PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD 830 AM EDT THU APR 15 2010 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 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). 9) AN OBJECTIVE CONSOLIDATION (ABBREVIATED CON IN THE TEXT) 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. EL NINO CONDITIONS CONTINUE ACROSS THE TROPICAL PACIFIC, AT LEAST IN OCEANIC TERMS. THE MOST RECENT MONTHLY SEA SURFACE TEMPERATURE DEPARTURES FROM NORMAL RANGE FROM +1.0 TO +2.0 C ABOVE NORMAL ACROSS MANY AREAS IN THE EQUATORIAL CENTRAL AND EASTERN PACIFIC. THE MJJ 2010 TEMPERATURE OUTLOOK INDICATES THAT ABOVE-NORMAL SEASONAL MEAN TEMPERATURES ARE FAVORED FOR MUCH OF THE WESTERN U.S. AND ALASKA, AS WELL AS FOR THE INTERIOR SOUTHEAST, WITH ENHANCED CHANCES FOR BELOW-NORMAL TEMPERATURES FOR PORTIONS OF THE GREAT PLAINS. THE CHANCES OF ABOVE MEDIAN SEASONAL PRECIPITATION DURING MJJ 2010 ARE GREATER THAN CLIMATOLOGY FOR PARTS OF THE NORTHEAST U.S. AND GREAT PLAINS. IN LOCATIONS WHERE THE LIKELIHOOD SEASONAL MEAN TEMPERATURE AND SEASONAL TOTAL PRECIPITATION IS SIMILAR TO THE CLIMATOLOGICAL PROBABILITIES, EQUAL CHANCES 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 SEA SURFACE TEMPERATURE (SST) ANOMALIES REMAIN ABOVE-NORMAL ACROSS MANY AREAS OF THE EQUATORIAL PACIFIC OCEAN. ALTHOUGH POSITIVE SST DEPARTURES NEAR THE DATE LINE HAVE DECREASED SOME IN RECENT WEEKS, A LARGE AREA IN EXCESS OF +1.0 DEGREE C ANOMALIES REMAINS FROM 170E TO THE SOUTH AMERICAN COAST. AT DEPTH, POSITIVE OCEAN TEMPERATURE ANOMALIES WELL OVER +1.0 C HAVE BEEN MOVING STEADILY EAST AND ARE COMING CLOSER TO THE SURFACE IN THE EAST PACIFIC. BELOW NORMAL TEMPERATURE DEPARTURES OF 2C OR BETTER AT DEPTHS GREATER THAN 75 METERS HAVE ALSO MOVED EAST AND HAVE REACHED 140W. ATMOSPHERIC CONDITIONS ARE NO LONGER CONSISTENT WITH EL NINO AS THEY WERE AS RECENT AS MARCH. THIS IS TRUE EVEN IN THE TROPICS. PROGNOSTIC DISCUSSION OF SST FORECASTS BIAS-CORRECTED FORECASTS FROM THE NCEP CLIMATE FORECAST SYSTEM (CFS) DYNAMICAL COUPLED OCEAN-ATMOSPHERE MODEL INDICATE THAT THE NINO 3.4 SST ANOMALY WILL FALL BELOW +0.5 C DURING MJJ 2010. THE CPC SST CONSOLIDATION FORECAST (AN OBJECTIVE, SKILL WEIGHTED COMBINATION OF THE CFS AND THREE STATISTICAL SST FORECASTS) ALSO TERMINATES THE PRESENT EL NINO. WHAT HAPPENS AFTER THAT IS UNCERTAIN. CFS SHOWS MILDLY COLD CONDITIONS TO DEVELOP BUT NO CLEAR LA NINA BY THE -0.5 C CRITERION. CCA AND MRK STAY ON THE WARM SIDE NEAR +0.5. ONLY THE CONSTRUCTED ANALOGUE GOES FOR A CLEAR LA NINA (10 OUT OF 12 MEMBERS DO SO) FROM LATE SUMMER ONWARD. SEVERAL OTHER MODELS RAN ELSEWHERE, SEE IRI PLUME, START TO HINT INCREASINGLY AT A LA NINA POSSIBILITY FOR NEXT WINTER. AT THIS TIME THE CPC CONSOLIDATED FORECAST IS NEAR NEUTRAL FOR THE NEXT 12 MONTHS. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS THE CPC CONSOLIDATION (A SKILL-WEIGHTED AND CALIBRATED-PROBABILITY FORECAST DERIVED FROM THE CFS, SMLR, OCN, ECCA AND CCA FORECAST TOOLS) WAS THE PRIMARY TOOL USED FOR THE MAJORITY OF THE SEASONAL TEMPERATURE AND PRECIPITATION OUTLOOKS AND ACTED AS A BACKGROUND FIRST GUESS FORECAST. DURING THE FIRST TWO LEADS SOIL MOISTURE AND SST CONDITIONS WERE USED IN SOME AREAS TO MODIFY THE FORECAST. THE CFS TEMPERATURE AND PRECIPITATION FORECASTS WERE USED UP TO AND INCLUDING OND 2010. THE TEMPERATURE AND PRECIPITATION OUTLOOKS FROM OND 2010 THROUGH MJJ 2011 ARE BASED ON THE CPC CONSOLIDATION FORECAST WHICH IS DOMINATED BY TREND. PROGNOSTIC DISCUSSION OF OUTLOOKS - MJJ 2010 TO MJJ 2011 TEMPERATURE: THE TEMPERATURE OUTLOOK