PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD 830 AM EDT THU SEP 21 2006 SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS THE MAIN FACTORS WHICH USUALLY INFLUENCE SEASONAL CLIMATE INCLUDE 1) EL NINO AND LA NINA - WHICH TOGETHER MAKE UP EL NINO/SOUTHERN OSCILLATION OR ENSO 2) TRENDS - APPROXIMATED BY 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 1971-2000) 3) TROPICAL 30-60-DAY OSCILLATION- WHICH MAY AFFECT CLIMATE VARIABILITY WITHIN A SEASON 4) THE NORTH ATLANTIC OSCILLATION (NAO) AND THE PACIFIC NORTH AMERICAN (PNA) PATTERNS 5) PERSISTENTLY DRY OR WET SOILS IN THE SUMMER AND SNOW AND ICE COVER ANOMALIES IN THE WINTER. 6) AN OBJECTIVE CONSOLIDATION (CALLED CON IN THE TEXT) OF THE OCN, CCA, SMLR AND CFS FORECASTS IS USED AS A FIRST-GUESS IN PREPARING THE FORECAST MAPS. SST ANOMALIES ACROSS THE EQUATORIAL PACIFIC BETWEEN 160E AND THE SOUTH AMERICAN COAST WERE AT LEAST +0.5 DEG CENTIGRADE ABOVE NORMAL... INDICATING WEAK ENSO CONDITIONS HAVE COMMENCED. MOST PREDICTION TOOLS INDICATE THAT SST ANOMALIES WILL REMAIN AT LEAST +0.5 DEGREE CENTIGRADE ABOVE NORMAL ACROSS THE TROPICAL PACIFIC THROUGHOUT THE FALL AND WINTER... IMPLYING THAT WARM EPISODE (ENSO) CONDITIONS WILL IMPACT THE UNITED STATES CLIMATE DURING THE NEXT THREE TO SIX MONTHS. ENSO COMPOSITES WERE STRONGLY CONSIDERED FOR THE OUTLOOKS FROM OCTOBER - DECEMBER (OND) THROUGH FEBRUARY - APRIL (FMA). HOWEVER THERE IS CONSIDERABLE UNCERTAINTY WITH THE EXPECTED INTENSITY OF THE EVENT... WITH SOME SOLUTIONS MAINTAINING A WEAK ENSO... WHILE OTHER FORECASTS STRENGTHEN THE EPISODE TO MODERATE LEVELS. ONGOING ASSESSMENTS OF THE GLOBAL CLIMATE SYSTEM MAY RESULT IN CHANGES TO THE UPCOMING WINTER TEMPERATURE AND PRECIPITATION FORECASTS AS THE MAGNITUDE OF THE DEVELOPING ENSO BECOMES MORE CLEAR. THE TEMPERATURE OUTLOOK FOR OCT-NOV-DEC (OND) 2006 CALLS FOR WARMER THAN NORMAL CONDITIONS OVER MOST OF THE WESTERN HALF OF THE U.S. AND THE ALASKAN PANHANDLE AND SOUTHEASTERN ALASKA. ELSEWHERE THERE ARE EQUAL CHANCES OF WARMER-THAN... COOLER-THAN... OR NEAR- NORMAL TEMPERATURES DURING OND. THE PRECIPITATION OUTLOOK FOR OCT-NOV-DEC (OND) 2006 CALLS FOR BELOW MEDIAN PRECIPITATION IN PARTS OF THE MIDWEST... AND IN MUCH OF THE PACIFIC NORTHWEST. THE CHANCES FOR ABOVE MEDIAN PRECIPITATION ARE ENHANCED OVER THE SOUTHERN HALF OF NEW MEXICO AND SOUTHERN AND WESTERN TEXAS. ELSEWHERE THERE ARE EQUAL CHANCES OF WARMER-THAN... COOLER-THAN... OR NEAR- NORMAL PRECIPITATION DURING OND. BASIS AND SUMMARY OF THE CURRENT LONG-LEAD OUTLOOK 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 IN THE MIDDLE OF SEPTEMBER SSTS IN THE EQUATORIAL PACIFIC ARE MORE THAN +0.5 DEG C ABOVE NORMAL FROM 160E TO THE SOUTH AMERICAN COAST... WITH DEPARTURES MORE THAN +1.0 DEG C OBSERVED BETWEEN 160E