PROGNOSTIC DISCUSSION FOR LONG-LEAD OUTLOOKS CLIMATE PREDICTION CENTER NCEP NATIONAL WEATHER SERVICE WASHINGTON DC 3 PM EDT THURSDAY JUNE 13 2002 . . . . . . . . SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS THIS SET OF OUTLOOKS IS AFFECTED BY THREE MAIN FACTORS - SOIL MOISTURE - EL NINO - AND TREND. THE OUTLOOK FOR JULY-AUGUST-SEPTEMBER 2002 CALLS FOR ABOVE NORMAL PRECIPITATION OVER THE CENTRAL ROCKIES - BASED PRIMARILY ON THE CONSTRUCTED ANALOG SOIL MOISURE MODEL - AND DRIER THAN NORMAL CONDITIONS OVER THE PACIFIC NORTHWEST AND NORTHERN GREAT BASIN - DUE TO A STRONG SIGNAL FROM TRENDS WITH SUPPORT FROM SIMILAR PRECEDING ATMOSPHERIC CONDITIONS AND SOIL MOISTURE. TEMPERATURES ARE EXPECTED TO BE ABOVE NORMAL OVER MOST OF THE WEST - TEXAS - AND FLORIDA - PRIMARILY DUE TO LONG-TERM TRENDS. PERSISTENT BELOW NORMAL SSTS ALONG THE WEST COAST WILL KEEP THE WARMTH FROM THE IMMEDIATE COASTAL REGION. ALTHOUGH THERE IS NO INDICATION FOR AVERAGE TEMPERATURES TO BE EITHER ABOVE OF BELOW NORMAL IN THE UPPER MIDWEST AND OHIO VALLEY - WET SOILS IN THESE REGION COULD CONTRIBUTE TO EXCESSIVELY HIGH HUMDIDITY AND DISCOMFORT DURING PERIODS WHEN TEMPERATURES DO GO ABOVE NORMAL. IMPACTS OF WET SOILS COULD CONTINUE INTO AT LEAST THE EARLY PART OF THE AUGUST-SEPTEMBER- OCTOBER SEASON - ALTHOUGH CONTINUING ABOVE NORMAL TEMPERATURES OVER THE SOUTHWEST AND PARTS OF THE SOUTHEAST ARE CONSISTENT WITH LONG-TERM TRENDS. ALTHOUGH RECENT CONDTIONS HAVE BEEN RATHER DRY IN SOUTHEASTERN ALASKA - CONFLICTING OR WEAK SIGNALS FROM THE VARIOUS FORECAST TOOLS REQUIRE THAT CLIMATOLOGICAL PROBABILITIES (EQUAL CHANCES) BE FORECAST FOR ALASKA UNTIL LATE FALL. BEGINNING AT THAT TIME - THE EXPECTED EL NINO - WITH SOME SUPPORT FROM TRENDS - FAVORS ABOVE NORMAL TEMPERATURES OVER AT LEAST THE SOUTHEASTERN PORTION OF THE STATE. RECENTLY THE EQUATORIAAL PACIFIC OCEAN SURFACE TEMPERATURES HAVE SHOWN FURTHER WARMING AND ARE CURRENTLY AT LEAST ONE DEGREE C ABOVE NORMAL FROM 165E TO 100W. THE STRENGTH OF THE ANOMALIES HAS VARIED FROM MONTH TO MONTH DUE TO SHORT-TERM CHANGES IN ATMOSPHERIC PATTERNS NEAR THE EQUATOR - BUT AT THE PRESENT CONDITIONS ARE INDICATIVE OF THE EARLY STAGES OF A WEAK OF MODERATE EL NINO. THE OUTLOOKS FOR THE COLD SEASON REFLECT THIS - SHOWING ABNORMALLY WARM CONDITIONS FOR THE NORTHERN CONTINENTAL U.S. WITH DRIER THAN NORMAL OVER EXPECTED OVER THE NORTHWEST AND NORTHERN GREAT PLAINS. ABNORMALLY WET - AND IN SOME AREAS COLD - CONDTIONS ARE EXPECTED ACROSS MUCH OF THE SOUTH DURING WINTER AND INTO NEXT SPRING. ABOVE MEDIAN PRECIPITATION OCCURS IN CALIFORNIA AND ARIZONA MAINLY WITH VERY STRONG EL NINOS - AND THUS IS NOT FORECAST AT THIS TIME. THE FORECAST REVERTS TO THE TREND - MAINLY WARMER THAN NORMAL TEMPERATURES AROUND THE