PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD 830 AM EST THU JAN 18 2007 SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS THE MAIN FACTORS WHICH USUALLY INFLUENCE SEASONAL CLIMATE INCLUDE: 1) EL NINO AND LA NINA - WHICH COMPRISE EL NINO/SOUTHERN OSCILLATION OR ENSO 2) TRENDS - APPROXIMATED BY 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 - 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) AN OBJECTIVE CONSOLIDATION (CALLED 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. EQUATORIAL SEA SURFACE TEMPERATURES (SST) IN THE PACIFIC OCEAN REMAINED ABOVE THEIR LONG-TERM AVERAGE FROM JUST OFF THE SOUTH AMERICAN COAST TO ABOUT 165E WITH DEPARTURES MORE THAN 1 DEGREE C ABOVE AVERAGE OBSERVED BETWEEN 165E AND 175W AND BETWEEN 145W AND 85W. HOWEVER THESE DEPARTURES ARE GENERALLY SMALLER THAN THOSE OBSERVED LAST MONTH... AS THE CURRENT EL NINO EPISODE HAS WEAKENED. THE ATMOSPHERIC INDICATORS DURING DECEMBER WERE ALSO CONSISTENT WITH WEAKENING EL NINO CONDITIONS... AS ENHANCED LOW LEVEL EASTERLIES DOMINATED THE CENTRAL PACIFIC. ANOMALOUS LARGE SCALE CONVECTIVE ACTIVITY IN THE CENTRAL PACIFIC OCEAN WAS CENTERED BETWEEN THE EQUATOR AND 10N. MJO ACTIVITY STRENGTHENED DURING LATE DECEMBER WITH THE CONVECTIVE PHASE ACTIVE OVER INDONESIA DURING LATE DECEMBER... BEFORE MOVING INTO THE WEST PACIFIC DURING EARLY JANUARY AND WEAKENING. DURING THE PAST FEW DAYS... LARGE LOW LEVEL WESTERLY WIND ANOMALIES HAVE RETURNED TO THE CENTRAL PACIFIC. AT THIS TIME IT IS NOT CLEAR HOW OR IF THIS MJO WAVE AND THE RECENTLY OBSERVED WESTERLY WIND ANOMALIES WILL INTERACT OR IMPACT THE CURRENT EL NINO. THE AVERAGE OF SSTS IN THE NINO 3.4 REGION - A BOX BOUNDED BY 120W AND 170W AND BY 5N AND 5S - IS OFTEN USED AS AN INDICATOR OF THE STRENGTH OF AN EL NINO EVENT. SSTS IN THIS REGION PEAKED AT A LITTLE MORE 1 DEGREE C ABOVE NORMAL... BEFORE DECREASING TO NEAR 1 DEG C IN EARLY JANUARY. MOST PREDICTION TOOLS INDICATE THAT SST ANOMALIES IN THE NINO 3.4 REGION WILL DECREASE DURING THE NEXT FEW MONTHS... ALTHOUGH AT VARYING SPEEDS. THUS WEAK OR POSSIBLY MODERATE EL NINO CONDITIONS ARE ANTICIPATED FOR NEXT FEW MONTHS. THEREFORE THIS EVENT HAS THE POTENTIAL TO IMPACT THE CLIMATE OF THE UNITED STATES FOR THE NEXT FEW MONTHS. THE TEMPERATURE OUTLOOK FOR FEB-MAR-APR (FMA) 2007 CALLS FOR WARMER THAN NORMAL CONDITIONS OVER MOST OF THE NORTHERN TWO-THIRDS OF THE NATION... INCLUDING ALASKA. THE CHANCES THAT TEMPERATURES WILL AVERAGE NEAR NORMAL ARE HIGHER THAN USUAL IN THE SOUTHEASTERN U.S FROM TEXAS TO THE SOUTH ATLANTIC COAST. ELSEWHERE THERE ARE EQUAL CHANCES OF WARMER-THAN- ... COOLER-THAN- ... OR NEAR-NORMAL TEMPERATURES. BELOW MEDIAN PRECIPITATION IS EXPECTED FOR FMA 2007 IN PARTS OF THE NORTHERN ROCKIES AND ALSO IN THE OHIO AND TENNESSEE RIVER VALLEYS... AND THE WESTERN GREAT LAKES. THE CHANCES FOR ABOVE MEDIAN PRECIPITATION ARE ELEVATED OVER MUCH OF THE SOUTHERN THIRD OF THE U.S. DUE TO EXPECTATIONS OF AN ENHANCED SOUTHERN JET STREAM ASSOCIATED WITH EL NINO CONDITIONS. THIS AREA INCLUDES THE SOUTHERN HALF OF CALIFORNIA... THE SOUTHWEST... TEXAS AND PARTS OF THE SOUTHERN PLAINS - THE GULF COAST - FLORIDA - AND COASTAL SECTIONS OF GEORGIA AND THE CAROLINAS. ELSEWHERE THERE ARE EQUAL CHANCES OF ABOVE-... BELOW-... OR NEAR-MEDIAN PRECIPITATION DURING FMA. 