PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD 830 AM EDT THU MAR 20 2008 SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS THE MAIN FACTORS WHICH USUALLY INFLUENCE THE SEASONAL CLIMATE OUTLOOK INCLUDE: 1) EL NINO AND LA NINA - WHICH COMPRISE EL NINO/SOUTHERN OSCILLATION OR ENSO. 2) TRENDS - APPROXIMATED BY THE OCN TOOL AS 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) THE TROPICAL 30-60 DAY OSCILLATION - SOMETIMES CALLED MADDEN JULIAN OSCILLATION (MJO) - AFFECTS CLIMATE VARIABILITY WITHIN SEASONS. 4) THE NORTH ATLANTIC OSCILLATION (NAO) AND THE PACIFIC NORTH AMERICAN (PNA) PATTERNS - WHICH AFFECT THE TEMPERATURE ANOMALY PATTERN ESPECIALLY DURING THE COLD SEASONS. THESE PHENOMENA ARE CURRENTLY KNOWN TO BE PREDICTABLE ONLY OVER A WEEK OR SO. 5) PERSISTENTLY DRY OR WET SOILS IN THE SUMMER AND SNOW AND ICE COVER ANOMALIES IN THE WINTER. THESE FACTORS TEND TO PERSIST FOR LONG PERIODS AND ACT AS A KIND OF MEMORY IN THE CLIMATE SYSTEM. 6) STATISTICAL FORECAST TOOLS - CANONICAL CORRELATION ANALYSIS (CCA) AND SCREENING MULTIPLE LINEAR REGRESSION (SMLR). 7) DYNAMICAL FORECAST MODELS - INCLUDING THE NCEP CLIMATE FORECAST SYSTEM (CFS). 8) AN OBJECTIVE CONSOLIDATION (ABBREVIATED CON IN THE TEXT) OF THE OCN, CCA, SMLR AND CFS FORECASTS IS USED AS A FIRST GUESS IN PREPARING THE FORECAST MAPS. THIS TECHNIQUE MAKES OPTIMUM USE OF THE KNOWN SKILL OF OUR FORECAST TOOLS. COLD EPISODE (LA NINA) CONDITIONS CONTINUE ACROSS THE TROPICAL PACIFIC, ALTHOUGH THE EPISODE HAS WEAKENED OVER THE PAST FEW WEEKS. SEA SURFACE TEMPERATURES (SSTS) ARE BELOW AVERAGE THROUGHOUT THE EQUATORIAL PACIFIC OCEAN BETWEEN 150E AND 110W. SSTS IN THE NINO 3.4 REGION (FROM 5N TO 5S AND 170W TO 120W) ARE A GOOD INDICATOR OF THE STRENGTH OF A LA NINA. THE WEEKLY NINO 3.4 INDEX VALUE PEAKED IN MID-FEBRUARY NEAR -2.0, AND HAS DECREASED TO NEAR -1.0 BY MID-MARCH. THIS DECREASE IN THE NINO 3.4 INDEX IS CONSISTENT WITH A WEAKENING OF LA NINA CONDITIONS. WEAKENING LA NINA CONDITIONS WERE ALSO OBSERVED AT THIS TIME OF YEAR DURING THE LAST STRONG LA NINA EPISODE IN BOTH 1999 AND 2000. FORECASTS GENERALLY INDICATE MODERATE LA NINA CONDITIONS FOR AMJ 2008, FOLLOWED BY WEAKER LA NINA CONDITIONS THEREAFTER. THE CONSENSUS OF MODEL FORECASTS FOR NINO 3.4 SSTS INDICATE THAT THE CURRENT SST ANOMALY OF MORE THAN 1.0 DEGREES C BELOW NORMAL WILL DECREASE DURING AMJ 2008. MANY MODELS PREDICT A CONTINUATION OF THE CURRENT LA NINA THROUGH NEXT AUTUMN, ALTHOUGH THERE IS A LARGE AMOUNT OF UNCERTAINTY AFTER AMJ 2008... RANGING FROM ENSO-NEUTRAL TO WEAK TO MODERATE LA NINA CONDITIONS. THE TEMPERATURE OUTLOOK FOR AMJ 2008 INDICATES GREATER THAN NORMAL CHANCES OF ABOVE AVERAGE TEMPERATURES FOR MOST OF THE WESTERN AND SOUTHERN U.S. AND ALSO FOR MUCH OF ALASKA, LARGELY BASED ON LONG-TERM TRENDS... WITH CONSIDERATION GIVEN TO AMJ LA