MARGINS OF THE NATION - IN LATE SPRING AND SUMMER 2003. BASIS AND SUMMARY OF THE CURRENT LONG-LEAD OUTLOOK . . . . . . . . THIS OUTLOOK REFLECTS THE EXPECTED U.S. CLIMATE ANOMALIES BASED ON THE LONG-TERM TREND AS ESTIMATED BY OCN - AND STATISTICALLY BASED RELATIONSHIPS BETWEEN RECENT OCEANIC AND ATMOSPHERIC CONDITIONS AND U.S. TEMPERATURE AND PRECIPITATION FROM THE CANONICAL CORRELATION ANOMALY (CCA) MODEL. DYNAMICAL FORECASTS FROM GENERAL CIRCULATION MODELS WERE ALSO CONSIDERED FOR THE FIRST FOUR SEASONS. THE OUTLOOKS FOR SON 2002 THROUGH MAM 2003 ARE INFLUENCED BY THE ANTICIPATION OF THE DEVELOPMENT OF AN EL NINO EVENT OF PROBABLY MODERATE STRENGTH BY LATE FALL OR EARLY NEXT WINTER. CURRENT ATMOSPHERIC AND OCEANIC CONDITIONS PACIFIC SSTS ARE NOW AT LEAST 1 DEG C ABOVE NORMAL ALONG THE EQUATOR FROM WEST OF THE INTERNATIONAL DATE LINE TO APPROXIMATELY 100W. SUB-SURFACE PACIFIC OCEAN TEMPERATURES ALONG THE EQUATOR ARE MODESTLY WARMER THAN NORMAL AS WELL. SO FAR CONVECTION HAS BEEN ENHANCED MAINLY NEAR AND JUST WEST OF THE DATE LINE. NORMALLLY SEASONALLY DECLINING SSTS OVER THE EASTERN EQUATORIAL PACIFIC WILL NOT SUPPORT CONVECTION UNTIL SOMETIME NEXT WINTER - EVEN WITH ABOVE NORMAL SSTS. CONVECTION NEAR THE DATELINE IS ALSO DECREASING DUE TO THE INFLUENCE OF LARGE SCALE PATTERNS ASSOCIATED WITH THE DEVELOPING ASIAN SUMMER MONSOON. THE SOUTHERN OSCILLATION INDEX HAS BEEN NEGATIVE FOR THREE CONSECUTIVE MONTHS - INDICATING THE ATMOSPHERE IS BEGINNING TO RESPOND TO THE SST ANOMALIES - ALTHOUGH SOME ATMOSPHERIC INDICIES ARE STILL MORE INDICATIVE OF NEUTRAL ENSO CONDITIONS. EXTRATROPICAL NORTH PACIFIC SSTS REMAIN LARGELY BELOW NORMAL NORTH OF 30N - AND ALONG THE WEST COAST OF NORTH AMERICA. SSTS IN THE VICINITY OF HAWAII HAVE WARMED AGAIN DURING THE LAST MONTH TO ABOVE NORMAL. . . . . . . . . PROGNOSTIC DISCUSSION OF SST FORECASTS STATISTICAL AND DYNAMICAL PREDICTIONS OF NINO 3.4 SSTS ARE IN GENERAL AGREEMENT WITH THE IDEA OF A DEVELOPING EL NINO OVER THE NEXT SEVERAL MONTHS TO YEAR. THE CANONICAL CORRELATION ANOMALY PREDICTS AT LEAST A PLUS 1 C ANOMALY FOR ALL SEASONS UNTIL NEXT SUMMER. THE NCEP COUPLED MODEL THIS MONTH IS MUCH SLOWER THAN LAST MONTH TO DEVELOP ABOVE NORMAL SSTS IN THE NINO 3.4 AREA. WE BELIEVE THIS IS DUE TO MONTH-TO-MONTH VARIATIONS IN INITIAL CONDITIONS DUE TO A STRONG MADDEN-JULIAN (MJO) WAVE. CURRENT TEMPERATURES INDICATE A MORE RAPID WARMING AND DEVELOPMENT OF EL NINO - CONSISTENT WITH THE CCA FORECAST. THE CONSTRUCTED ANALOG (CA) METHOD KEEPS TEMPERATURES NEAR NORMAL THROUGH THE REST OF 2002. THE CA PREDICTION DOES NOT ACCOUNT FOR THE SUB-SURFACE OBSERVATIONS WHICH HAVE CHANGED DRAMATICALLY IN THE LAST 6 MONTHS. THIS MAY EXPLAIN ITS LACK OF RESPONSE TO RECENT CHANGES IN EQUATORIAL