PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD 830 AM EST THU FEB 16 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. WEAK LA NINA CONDITIONS HAVE DEVELOPED DURING THE PAST FEW MONTHS... AS SSTS IN THE CENTRAL EQUATORIAL PACIFIC HAVE BECOME INCREASINGLY NEGATIVE. ALTHOUGH LA NINA CONDITIONS ARE EXPECTED TO CONTINUE FOR THE NEXT THREE TO SIX MONTHS... SINCE THIS IS A WEAK LATE DEVELOPING EPISODE... ITS EFFECT ON THE CLIMATE OF THE NORTH AMERICAN REGION FOR THE NEXT SEASON OR TWO MAY BE WEAK AND INTERMITTENT. IT IS - NEVERTHELESS - A FACTOR CONSIDERED IN THE PREPARATION OF THIS SERIES OF OUTLOOKS. THE TEMPERATURE OUTLOOK FOR MARCH-APRIL-MAY (MAM) 2006 CALLS FOR WARMER-THAN-NORMAL CONDITIONS IN THE SOUTHWESTERN AND SOUTHERN U.S. FROM CALIFORNIA ABOUT AS FAR EAST AS ALABAMA. TEMPERATURES ARE EXPECTED TO BE BELOW AVERAGE FROM EASTERN WASHINGTON AND NORTHEAST OREGON EASTWARD AS FAR AS NORTHWESTERN MINNESOTA. ELSEWHERE THERE ARE EQUAL CHANCES OF WARMER- THAN... COOLER-THAN OR NEAR-NORMAL TEMPERATURES DURING MAM. ABOVE NORMAL TEMPERATURES ARE ANTICIPATED FOR WESTERN ALASKA AND HAWAII. THE PRECIPITATION OUTLOOK FOR MAM CALLS FOR DRIER THAN NORMAL CONDITIONS OVER MOST OF THE SOUTHEAST AND ALSO IN THE SOUTHWEST AND WESTERN PORTIONS OF THE CENTRAL AND SOUTHERN PLAINS. THIS IS A CONSISTENT RESPONSE TO WEAK LA NINA CONDITIONS AND IS PRESENT TO SOME DEGREE AMONG MOST SEASONAL FORECAST TOOLS... PARTICULARLY THE DYNAMICAL MODELS. ELSEWHERE THERE ARE EQUAL CHANCES OF PRECIPITATION BEING WETTER-THAN... DRIER-THAN... OR NEAR-MEDIAN DURING MAM. ABOVE-MEDIAN PRECIPITATION IS ANTICIPATED OVER HAWAII... WHILE THERE ARE NO CLEAR INDICATIONS FOR ALASKA... WHICH IS LEFT WITH EQUAL CHANCES. 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 OCEAN HAVE REACHED VALUES CONSISTENT WITH WEAK LA NINA CONDITIONS DURING RECENT MONTHS. DURING THE PAST WEEK... SSTS ALONG THE EQUATOR IN THE EASTERN AND CENTRAL TROPICAL PACIFIC AVERAGE MORE THAN .5 DEG C BELOW NORMAL FROM 165E TO 110W... WITH MUCH OF THE REGION BETWEEN 170W AND 125W MORE THAN 1 C BELOW NORMAL. SSTS ALONG THE EQUATOR WEST OF 160E REMAIN ABOVE AVERAGE. BELOW NORMAL OCEAN TEMPERATURES IN THE EASTERN PACIFIC EXTEND FROM ABOUT 50 METERS TO OVER 150 METERS DEPTH... SO THE SLIGHT WARMING OF THE EQUATORIAL SSTS TO NEAR AND SLIGHTLY ABOVE NORMAL VALUES EAST OF 110W IS NOT EXPECTED TO HAVE ANY SIGNIFICANT IMPACT ON THE CLIMATE IN THE UPCOMING SEASONS. ABOVE NORMAL OCEAN TEMPERATURES IN THE WESTERN PACIFIC ALSO EXTEND TO DEPTHS OF 150 METERS OR MORE... SO THE PATTERN OF SSTS SHOULD CONTINUE WITH LITTLE CHANGE THROUGH AT LEAST THE NEXT MONTH. MJO ACTIVITY IS CURRENTLY WEAK. SSTS REMAIN ABOVE NORMAL IN MUCH OF THE TROPICAL AND SUBTROPICAL NORTH ATLANTIC... ALTHOUGH SSTS SURROUNDING FLORIDA AND ALONG THE SOUTH ATLANTIC COAST ARE WELL BELOW NORMAL. SSTS IN THE GULF OF ALASKA AVERAGE NEAR NORMAL... ALTHOUGH THE STRONG TROUGH AND OUTFLOW OF