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 SSTS IN THE EQUATORIAL PACIFIC ARE MORE THAN 0.5 DEG C ABOVE NORMAL FROM ABOUT 160E TO NEAR THE SOUTH AMERICAN COAST...WITH DEPARTURES OF MORE THAN +1.0 DEG C OBSERVED BETWEEN 165E AND 175W AND ALSO FROM 145W TO ABOUT 85W. THE LOW LEVEL EASTERLY WINDS (AT 850 MB) IN THE TROPICAL PACIFIC AVERAGED STRONGER THAN NORMAL DURING THE PAST MONTH AFTER HAVING BEEN GENERALLY WEAKER THAN NORMAL ACROSS MUCH OF THE CENTRAL AND EASTERN EQUATORIAL PACIFIC BETWEEN JULY AND NOVEMBER. THE UPPER OCEAN HEAT CONTENT IN THE EQUATORIAL PACIFIC CONTINUES TO BE ABOVE THE LONG-TERM AVERAGE BUT HAS DECREASED SIGNIFCANTLY DURING THE PAST MONTH. CONVECTIVE ACTIVITY IN THE CENTRAL EQUATORIAL PACIFIC HAS BEEN SLIGHTLY ENHANCED ON THE EQUATOR... BUT MORE SIGNIFICANTLY ENHANCED BETWEEN THE EQUATOR AND 10N. MADDEN-JULIAN OSCILLATION (MJO)ACTIVITY STRENGTHEND DURING LATE DECEMBER AND EARLY JANUARY... ENHANCING CONVECTION OVER INDONESIA AND THEN THE WESTERN PACIFIC. THE SOI INDEX WAS SLIGHTLY NEGATIVE DURING DECEMBER AFTER TURNING SLIGHTLY POSITIVE DURING NOVEMBER. HOWEVER... THE MEAN SEA LEVEL PRESSURE HAS BEEN ABOVE NORMAL AT DARWIN SINCE MAY 2006... WHICH IS PROBABLY A BETTER INDICATOR OF THE WEAK TO MODERATE EL NINO. PROGNOSTIC DISCUSSION OF SST FORECASTS MOST PREDICTION TOOLS FOR NINO 3.4 SST ANOMALIES INDICATE THAT THE CURRENT EL NINO HAS PASSED ITS PEAK AND THE DECLINE IN SST ANOMALIES SEEN IN LATE DECEMBER/EARLY JANUARY WILL CONTINUE. THE MAIN DISAGREEMENT AMONG THE VARIOUS MODEL SOLUTIONS IS THE SPEED WITH WHICH SST ANOMALIES DECREASE AND WHETHER THE DEPARTURES REMAIN SLIGHTLY WARM OR RETURN TO ZERO. THE NCEP CONSOLIDATION SHOWS THAT NINO 3.4 APPROACHES 0.5 DEG C BY MAM. OTHER MODEL SOLUTIONS DO NOT SHOW SUCH A RAPID RETURN TO NEUTRAL CONDITIONS. ALL OF THESE SOLUTIONS ARE MADE LESS CERTAIN BY THE MJO WAVE THAT HAS RESULTED IN WESTERLY WIND ANOMALIES OVER THE WESTERN AND WEST-CENTRAL PACIFIC DURING THE PAST FEW DAYS. IF THESE WINDS PERSIST... THEY MAY KICK OFF AN OCEANIC KELVIN WAVE THAT COULD TEMPORARILY INCREASE THE HEAT CONTENT OF THE UPPER LAYERS OF THE CENTRAL AND EASTERN PACIFIC AND EVENTUALLY INCREASE SST ANOMALIES IN THE EASTERN PACIFIC... DELAYING THE DEMISE OF THIS EPISODE BY A FEW MONTHS. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS THE OUTLOOK FOR FMA 2007 AND MAM 2007 IS BASED ON TEMPERATURE AND PRECIPITATION COMPOSITES FROM EL NINO YEARS. SIGNALS FROM WEAK-TO-MODERATE EL NINOS WERE CONSIDERED... ALTHOUGH THE CFS AND IRI MULTI MODEL ENSEMBLE INDICATE THAT THE EL NINO TELECONNECTIONS MAY BE FAIRLY WEAK. STATISTICAL TOOLS CCA AND SMLR... ALSO SHOW WEAK HINTS OF EL NINO INFLUENCE. THUS CONFIDENCE IN THE EL NINO TELECONNECTIONS WAS REDUCED FROM WHAT MIGHT BE EXPECTED FOR A MODERATE EVENT. THERE IS ALSO SOME UNCERTAINTY