PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD 830AM EDT THURSDAY AUG 16 2012 SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS THE MAIN FACTORS WHICH 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). THE UPGRADED PARALLEL VERSION OF THE CFS (CFSV2) BECAME OPERATIONAL IN LATE MARCH OF 2011. BOTH VERSIONS OF CFS ARE CURRENTLY RUN IN PARALLEL. 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 OUR FORECAST TOOLS. ENSO NEUTRAL CONDITIONS CONTINUE INTO AUGUST. SEA SURFACE TEMPERATURES (SSTS) ARE NOW ABOVE NORMAL ALONG THE EQUATOR IN THE PACIFIC OCEAN FROM JUST WEST OF THE SOUTH AMERICAN COAST TO APPROXIMATELY 170 W. SST ANOMALIES IN THE NINO 3.4 REGION IN THE EAST-CENTRAL EQUATORIAL PACIFIC HAVE BEEN INCREASING IN THE LAST SEVERAL MONTHS AND ARE NOW ABOVE THE POSITIVE 0.5 C THRESHOLD. DYNAMICAL MODELS PREDICT SST ANOMALIES TO CONTINUE TO INCREASE IN THIS REGION USED FOR MONITORING OF THE ENSO STATE, SUGGESTING THE INCREASING CHANCE THAT EL NINO CONDITIONS WILL DEVELOP , PROBABLY DURING SON. STATISTICAL MODELS PREDICT SST ANOMALIES THAT ARE LESS POSITIVE, INDICATING THAT NEUTRAL CONDITIONS ARE MORE LIKELY TO CONTINUE UNTIL AT LEAST AUTUMN. IT IS UNCERTAIN AT THIS TIME HOW STRONG SST ANOMALIES WILL BE OR HOW MUCH THEY WILL ALTER THE LARGE SCALE CIRCULATION IMPACTING NORTH AMERICA. THE SON 2012 TEMPERATURE OUTLOOK INDICATES ENHANCED CHANCES FOR ABOVE NORMAL TEMPERATURES FOR THE GREAT PLAINS, THE UPPER AND MIDDLE MISSISSIPPI VALLEY, THE TENNESSEE AND OHIO VALLEYS, THE GREAT LAKES, THE APPALACHIANS, THE MID-ATLANTIC, AND THE NORTHEAST. THIS IS SUPPORTED BY DYNAMICAL MODELS AND TRENDS. INITIAL SOIL MOISTURE CONDITIONS ARE DRIER THAN NORMAL FOR MUCH OF THE CONUS ALSO SUPPORT ABOVE NORMAL TEMPERATURES FOR MUCH OF THE GREAT PLAINS AND THE UPPER MIDWEST. BELOW NORMAL TEMPERATURES ARE LIKELY FOR SOUTHWESTERN AND SOUTHERN SECTIONS OF ALASKA AND ALONG THE U.S. WEST COAST DUE TO THE LIKELY CONTINUATION OF COLDER THAN AVERAGE SSTS IN THOSE REGIONS. THE SON 2012 PRECIPITATION OUTLOOK INDICATES AN INCREASED LIKELIHOOD FOR BELOW-MEDIAN PRECIPITATION FOR MUCH OF THE NORTHWEST CONUS, NORTHERN CALIFORNIA, NORTHWESTERN NEVADA, WESTERN IDAHO, AND SOUTHEASTERN ALASKA BASED ON THE DYNAMICAL MODELS. ABOVE MEDIAN PRECIPITATION IS PREDICTED IN SECTIONS OF THE SOUTHWEST BASED ON CONTINUATION OF ENHANCED MONSOON CONDITIONS AT LEAST THROUGH SEPTEMBER. THE INCREASED LIKELIHOOD OF BELOW MEDIAN PRECIPITATION IN THE UPPER MIDWEST IS DUE TO THE IMPACT OF DRIER THAN NORMAL INITIAL SOIL MOISTURE CONDITIONS, WITH SUPPORT FROM THE CFSV2 FORECAST. IN LOCATIONS WHERE THE LIKELIHOODS OF SEASONAL MEAN TEMPERATURES AND SEASONAL PRECIPITATION AMOUNTS ARE SIMILAR TO THE CLIMATOLOGICAL PROBABILITIES, EQUAL CHANCES (EC) OF BELOW, NEAR, AND ABOVE AVERAGE TEMPERATURE AND PRECIPITATION ARE INDICATED. 