AND 160W... 150W AND 140W... AND 120W AND 85W. THIS RESULTS IN VALUES ABOVE +0.5 IN ALL FOUR NINO INDEX AREAS... WITH THE LARGEST VALUES OF +1.0 IN NINO 3 AND NINO 4. THE LOW LEVEL EASTERLY WINDS (AT 850 MB) IN THE TROPICAL PACIFIC AVERAGED WEAKER THAN NORMAL DURING AUGUST AND HAVE BEEN GENERALLY WEAKER THAN NORMAL ACROSS MUCH OF THE CENTRAL AND EASTERN EQUATORIAL PACIFIC SINCE JULY. ALSO, THE SOI INDEX WAS NEGATIVE FOR THE FOURTH CONSECUTIVE MONTH. TOGETHER THESE INDICATORS SUGGEST THAT WEAK ENSO CONDITIONS HAVE DEVELOPED ACROSS THE TROPICAL PACIFIC. THE UPPER OCEAN HEAT CONTENT IN THE EQUATORIAL PACIFIC HAS INCREASED MARKEDLY SINCE FEBRUARY ... AND IS NOW WELL ABOVE THE LONG TERM AVERAGE. THE HEAT CONTENT IS SIMILAR TO LEVELS SEEN DURING PREVIOUS MODERATE ENSO EPISODES... INDICATING THAT THE CURRENT WEAK EPISODE MAY CONTINUE TO STRENGTHEN. MADDEN-JULIAN OSCILLATION (MJO) ACTIVITY CONTINUES TO BE WEAK OVER THE TROPICAL PACIFIC. PROGNOSTIC DISCUSSION OF SST FORECASTS A CONSOLIDATION OF NCEP SST MODELS PREDICTS THAT NINO 3.4 SSTS WILL MOST LIKELY PEAK SLIGHTLY ABOVE +0.5 DEG C. HOWEVER THERE IS A LARGE AMOUNT OF SPREAD AMONG THE FOUR MODEL SOLUTIONS FOR THE NEXT FEW MONTHS... INDICATING A LARGE AMOUNT OF UNCERTAINTY IN THIS FORECAST. THE ENSEMBLE MEAN OF THE CFS INDICATES THE STRONGEST EPISODE... WITH SSTS IN NINO 3.4 PEAKING NEAR 1.5 DEG C ABOVE AVERAGE... WHILE THE CONSTRUCTED ANALOG WEAKENS ANOMALIES IN NINO 3.4 TO NEAR ZERO BY FMA. AN ENSEMBLE OF 17 DIFFERENT STATISTICAL AND DYNAMICAL MODELS SHOWS THAT A FEW MEMBERS PROVIDE SUPPORT FOR A MODERATE STRENGTH ENSO... BUT THE MAJORITY OF MEMBERS FORECAST THAT THE CURRENT EVENT WILL REMAIN WEAK. BASED ON CURRENT CONDITIONS AND THE GENERAL WARMING TREND OBSERVED DURING THE PAST FEW MONTHS... IT IS ANTICIPATED THAT THIS EPISODE WILL STRENGTHEN AND MAY REACH MODERATE STRENGTH DURING THE UPCOMING COLD SEASON. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS THE OUTLOOK FOR OND 2006 THROUGH OND 2007 IS BASED ON THE CFS... THE MULTI-MODEL ENSEMBLE FROM THE IRI... AND THE CDC-CCA RENDERING OF THE MOST LIKELY CONSENSUS FORECAST OF SEVERAL DYNAMICAL MODEL FORECASTS... AS WELL AS CCA... SMLR... AND OCN. FORECASTS PRIMARILY REFLECT THE CONSOLIDATED TEMPERATURE AND PRECIPITATION PRODUCTS (A SKILL-WEIGHTED OBJECTIVE BLEND OF CFS... CCA... SMLR... AND OCN)... COMBINED WITH COMPOSITES FOR WEAK AND MODERATE STRENGTH WARM EPISODES DURING THE PERIOD OND 2006 THROUGH FMA 2007. THE OUTLOOKS FOR MAM 2007 THROUGH OND 2007 ARE BASED LARGELY ON A CONSOLIDATION OF CCA... SMLR... AND OCN (CFS IS NOT AVAILABLE AFTER LEAD 6). PROGNOSTIC DISCUSSION OF OUTLOOKS - OND 2006 TO OND 2007 TEMPERATURE: TEMPERATURE PROBABILITIES FOR OND 2006 ARE SIMILAR TO THOSE ISSUED LAST MONTH WITH AN EXPANDED COVERAGE