PROGNOSTIC DISCUSSION FOR LONG-LEAD OUTLOOKS CLIMATE PREDICTION CENTER NCEP NATIONAL WEATHER SERVICE WASHINGTON DC 3 PM EST THURSDAY MAR 15 2001 BASIS AND SUMMARY OF THE CURRENT LONG-LEAD OUTLOOK . . . . . . . . THE AMJ 2001 FORECASTS REFLECT - IN PART - THE U.S. CLIMATE ANOMALIES EXPECTED IN A WEAKENING ENSO COLD EVENT. THE IMPACT OF LA NINA ON US CLIMATE IS WEAK AT THIS TIME OF YEAR. STATISTICAL PREDICTIONS OF NINO 3.4 INDICATE THE POSSIBILITY OF VERY WEAK WARM ENSO CONDITIONS BY WINTER 2001/2002. GIVEN THE UNCERTAINTIES IN THE OUTLOOK - NEXT WINTERS FORECASTS DO NOT REFLECT WARM EVENT US IMPACTS. CURRENT ATMOSPHERIC AND OCEANIC CONDITIONS ATMOSPHERIC AND OCEANIC INDICES OF ENSO SHOW WEAK COLD PHASE (LA NINA) CONDITIONS. PACIFIC SSTS NEAR THE EQUATOR HAVE DECLINED SINCE LAST MONTH AND ARE AROUND 0.5 TO 1 DEGREE C BELOW NORMAL SSTS FROM 160W TO 160E. THE TRADE WINDS ARE STRONGER THAN NORMAL WEST OF 150W IN THE TROPICAL PACIFIC - WHILE CONVECTION IS ENHANCED IN THE FAR WESTERN TROPICAL PACIFIC AND SUBNORMAL TO THE EAST. . . . . . . . . PROGNOSTIC DISCUSSION OF SST FORECASTS THE NCEP DYNAMIC AND STATISTICAL MODELS (THE COUPLED MODEL) CONSTRUCTED ANALOG (CA) METHOD AND CANONICAL CORRELATION ANALYSIS (CCA)) CONTINUE TO PREDICT SLIGHTLY BELOW NORMAL NINO 3.4 REGION (5N TO 5S AND 120-170W) SSTS THROUGH MAM 2001. ALL MODELS CROSS ZERO ANOMALY BETWEEN MAM AND AMJ AND THEN FORECAST VARYING DEGREES OF POSITIVE ANOMALIES THROUGH FMA 2002. THE CA SST FORECAST HOLDS TEMPERATURES CLOSE TO NEAR-NORMAL THROUGH THE END OF THE SUMMER AND THEN WARMS SLIGHTLY BY THE END OF THE YEAR. THE CCA IS A DEGREE WARMER THAN CA THROUGH MOST OF THIS YEAR. THE COUPLED MODEL SST OUTLOOK IS IN CLOSE AGREEMENT WITH THE CCA - CALLING FOR POSITIVE ANOMALIES OF UP TO 1.3 STANDARD DEVIATIONS BY AUTUMN. THESE ANOMALIES ARE PREDICTED TO DECLINE TO 1 STANDARD DEVIATION BY THE END OF 2001 AND TO CONTINUE TO DROP THEREAFTER. A CONSOLIDATION OF THE THREE MODELS BASED ON THEIR PAST PERFORMANCE PREDICTS THAT NINO 3.4 SST ANOMALIES WILL AVERAGE SLIGHTLY BELOW ZERO IN AMJ - INCREASE TO ZERO BY MJJ AND THEN CONTINUE TO INCREASE BEFORE GENERALLY LEVELING OFF AT AROUND 0.5 DEGREES C DURING THE SECOND HALF OF 2001. WE EXPECT NEAR-NEUTRAL SST CONDITIONS ARE MOST LIKELY IN THE TROPICAL PACIFIC DURING WINTER 2001-2002. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOK THE CCA - OCN AND SMLR WERE CONSULTED AT ALL LEAD TIMES. THE CONSTRUCTED ANALOG SOIL MOISTURE-BASED FORECAST TOOL (CAS) WHICH INCORPORATES THE HISTORICAL INFLUENCE OF SOIL MOISTURE ANOMALIES INTO FORECASTS OF TEMPERATURE AND PRECIPITATION WAS USED FOR THE WARM SEASON FORECASTS. ALL TOOLS PLUS THE CMP INFLUENCED THE FORECAST FOR THE FIRST THREE LEAD TIMES. AT LONGER LEADS THE OCN