AIR FROM THE ARCTIC THAT WAS IN THE VICINITY DURING JANUARY HAS COOLED THE SSTS NEAR THE ALEUTIANS TO SLIGHTLY 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) ARE CLOSE TO THEIR MINIMUM VALUES. THE 3-MONTH SEASONAL MEAN NINO 3.4 SST ANOMALIES ARE FORECAST TO BE LOWEST IN DJF 2005-06... AT AROUND -.6 DEG C... INCREASING TO LESS THAN .5 DEG C BELOW NORMAL BY FMA 2006 AND REMAINING VERY CLOSE TO ZERO FROM THE LATE SPRING THROUGH THE END OF 2006. HOWEVER CURRENT OBSERVATIONS CONTINUE TO BE LOWER THAN THE LOWEST FORECAST VALUES... SO THAT WE MAY HAVE SLIGHTLY STRONGER OR LONGER LASTING LA NINA INFLUENCES THAN WERE FORECAST PREVIOUSLY. IT MIGHT BE NOTED THAT THE CFS AND MKV TOOLS FORECAST LA NINA CONDITIONS TO PERSIST THROUGH THE END OF THE YEAR... WHILE CA AND CCA ARE INDICATING A QUICK RETURN TO NEAR NEUTRAL CONDITIONS BY MAM 2006 AND THE POSSIBILITY OF A WEAK EL NINO BY LATE IN 2006. WITH ALL THINGS CONSIDERED... INCLUDING THE UPCOMING SO-CALLED SPRING BARRIER BEYOND WHICH SKILL IN FORECASTING THE STATUS OF ENSO DECLINES ABRUPTLY... THE ONLY THING MODERATELY CERTAIN IS THAT WEAK LA NINA CONDITIONS ARE LIKELY TO PERSIST FOR ONLY THE NEXT FEW MONTHS. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS THE GRADIENT OF SSTS IN THE EQUATORIAL PACIFIC... BELOW NORMAL IN THE EAST AND CENTRAL PACIFIC WITH NEAR TO ABOVE NORMAL SSTS IN THE WESTERN PACIFIC... IS EXPECTED TO HELP MAINTAIN STRONGER THAN AVERAGE LOW LEVEL EASTERLIES IN THE CENTRAL EQUATORIAL PACIFIC... MAINTAINING LA NINA CONDITIONS FOR THE NEXT FEW MONTHS. CLIMATE MODELS SUGGEST THAT THE ATMOSPHERIC RESPONSE TO THESE CONDITIONS IS SIMILAR TO THAT OF A WEAK LA NINA. THE MODELS HAVE DONE REASONABLY WELL IN REPRODUCING THE CIRCULATION PATTERNS OBSERVED THUS FAR IN RECENT SEASONS... AND THEREFORE THE CLIMATE MODELS ARE GIVEN MORE WEIGHT IN OUTLOOKS FOR MAM AND AMJ 2006 THAN THEY WOULD FROM LONG-TERM SKILL CONSIDERATIONS ALONE. THE OUTLOOK FOR MAM 2006 THROUGH AMJ 2006 IS BASED ON THE CLIMATE MODELS... 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... OCN AND CAS. FORECASTS FROM AMJ THROUGH JAS 2006 REFLECT THE CONSOLIDATED TEMPERATURE PRODUCT... WHICH PRODUCES A SKILL WEIGHTED MIX OF CFS... CCA... SMLR... AND OCN. THE OUTLOOKS FOR ASO 2006 THROUGH MAM 2007 ARE BASED ON A CONSOLIDATION OF CCA... SMLR... AND OCN... ALTHOUGH OCN IS THE PRIMARY INFLUENCE BEYOND JAS. PROGNOSTIC DISCUSSION OF OUTLOOKS - MAM 2006 TO MAM 2007 TEMPERATURE: TEMPERATURE PROBABILITIES FOR MAM 2006 HAVE BEEN REVISED SLIGHTLY FROM THE CORRESPONDING OUTLOOK ISSUED LAST MONTH... WITH THE OUTLOOK NOW FAVORING A SOMEWHAT LARGER AREA OF BELOW AVERAGE TEMPERATURES IN THE PACIFIC NORTHWEST... DUE TO GOOD AGREEMENT AMONG MOST OF THE DYNAMICAL MODELS... CAS... AND LA NINA COMPOSITES OF PAST CASES WITH NEUTRAL OR NEGATIVE ARCTIC AND NORTH ATLANTIC OSCILLATION INDICES. THE ENHANCED CHANCES OF ABOVE NORMAL TEMPERATURES PREDICTED OVER MUCH OF THE