PROGNOSTIC DISCUSSION FOR LONG-LEAD OUTLOOKS CLIMATE PREDICTION CENTER NCEP NATIONAL WEATHER SERVICE WASHINGTON DC 3 PM EST THURSDAY NOVEMBER 15 2001 BASIS AND SUMMARY OF THE CURRENT LONG-LEAD OUTLOOK . . . . . . . . THESE OUTLOOKS REFLECT THE EXPECTED U.S. CLIMATE ANOMALIES FOR ENSO-NEUTRAL CONDITIONS ... THE LONG-TERM TREND AS ESTIMATED BY OCN AND FORECASTS OF OCEANIC AND ATMOSPHERIC CONDITIONS FROM DYNAMICAL MODELS. EQUATORIAL PACIFIC SSTS ARE NOW SLIGHTLY ABOVE NORMAL IN THE WEST AND CENTRAL PACIFIC AND BELOW NORMAL EAST OF 150W. IF ANYTHING THE SST PATTERN RESEMBLES IN SOME WAYS A WEAK LA NINA... ESPECIALLY THE WARM WEST PACIFIC. SOME MODELS REACT IN LA NINA-LIKE FASHION TO THE SST ANOMALIES BY WHICH THEY ARE FORCED. MOST STATISTICAL AND DYNAMIC PREDICTIONS OF NINO 3.4 SSTS INDICATE ANOMALIES AVERAGING VERY NEAR ZERO THROUGHOUT THE COOL SEASON WITH SLIGHT WARM EPISODE (EL NINO) CONDITIONS BY LATE IN THE SPRING OR EARLY IN THE SUMMER OF 2002. WHILE IT IS LIKELY THAT EQUATORIAL PACIFIC SSTS NEAR AND JUST WEST OF THE DATELINE WILL BE ABOVE AVERAGE ... THE ANOMALIES ARE EXPECTED TO BE SMALL AND NOT LIKELY TO PRODUCE THE LARGE-SCALE ATMOSPHERIC EFFECTS ASSOCIATED WITH STRONG EL NINO EVENTS THIS COOL SEASON. THE ABSENCE OF SIGNIFICANT ENSO-RELATED INFLUENCES SUGGESTS THE UPCOMING COOL SEASON MAY BE MARKED BY SIGNIFICANT MONTH-TO-MONTH VARIABILITY...WHICH MAY BE ENHANCED IF THE CURRENTLY STRONG SERIES OF MADDEN AND JULIAN OSCILLATION (MJO) WAVES CONTINUES OVER THE PACIFIC. CURRENT ATMOSPHERIC AND OCEANIC CONDITIONS NEAR-NORMAL ATMOSPHERIC AND OCEANIC CONDITIONS CONTINUE TO PREVAIL IN THE TROPICAL PACIFIC IN NOVEMBER. SST ANOMALIES ALONG THE EQUATOR CURRENTLY ARE NEAR +1.0 DEG C WEST OF THE DATELINE AND ARE AROUND -1.0 DEG IN THE EASTERN PACIFIC - EAST OF ABOUT 130W. ABOVE NORMAL OCEAN TEMPERATURES EXTEND FROM THE SURFACE OR NEAR THE SURFACE TO OVER 200 M DEPTH OVER MOST OF THE CENTRAL PACIFIC OCEAN AND TO 100 M DEPTH AS FAR EAST AS 130 W. IT IS THIS EXTENSIVE SUBSURFACE WARMTH OF MODEST MAGNITUDE THAT LEADS SOME FORECAST TOOLS TO FORECAST A SWING TO MILD WARM ENSO CONDITION NEXT YEAR. ENHANCED MJO ACTIVITY HAS BEEN NOTED DURING THE LAST SIX MONTHS. THIS IS EXPECTED TO CONTINUE. WITH WARM SSTS FARTHER EAST THAN LAST WINTER THERE IS A BETTER CHANCE STRONG MJO WILL MAKE IT TO THE DATELINE AND HAVE AN OPPORTUNITY TO IMPACT PRECIPITATION IN THE WESTERN UNITED STATES. . . . . . . . . PROGNOSTIC