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 PACIFIC SST ANOMALIES ALONG THE EQUATOR EXCEED 0.5 DEGREES C FROM ABOUT 170 W TO JUST WEST OF THE SOUTH AMERICAN COAST, WITH ANOMALIES EXCEEDING POSITIVE 1.0 DEGREES C EAST OF 150 W. THE AVERAGE HEAT CONTENT IN THE UPPER OCEAN NEAR THE EQUATOR HAS REMAINED ALMOST UNCHANGED DURING THE PAST MONTH WITH ANOMALIES EXCEEDING 1 C EAST OF130W. OCEAN TEMPERATURES BELOW THE SURFACE ARE NOW ABOVE AVERAGE BETWEEN 100 AND 200 METERS DEPTH IN THE WESTERN PACIFIC, AND FROM THE SURFACE TO GREATER THAN 200 METERS DEPTH IN THE EASTERN PACIFIC. A SMALL REGION OF COLD ANOMALIES HAS DEVELOPED NEXT TO THE SOUTH AMERICAN COAST ABOVE ABOUT 50 M DEPTH. LOWER LEVEL TRADE WINDS, AND UPPER LEVEL WINDS OVER THE TROPICAL PACIFIC OCEAN WERE ABOUT AVERAGE IN STRENGTH INTO EARLY AUGUST. OLR ANOMALIES WERE NEGATIVE BETWEEN ABOUT 120 AND 160E, INDICATING CONTINUED CONVECTION IN THAT REGION. DURING EL NINO, THAT REGION SHOULD SEE SUPPRESSED CONVECTION. ALSO, OLR ANOMALIES ARE NEAR-ZERO AT THE DATELINE. THUS, NEUTRAL ENSO CONDITIONS CONTINUE. PROGNOSTIC DISCUSSION OF SST FORECASTS AUGUST OBSERVATIONS PLACE THE NINO 3.4 INDEX AT ABOUT 0.55 C. ALL OF THE MOST RECENT DYNAMICAL MODELS PREDICT ABOVE ZERO ANOMALIES THROUGH JFM, RANGING FROM A MAXIMUM OF +0.25 C TO +1.9 C. ABOUT HALF OF THE STATISTICAL MODELS PREDICT ANOMALIES ABOVE +0.5 C, WHILE NONE EXCEEDS +0.8 C. THE DYNAMICAL MODEL ENSEMBLE FORECASTS PEAK DURING NDJ-DJF AT ABOUT +1.0 C. THE ENSEMBLE MEAN DIPS BELOW +0.5 C BY ABOUT JFM-FMA. THIS IS IN REASONABLE AGREEMENT WITH CFSV2. BASED ON THESE FORECAST TOOLS, IT IS LIKELY THAT AN EL NINO EVENT OF WEAK TO MODERATE AMPLITUDE IS LIKELY TO BEGIN DURING SON, AND CONTINUE THROUGH THE LATE WINTER. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS THE OUTLOOKS FOR SON 2012 PRIMARILY REFLECT DYNAMICAL MODEL FORECASTS INCLUDING THE CFSV2 AND NMME FORECASTS, AS WELL AS DECADAL TIMESCALE TRENDS. SOME OF THE DYNAMICAL MODEL FORECASTS INCLUDING THE CFSV2 INCLUDE THE INFLUENCE OF THE OBSERVED INITIAL CONDITIONS OF SOIL MOISTURE AS WELL AS THE INFLUENCE OF PREDICTED SST ANOMALIES. ENSO COMPOSITES ARE USED WITH GRADUALLY INCREASING EMPHASIS FROM OND THROUGH MAM 2013. THE CONSOLIDATION OF STATISTICAL TOOLS FOR FORECASTS FROM AMJ 2013 ONWARD. PROGNOSTIC DISCUSSION OF OUTLOOKS - SON 2012 TO SON 2013 TEMPERATURE THE SON 2012 TEMPERATURE OUTLOOK INDICATES ENHANCED CHANCES FOR ABOVE NORMAL TEMPERATURES FOR THE GREAT PLAINS, THE UPPER AND MIDDLE MISSISSIPPI VALLEY, THE TENNESSEE AND OHIO VALLEYS, THE GREAT LAKES, THE APPALACHIANS, THE MID-ATLANTIC, AND THE NORTHEAST. THIS IS SUPPORTED BY DYNAMICAL MODELS AND TRENDS. INITIAL SOIL MOISTURE CONDITIONS ARE DRIER THAN NORMAL FOR MUCH OF THE CONUS ALSO SUPPORT ABOVE NORMAL TEMPERATURES FOR MUCH OF THE GREAT PLAINS AND THE UPPER MIDWEST. BELOW NORMAL TEMPERATURES ARE LIKELY FOR SOUTHWESTERN AND SOUTHERN SECTIONS OF ALASKA AND ALONG THE U.S. WEST COAST DUE TO THE LIKELY CONTINUATION OF COLDER