AND CCA WERE THE ONLY AVAILABLE TOOLS. . . . . . . . . PROGNOSTIC DISCUSSION OF OUTLOOKS - AMJ 2001 TO AMJ 2002. TEMPERATURE: THE OUTLOOK FOR AMJ 2001 CALLS FOR WARMER THAN NORMAL TEMPERATURES FROM TEXAS INTO SOUTHERN SECTIONS OF THE WEST AND FOR SOUTHERN FLORIDA - BASED ON CMP - CCA - OCN. CCA - CMP PREDICT ABOVE NORMAL TEMPERATURES OVER THE SOUTHWESTERN STATES - TEXAS AND OVER FLORIDA DURING AMJ. CCA AND OCN PREDICT ABNORMAL WARMTH IN CENTRAL AND NORTHERN ALASKA - WHILE CMP PREDICTS COLD THROUGHOUT THE STATE. THE CMP COLD FORECAST OVERCOMES THE EXTRA WARMTH PREDICTED BY THE OTHER TOOLS IN THE ALEUTIANS AND SOUTHERN SECTIONS OF ALASKA. . . . . . . . . ALTHOUGH CCA AND CMP PREDICT SUB-NORMAL TEMPERATURES IN THE NORTHWEST DURING THE SPRING AND EARLY SUMMER - CAS AND OCN INDICATIONS FOR WARMTH COUNTER THESE - AND CL IS PREDICTED THERE. WITH ENSO CONDITIONS PREDICTED TO BE NEAR-NEUTRAL FOR MJJ THROUGH FALL - THE FORECAST FOR THE SUMMER AND FALL LARGELY REFLECTS THE LONG TERM TRENDS AND ON THE CAS TOOL - WHICH HAS HIGH SKILL DURING THE SUMMER RELATIVE TO THE OTHER TOOLS. OCN INDICATES STRONG WARMING TRENDS IN ALASKA IN THE SPRING AND EARLY SUMMER. THIS IS SUPPORTED BY THE CCA PREDICTION FOR THE INTERIOR AREAS BY JJA 2001. POSITIVE TEMPERATURE ANOMALIES FROM OCN EXTEND NORTH ALONG THE EASTERN SEABOARD DURING MJJ AND JJA. WARM SEASON PROBABILITIES FOR ABOVE NORMAL TEMPERATURES ARE HIGHEST IN THE SOUTH AND SOUTHWEST WHERE YEAR-TO-YEAR VARIABILITY IS SMALL IN RELATION TO THE TRENDS. CLIMATOLOGICAL ODDS ARE FAVORED OVER MOST OF THE NORTHERN AND CENTRAL PARTS OF THE COUNTRY EXCEPT FOR PORTIONS OF THE MIDWEST IN JJA AND JAS WHEN OCN SLIGHTLY FAVORS BELOW NORMAL. . . . . . . . . CAS INDICATES ABNORMALLY COLD TEMPERATURES IN THE CENTRAL AND NORTH-CENTRAL US. THESE INDICATIONS COMBINED WITH OCN CONTRIBUTED TO AN INCREASE OVER LAST MONTHS FORECAST IN THE AREA OF SUB-NORMAL TEMPERATURES PREDICTED FOR JJA AND JAS. COVERAGE OF THE WEST BY WARMTH PEAKS IN JAS AND ASO WHEN ABOVE NORMAL IS PREDICTED FROM THE NORTHWEST THROUGH THE CENTRAL AND SOUTHERN ROCKIES. THE AREA OF ABNORMAL WARMTH SHRINKS RAPIDLY FOLLOWING SON - INCLUDING ONLY SOUTHERN SECTIONS OF CALIFORNIA AND NEVADA ALONG WITH ARIZONA AND SOUTHWESTERN NEW MEXICO. BY OND AND NDJ THE SOUTHWESTERN REGION OF ABOVE NORMAL TEMPERATURES RECEDES FURTHER INTO THE INTERIOR SOUTHWEST AND EXPANDS INTO SOUTHWESTERN TEXAS. THESE FORECASTS REFLECT MAINLY THE INFLUENCE OF CCA AND OCN. ENSO-NEUTRAL CONDITIONS ARE ASSUMED FOR DJF-AMJ 2001-2002 TEMPERATURE OUTLOOKS. CCA AND OCN PREDICT WARMER THAN NORMAL IN THE SOUTHWEST AND IN MUCH OF THE EAST IN DJF AND OVER VIRTUALLY THE ENTIRE NATION IN JFM. ABNORMAL WARMTH LEAVES THE EAST IN FMA AND MAM BUT REMAINS IN THE WEST AND IN