PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD 830AM EDT THURSDAY OCT 21 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) CONSOLIDATION (CON) - AN OBJECTIVE, SKILL AND SPREAD-WEIGHTED 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-TO-STRONG LA NINA CONDITIONS CONTINUE IN THE TROPICAL PACIFIC OCEAN. SEA SURFACE TEMPERATURES (SSTS) IN THE TROPICAL PACIFIC HAVE DECLINED TO VALUES RANGING FROM 1 TO 2.5 DEGREES C BELOW LONG-TERM AVERAGES. BUOY MEASUREMENTS OF OCEAN TEMPERATURE FROM THE SURFACE TO 600 METERS BELOW THE SURFACE INDICATE THE EXISTENCE OF A POOL OF SUBSURFACE WATER WHICH IS FROM 1 TO 6 CENTIGRADE DEGREES COOLER THAN LONG TERM AVERAGES, BETWEEN ABOUT THE DATE LINE TO NEAR THE COAST OF SOUTH AMERICA, WITH COLDEST TEMPERATURES BETWEEN ABOUT 50 AND 125 METERS BELOW THE SURFACE, BETWEEN ABOUT 160W AND 110W. THIS FEATURE SUPPORTS THE MAINTENANCE AND CONTINUATION OF THIS LA NINA EVENT. THE NDJ 3-MONTH TEMPERATURE OUTLOOK CALLS FOR BELOW AVERAGE TEMPERATURES OVER CENTRAL AND SOUTHERN ALASKA, MUCH OF WASHINGTON, AND FOR COASTAL REGIONS OF OREGON AND NORTHERN CALIFORNIA. ABOVE AVERAGE TEMPERATURES ARE CALLED-FOR FROM TEXAS AND THE SOUTHWEST ACROSS THE SOUTHERN AND CENTRAL ROCKIES, THE CENTRAL AND SOUTHERN GREAT PLAINS, THE LOWER AND MIDDLE MISSISSIPPI VALLEY, TO SOUTHERN SECTIONS OF THE GREAT LAKES. THE NDJ 3-MONTH PRECIPITATION OUTLOOK CALLS FOR ABOVE-MEDIAN PRECIPITATION FOR THE NORTHWEST, SECTIONS OF NORTHERN CALIFORNIA, SECTIONS OF THE NORTHERN ROCKY MOUNTAINS, AND FOR THE SOUTHERN GREAT LAKES, OHIO, INDIANA AND KENTUCKY. BELOW-MEDIAN PRECIPITATION IS LIKELY FOR EASTERN SECTIONS OF THE SOUTHWEST, TEXAS, OKLAHOMA, SECTIONS OF KANSAS AND MISSOURI, THE GULF COAST STATES, AND THE MIDDLE ATLANTIC COAST STATES AS FAR NORTH AS NEW JERSEY. IN LOCATIONS WHERE THE LIKELIHOODS OF SEASONAL MEAN TEMPERATURES AND SEASONAL PRECIPITATION AMOUNTS ARE 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 OCEAN TEMPERATURES IN THE CENTRAL AND EASTERN TROPICAL PACIFIC CONTINUED TO COOL DURING SEPTEMBER. NEGATIVE SEA SURFACE TEMPERATURE (SST) ANOMALIES REACHED AT LEAST -1.0C ACROSS MOST OF THE EQUATORIAL PACIFIC OCEAN EAST OF 165E BY THE END OF SEPTEMBER. ALSO ALL OF THE NINO INDICES REMAINED BETWEEN –1.3C AND –1.8C AT THE END OF THE MONTH. THE SUBSURFACE HEAT CONTENT (AVERAGE TEMPERATURES IN THE UPPER 300M OF THE OCEAN) AT THE END OF SEPTEMBER INDICATED THE CONTINUED PRESENCE OF A LARGE VOLUME OF RELATIVELY COLD WATER BETWEEN ABOUT THE DATE LINE AND THE SOUTH AMERICAN COAST, FROM ABOUT 50 METERS, TO ABOUT 125 METERS BELOW THE SURFACE. ATMOSPHERIC CONDITIONS CONSISTENT WITH LA NINA, OBSERVED DURING SEPTEMBER INCLUDE: ENHANCED CONVECTION OVER INDONESIA, SUPPRESSED CONVECTION OVER THE WESTERN AND CENTRAL EQUATORIAL PACIFIC, AND UNUSUALLY STRONG LOW-LEVEL EASTERLY WINDS AND UPPER-LEVEL WESTERLY WINDS OVER THE WESTERN AND CENTRAL EQUATORIAL PACIFIC. PROGNOSTIC DISCUSSION OF SST FORECASTS STATISTICAL AND DYNAMICAL MODELS PREDICT NEGATIVE SST ANOMALIES TO CONTINUE INTO NEXT SPRING. BIAS-CORRECTED SST FORECASTS FROM THE NCEP CLIMATE FORECAST SYSTEM (CFS)INDICATE THAT THE NINO 3.4 ANOMALY WILL BE NEAR -1.75 C DURING NDJ. THE CFS BIAS-CORRECTED FORECASTS INDICATE SSTS ARE LIKELY TO DECLINE AFTER THE NOVEMBER-DECEMBER TIME FRAME, TO ABOUT -.75 C BELOW NORMAL IN MAM. THE CPC SST CONSOLIDATION FORECAST IS MORE CONSERVATIVE, PREDICTING ANOMALIES BETWEEN -1.0 AND -1.5 C THROUGH 2010, AND DECLINING TO ABOUT -0.5 C BY MAM 2011. AN INCREASING ARRAY OF FORECAST TOOLS INDICATE THE LA NINA EVENT MAY CONTINUE BEYOND SPRING. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS THERE WAS OUTSTANDING CONSISTENCY AMONG THE STATISTICAL AND DYNAMICAL FORECAST TOOLS FOR THIS FORECAST. THE CPC CONSOLIDATION WAS THE STARTING POINT USED FOR THE SEASONAL TEMPERATURE AND PRECIPITATION OUTLOOKS. TEMPERATURE AND PRECIPITATION COMPOSITES FOR LA NINA CONDITIONS WERE EXTENSIVELY USED TO MODIFY THE CONSOLIDATION FOR NDJ 2010 THROUGH THE AMJ 2011 OUTLOOKS. THE CFS TEMPERATURE AND PRECIPITATION FORECASTS CONTRIBUTED TO THE FORECASTS UNTIL AMJ 2011. OUTLOOKS FOR MJJ 2011 AND BEYOND ARE BASED PRIMARILY ON THE CPC CONSOLIDATION FORECAST WHICH IS INFLUENCED IN SOME REGIONS BY TEMPERATURE AND PRECIPITATION TRENDS RELATED TO DECADAL VARIABILITY IN THE LONG TERM CLIMATE STATE. PROGNOSTIC DISCUSSION OF OUTLOOKS - NDJ 2010 TO NDJ 2011 TEMPERATURE THE 3-MONTH TEMPERATURE OUTLOOKS FOR NDJ 2010-11 THROUGH AMJ 2011 PRIMARILY REFLECT EXPECTED LA NINA IMPACTS. PROBABILITIES OF BELOW NORMAL TEMPERATURES ARE ENHANCED IN MOST OF ALASKA, THE PACIFIC NORTHWEST, THE NORTHERN ROCKIES, AND EXTENDING EASTWARD INTO THE NORTHERN PLAINS AND THE WESTERN GREAT LAKES DURING MID-WINTER. PROBABILITIES OF ABOVE NORMAL TEMPERATURES ARE ENHANCED IN MUCH OF THE CENTRAL AND SOUTHERN U.S. THE OUTLOOKS FOR MJJ THROUGH NDJ 2011-12 PRIMARILY REFLECT DECADAL VARIABILITY IN THE LONG TERM CLIMATE STATE FAVORING ABOVE NORMAL TEMPERATURES FOR MUCH OF THE WEST. AN ELEVATED CHANCE OF BELOW NORMAL TEMPERATURES IN THE NORTHERN PLAINS IN MJJ 2011 REFLECTS RECENT DECADAL VARIABILITY IN THIS REGION. ABOVE NORMAL TEMPERATURES ARE ALSO FAVORED FOR ALASKA IN THESE LATER LEADS WHERE AND WHEN WARMING TRENDS HAVE BEEN RELIABLE INDICATORS OF SEASONAL MEAN TEMPERATURES. PRECIPITATION THE PRECIPITATION OUTLOOK FOR NDJ 2010 INDICATES INCREASED CHANCES FOR ABOVE MEDIAN PRECIPITATION FOR SECTIONS OF THE NORTHWEST, AND FOR THE TENNESSEE AND OHIO VALLEY TO SOUTHERN SECTIONS OF THE GREAT LAKES DUE TO LA NINA IMPACTS. LA NINA ALSO FAVORS BELOW MEDIAN RAINFALL IN MUCH OF THE SOUTH, AND ESPECIALLY IN SECTIONS OF THE SOUTHEAST. THE OUTLOOKS FOR DJF 2010-11 THROUGH AMJ 2011 SHOW THE EXPECTED IMPACT OF LA NINA. THIS INCLUDES ENHANCED PROBABILITIES OF ABOVE MEDIAN PRECIPITATION IN THE PACIFIC NORTHWEST AND NORTHERN ROCKIES, AND IN THE OHIO VALLEY AND TENNESSEE. DRY CONDITIONS PREDICTED FOR THE SOUTHWEST AND SOUTHEAST DURING DJF-MAM RELFECT LA NINA. BOTH THE IMPACT OF LA NINA CONDITIONS AND THE CONFIDENCE IN ENSO PREDICTIONS DECREASE IN THE SPRING OF 2011. 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. NOTE - AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL PROBABILITIES) ARE NOW LABELED EC (EQUAL CHANCES). FORECASTER: ED O'LENIC 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 NOV 18 2010 1971-2000 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 17, 2001 FORECAST RELEASE. $$