THAN AVERAGE SSTS IN THOSE REGIONS. TEMPERATURE OUTLOOKS FROM OND 2012 THROUGH FMA 2013 SHOW INCREASED CHANCES OF ABOVE NORMAL TEMPERATURES ACROSS MUCH OF THE NORTHERN CONUS AND SOME AREAS WITH INCREASED CHANCES OF BELOW NORMAL TEMPERATURES IN PORTIONS OF THE SOUTHERN CONUS, DUE TO THE LIKELY INCREASING INFLUENCE OF EL NINO CONDITIONS. THE INCREASED CHANCES FOR BELOW NORMAL TEMPERATURES DUE TO POSSIBLE EL NINO CONDITIONS OPPOSE TRENDS FOR ABOVE NORMAL TEMPERATURES, ESPECIALLY IN THE SOUTHWEST, LEADING TO A FORECAST OF EQUAL CHANCES FOR ABOVE, NEAR OR BELOW NORMAL TEMPERATURES FROM OND 2012 THROUGH FMA 2013. AN EL NINO INCREASES THE PROBABILITIES FOR ABOVE NORMAL TEMPERATURES IN SOUTHERN PORTIONS OF ALASKA, WHILE TRENDS INCREASE THE CHANCES IN NORTHERN ALASKA. THE FORECAST FOR MAM REFLECTS AN EXPECTED TRANSITION FROM EL NINO TO NEUTRAL CONDITIONS BY THAT TIME. IN AREAS WITHOUT STRONG CLIMATE SIGNALS, EQUAL CHANCES FOR BELOW NORMAL, NEAR NORMAL, OR ABOVE NORMAL SEASONAL MEAN TEMPERATURES IS PREDICTED. PRECIPITATION THE SON 2012 PRECIPITATION OUTLOOK INDICATES AN INCREASED LIKELIHOOD FOR BELOW-MEDIAN PRECIPITATION FOR MUCH OF THE NORTHWEST CONUS, NORTHERN CALIFORNIA, NORTHWESTERN NEVADA, WESTERN IDAHO, AND SOUTHEASTERN ALASKA BASED ON THE DYNAMICAL MODELS. ABOVE MEDIAN PRECIPITATION IS PREDICTED IN SECTIONS OF THE SOUTHWEST BASED ON CONTINUATION OF ENHANCED MONSOON CONDITIONS AT LEAST THROUGH SEPTEMBER. THE INCREASED LIKELIHOOD OF BELOW MEDIAN PRECIPITATION IN THE UPPER MIDWEST IS DUE TO THE IMPACT OF DRIER THAN NORMAL INITIAL SOIL MOISTURE CONDITIONS, WITH SUPPORT FROM THE CFSV2 FORECAST. ONCE EL NINO CONDITIONS ARE ESTABLISHED, THE EXTENSION OF THE SUBTROPICAL JET ENHANCES THE CHANCES OF ABOVE MEDIAN PRECIPITATION ACROSS THE SOUTHERN CONUS FOR OND 2012 THROUGH MAM 2013, AND INCREASES THE LIKELIHOOD OF BELOW MEDIAN PRECIPITATION IN THE PACIFIC NORTHWEST AND THE CENTRAL MISSISSIPPI AND OHIO VALLEYS. TREND-ADJUSTED EL NINO COMPOSITES INDICATE EQUAL CHANCES FOR ABOVE, MEDIAN OR BELOW-MEDIAN PRECIPITATION ALONG THE CENTRAL GULF COAST IN LATE WINTER INTO SPRING. EL NINO COMPOSITES PAINT A COMPLICATED PICTURE, INDICATING DRY IN OND, AT TRANSITION TO WET IN DJF AND JFM, AND THEN BACK TO DRY IN FMA-MAM. WHILE SUCH TRANSITIONS MAY BE PHYSICALLY MEANINGFUL, THEY MAY ALSO BE INFLUENCED BY SAMPLE SIZE. NONETHELESS, THE INDICATIONS OF THE COMPOSITES WERE FOLLOWED. THESE INDICATIONS WERE ACCOMMODATED BY COMPROMISES BETWEEN THE COMPOSITES AND TEMPORAL CONTINUITY AMONG ADJACENT LEADS. THE ENSO STATE IS UNCERTAIN BEYOND MAM 2013, WITH WEAK SIGNALS FOR ANOMALOUS PRECIPITATION DUE TO DECADAL TRENDS. BELOW MEDIAN PRECIPITATION IS SLIGHTLY MORE LIKELY FOR THE PACIFIC NORTHWEST IN SUMMER 2013. FORECASTER: ED O'LENIC 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 SEP 20 2012 1981-2010 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 19, 2011 FORECAST RELEASE. $$