PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD 830 AM EDT THU APR 20 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 - 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 - OR NAO - AND 5) PERSISTENTLY DRY OR WET SOILS IN THE SUMMER AND SNOW AND ICE COVER ANOMALIES IN THE WINTER. RAPIDLY WEAKENING LA NINA CONDITIONS ARE APPARENT AS SST ANOMALIES ACROSS MUCH OF THE CENTRAL AND EASTERN EQUATORIAL PACIFIC HAVE DECREASED TO WITHIN HALF A DEGREE CENTIGRADE OF NORMAL BY MID-APRIL. HAVING BOTTOMED OUT IN LATE JANUARY, SEA SURFACE TEMPERATURE ANOMALIES HAVE RETURNED TO ENSO-NEUTRAL VALUES, AND NO IMPACTS FROM ENSO ARE ANTICIPATED AT LEAST THROUGH SUMMER. THE TEMPERATURE OUTLOOK FOR MAY-JUN-JUL (MJJ) 2006 CALLS FOR WARMER THAN NORMAL CONDITIONS ACROSS THE WESTERN AND SOUTHERN U.S., FROM THE PACIFIC COAST STATES TO THE GULF COAST STATES, AND ALSO OVER WESTERN AND SOUTHERN ALASKA. COLDER THAN NORMAL TEMPERATURES ARE EXPECTED ACROSS THE NORTH-CENTRAL UNITED STATES FROM THE DAKOTAS TO MICHIGAN. ELSEWHERE THERE ARE EQUAL CHANCES OF WARMER-THAN ... COOLER-THAN... OR NEAR-NORMAL TEMPERATURES DURING MJJ. THE PRECIPITATION OUTLOOK FOR MAY-JUN-JUL (MJJ) 2006 CALLS FOR DRIER THAN NORMAL CONDITIONS FROM THE SOUTHERN AND CENTRAL GREAT PLAINS NORTHWESTWARD ACROSS THE NORTHERN ROCKIES TO THE INTERIOR PACIFIC NORTHWEST. ABOVE MEDIAN PRECIPITATION IS EXPECTED IN MJJ IN THE WESTERN GREAT LAKES REGION AND UPPER MISSISSIPPI VALLEY. ELSEWHERE THERE ARE EQUAL CHANCES OF PRECIPITATION BEING WETTER-THAN... DRIER-THAN... OR NEAR-MEDIAN DURING MJJ, WHICH ALSO INCLUDES ALL OF ALASKA. 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 THE OCEANIC AND ATMOSPHERIC INDICATORS IN THE TROPICAL PACIFIC REMAIN CONSISTENT WITH RAPIDLY WEAKENING LA NINA CONDITIONS. SEA SURFACE TEMPERATURES DURING MARCH WERE BELOW NORMAL BETWEEN 90W AND THE DATE LINE. AT DEPTH, OCEAN TEMPERATURES WERE BELOW NORMAL ACROSS THE CENTRAL AND EASTERN EQUATORIAL PACIFIC. THE WEST PACIFIC REMAINS WARM BOTH AT THE SURFACE AND AT DEPTH. THE PATTERN OF OLR ACROSS THE TROPICAL PACIFIC HAS BEEN CONSISTENT WITH LA NINA CONDITIONS SINCE NOVEMBER...WITH ENHANCED CONVECTION NEAR INDONESIA AND SUPPRESSED CONVECTION NEAR THE DATE LINE. LOW LEVEL EASTERLIES HAVE BEEN STRONG ACROSS THE EQUATORIAL PACIFIC, ESPECIALLY THE CENTRAL PORTION OF THE BASIN. MJO ACTIVITY IS CURRENTLY VERY WEAK. SSTS ARE ABOVE NORMAL IN MUCH OF THE EXTRATROPICAL NORTH ATLANTIC...ALTHOUGH SSTS SURROUNDING FLORIDA AND ALONG THE SOUTH ATLANTIC COAST ARE BELOW NORMAL. PROGNOSTIC DISCUSSION OF SST FORECASTS THE CONSENSUS OF SEVERAL MODELS USED AT CPC SUGGEST THAT SST ANOMALIES IN THE NINO 3.4 REGION (BETWEEN 5N AND 5S AND 170W TO 120W) HAVE PASSED THEIR MAXIMUM NEGATIVE VALUES. THE MARKOV METHOD MAINTAINS AN ANOMALY SLIGHTLY COLDER THAN -0.5 C THROUGH SUMMER 2006....SUGGESTING THE WEAK LA NINA COULD PERSIST, THOUGH THE CFS CLEARLY PREDICTS ENSO-NEUTRAL CONDITIONS WILL COMMENCE BY EARLY SUMMER. THE CCA IS VERY CLOSE TO ZERO FOR MOST OF THE YEAR, WHILE THE CA STARTS OFF NEAR ZERO, BUT ENDS UP NEAR +0.5 C. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS THE OUTLOOK FOR MJJ 2006 THROUGH MJJ 2007 IS BASED ON THE MULTI-MODEL ENSEMBLE FROM IRI... THE CFS... AND CDC TOOLS BASED ON CLIMATE MODELS ... AS WELL AS THE VARIOUS STATISTICAL TOOLS... INCLUDING CCA... ECCA... SMLR... AND OCN. THE FORECASTS FOR THE FIRST FEW LEADS ARE INFLUENCED TO SOME DEGREE BY THE CONSTRUCTED ANALOG BASED ON SOIL MOISTURE (CAS). FORECASTS FROM MJJ THROUGH OND 2006 PRIMARILY REFLECT THE CONSOLIDATED TEMPERATURE AND PRECIPITATION PRODUCTS (WHICH PRODUCE A SKILL WEIGHTED MIX OF CFS...CCA...SMLR...AND OCN)...AS WELL AS THE CFS...AND LAST MONTHS OFFICIAL FORECASTS VALID FOR THE SAME RESPECTIVE TARGET SEASON. THE OUTLOOKS FOR NDJ 2006 THROUGH MJJ 2007 ARE BASED LARGELY ON A CONSOLIDATION OF CCA... SMLR... AND OCN (CFS IS NOT AVAILABLE AFTER LEAD 6)... AS WELL AS LONG-TERM TRENDS. PROGNOSTIC DISCUSSION OF OUTLOOKS - MJJ 2006 TO MJJ 2007 TEMPERATURE: TEMPERATURE PROBABILITIES FOR MJJ 2006 HAVE BEEN SLIGHTLY REVISED FROM THE CORRESPONDING OUTLOOK ISSUED LAST MONTH... WITH THE OUTLOOK NOW FAVORING A LARGER AREA OF BELOW NORMAL TEMPERATURES ACROSS THE NORTH-CENTRAL U.S. DUE TO GOOD AGREEMENT AMONG MOST OF THE TOOLS. THE OUTLOOK FOR JJA 2006 WAS SLIGHTLY REVISED BY INCREASING THE WARMTH ACROSS THE NORTHERN ROCKIES, REMOVING THE ABOVE NORMAL TEMPERATURES FROM THE CENTRAL PLAINS, AND EXPANDING THE WARMTH ACROSS THE CAROLINAS. THE LAST FEATURE IS TIED TO THE POSSIBILITY OF INCREASING DROUGHT CONDITIONS OVER THE CAROLINAS. ABOVE AVERAGE TEMPERATURES ARE ALSO PREDICTED FOR FAR WESTERN AND FAR SOUTHERN SECTIONS OF ALASKA. FOR JAS 2006, THE FORECAST WAS REVISED TO INCLUDE WARMER THAN NORMAL CONDITIONS ACROSS THE NORTHERN ROCKIES AND NORTHERN GREAT PLAINS. OUTLOOKS FOR THE SEASONS FROM ASO 2006 TO MJJ 2007 MAINLY REFLECT THE CONSOLIDATION FORECASTS, AS WELL AS THE INFLUENCE OF TRENDS. SOME MAPS HAVE 80-90% COVERAGE FOR ABOVE NORMAL DUE TO RECENT UPWARD TRENDS WHICH HAVE BEEN LARGE ESPECIALLY IN WINTER. PRECIPITATION: THERE IS WIDESPREAD CONSENSUS AMONG DYNAMICAL MODELS FOR THE AREA OF BELOW MEDIAN PRECIPITATION ACROSS THE SOUTHERN AND CENTRAL PLAINS ON THE PREVIOUS OUTLOOK TO EXPAND NORTHWESTWARD INTO THE INTERIOR PACIFIC NORTHWEST. THE SMALL WET AREA ACROSS THE UPPER MISSISSIPPI VALLEY IS RETAINED DUE TO SUPPORT FROM THE TOOLS AND ALSO CONSISTENCY WITH BELOW AVERAGE TEMPERATURES PREDICTED OVER THE SAME GENERAL AREA. THE SMALL AREA OF ABOVE MEDIAN PRECIPITATION OVER SOUTHERN ARIZONA WAS REMOVED DUE TO LACK OF STRONG SUPPORT. FOR JJA 2006, THE AREA OF DRIER THAN NORMAL CONDITIONS CENTERED OVER THE CENTRAL HIGH PLAINS WAS REMOVED DUE TO THE LACK OF SOLID AGREEMENT AMONG THE TOOLS REGARDING THIS FEATURE. FOR JAS 2006, AN AREA OF WETNESS OVER THE SOUTH ATLANTIC COAST IS DUE TO THE EXPECTATION OF AN UNUSUALLY ACTIVE ATLANTIC HURRICANE SEASON. OTHERWISE...PRECIPITATION FORECASTS FROM SON 2006 TO MJJ 2007 - WHERE DIFFERENT FROM EQUAL CHANCES - PRIMARILY REFLECT THE CONSOLIDATION TOOL AND LONG-TERM TRENDS. NOTE - AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL PROBABILITIES) ARE NOW LABELED EC (EQUAL CHANCES). FORECASTER: ANTHONY ARTUSA 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 MAY 18 2006. 1971-2000 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 17, 2001 FORECAST RELEASE $$