DISCUSSION OF SST FORECASTS NEAR-NEUTRAL ENSO CONDITIONS ARE PREDICTED FOR MUCH OF THE WINTER. MOST DYNAMICAL MODELS (NCEP - SCRIPPS) GRADUALLY PRODUCE POSITIVE NINO 3.4 SST ANOMALIES BEGINNING IN THE LATE SPRING 2002. THE CONSTRUCTED ANALOG PREDICTS NEUTRAL OR SLIGHTLY COOL NINO 3.4 SSTS UNTIL MAY 2002 WHILE CCA PREDICTS MODESTLY ABOVE NORMAL SSTS APPEARING SOME TIME IN SPRING 2001. A CONSOLIDATION OF THE THREE NCEP TOOLS BASED ON THEIR PAST PERFORMANCE INDICATES NEAR NORMAL CONDITIONS WILL PREVAIL THROUGH THE WINTER WITH GRADUALLY INCREASING POSITIVE NINO 3.4 ANOMALIES THAT REACH AROUND +0.5 DEGREES C BY LATE NEXT SPRING. IT IS PREMATURE TO SPECULATE ABOUT THE STATE OF ENSO LATER IN 2002. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOK THE STATISTICAL TOOLS ... CCA ... OCN AND SMLR ... WERE CONSULTED AT ALL LEAD TIMES. ENSO-NEUTRAL COMPOSITES WERE CONSULTED FOR LEADS THRU JFM. THE DATA WERE SUBJECTED TO A RUNNING 9 YEAR FILTER PRIOR TO COMPOSITING IN ORDER TO ISOLATE INTERANNUAL SIGNALS FROM LONGER TIME SCALES WHICH ARE ALREADY IN OCN. DYNAMICAL MODEL FORECASTS FROM NCEP WERE CONSULTED. THE LATEST RUNS ARE FORCED BY SST ANOMALIES EVEN WEAKER THAN WHAT WAS EXPECTED A MONTH AGO. NEVERTHELESS THERE IS A WAVE-TRAIN EMANATING FROM THE ABNORMALLY WARM POOL OF WATER IN THE WESTERN TROPICAL PACIFIC WHICH APPEARS TO CAUSE A PERSISTENT PATTERN OVER NORTH AMERICA. THIS PATTERN FAVORS POSITIVE UPPER AIR HEIGHT ANOMALIES OVER THE GULF OF ALASKA AND WEST COAST AND NEGATIVE ANOMALIES OVER EASTERN NORTH AMERICA. THE TEMPERATURE FORECASTS FROM THESE DYNAMICAL MODELS ARE IN OVERALL AGREEMENT WITH SOME OF THE STATISTICAL TOOLS - PARTICULARLY THE ENSO-NEUTRAL COMPOSITES WHICH ALSO PREDICT BELOW NORMAL TEMPERATURES IN THE NORTHEASTERN US. IN PARTS OF THE EAST WE GAVE GREATER WEIGHT TO THESE TOOLS THAN TO THE TREND (OCN) - LEADING TO FORECASTS OF ONLY WEAKLY ABOVE IN THE SOUTHEAST AND BELOW NORMAL IN THE NORTH-CENTRAL AND NORTHEASTERN U.S. . . . . . . . . PROGNOSTIC DISCUSSION OF OUTLOOKS - DJF 2001-2 TO DJF 2002-3 TEMPERATURE: MOST FORECAST TOOLS INDICATE WARMER-THAN-NORMAL TEMPERATURES FOR DJF 2001-2 THROUGH DJF 2002-3 IN THE SOUTHWEST U.S. THIS SIGNAL IS THE STRONGEST TREND SIGNAL ON THE MAP AND THE PROBABILITIES ARE ACCORDINGLY HIGH. MIXED SIGNALS APPEAR OVER ALASKA AND CLIMATOLOGICAL PROBABILITIES ARE OFTEN PREDICTED THERE. ONE MAJOR FACTOR INFLUENCING THE SEASONAL CLIMATE ANOMALIES OVER THE EASTERN