PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD 830 AM EST THU DEC 21 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 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. SEA SURFACE TEMPERATURES (SST) ALONG THE EQUATOR IN THE PACIFIC OCEAN ARE MORE THAN 1 DEGREE C ABOVE THEIR LONG-TERM AVERAGE FROM JUST OFF THE SOUTH AMERICAN COAST TO ABOUT 165E AND ARE CLOSE TO 2 DEGREES C ABOVE AVERAGE JUST TO THE EAST OF THE INTERNATIONAL DATE LINE. THESE SST ANOMALIES SUGGEST THAT MODERATE EL NINO CONDITIONS WILL BE OBSERVED THIS WINTER. MOST ATMOSPHERIC INDICATORS ALSO POINT TO EL NINO CONDITIONS... ALTHOUGH THE CURRENT ATMOSPHERE-OCEAN COUPLING IS STILL WEAK. LARGE SCALE CONVECTIVE ACTIVITY IN THE CENTRAL PACIFIC OCEAN NEAR THE EQUATOR HAS BEEN INCREASING IN RECENT WEEKS... SO THE COUPLING IS EXPECTED TO STRENGTHEN IN THE NEXT MONTH. THE AVERAGE OF SSTS IN THE NINO 3.4 REGION - A BOX BOUNDED BY 120W AND 170W AND BY 5N AND 5S - IS A GOOD INDICATOR OF THE STRENGTH OF EL NINO. SSTS IN THIS REGION ARE CURRENTLY JUST OVER 1 DEGREE C ABOVE NORMAL... AND MOST PREDICTION TOOLS INDICATE THAT SST ANOMALIES IN THE NINO 3.4 REGION WILL REMAIN AT CURRENT LEVELS FOR THE NEXT MONTH OR SO... AND THEN GRADUALLY DIMINISH IN THE EARLY 2007. THUS MODERATE EL NINO CONDITIONS CAN BE EXPECTED FOR THE EARLY PART OF 2007... AND THIS SHOULD HAVE SIGNIFICANT IMPACTS ON THE UNITED STATES CLIMATE IN THE NEXT THREE TO FOUR MONTHS. THE GENERAL CIRCULATION MODELS AVAILABLE FOR THIS FORECAST INDICATE THAT THE ATMOSPHERIC RESPONSE TO THIS YEARS EL NINO IS NOT AS RELIABLE AS MIGHT BE EXPECTED FOR A STRONGER EL NINO... SUCH AS THE 1997-1998 EVENT. THE TEMPERATURE OUTLOOK FOR JAN-FEB-MAR (JFM) 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.... TEXAS AND THE PARTS OF THE SOUTHERN ROCKIES. ELSEWHERE THERE ARE EQUAL CHANCES OF WARMER-THAN- ... COOLER-THAN- ... OR NEAR-NORMAL TEMPERATURES THE OUTLOOK FOR HAWAII CALLS FOR BELOW-NORMAL AVERAGE TEMPERATURE FROM JFM TO FMA. BELOW MEDIAN PRECIPITATION IS EXPECTED FOR JFM 2007 IN PARTS OF THE NORTHERN ROCKIES AND ALSO IN OHIO AND TENNESSEE RIVER VALLEYS - THE CENTRAL MISSISSIPPI VALLEY AND MUCH OF THE 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 JFM. THE OUTLOOK FOR HAWAII CALLS FOR BELOW-MEDIAN PRECIPITATION FROM JFM TO 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 1 DEG C ABOVE NORMAL FROM ABOUT 160E TO NEAR THE SOUTH AMERICAN COAST...WITH DEPARTURES OF MORE THAN +1.5 DEG C OBSERVED BETWEEN THE DATE LINE AND 160W AND ALSO FROM 130W TO ABOUT 100W. THE LOW LEVEL EASTERLY WINDS (AT 850 MB) IN THE TROPICAL PACIFIC AVERAGED WEAKER THAN NORMAL DURING THE PAST MONTH AND HAVE BEEN GENERALLY WEAKER THAN NORMAL ACROSS MUCH OF THE CENTRAL AND EASTERN EQUATORIAL PACIFIC SINCE JULY. THE UPPER OCEAN HEAT CONTENT IN THE EQUATORIAL PACIFIC CONTINUES TO BE WELL ABOVE THE LONG-TERM AVERAGE AND IS SIMILAR TO LEVELS SEEN DURING PREVIOUS MODERATE WARM ENSO EPISODES. CONVECTIVE ACTIVITY IN THE CENTRAL EQUATORIAL PACIFIC HAS BEEN INCREASING IN THE LAST FEW WEEKS. THE SSTS NEAR THE SOUTH AMERICAN COAST ARE CURRENTLY NEAR OR EVEN SLIGHTLY BELOW NORMAL... ALTHOUGH THIS IS LIKELY DUE TO THE INFLUENCE OF A PASSING KELVIN WAVE... AND WARMER THAN NORMAL TEMPERATURES ARE EXPECTED TO DEVELOP THERE IN THE NEXT FEW WEEKS AS A NEW KELVIN WAVE MIGRATES EASTWARD. MADDEN-JULIAN OSCILLATION (MJO)ACTIVITY HAS BEEN WEAK IN THE PAST FEW WEEKS. THE SOI INDEX WAS VERY SLIGHTLY POSITIVE IN THE PAST MONTH... WHICH IS UNUSUAL IN RELATION TO OTHER ENSO