PROGNOSTIC DISCUSSION FOR LONG-LEAD OUTLOOKS CLIMATE PREDICTION CENTER NCEP NATIONAL WEATHER SERVICE WASHINGTON DC 3 PM EDT THURSDAY OCTOBER 18 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 NEAR SOUTH AMERICA. MOST STATISTICAL AND DYNAMIC PREDICTIONS OF NINO 3.4 SSTS INDICATE ANOMALIES VERY NEAR ZERO THROUGHOUT THE UPCOMING 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 WEAK 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 SEPTEMBER. SST ANOMALIES ALONG THE EQUATOR CURRENTLY ARE NEAR +1.0 DEG C WEST OF THE DATELINE AND ARE AROUND -1.O 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. ENHANCED MJO ACTIVITY HAS BEEN NOTED DURING THE LAST SIX MONTHS. THIS IS EXPECTED TO CONTINUE AND WILL HAVE AN IMPACT ON SSTS IN THE CENTRAL EQUATORIAL PACIFIC. 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 INCREASE NINO 3.4 SSTS BEGINNING IN THE SPRING. THE CONSTRUCTED ANALOG AND INVERSE MODEL PREDICT NEUTRAL OR COOL NINO 3.4 SSTS FOR THIS COOL SEASON WHILE CCA PREDICTS MODESTLY ABOVE NORMAL SSTS. A MARKOV SST MODEL INDICATES PERSISTENCE OF CURRENT SSTS THROUGH THE SPRING WITH WARM ENSO CONDITIONS DEVELOPING DURING APRIL THROUGH JUNE 2002. A CONSOLIDATION OF THREE NCEP TOOLS BASED ON THEIR PAST PERFORMANCE INDICATES NEAR NORMAL CONDITIONS WILL PREVAIL THROUGH THE WINTER WITH GRADUALLY INCREASING ANOMALIES THAT REACH AROUND +0.5 DEGREES C BY LATE NEXT SPRING. 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 ALSO CONSULTED. THESE WERE SUBJECTED TO A HIGH-PASS FILTER PRIOR TO ISOLATE INTERANNUAL SIGNALS FROM LONGER TIME SCALES. FINALLY DYNAMICAL MODEL FORECASTS FROM NCEP - EC HAMBURG - NASA AND NCAR - INITIATED FROM ATMOSPHERIC AND OCEANIC CONDITIONS FROM LATE SEPTEMBER - WERE ALL CONSULTED. ALTHOUGH THE INITIAL ENSO STATE IS NEAR ZERO - THERE WAS AGREEMENT AMONG 3 OF THE 4 DYNAMICAL MODELS ON 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 NEGATIVE ANOMALIES OVER EASTERN NORTH AMERICA. THE TEMPERATURE FORECASTS FROM THESE DYNAMICAL MODELS ARE IN OVERALL AGREEMENT WITH MANY OF THE STATISTICAL TOOLS - INCLUDING THE ENSO-NEUTRAL COMPOSITES AND CCA - BOTH OF WHICH PREDICT BELOW NORMAL TEMPERATURES IN THE NORTHEASTERN US AND ABOVE NORMAL IN THE SOUTHWEST DURING THE COLD SEASON. IN PARTS OF THE EAST WE GAVE GREATER WEIGHT TO THESE TOOLS THAN TO THE TREND (OCN) - LEADING TO FORECASTS OF CL IN THE SOUTHEAST AND BELOW NORMAL IN THE NORTH-CENTRAL AND NORTHEASTERN U.S. . . . . . . . . PROGNOSTIC DISCUSSION OF OUTLOOKS - NDJ 2001-2 TO NDJ 2002-3 TEMPERATURE: MOST FORECAST TOOLS INDICATE WARMER-THAN-NORMAL TEMPERATURES FOR NDJ 2001-2 THROUGH NDJ 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. BELOW-NORMAL TEMPERATURE WHICH CCA PREDICTED FOR ALASKA IN NDJ AND DJF IN LAST MONTHS FORECAST HAVE BEEN REMOVED - SINCE OCN AND CMP BOTH PREDICT WARM. 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 NDJ THROUGH JFM AND SUB-NORMAL RAINFALL OVER FLORIDA AND PARTS OF THE SOUTHEAST FOR NDJ THROUGH DJF. 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 SCATTERED SMALL REGIONS ASSOCIATED WITH LONG-TERM TRENDS. THE BIGGEST CHANGES FROM LAST MONTHS OUTLOOK ARE REMOVING ABOVE-MEDIAN PRECIPITATION FROM THE NDJ THROUGH JFM FORECASTS FOR THE PANHANDLE OF FLORIDA AND FORECASTING SUB-MEDIAN PRECIPITATION FOR NDJ AND DJF FOR FLORIDA AND PARTS OF THE SOUTHEAST. THIS SIGNAL COMES FROM CCA AND THE DYNAMICAL MODELS - WHICH INDICATE THAT THE SIGNAL FADES RAPIDLY AFTER DJF. LAST MONTHS FORECAST OF BELOW-MEDIAN IN THE SOUTHWEST FOR NDJ AND DJF HAS BEEN MODIFIED TO CL IN LIGHT OF DYNAMICAL MODEL FORECASTS OF ABOVE-MEDIAN RAINFALL. ABOVE MEDIAN PRECIPITATION PREDICTED FOR ALASKA IN DJF THIS MONTH COMES FROM THE DYNAMICAL MODEL FORECASTS. FORECASTERS: ED OLENIC AND HUUG VAN DEN DOOL 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 NOVEMBER 15 2001. 1971-2000 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 17 2001 FORECAST RELEASE. NNNN NNNN