FOR MJJ 2010 INDICATES THAT THE CHANCES OF BELOW NORMAL TEMPERATURES ARE ELEVATED OVER THEIR CLIMATOLOGICAL PROBABILITY FOR MUCH OF THE GREAT PLAINS. ABOVE NORMAL TEMPERATURES ARE FAVORED FOR MOST OF THE WESTERN THIRD OF THE CONUS, ALASKA AND PARTS OF THE INTERIOR SOUTHEAST. ABOVE NORMAL SOIL MOISTURE AND DECADAL TEMPERATURE TRENDS CONTRIBUTE TO THE FORECAST OF ENHANCED CHANCES FOR BELOW NORMAL TEMPERATURES FOR THE NORTHERN PLAINS. FOR THE SOUTHERN PLAINS, A COMBINATION OF DYNAMICAL MODEL FORECASTS, AND ABOVE NORMAL SOIL MOISTURE ENHANCE CHANCES FOR BELOW-NORMAL TEMPERATURES. THE CONSOLIDATION INDICATES INCREASED CHANCES FOR ABOVE NORMAL TEMPERATURES IN THE SOUTHEAST AS WELL BUT WE KEEP THE PROBABILITIES MODEST BECAUSE OF COLD SEA SURFACE TEMPERATURES. FOR THE WESTERN CONUS, ABOVE-NORMAL TEMPERATURES ARE FAVORED WITH THE HIGHEST PROBABILITY IN THE INTERIOR SOUTHWEST WHERE TRENDS HAVE BEEN HUGE IN THIS SEASON, ENOUGH TO OVERCOME SOMEWHAT COOL INDICATIONS FROM DYNAMICAL MODELS. NO SUBSTANTIAL CLIMATE SIGNALS ARE PRESENT FROM THE FORECAST TOOLS ACROSS THE REMAINDER OF THE U.S. SO CLIMATOLOGICAL PROBABILITIES FOR THE THREE CATEGORIES ARE INDICATED. THE LATER LEADS FROM JJA 2010 TO MJJ 2011 ARE LARGELY BASED ON THE CON WITH MOST OF THE PREDICTABILITY OF SEASONAL MEAN TEMPERATURES ARISING FROM RECENT TRENDS. FOR THE JJA 2010 TO ASO 2010 SEASONS, ABOVE NORMAL TEMPERATURES ARE FAVORED ACROSS MUCH OF THE WESTERN CONUS, PARTS OF ALASKA AND THE SOUTHEAST U.S.. ELEVATED CHANCES FOR BELOW-NORMAL TEMPERATURES ARE INDICATED DURING JJA 2010 ACROSS PARTS OF THE UPPER-MISSISSIPPI VALLEY MAINLY AS A RESULT OF DYNAMICAL MODEL FORECASTS. INCREASED PROBABILITIES OF ABOVE NORMAL TEMPERATURES ARE EXPECTED PRIMARILY ACROSS THE SOUTHWEST U.S. AND PARTS OF THE GREAT LAKES AND NORTHEAST DURING SON 2010 THROUGH NDJ 2010. THEREAFTER THROUGH MJJ 2011, INCREASED CHANCES FOR ABOVE-NORMAL TEMPERATURES ARE INDICATED ACROSS THE SOUTHWEST U.S. AND PARTS OF ALASKA, WITH ELEVATED CHANCES OF BELOW-NORMAL TEMPERATURES IN THE NORTHERN PLAINS IN AMJ AND MJJ 2011. ALL THESE SIGNALS ARE PRIMARILY TRENDS. PRECIPITATION: THE PRECIPITATION OUTLOOK FOR MJJ 2010 INDICATES INCREASED CHANCES FOR ABOVE-MEDIAN PRECIPITATION FOR MUCH OF THE CENTRAL PLAINS, AND NORTHEAST U.S.. THE LATTER SIGNAL IS BASED ON TREND. THE CENTRAL PLAINS WETNESS HAS SOME SUPPORT FROM DIFFERENT TOOLS IN DIFFERENT AREAS. RECYCLING OF MOISTURE FROM INITIALLY WET SOIL CONTRIBUTE TO THIS WET AND COOL FORECAST. NO SUBSTANTIAL CLIMATE SIGNALS ARE PRESENT FROM THE FORECAST TOOLS ACROSS THE REMAINDER OF THE U.S. SO CLIMATOLOGICAL PROBABILITIES FOR ABOVE-, NEAR- AND BELOW-MEDIAN PRECIPITATION ARE INDICATED. FROM JJA 2010 THROUGH MJJ 2011, THE CON WAS THE PRIMARY BASIS FOR THE FORECASTS WITH THE STRONGEST INFLUENCE FROM LONG-TERM TRENDS AND STATISTICAL FORECAST TOOLS. SOME NOTABLE HIGHLIGHTED AREAS INCLUDE ENHANCED CHANCES FOR BELOW-MEDIAN PRECIPITATION FOR THE PACIFIC NORTHWEST AND ABOVE-MEDIAN PRECIPITATION FOR PARTS OF THE CENTRAL AND NORTHERN PLAINS FROM JJA 2010 THROUGH ASO 2010. THE DRYNESS IN SUMMER IN THE WEST AND NORTHWEST WAS EXTENDED SOMEWHAT INTO THE SOUTHWEST FROM JAS THROUGH SON, MAINLY BASED ON CFS. DECADAL PRECIPITATION TRENDS INDICATE AN INCREASED LIKELIHOOD OF BELOW MEDIAN PRECIPITATION FOR THE SOUTHEAST FROM DJF 2011 TO MAM 2011, AND FOR THE SOUTH COAST OF ALASKA FROM FMA 2011 TO AMJ 2011. 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 THU MAY 20 2010 1971-2000 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 17, 2001 FORECAST RELEASE. $$