NINA COMPOSITES. ELSEWHERE, THE FORECAST CALLS FOR EQUAL CHANCES (EC) OF ABOVE, NEAR AND BELOW AVERAGE TEMPERATURES. THE PRECIPITATION OUTLOOK FOR AMJ 2008 INDICATES AN ENHANCED PROBABILITY OF BELOW AVERAGE PRECIPITATION AMOUNTS IN THE SOUTHWEST FROM CENTRAL AND WESTERN TEXAS TO NEVADA. ELSEWHERE, THE FORECAST CALLS FOR EQUAL CHANCES (EC) OF ABOVE, NEAR AND BELOW AVERAGE PRECIPITATION. BASIS AND SUMMARY OF THE CURRENT LONG-LEAD OUTLOOKS 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 SEA SURFACE TEMPERATURES (SSTS) ACROSS THE EQUATORIAL PACIFIC REMAIN BELOW AVERAGE BETWEEN 110W AND 150E. BY MID-MARCH SSTS WERE MORE THAN 1 DEG C BELOW AVERAGE BETWEEN 160E AND 120W, WITH DEPARTURES MORE THAN 2 DEG CENTERED ON THE DATE LINE. OCEAN TEMPERATURES IN THE UPPER 100 METERS IN THE CENTRAL AND EASTERN EQUATORIAL PACIFIC ALSO REMAINED BELOW NORMAL, WITH THE LARGEST NEGATIVE ANOMALIES... BETWEEN -3 AND -4 C... OBSERVED BETWEEN 120W AND 100W. IN THE WESTERN PACIFIC, SUBSURFACE OCEAN TEMPERATURES ARE GENERALLY 2 C TO 4 C ABOVE AVERAGE BETWEEN 100 AND 250 METERS DEPTH... IMPLYING AN ANOMALOUSLY DEEP THERMOCLINE. OVER THE PAST 30 DAYS, TROPICAL CONVECTION HAS BEEN ENHANCED OVER THE MARITIME CONTINENT AND SUPPRESSED ACROSS THE PACIFIC BETWEEN 140E AND 100W. IN ADDITION, LOW LEVEL (850-HPA) EASTERLY WIND ANOMALIES WERE OBSERVED BETWEEN 130E AND 160W... AND UPPER LEVEL (200-HPA) WESTERLY WIND ANOMALIES WERE OBSERVED OVER THE CENTRAL PACIFIC IN ASSOCIATION WITH CYCLONIC ANOMALIES IN THE SUBTROPICS OF BOTH HEMISPHERES. THESE ATMOSPHERIC CIRCULATION ANOMALIES ARE ALL CONSISTENT WITH MODERATE TO STRONG LA NINA CONDITIONS. PROGNOSTIC DISCUSSION OF SST FORECASTS THE STATISTICAL TOOLS (CCA, MARKOV MODEL AND CONSTRUCTED ANALOG) PREDICT SSTS REMAINING BELOW AVERAGE THROUGH AMJ 2008... PREDICTING A NINO 3.4 SST INDEX VALUE BETWEEN -0.3 AND -1.2 C. WEAK LA NINA CONDITIONS ARE NOW PREDICTED TO CONTINUE BY THE CONSTRUCTED ANALOG AND THE CCA UNTIL NEXT WINTER. THEREAFTER BOTH TECHNIQUES FEATURE SOME DEGREE OF WARMING. IN COMPARISON, BOTH THE CFS AND MARKOV STATISTICAL TECHNIQUE FORECAST THE CONTINUATION OF MODERATE LA NINA CONDITIONS UNTIL THE BEGINNING OF NEXT WINTER. A CONSOLIDATION FORECAST BASED ON THE CCA, CONSTRUCTED ANALOG (CA), MARKOV AND CFS MODEL PREDICTS WEAK LA NINA CONDITIONS FOR AMJ 2008 CONTINUING ALL THE WAY UNTIL DJF 2008. IT IS TOO EARLY TO MAKE A CONFIDENT FORECAST FOR NEXT WINTER, ALTHOUGH IT IS NOTED THAT MANY MODEL FORECASTS DO INDICATE THE POSSIBILITY OF THE CONTINUATION OF AT LEAST WEAK LA NINA CONDITIONS FOR THE REMAINDER OF THE YEAR. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS THE TEMPERATURE AND PRECIPITATION OUTLOOKS FOR ALL LEAD TIMES ARE BASED ON THE CONSOLIDATION (CON), A SKILL-WEIGHTED AND CALIBRATED OBJECTIVE BLEND OF THE CFS, CCA, SMLR AND OCN FORECAST TOOLS. THE TREND DOMINATES THE TEMPERATURE CONSOLIDATION FORECAST FOR ALL PERIODS BEGINNING WITH AMJ 2008... WHILE LA NINA COMPOSITES WERE CONSIDERED FOR SOME OF THE EARLY LEADS. THE CON IS NOT AVAILABLE FOR ALASKA, SO THE FORECAST THERE IS BASED MOSTLY ON THE TRENDS FROM OCN AND THE CFS. THE PRECIPITATION OUTLOOK FOR AMJ THROUGH ASO 2008 IS BASED ON LA NINA COMPOSITES AND ALSO WEAK TRENDS AS INDICATED BY OCN... WITH THE REMAINDER OF THE SUITE OF PRECIPITATION FORECASTS BASED LARGELY ON ANY AVAILABLE WEAK TRENDS. PROGNOSTIC DISCUSSION OF OUTLOOKS - AMJ 2008 TO AMJ 2009 TEMPERATURE: THE TEMPERATURE OUTLOOK FOR AMJ 2008 DEPICTS AN INCREASED PROBABILITY OF ABOVE AVERAGE TEMPERATURES FOR MOST OF THE SOUTHERN PART OF THE NATION, FROM THE SOUTHWEST, ACROSS THE SOUTH CENTRAL TO THE SOUTHEAST AND ALSO OVER MOST OF ALASKA. EQUAL CHANCES (EC) OF ABOVE, NEAR AND BELOW AVERAGE TEMPERATURES ARE EXPECTED ELSEWHERE. FOR ALL LONGER LEADS ENHANCED PROBABILITIES OF ABOVE NORMAL TEMPERATURE COVER DIFFERENT REGIONS OF THE U.S. GREATER PROBABILITIES OF ABOVE NORMAL TEMPERATURES ARE PRIMARILY IN THE WEST FROM MJJ THROUGH JAS AND PRIMARILY IN THE SOUTHWEST, THE GREAT PLAINS AND UPPER MISSISSIPPI VALLEY AS WE PROGRESS INTO NEXT WINTER. GENERALLY SMALL CHANGES HAVE BEEN MADE IN THE FORECASTS RELEASED LAST MONTH. PRECIPITATION: THE PRECIPITATION OUTLOOK FOR AMJ 2008 INDICATES A GREATER PROBABILITY OF BELOW MEDIAN PRECIPITATION FOR THE SOUTHWEST FROM NEVADA THROUGH WESTERN AND CENTRAL TEXAS. FORECASTS FOR ALL LEADS ARE BASED ON THE CONSOLIDATION AND LONG-TERM TRENDS... WITH CONSIDERATION GIVEN TO LA NINA COMPOSITES AND THE CFS FOR LEADS THROUGH ASO 2008. THE CHANCES OF BELOW MEDIAN PRECIPITATION ARE INCREASED FOR PARTS OF THE PACIFIC NORTHWEST FROM MJJ THROUGH ASO 2008 AND AGAIN DURING NEXT WINTER, AS INDICATED BY THE CONSOLIDATION. AN ENHANCED PROBABILITY OF BELOW MEDIAN PRECIPITATION IS INDICATED FOR A BAND EXTENDING FROM THE NORTHWEST THROUGH THE CENTRAL PLAINS TO PARTS OF THE MIDWEST DURING THE SUMMER, CORRESPONDING TO POSSIBLE WEAK TO MODERATE LA NINA CONDITIONS AND THE TREND. THE LIKELIHOOD OF ABOVE MEDIAN PRECIPITATION IS INCREASED FOR MOST OF THE FLORIDA PENINSULA FROM JAS TO SON 2008, AS INDICATED BY THE TRENDS WHICH ARE LARGELY RELATED TO AN INCREASE IN SEASONAL TROPICAL ACTIVITY. BEGINNING IN WINTER (DJF) THROUGH MAM 2009, BELOW MEDIAN PRECIPITATION IS PREDICTED FOR PARTS OF THE SOUTHEAST, RESULTING FROM THE TRENDS. NOTE - AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL PROBABILITIES) ARE NOW LABELED EC (EQUAL CHANCES). FORECASTER: MIKE HALPERT FOR A DESCRIPTION OF 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 FORMATION OF 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 APR 17 2008 1971-2000 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 17, 2001 FORECAST RELEASE. $$