INDICATORS. ALTHOUGH THE SOI IS OFTEN A NOISY INDICATOR... ITS BEHAVIOR SUGGESTS THAT THE ATMOSPHERIC TELECONNECTIONS TO ENSO ARE STILL FAIRLY WEAK. HOWEVER...GIVEN THE STRENGTH OF THE SST ANOMALIES IN THE CENTRAL PACIFIC... ATMOSPHERIC TELECONNECTIONS ARE EXPECTED TO SOON DEVELOP AND MODERATE EL NINO CONDITIONS SHOULD PREVAIL FOR THE NEXT FEW MONTHS. PROGNOSTIC DISCUSSION OF SST FORECASTS MOST PREDICTION TOOLS FOR NINO 3.4 SST ANOMALIES INDICATE ANOMALIES BETWEEN 0.4 DEG C TO 1.2 DEG C FOR JFM 2007. GIVEN THAT THE MODELS HAVE CONSISTENTLY UNDER-ESTIMATED THE MAGNITUDE OF NINO 3.4 ANOMALIES... THE MODELS PREDICTING HIGHER SST ANOMALIES ARE FAVORED... AT LEAST FOR JFM. THERE IS STRONG CONSENSUS THAT NINO 3.4 SST ANOMALIES ARE CURRENTLY NEAR THEIR PEAK VALUES AND SHOULD BEGIN TO DIMINISH IN JANUARY AND GRADUALLY FALL THROUGH THE EARLY MONTHS OF 2007. GIVEN THAT ANOMALIES ARE ALREADY ABOVE 1 DEG. C OVER MUCH OF THE PACIFIC... IT SEEMS LIKELY THAT THE EL NINO WILL MAINTAIN MODERATE INTENSITY THROUGH THE EARLY PART OF THE YEAR... WITH LITTLE CHANCE OF SIGNIFICANT STRENGTHENING. ANOMALIES ARE EXPECTED TO GRADUALLY DECREASE TO LESS THAN +.5 DEG. C BY APR OR MAY. BEYOND THAT NINO 3.4 SST ANOMALIES ARE QUITE UNCERTIAN. RECENT RUNS OF THE CFS PREDICT NINO 3.4 SSTS CLOSER TO NORMAL BY MID-YEAR THAN DID CFS RUNS INITIALIZED LAST MONTH. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS THE OUTLOOK FOR JFM 2007 THROUGH AMJ 2007 IS BASED ON TEMPERATURE AND PRECIPITATION COMPOSITES FROM EL NINO YEARS. SIGNALS FROM WEAK-TO-MODERATE AND MODERATE-TO-STRONG 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 ONLY WEAK HINTS OF EL NINO INFLUENCE. THUS CONFIDENCE IN THE EL NINO TELECONNECTIONS WAS REDUCED FROM WHAT MIGHT BE EXPECTED FOR A MODERATE OR STRONG EVENT. THE OUTLOOK FOR MJJ 2007 THROUGH JFM 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 AMJ 2007. PROGNOSTIC DISCUSSION OF OUTLOOKS - JFM 2007 TO JFM 2008 TEMPERATURE: TEMPERATURE OUTLOOK FOR JFM 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 BOTH JFM AND FMA 2007 DUE TO THE INFLUENCE OF CLOUDS AND PRECIPITATION. AS A RESULT... THESE AREAS SHOULD HAVE ENHANCED CHANCES OF EITHER NEAR OR BELOW NORMAL TEMPERATURES... WITH NEAR NORMAL TEMPERATURES SLIGHTLY FAVORED IN MOST REGIONS (BECAUSE THE AMOUNT OF EXPECTED COOLING IS NOT SUFFICIENT TO OVERCOME WINTER TIME WARMING TRENDS). BELOW NORMAL TEMPERATURES ARE SLIGHTLY FAVORED OVER THE NEAR NORMAL CATEGORY IN THE SOUTHERN ROCKIES IN FMA. 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 AMJ 2007. OUTLOOKS FOR AMJ 2007 AND BEYOND ARE BASED PRIMARILY ON THE CONSOLIDATION TOOL WHICH IS DOMINATED BY THE TREND. THE OUTLOOK FOR HAWAII CALLS FOR BELOW-NORMAL AVERAGE TEMPERATURE FROM JFM TO FMA. PRECIPITATION: THE PRECIPITATION OUTLOOKS FOR JFM-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. BELOW-MEDIAN PRECIPITATION IS LIKELY DURING JFM-FMA FOR THE MIDDLE MISSISSIPPI VALLEY - THE OHIO VALLEY - THE GREAT LAKES AND ALSO IN PARTS OF THE NORTHERN ROCKIES. THE SIGNAL IS STRONGEST FOR JFM AND DIMINISHES STEADILY UNTIL VANISHING BY MJJ. FOR MJJ 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. THE OUTLOOK FOR HAWAII CALLS FOR BELOW-MEDIAN RAINFALL FROM JFM TO FMA. NOTE - AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL PROBABILITIES) ARE NOW LABELED EC (EQUAL CHANCES). FORECASTER: D. UNGER 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 JAN 18 2007. 1971-2000 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 17, 2001 FORECAST RELEASE $$