PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD 830AM EST THURSDAY FEB 17 2011 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. IMPACTS OF THESE EVENTS ARE SUMMARIZED BY SEPARATING 3-MONTH OBSERVATIONS FROM 3 OR MORE DECADES INTO EL NINO, NEUTRAL, AND LA NINA SETS, AVERAGING EACH SEPARATELY, AND THEN COMPUTING ANOMALIES. THESE ARE CALLED "ENSO COMPOSITES", AND ARE USED TO SUBJECTIVELY MODIFY THE FORECAST. 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) THE PACIFIC DECADAL OSCILLATION (PDO) - AN ENSO-LIKE PATTERN OF CLIMATE VARIABILITY AFFECTING BOTH THE TROPICS AND THE NORTH PACIFIC AND NORTH AMERICAN REGIONS, BUT WHICH VARIES ON A MUCH LONGER TIME-SCALE THAN ENSO. 6) PERSISTENTLY DRY OR WET SOILS IN THE SPRING AND 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. 7) STATISTICAL FORECAST TOOLS - CANONICAL CORRELATION ANALYSIS (CCA), SCREENING MULTIPLE LINEAR REGRESSION (SMLR), CONSTRUCTED ANALOGUE (CA) AND ENSEMBLE CCA (ECCA). 8) DYNAMICAL FORECAST MODELS - INCLUDING THE NCEP CLIMATE FORECAST SYSTEM (CFS). AN UPGRADED PARALLEL VERSION OF THE CFS (CFSV2) IS EXPECTED TO BECOME OPERATIONAL BY LATE MARCH 2011. IT IS ANTICIPATED THAT BOTH CFS VERSIONS WILL BE RUN IN PARALLEL UNTIL JUNE 2011, AFTER WHICH THE OLDER VERSION WILL BE TURNED OFF. 9) CONSOLIDATION (CON) - AN OBJECTIVE, SKILL WEIGHTED COMBINATION OF THE OCN, CCA, SMLR, ECCA, 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. MODERATE LA NINA CONDITIONS CONTINUE IN THE TROPICAL PACIFIC OCEAN. SEA SURFACE TEMPERATURES (SSTS) IN THE EQUATORIAL PACIFIC OCEAN ARE BELOW AVERAGE FROM AROUND 160E TO THE SOUTH AMERICAN COAST, WITH SSTS BETWEEN 1 AND 2 DEGREES C BELOW NORMAL IN SOME AREAS. THIS VERY LARGE AREA OF ANOMALOUSLY COOL SSTS HAS SIGNIFICANT IMPACT ON THE LARGE SCALE ATMOSPHERIC CIRCULATION THROUGHOUT THE TROPICAL PACIFIC REGION, WHICH, IN TURN, IS EXPECTED TO CONSIDERABLY INFLUENCE THE MEAN ATMOSPHERIC CIRCULATION PATTERNS OVER NORTH AMERICA. FORECASTS FROM MOST SST PREDICTION MODELS INDICATE LA NINA CONDITIONS AT LEAST THROUGH THE SPRING, WITH SST ANOMALIES PREDICTED TO GRADUALLY DIMINISH INTO THE EARLY SUMMER MONTHS. IT IS TOO EARLY TO SPECULATE WHAT WILL HAPPEN NEXT FALL. TYPICALLY LA NINAS CAN CONTINUE FOR A 2ND YEAR OR TURN TO NORMAL OR INTO EL NINO TERRITORY. THE TEMPERATURE OUTLOOK FOR MAM 2011 REFLECTS TYPICAL SPRING LA NINA CONDITIONS AND FAVORS BELOW AVERAGE TEMPERATURES OVER CENTRAL AND SOUTHERN ALASKA, ALONG THE NORTHERN TIER OF THE CONUS FROM WASHINGTON AND OREGON EASTWARD ACROSS THE NORTHERN ROCKIES TO THE WESTERN GREAT LAKES REGION. THE CHANCES FOR ABOVE AVERAGE MEAN TEMPERATURES ARE ENHANCED FROM THE INTERIOR SOUTHWEST AND SOUTHERN ROCKIES TO THE CENTRAL GULF COAST STATES. THE SEASONAL PRECIPITATION OUTLOOK FOR MAM 2011 FAVORS BELOW-MEDIAN PRECIPITATION AMOUNTS FROM CENTRAL AND SOUTHERN CALIFORNIA EASTWARD THROUGH THE SOUTHERN HALF OF THE ROCKIES, THE CENTRAL PLAINS AND MUCH OF THE SOUTHERN PLAINS, CONTINUING EASTWARD ACROSS THE GULF COAST STATES AND SOUTHERN ATLANTIC COAST STATES. IN LOCATIONS WHERE THE LIKELIHOODS OF SEASONAL MEAN TEMPERATURES AND SEASONAL PRECIPITATION AMOUNTS ARE SIMILAR TO THE CLIMATOLOGICAL PROBABILITIES, EQUAL CHANCES (EC) OF BELOW, NEAR, AND ABOVE AVERAGE TEMPERATURE AND PRECIPITATION ARE INDICATED. 