ALASKA. IN AMJ OCN AND CCA PREDICT ABNORMAL WARMTH FROM THE INTERIOR SOUTHWEST THROUGH CALIFORNIA AND THE GREAT BASIN AND NORTHWEST NORTHWARD TO INCLUDE MUCH OF ALASKA. . . . . . . . . PRECIPITATION: PRECIPITATION TRENDS FAVOR RELATIVELY WET SPRING AND EARLY SUMMER CONDITIONS IN THE PACIFIC NORTHWEST - AND THIS IS SUPPORTED BY CMP AND CCA. EVEN IF ABOVE MEDIAN PRECIPITATION FALLS IN THOSE REGIONS - AND OUR FORECAST PROBABILITIES ARE QUITE LOW - IT IS HIGHLY UNLIKELY TO BE SUFFICIENT TO SIGNIFICANTLY IMPROVE WATER CONDITIONS THERE. THE AMJ AND MJJ PRECIPITATION OUTLOOKS FOR ABNORMALLY DRY CONDITIONS OVER THE SOUTHEAST REFLECT THE LA NINA COMPOSITES AND CMP FORECAST - AS WELL AS INDICATIONS FROM BOTH CCA - SMLR. THE CAS STRONGLY FAVORS ABNORMAL DRYNESS IN THE SOUTHEAST - BUT PREDICTS WET IN THE SOUTHWEST IN AMJ - WHERE MAJORITY OF TOOLS ARE UNSURE. CL IS PREDICTED FOR THE LATTER REGION. . . . . . . . . ABOVE-MEDIAN PRECIPITATION IS PREDICTED FOR THE NORTHWEST IN AMJ BY OCN - BUT WITH HIGHEST LIKELIHOOD INLAND. ABOVE MEDIAN PRECIPITATION FROM THE WESTERN GREAT LAKES TO EASTERN SECTIONS OF THE DAKOTAS IS PREDICTED BY THE CMP AND BY CAS AND IS CONSISTENT WITH LAST MONTHS AMJ OUTLOOK. CCA AND OCN ALSO PREDICT BELOW MEDIAN PRECIPITATION FOR THE ALEUTIANS - SOUTHERN ALASKA AND THE PANHANDLE. OCN INDICATES BELOW MEDIAN PRECIPITATION IN JAS IN THE FAR WEST AND NORTHWEST. WEAK INDICATIONS IN CCA FOR DRYNESS IN THE SAME REGION DURING ASO - THOUGH INCLUDED IN LAST MONTHS ASO FORECAST - WERE TOO WEAK TO INCLUDE THIS MONTH. WET CONDITIONS ARE PREDICTED IN THE INTERIOR SOUTHWEST IN JJA AND JAS BASED ON THE POSSIBLE LAGGED IMPACT OF THE LA NINA DURING LATE WINTER ON THE GLOBAL MONSOON CIRCULATION AND ALSO ON CAS. INDICATIONS FOR ASO AND SON WERE WEAK EVERYWHERE AND CL WAS PREDICTED. THE PRECIPITATION OUTLOOK FOR OND THROUGH DJF INCLUDES A REGION OF ABNORMAL WETNESS IN THE CENTRAL AND SOUTH-CENTRAL US WHICH COMES FROM OCN. LIKEWISE THE CHANCE RISES FOR ABOVE MEDIAN PRECIPITATION OVER PORTIONS OF THE SOUTHERN U.S. - HOWEVER THE PROBABILITY SHIFT IS VERY SMALL - INDICATING A HIGH DEGREE OF UNCERTAINTY. OCN DOES INDICATE ABOVE MEDIAN PRECIPITATION FOR PORTIONS OF THE PLAINS AND TEXAS FOR OND 2001 THROUGH DJF 2001/2002. PRECIPITATION FORECASTS FOR JFM-AMJ ARE MAINLY CL EVERYWHERE - EXCEPT FOR A FORECAST OF ABOVE IN AMJ 2002 IN THE NORTHWEST BASED ON OCN. 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 INFORMATION ON THE FORMULATION AND SKILL OF THE CAS FORECASTS MAY BE FOUND AT: http://www.cpc.ncep.noaa.gov/soilmst/forecasts.html NOTE - 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 APRIL 12 2001. 1971-2000 BASE PERIOD MEANS WILL BE IMPLEMENTED BEGINNING WITH THE FORECAST ISSUED APRIL 12, 2001. NNNN NNNN