OF ABOVE NORMAL MEAN TEMPERATURES ACROSS MONTANA... CONSISTENT WITH THE CONSOLIDATION. THE CONSOLIDATION ALSO WEAKLY FAVORS ABOVE NORMAL TEMPERATURES ACROSS THE SOUTHEAST... BUT THESE INDICATIONS WERE DISREGARED DUE TO THE POTENTIAL COOLING EFFECTS OF ENSO IN THAT REGION. DUE TO THE POTENTIAL IMPACTS FROM ENSO... NEAR NORMAL TEMPERATURES ARE FAVORED ACROSS THE SOUTHEAST DURING NDJ AND DJF. INCREASED PROBABILITIES FOR ABOVE NORMAL TEMPERATURES WERE ALSO ADDED ACROSS THE NORTHEAST DURING DJF... CONSISTENT WITH THE CPC CONSOLIDATION AND COMPOSITES BASED ON A MODERATE STRENGTH ENSO EPISODE. PROBABILITIES FOR ABOVE NORMAL TEMPERATURES ACROSS THE GULF REGION FROM SOUTH CAROLINA TO TEXAS DURING JFM IN THE FORECAST ISSUED LAST MONTH WERE REMOVED DUE TO POTENTIAL EFFECTS FROM ENSO. EFFECTS FROM ENSO DURING FMA ALSO RESULTED IN FORECASTS OF EQUAL CHANCES OVER FLORIDA AND TEXAS. OUTLOOKS FOR MAM 2007 AND BEYOND ARE BASED PRIMARILY ON THE CONSOLIDATION TOOL (THE CFS COMPONENT DROPS OUT AFTER LEAD 6) WHICH IS ALMOST ENTIRELY A REFLECTION OF TEMPERATURE TRENDS. PRECIPITATION: THE PRECIPITATION OUTLOOK FOR OND 2006 IS BASED PRIMARILY ON THE CPC CONSOLIDATION... WITH MODIFICATIONS DUE TO THE DEVELOPING ENSO. THE MAIN CHANGE FROM THE PREVIOUS FORECAST WAS THE REMOVAL OF BELOW AVERAGE PROBABILITIES FROM ARIZONA... AS ENSO COMPOSITES PAINT A NEUTRAL SIGNAL IN THAT REGION. FORECASTS FOR NDJ 2006 THROUGH JFM 2007 WERE LARGELY BASED ON COMPOSITES OF WEAK AND MODERATE STRENGTH WARM EPISODES. THIS HAS RESULTED IN SOME SIGNIFICANT CHANGES TO THE PREVIOUSLY ISSUED FORECASTS FOR THESE SEASONS. IN PARTICULAR INCREASED PROBABILITIES FOR ABOVE AVERAGE PRECIPITATION HAVE BEEN INTRODUCED INTO THE EXTREME SOUTHEAST DURING THESE SEASONS... REPLACING THE PROBABILITIES FOR BELOW AVERAGE PRECIPITATION THAT CONTINUES TO BE FAVORED BY THE CPC CONSOLIDATION. PROBABILITIES FOR ABOVE AVERAGE PRECIPITATION HAVE ALSO BEEN INTRODUCED INTO THE SOUTHWEST AND SOUTHERN CALIFORNIA... AGAIN CONSISTENT WITH ENSO COMPOSITES. THE REMAINING OUTLOOKS HAVE BEEN MODIFIED ONLY SLIGHTLY FROM THOSE ISSUED FOR CORRESPONDING SEASONS LAST MONTH... AND WERE BASED EXCLUSIVELY ON THE CPC CONSOLIDATION. NOTE - AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL PROBABILITIES) ARE NOW LABELED EC (EQUAL CHANCES). FORECASTER: MICHAEL HALPERT STARTING WITH THE SEASONAL OUTLOOK RELEASED IN FEBRUARY, 2006, THE GLOSSARY OF TERMS WILL NO LONGER APPEAR WITH THIS MESSAGE. INSTEAD, TERMS THAT ARE IN THE GLOSSARY WILL BE LINKED TO THEIR DEFINITION. FOR A DESCRIPTION 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 FORMULATION AND 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 THU OCT 19 2006. 1971-2000 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 17, 2001 FORECAST RELEASE $$