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 OCEAN TEMPERATURES IN THE CENTRAL AND EASTERN TROPICAL PACIFIC REMAINED FAIRLY STEADY IN JANUARY 2011 AND EARLY FEBRUARY. NEGATIVE SEA SURFACE TEMPERATURE (SST) ANOMALIES OF AT LEAST -1.0 C EXTEND ALONG THE EQUATOR FROM ABOUT 160E TO 120W IN EARLY FEBRUARY. IN THE EAST PACIFIC THE SURFACE WATERS HAVE WARMED SOMEWHAT. THE SUB-SURFACE HEAT CONTENT (NEAR-EQUATORIALLY AVERAGED TEMPERATURES IN THE UPPER 300 METERS OF THE OCEAN) STILL INDICATES A LARGE VOLUME OF WATER WITH BELOW NORMAL TEMPERATURES IN THE EAST PACIFIC, BUT LESS SO THAN THREE WEEKS AGO. MOREOVER, WARM WATER BELOW THE SURFACE IN THE WEST PACIFIC HAS MOVED SLIGHTLY EASTWARD. ATMOSPHERIC CONDITIONS THROUGHOUT THE TROPICAL PACIFIC OCEAN ARE CONSISTENT WITH THESE LARGE SCALE SST ANOMALIES, AND INCLUDE: SUPPRESSED CONVECTION OVER THE WESTERN AND CENTRAL EQUATORIAL PACIFIC, UNUSUALLY STRONG LOW-LEVEL EASTERLY WINDS IN THE WEST PACIFIC, AND STRONG UPPER-LEVEL WESTERLY WIND ANOMALIES OVER THE WESTERN AND CENTRAL EQUATORIAL PACIFIC. ENHANCED CONVECTION CONTINUES OVER INDONESIA AND SOUTH AMERICA. COLLECTIVELY, THESE ATMOSPHERIC AND OCEANIC INDICATORS SUGGEST MODERATE TO STRONG LA NINA CONDITIONS. PROGNOSTIC DISCUSSION OF SST FORECASTS STATISTICAL AND DYNAMICAL MODELS PREDICT NEGATIVE SST ANOMALIES IN THE EQUATORIAL PACIFIC TO CONTINUE INTO THE SPRING OF 2011. THEREAFTER, MOST METHODS PREDICT A CONTINUED DECREASE IN SST ANOMALY INTO ENSO NEUTRAL TERRITORY, APPROACHING THE ZERO-ANOMALY LINE BY THE SUMMER. THE HISTORICAL RECORD SHOWS A FAIRLY EVEN MIX OF MULTI-YEAR AND SINGLE YEAR LA NINA EVENTS, SO AT THIS POINT THERE ARE NO STRONG INDICATIONS OF THE ENSO STATE PAST MID 2011. A CONSOLIDATION FORECAST OF THE CFS, A CONSTRUCTED ANALOG TOOL, THE MARKOV MODEL AND THE CCA FORECASTS FOR NINO 3.4 SSTS SHOWS ANOMALIES COOLER THAN -0.5 C ONLY THROUGH MAM2011, SUGGESTING THE STRONG POSSIBILITY OF A TRANSITION FROM LA NINA TO ENSO NEUTRAL CONDITIONS BY THE SUMMER. THEREAFTER, THE CONSOLIDATION TOOL PREDICTS SST DEPARTURES TO REMAIN NEAR ZERO THROUGHOUT THE SUMMER AND INTO THE AUTUMN AND POSSIBLY NEXT WINTER. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS MOST TOOLS PRODUCED FORECASTS CONSISTENT WITH LA NINA COMPOSITES FOR THE SPRING. THEREFORE, THE OUTLOOKS FOR MAM THROUGH AMJ 2011 WERE HEAVILY BASED ON LA NINA COMPOSITES, AS WELL AS THE SKILL-WEIGHTED CONSOLIDATION (CON) FORECASTS, THE CFS DYNAMICAL MODEL, AND TO A LESSER EXTENT, VARIOUS OTHER STATISTICAL AND DYNAMICAL TOOLS MENTIONED IN THE OPENING SUMMARY PARAGRAPH. LA NINA IMPACTS MAY EXTEND INTO THE LATE SPRING DUE TO THE SOIL MOISTURE ANOMALIES CAUSED BY WINTERTIME PRECIPITATION ANOMALIES ASSOCIATED WITH LA NINA. THIS PRIMARILY INCREASES THE LIKELIHOOD OF ABOVE NORMAL TEMPERATURES AND DRIER THAN AVERAGE CONDITIONS IN THE SOUTHERN PART OF THE COUNTRY, AND BELOW NORMAL TEMPERATURES AND WETTER THAN MEDIAN CONDITIONS IN THE INTERIOR NORTHWEST. THE CHANCES OF BELOW-MEDIAN PRECIPITATION AMOUNTS ARE ALSO ENHANCED ACROSS SOUTHERN ALASKA. THIS OVERALL PRECIPITATION PATTERN REFLECTS THE WEAKER THAN AVERAGE SOUTHERN UPPER LEVEL