SSTS. AT THIS POINT WE CAN RULE OUT A COLD EVENT AND PLACE FAIRLY STRONG CONFIDENCE IN THE DEVELOPMENT OF A MODERATE WARM EVENT BY NEXT WINTER. THE MOST RECENT OBSERVATIONS OF SSTS IN THE CENTRAL PACIFIC - ALONG WITH THE SUB SURFACE STRUCTURE SUPPORTS THE ENSO PREDICTION TOOLS THAT FAVOR WARM SSTS. HENCE THE OFFICIAL FORECAST IS FOR A WARM ENSO EVENT TO CONTINUE TO DEVELOP - AT A RATE SIMILAR TO THAT INDICATED BY THE CCA. ABOVE NORMAL CENTRAL EQUATORIAL PACIFIC SSTS ARE ALSO SUPPORTED BY NEARLY ALL MODELS RUN AT OTHER CLIMATE CENTERS. WE NOTE A FEW MODEL RUNS ELSWHERE SHOWING A QUICKLY DEVELOPING WARM EVENT WITH A DEMISE BY FALL. THIS SCENARIO - WHILE POSSIBLE - IS NOT ADOPTED HERE. THE OFFICIAL FORECAST IS FOR A WARM ENSO EVENT TO FURTHER DEVELOP IN THE NEXT 3-6 MONTHS AND PERSIST INTO NEXT SPRING. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOK THE STATISTICAL TOOLS ... CCA - OCN - SMLR... WERE CONSIDERED AT ALL LEAD TIMES. DYNAMICAL MODEL FORECASTS FROM NCEP AND OTHER FORECAST CENTERS WERE CONSULTED FOR THE PERIOD JAS-OND 2002. THE LARGE SCALE CIRCULATION PATTERNS ARE ANTICIPATED TO REFLECT WARM ENSO CONDITIONS BY SOMETIME IN THE FALL AND EXTEND INTO NEXT SPRING - SO WARM EVENT COMPOSITES WERE CONSULTED FOR SEASONS FROM SON 2002 THROUGH MAM 2003. . . . . . . . . PROGNOSTIC DISCUSSION OF OUTLOOKS - JAS 2002 TO JAS 2003 TEMPERATURE: THE AREA OF ABOVE NORMAL TEMPERATURE PREDICTED FOR ASO 2002 IN THE SOUTHEAST WAS EXTENDED TO NORTHERN ALABAMA DUE TO A STRONG OCN SIGNAL. TEMPERATURES FOR OND 2002 THROUGH MAM 2003 REFLECT THE INFLUENCE OF TRENDS AND AN ANTICIPATED MATURE EL NINO EVENT OF MODERATE STRENGHT COMBINED. PROBABILITY ANOMALIES WERE INCREASED SLIGHTLY IN THE NORTH SINCE IT IS NOW SOMEWHAT MORE LIKELY THAT THE STRENGTH OF THE DEVELOPING WARM EVENT WILL BE MODERATE. IN THE ABSENCE OF TRENDS THE WINTERTIME TEMPERATURES THROUGHOUT MUCH OF THE SOUTHERN U.S. TEND TO BE BELOW NORMAL IN A WARM ENSO EVENT. HOWEVER A WARMING TREND ACROSS MUCH OF THE SOUTH MODERATES THE EL NINO SIGNAL. THE ENSO SIGNAL FOR BELOW NORMAL IS STRONG ENOUGH RELATIVE TO THE TREND TO FAVOR BELOW NORMAL TEMPERATURES ONLY OVER FLORIDA NEXT WINTER AND SPRING AND BRIEFLY OVER THE LOWER RIO GRANDE VALLEY DURING FMA 2003. INABILITY TO PREDICT THE PHASE OF THE NAO ON A SEASONAL BASIS - WHICH WOULD DETERMINE THE AMOUNT OF COLD AIR AVAILABLE EAST OF THE ROCKIES - PREVENTS A CLEAR INDICATION OF THE CATEGORICAL FORECAST ACROSS MOST OF THE SOUTH - LEAVING THE ODDS CLOSE TO CLIMATOLOGY IN MOST OF THE GULF COAST AND TEXAS REGION. OCN - WITH VARYING AMOUNTS OF SUPPORT FROM CCA AND SMLR - INDICATES WARMER THAN NORMAL TEMPERATURES FOR MOST SEASONS IN THE SOUTHWEST U.S. HOWEVER THE OCN WARM SIGNAL IN THE SOUTHWEST FOR OND AND DJF WAS NULLIFIED