AS TO HOW RADIDLY THIS EVENT WILL END AND WHETHER THERE WILL BE ANY SIGNIFICANT ATMOSPHERIC-OCEANIC COUPLING. THE OUTLOOK FOR AMJ 2007 THROUGH FMA 2008 LARGELY REFLECT TRENDS. TEMPERATURE TRENDS ARE POSITIVE AND SUBSTANTIAL FOR THE SOUTHWESTERN U.S. IN MOST OF THE YEAR AND OVER MUCH OF THE COUNTRY IN THE WINTER... AND ARE WEAKEST IN THE FALL. PRECIPITATION TRENDS APPEAR ONLY IN SCATTERED AREAS AND ARE WEAK. A SKILL-WEIGHTED OBJECTIVE BLEND OF CFS... CCA... SMLR... AND OCN IS USED AS THE STARTING POINT FOR THE FORECASTS BEYOND MAM 2007. PROGNOSTIC DISCUSSION OF OUTLOOKS - FMA 2007 TO FMA 2008 TEMPERATURE: THE TEMPERATURE OUTLOOK FOR FMA 2007 CALLS FOR ELEVATED CHANCES OF ABOVE NORMAL SEASONAL AVERAGE TEMPERATURE OVER MUCH OF THE NORTHERN TWO-THIRDS OF THE NATION... INCLUDING ALASKA. THE POSSIBILITY OF AN ACTIVE SOUTHERN STORM TRACK IS EXPECTED TO REDUCE TEMPERATURES ALONG MUCH OF THE SOUTHERN THIRD OF THE CONUS IN FMA 2007 DUE TO THE INFLUENCE OF CLOUDS AND PRECIPITATION. AS A RESULT... THESE AREAS SHOULD HAVE ENHANCED CHANCES OF NEAR NORMAL TEMPERATURES (BECAUSE THE AMOUNT OF EXPECTED COOLING IS NOT SUFFICIENT TO OVERCOME WINTER TIME WARMING TRENDS). THE EL NINO SIGNAL RAPIDLY DIMINISHES IN THE SPRINGTIME... BOTH DUE TO WEAKENING TELECONNECTIONS AND SMALLER SST ANOMALIES EXPECTED AT THAT TIME. THUS EL NINO IS EXPECTED TO HAVE LITTLE INFLUENCE PAST MAM 2007. OUTLOOKS FOR AMJ 2007 AND BEYOND ARE BASED PRIMARILY ON THE CONSOLIDATION TOOL WHICH IS DOMINATED BY THE TREND. PRECIPITATION: THE PRECIPITATION OUTLOOKS FOR FMA 2007 CALL FOR GREATER THAN AVERAGE CHANCES OF ABOVE-MEDIAN PRECIPITATION FOR CENTRAL AND SOUTHERN CALIFORNIA - THE SOUTHWEST - TEXAS - THE SOUTHERN PLAINS - LOUISIANA - COASTAL MISSISSIPPI AND ALABAMA - FLORIDA - AND SOUTHEASTERN SECTIONS OF GEORGIA AND THE CAROLINAS. DUE TO THE UNCERTAINTY ASSOCIATED WITH THE SLOW DEMISE OF THE EL NINO EVENT... PROBABILITIES FOR ABOVE MEDIAN PRECIPITATION IN CALIFORNIA WERE REDUCED. BELOW-MEDIAN PRECIPITATION IS LIKELY DURING FMA FOR THE MIDDLE MISSISSIPPI VALLEY - THE OHIO VALLEY - THE GREAT LAKES AND ALSO IN PARTS OF THE NORTHERN ROCKIES. THE MAM OUTLOOK STILL REFLECTS EL NINO CONSIDERATIONS... NAMELY AN ENHANCED CHANCE FOR WETTER THAN MEDIAN CONDITIONS IN SOUTHERN CALIFORNIA AND THE SOUTHWEST AND ALSO IN FLORIDA AND DRIER THAN AVERAGE IN THE OHIO VALLEY. FOR AMJ 2007 AND BEYOND... THE PRECIPITATION OUTLOOK MAINLY REFLECTS WEAK TRENDS... MOSTLY CONFINED TO THE PACIFIC NORTHWEST AND PARTS OF THE GREAT BASIN... WHERE ABOVE MEDIAN PRECIPITATION IS FAVORED IN MJJ AND BELOW MEDIAN PRECIPITATION IS FAVORED IN JAS AND ASO. THE PRECIPITIATION PROBABILITIES FOR WINTER 2007-08 REFLECT ONLY CLIMATOLOGY BECAUSE OF A WIDE SCATTER IN THE ENSO FORECAST FOR NEXT WINTER. NOTE - AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL PROBABILITIES) ARE NOW LABELED EC (EQUAL CHANCES). FORECASTER: M HALPERT 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 FEB 15 2007. 1971-2000 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 17, 2001 FORECAST RELEASE $$