JET STREAM THAT IS USUALLY OBSERVED IN LA NINA WINTERS AND SPRINGS. THE OUTLOOKS FOR MJJ 2011 AND BEYOND ARE BASED ON THE CONSOLIDATION TOOL WHICH IS PRIMARILY INFLUENCED AT THOSE LEADS BY TRENDS RELATED TO DECADAL VARIABILITY AND CHANGES IN THE LONG TERM CLIMATE STATE. PROGNOSTIC DISCUSSION OF OUTLOOKS - MAM 2011 TO MAM 2012 TEMPERATURE THE 3-MONTH TEMPERATURE OUTLOOKS FOR MAM THROUGH AMJ 2011 PRIMARILY REFLECT EXPECTED LA NINA IMPACTS, WHICH DECREASE WITH TIME, AND THE CPC CONSOLIDATION TOOL. PROBABILITIES OF BELOW NORMAL TEMPERATURES ARE ENHANCED IN CENTRAL AND SOUTHERN ALASKA, AS WELL AS FROM THE PACIFIC NORTHWEST EASTWARD ACROSS THE NORTHERN ROCKIES TO THE WESTERN GREAT LAKES REGION. ENHANCED ODDS FOR BELOW NORMAL TEMPERATURES ARE ALSO INDICATED ACROSS THE WEST COAST AS FAR SOUTH AS CENTRAL CALIFORNIA, DUE TO THE EXPECTED INFLUENCE OF ANOMALOUSLY COOL SSTS. BY AMJ, THE OCN PREDICTS A STRONGER TREND FOR ABOVE NORMAL TEMPERATURES IN NORTHERN ALASKA, AND INCREASED PROBABILITIES FOR ABOVE NORMAL TEMPERATURES ACROSS THE INTERIOR SOUTHWEST. FOR MJJ 2011, THERE IS AN ELEVATED CHANCE OF BELOW NORMAL TEMPERATURES IN THE NORTHERN PLAINS, WHICH REFLECTS RECENT LONG-TERM VARIABILITY AND INITIALLY VERY WET SOIL IN THIS REGION. APART FROM THIS, OUTLOOKS FOR MJJ 2011 THROUGH MAM 2012 PRIMARILY REFLECT DECADAL OR LONGER VARIABILITY IN THE LONG TERM CLIMATE STATE FAVORING ABOVE NORMAL TEMPERATURES FOR MUCH OF THE WEST. IN THE LATER LEADS, THE LONGER-TERM TRENDS TILT THE ODDS SLIGHTLY IN FAVOR OF ABOVE NORMAL TEMPERATURES FOR NEW ENGLAND AND THE GREAT LAKES REGION. ABOVE NORMAL TEMPERATURES ARE ALSO SLIGHTLY FAVORED FOR THE LATER LEADS IN ALASKA, WHERE AND WHEN WARMING TRENDS HAVE BEEN RELIABLE INDICATORS OF SEASONAL MEAN TEMPERATURES. PRECIPITATION THE OUTLOOKS FOR MAM THROUGH AMJ 2011 SHOW THE EXPECTED IMPACT OF CIRCULATION ANOMALIES ASSOCIATED WITH LA NINA. THE ODDS OF BELOW MEDIAN PRECIPITATION ARE ELEVATED ACROSS MUCH OF THE SOUTHERN CONUS, WITH A NORTHEAST EXTENSION FROM THE SOUTHERN ROCKIES INTO THE CENTRAL PLAINS. THE LA NINA SIGNAL GRADUALLY DIMINISHES THROUGHOUT THE SPRING. THE ODDS FOR BELOW MEDIAN PRECIPITATION ARE ALSO ENHANCED NEAR THE SOUTHERN COAST OF ALASKA. IN SPITE OF THE FORECAST WEAKENING OF LA NINA INTO THE SPRING, SOIL MOISTURE ANOMALIES IN REGIONS OF EXPECTED DEFICIENT WINTERTIME PRECIPITATION MAY DIMINISH LOCAL EVAPORATIVE MOISTURE SOURCES AND ELEVATE THE CHANCES FOR CONTINUED DRY CONDITIONS LATER IN THE SPRING. DECADAL TRENDS LEAD TO ENHANCED CHANCES OF BELOW MEDIAN PRECIPITATION IN THE PACIFIC NORTHWEST AND OF ABOVE MEDIAN PRECIPITATION IN FLORIDA AND THE CENTRAL PLAINS DURING LATE SUMMER AND EARLY FALL OF 2011. MOST OF THE OUTLOOKS BEYOND SON 2011 SHOW EQUAL CHANCES (EC) BECAUSE OF A LACK OF SKILLFUL INDICATORS, EXCEPT FOR ENHANCED CHANCES OF BELOW MEDIAN PRECIPITATION IN THE SOUTHEAST US DUE TO LONG TERM TRENDS IN JFM THROUGH MAM 2012. NOTE - AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL PROBABILITIES) ARE NOW LABELED EC (EQUAL CHANCES). FORECASTER: HUUG VAN DEN DOOL 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 MAR 17 2011 1971-2000 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 17, 2001 FORECAST RELEASE. $$