BY INDICATIONS FOR COLD AS SEEN IN ENSO COMPOSITES - HENCE A CL FORECAST FOR THOSE SEASONS. FOR ALASKA ANY SIGNALS SHOWN ARE FOR WARM AND ARE BASED ON ENSO COMPOSITES WITH SOME AGREEMENT FROM OCN. IN MANY CASES - INCLUDING THE EARLY LEADS - CCA AND OCN CONFLICTED AND WE OPTED FOR CL. . . . . . . . . PRECIPITATION: BELOW MEDIAN PRECIPITATION IS FAVORED IN THE PACIFIC NORTHWEST IN JAS DUE TO LONG-TERM TRENDS - CCA AND DYNAMICAL MODEL FORECASTS. LARGE PORTIONS OF THE NATION HAVE DRY INITIAL SOIL MOISTURE CONDITIONS - A MAJOR CONCERN. CONSTRUCTED ANALOG SOIL MOISTURE FORECASTS INDICATE A STRONG IMPACT OF BOTH THE DRY CONDITIONS IN SOUTH TEXAS AND THE ROCKIES AND THE WET CONDITIONS IN THE MIDWEST. THE JAS 2002 FORECAST OF ABNORMAL DRYNESS OVER THE NORTHWEST IS FROM CCA - OCN AND CA. FOR JAS WE ADDED A REGION OF WET CONDITIONS EXPECTED OVER MUCH OF UTAH AND COLORADO PRIMARILY DUE TO A STRONG STATISTICALLY SIGNIFICANT SIGNAL FROM THE CAS MODEL WHICH REQUIRED US TO TRIM THE SOUTHEASTERN PART OF THE DRY AREA FORECAST FOR THE NORTHWEST. AN AREA OF BELOW MEDIAN PRECIPITATION WAS ADDED WEST OF THE CASCADES IN WASHINGTON AND OREGON FOR SON DUE TO ENSO COMPOSITES - AND ALTHOUGH THE MAIN SIGNAL FOR RELATIVE DRYNESS IS CENTERED OVER MONTANA IN SUBSEQUENT SEASONS - RELATIVE DRYNESS OVER WASHINGTON WAS ADDED FOR DJF THROUGH MAM 2003 DUE TO ENSO COMPOSITES - AS WAS A DRY AREA IN THE NORTHERN PLAINS DURING MAM 2003. THE AREAS OF ABOVE MEDIAN IN THE SOUTH WERE CUT FROM ARIZONA IN OND AND NDJ 2002 SINCE AS IN CALIFORNIA - HEAVY PRECIPITATION OCCURS THERE MAINLY DURING STORNG EL NINOS. THE PROBABILITIES FOR WETNESS OVER EAST TEXAS WERE INCREASED DUE TO STRONG AGREEING SIGNALS FROM ENSO COMPOSITES AND OCN. A WET AREA FORECAST OVER FLORIDA AND ADJACENT EAST GULF AND SOUTH ATLANTIC COASTAL AREAS FROM LATE FALL INTO WINTER IS FROM EL NINO COMPOSITES - AND BASED ON THE CURRENT EXPECTATION OF A MODERATE EL NINO - WAS EXTENDED NORTHWARD TO SOUTHERN NEW ENGLAND FOR MAM 2003. BELOW MEDIAN PRECIPITATION PREDICTED FOR THE NORTH CENTRAL STATES AND THE OHIO VALLEY FROM DJF 2003 THROUGH MAM 2003 IS ALSO DUE TO EXPECTED EL NINO INFLUENCES. ABOVE MEDIAN PRECIPITATION PREDICTED FOR THE NORTHWEST IN MJJ 2003 IS FROM OCN WITH SOME SUPPORT FROM CCA - BUT IT WAS REMOVED FOR AMJ DUE TO THE POSSIBILITY THAT LINGERING WINTER DRYNESS FROM EL NINO INFLUDENCES COULD COUNTERACT THE TREND THEN. THERE ARE NO RELIABLE FORECAST INDICATIONS FOR ALASKA PRECIPITATION TO DEPART FROM CLIMATOLOGICAL PROBABILITIES DURING ANY OF THE LEADS AT THIS TIME. FORECASTERS: A. J. WAGNER AND VERN KOUSKY 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 JULY 18 2002. 1971-2000 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 17 2001 FORECAST RELEASE. NNNN NNNN