SOUTHWEST ARE MAINLY DUE TO TRENDS... WITH SOME ENHANCEMENTS IN CONFIDENCE DUE TO SUPPORT FROM THE CFS AND OTHER MODELS IN THE SOUTHWEST INTO WESTERN TEXAS. THE OUTLOOK FOR FLORIDA WAS ALSO REVISED FROM ABOVE AVERAGE TO EQUAL CHANCES DUE TO THE OBSERVED BELOW NORMAL SSTS CURRENTLY SURROUNDING THE STATE. THE OUTLOOKS FOR AMJ AND MJJ 2006 WERE ALSO REVISED... WITH A LONGER PERSISTENCE OF BELOW AVERAGE TEMPERATURES OVER NORTH DAKOTA AND MINNESOTA. BELOW NORMAL TEMPERATURES ARE FORECAST IN PARTS OF THE NORTHERN TIER OF THE U.S. BY MOST STATISTICAL TOOLS AND DYNAMICAL FORECASTS USED HERE. THE AREA OF ABOVE NORMAL TEMPERATURES WAS EXPANDED EASTWARD SOMEWHAT OVER THE SOUTHERN AND CENTRAL PLAINS WITH SUPPORT FROM CAS AND MOST OF THE DYNAMICAL MODELS... WHICH ARE RESPONDING TO LA NINA CONDITIONS AND INCREASING DROUGHT OVER THE SOUTHERN PLAINS. OUTLOOKS FOR JJA 2006 AND BEYOND ARE SIMILAR TO THOSE ISSUED LAST MONTH... EXCEPT FOR INCREASES IN AREAL COVERAGE OF ABOVE NORMAL TEMPERATURES OVER THE SOUTHERN AND CENTRAL PLAINS DURING THE LATE SUMMER MONTHS TO REFLECT THE LIKELIHOOD OF DROUGHT CONDITIONS CONTINUING THERE. OUTLOOKS FOR THE SEASONS FROM SON 2006 THROUGH MAM 2007 MAINLY REFLECT THE INFLUENCE OF TRENDS. PRECIPITATION: THERE IS WIDESPREAD CONSENSUS AMONG DYNAMICAL MODELS FOR BELOW MEDIAN PRECIPITATION OVER LARGE PARTS OF THE SOUTHERN THIRD OF THE CONUS FOR MAM 2006. CCA... ECCA AND SMLR FORECASTS ALSO SUPPORT THE FORECAST FOR BELOW MEDIAN PRECIPITATION OVER PORTIONS OF THE SOUTHERN CONUS. THE STRONGEST INDICATIONS ARE OVER THE SOUTHWEST... IN THE CENTRAL PLAINS... AND IN THE EXTREME SOUTHEAST. ABOVE MEDIAN PRECIPITATION IS FORECAST FOR THE NORTHERN OHIO VALLEY... WHICH IS CONSISTENT WITH LA NINA CONDITIONS AND IS EVIDENT IN SOME OF THE DYNAMICAL MODELS AND THE CONSOLIDATION FORECAST. DYNAMICAL MODELS PERSIST THE DRY CONDITIONS IN PARTS OF THE SOUTHERN CONUS THROUGH MJJ 2006... AND SHOW WETTER THAN MEDIAN CONDITIONS IN THE GREAT LAKES REGION FOR AMJ AND ALONG THE BORDER OVER NORTH DAKOTA AND MINNESOTA THROUGH JJA... AND THESE INDICATIONS WERE INCORPORATED INTO THE OFFICIAL FORECAST. INDICATIONS FOR INCREASING DRYNESS OVER THE GREAT PLAINS FROM CAS WERE ALSO USED IN THE PRECIPITATION FORECASTS FROM MAM THROUGH JJA 2006. A SLIGHTLY ENHANCED SUMMER MONSOON IS FORECAST FOR ARIZONA DUE TO HINTS FROM CAS... SOME OF THE DYNAMICAL MODELS... AND COMPOSITES OF SUMMERS FOLLOWING PAST SEASONS WITH LA NINA OR DEFICIENT COLD-SEASON SNOW PACK IN THE GREAT BASIN. OTHERWISE... PRECIPITATION FORECASTS FOR SEASONS BEYOND JJA... WHERE DIFFERENT FROM EQUAL CHANCES... PRIMARILY REFLECT LONG-TERM TRENDS. NOTE - AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL PROBABILITIES) ARE NOW LABELED EC (EQUAL CHANCES). FORECASTER: A. J. WAGNER 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 MAR 16 2006. 1971-2000 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 17, 2001 FORECAST RELEASE $$