U.S. THIS WINTER WILL BE THE PHASE OF THE NAO- WHICH IS NOT YET PREDICTABLE BEYOND ABOUT 1-2 WEEKS IN ADVANCE. ENSO-NEUTRAL COMPOSITES INDICATE COOLER THAN NORMAL TEMPERATURES OVER MUCH OF THE CENTRAL AND EASTERN U.S. - WHICH OPPOSES RECENT WARM TRENDS. CHANGES FROM LAST MONTH'S FORECASTS ARE SMALL. MOST NOTEWORTHY IS EXTENSION OF ABOVE NORMAL TEMPERATURES INTO THE SOUTHEASTERN US BECAUSE THE COUPLED MODEL BACKED OFF ITS PREVIOUS FORECAST FOR COLD FROM LAST MONTH AND TRENDS FOR WARM ARE VERY STRONG IN THAT AREA. BEYOND FMA 2002 CCA AND OCN ARE THE PRIMARY TOOLS. THESE SHOW THE WARM TREND IN THE WESTERN AND SOUTHERN U.S. DURING THE WARM SEASON AND A COOL TREND IN THE NORTH-CENTRAL U.S. DURING THE LATE SUMMER. . . . . . . . . . PRECIPITATION: CCA AND OCN PREDICT ABOVE-MEDIAN PRECIPITATION OVER TEXAS FOR DJF AND JFM. THE COUPLED MODEL AND CCA PREDICT SUB-NORMAL RAINFALL OVER FLORIDA AND PARTS OF THE SOUTHEAST FOR DJF AND JFM. A DRY SOUTHEAST IS ALSO A WEAK SIGNAL FROM THE NEUTRAL ENSO COMPOSITES. WHILE MJO ACTIVITY IS EXPECTED TO BE STRONG DURING THE COLD SEASON AND SUCH ACTIVITY CAN BE ASSOCIATED WITH HEAVY PRECIPITATION EVENTS ALONG THE WEST COAST - THE TOOLS CURRENTLY GIVE MIXED INDICATIONS IN THAT REGION AND CL IS PREDICTED THERE. ODDS FOR ABOVE-MEDIAN PRECIPITATION INCREASE IN THE NORTHWEST IN AMJ AND MJJ DUE TO LONG-TERM TRENDS. BEYOND MJJ PREDICTABILITY OF PRECIPITATION IS LIMITED TO SEVERAL SCATTERED SMALL REGIONS ASSOCIATED WITH LONG-TERM TRENDS. FORECAST MADE TWO MONTHS AGO FOR BELOW-MEDIAN IN THE SOUTHWEST FOR NDJ AND DJF WAS MODIFIED LAST MONTH TO CL IN LIGHT OF DYNAMICAL MODEL FORECASTS OF ABOVE-MEDIAN RAINFALL. THE MODELS SEEM TO HAVE WEAKENED THIS OPINION MORE RECENTLY BUT WE CONTINUED WITH CL IN DJF IN THE SOUTHWEST IN VIEW OF MULTIPLE CONFLICTING OPINIONS. ABOVE MEDIAN PRECIPITATION PREDICTED FOR ALASKA IN DJF COMES FROM THE DYNAMICAL MODEL FORECASTS BUT HAD LITTLE SUPPORT FROM OTHER TOOLS. FORECASTERS: H. VAN DEN DOOL AND A.J. WAGNER 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/MULTI-SEASON/ 13_SEASONAL_OUTLOOKS/TOOLS (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 LOWER CASE LETTERS) NOTES - THESE CLIMATE OUTLOOKS ARE INTENDED FOR USE PRIOR TO THE START OF THEIR VALID PERIODS. 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 THURSDAY DECEMBER 13 2001. 1971-2000 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 17 2001 FORECAST RELEASE. NNNN NNNN