTS OF THE GULF COAST IN JAS DUE TO ELEVATED SOIL MOISTURE ANOMALIES. COMPOSITES SUGGEST NEAR- TO BELOW-NORMAL TEMPERATURES IN MUCH OF THE EASTERN AND CENTRAL CONUS DURING DEVELOPING EL NINO EVENTS, HOWEVER THE CONSENSUS AMONG DYNAMICAL MODELS IS NOT SUPPORTIVE OF THAT SOLUTION. THE COMPOSITES RESEMBLE THE IMME TEMPERATURE ANOMALY FORECAST ACROSS THE NORTHERN PLAINS AND PARTS OF THE FRONT RANGE OF THE ROCKIES, WHERE BELOW-NORMAL TEMPERATURES ARE FAVORED. THE NMME AND IMME BOTH FAVOR ABOVE-MEDIAN PRECIPITATION AMOUNTS FOR PARTS OF THE SOUTHERN AND CENTRAL ROCKY MOUNTAINS, WHICH IS EXPECTED TO HAVE A MODERATING EFFECT ON TEMPERATURES, REDUCING THE CHANCES OF ABOVE-NORMAL TEMPERATURES IN SPITE OF RECENT TRENDS FAVORING WARM CONDITIONS. OUTLOOKS FROM SON 2014 THROUGH NDJ 2014-2015 SHOW A SLOW TRANSITION TO THE EXPECTED WINTERTIME TEMPERATURE PATTERN ASSOCIATED WITH EL NINO. ABOVE-NORMAL TEMPERATURES ARE GENERALLY FAVORED IN THE NORTHERN CONUS AND ALASKA, WITH INCREASING ODDS OF BELOW-NORMAL TEMPERATURES IN THE SOUTHERN CONUS. THE TEMPERATURE OUTLOOKS FOR DJF 2014-2015 THROUGH FMA 2015 REFLECT TEMPERATURE PATTERNS ASSOCIATED WITH EL NINO. THE OUTLOOKS FROM MAM TO JAS 2015 SHOW A COMBINATION OF RECENT TRENDS AND TYPICAL EVOLUTION FOLLOWING EL NINO EVENTS. PROBABILITIES OF ABOVE-NORMAL TEMPERATURES WERE NOTICEABLY DECREASED ACROSS PARTS OF THE SOUTHWESTERN CONUS FROM AMJ TO JAS 2015, SINCE ODDS OF ABOVE-MEDIAN PRECIPITATION ARE ELEVATED IN THAT REGION FROM JAS 2014 TO FMA 2015. IN AREAS WITHOUT SUBSTANTIAL AND RELIABLE CLIMATE SIGNALS, EQUAL CHANCES OF BELOW-, NEAR- AND ABOVE-NORMAL SEASONAL MEAN TEMPERATURES ARE INDICATED. PRECIPITATION THERE ARE FAIRLY STRONG AND CONSISTENT INDICATIONS FROM MOST MODELS RUN AS PART OF THE NMME AND IMME FOR ABOVE-MEDIAN PRECIPITATION AMOUNTS THROUGHOUT MUCH OF THE SOUTHWEST, SOUTHERN AND CENTRAL ROCKY MOUNTAINS AND THE INTERMOUNTAIN WEST FOR ABOVE-MEDIAN PRECIPITATION AMOUNTS. THE MODELS HAVE CONSISTENTLY POINTED TO THIS POSSIBILITY FOR THE PAST FEW MONTHS, AND CONSIDERING THAT THE MODEL FORECAST FOR DEVELOPING EL NINO CONDITIONS APPEARS ON TRACK, THE CHANCES FOR ABOVE-MEDIAN PRECIPITATION ARE ELEVATED FOR MANY PARTS OF THE WESTERN CONUS. COMPOSITES BASED ON SUMMERTIME EL NINO CONDITIONS TEND TO CONTRADICT THE NMME AND IMME IN THAT THEY GENERALLY SUPPORT A WEAK SOUTHWEST MONSOON, AT LEAST IN THE EARLY PART OF THE SUMMER. THIS LEADS TO GREATER UNCERTAINTY IN THE PRECIPITATION FORECAST ALONG THE U.S. - MEXICO BORDER. THIS IS ESPECIALLY THE CASE IN SOUTHERN ARIZONA, WHERE EQUAL CHANCES IS DEPICTED FOR JAS DUE TO THE CONFLICT BETWEEN THE DYNAMICAL MODEL CONSENSUS AND STATISTICAL TOOLS THAT EMPHASIZE ENSO DEVELOPMENT. ABOVE-NORMAL SSTS IN THE PACIFIC OFF THE CALIFORNIA AND MEXICO COASTS DURING EL NINO AUTUMNS PROVIDE AN ADDITIONAL MOISTURE SOURCE FOR PARTS OF THE DESERT SOUTHWEST AND SOUTHERN CALIFORNIA, ELEVATING CHANCES FOR ABOVE-MEDIAN PRECIPITATION AMOUNTS. THIS FORECAST IS ALSO SUPPORTED BY THE NMME AND IMME. AS SEASONS PROGRESS INTO WINTER THE OUTLOOKS REFLECT THE PRECIPITATION PATTERN ASSOCIATED WITH EL NINO EVENTS, WITH ABOVE-MEDIAN PRECIPITATION AMOUNTS FAVORED THROUGHOUT MUCH OF THE SOUTHERN CONUS IN ASSOCIATION WITH AN EXPECTED ENERGIZED MEAN SOUTHERN JET STREAM, AND A TENDENCY FOR BELOW-MEDIAN AMOUNTS NEAR THE OHIO RIVER VALLEY AND ALSO IN PARTS OF THE NORTHERN ROCKIES. AT THIS POINT PROBABILITIES ARE ONLY MARGINALLY DIFFERENT FROM CLIMATOLOGICAL VALUES IN MOST AREAS DUE TO UNCERTAINTIES IN THE EVENTUAL STRENGTH OF EL NINO. THE PRECIPITATION OUTLOOK FOR MAM 2015 AND BEYOND SHOW EQUAL CHANCES FOR BELOW-, NEAR- AND ABOVE-MEDIAN SEASONAL ACCUMULATED PRECIPITATION THROUGHOUT THE CONUS AND ALASKA. STATISTICAL MODELS SHOW THE NINO 3.4 SST'S WEAKENING TO NEAR NORMAL BY LATE SPRING 2015, LEAVING LITTLE PREDICTABLE SIGNAL FOR PRECIPITATION ANOMALIES. FORECASTER: STEPHEN BAXTER 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 JUL 17 2014 1981-2010 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 19, 2011 FORECAST RELEASE. $$