PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD 830 AM EDT THU OCTOBER 21 2004 . . . . . . . . SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS CURRENT OBSERVATIONS INDICATE THAT WEAK WARM EPISODE CONDITIONS (EL NINO) CONTINUE OVER THE EQUATORIAL PACIFIC AND A MAJORITY OF SEA SURFACE TEMPERATURE (SST) PREDICTION TOOLS INDICATE THAT AT LEAST WEAK EL NINO CONDITIONS WILL CONTINUE FROM THIS FALL THROUGH THE FIRST FEW MONTHS OF 2005. THERE IS A CHANCE THAT THE EL NINO COULD STRENGTHEN TO MODERATE INTENSITY AND A SMALLER CHANCE THAT IT WILL WEAKEN BACK TO NEUTRAL STATUS. HOWEVER THE CONSENSUS AMONG STATISTICAL AND DYNAMICAL MODEL PREDICTIONS CONTINUES TO INDICATE THAT THREE-MONTH AVERAGED SST ANOMALIES IN THE CENTRAL EQUATORIAL PACIFIC AVERAGED OVER THE REGION BOUNDED BY 120W TO 170W AND WITHIN 5 DEGREES OF THE EQUATOR (NINO 3.4 REGION) WILL MOST LIKELY REMAIN IN THE RANGE OF +0.5 TO +1.0 DEG C FROM OND 2004 THROUGH MAM 2005. AFTER MAM 2005 THE OUTLOOK BECOMES MORE UNCERTAIN... BUT MOST MODELS INDICATE A WEAKENING AND EVENTUAL END OF THE WARM EPSIODE LATER IN 2005. THE EXPECTED STRENGTH AND LOCATION OF THE ABNORMALLY WARM TROPICAL PACIFIC SSTS DURING THE WINTER AND SPRING MONTHS ADD UNCERTAINTY INTO THE FORECAST... ALTHOUGH THE CONSENSUS OF MOST MODELS... BOTH STATISTICAL AND DYNAMICAL... IS THAT THERE WILL BE A LARGE AREA OF ABOVE NORMAL SSTS NEAR AND EAST OF THE DATE LINE... BUT THAT THERE WILL NOT BE SIGNIFICANTLY ABOVE NORMAL SSTS IN THE EASTERN PART OF THE EQUATORIAL PACIFIC. IT SHOULD BE NOTED THAT THE PATTERN AND MAGNITUDE OF THE SST ANOMALIES IN THE TROPICAL PACIFIC STRONGLY INFLUENCES THE MIDDLE LATITUDE IMPACTS OF EL NINO... ESPECIALLY DURING THE COLD SEASON. BASIN-WIDE... OR CLASSICAL STRONG EL NINOS LIKE THOSE OF 1982-83 AND 1997-98 HAVE A PATTERN OF ABNORMALLY WARM SSTS WHICH EXTEND ALL THE WAY FROM THE DATE LINE TO THE COAST OF PERU. IMPACTS OF SUCH EL NINOS OFTEN INCLUDE ABNORMAL WETNESS FROM CALIFORNIA TO FLORIDA ASSOCIATED WITH AN ACTIVE SUBTROPICAL JET STREAM AND EASTWARD EXTENSION OF THE PACIFIC JET...RESPECTIVELY...AND ABNORMAL DRYNESS CENTERED ON MONTANA AND THE OHIO VALLEY. THESE EVENTS ARE ALSO CHARACTERIZED BY ABNORMALLY WARM TEMPERATURES ACROSS THE NORTHERN TWO-THIRDS OF THE CONTINENTAL U.S. CENTRAL PACIFIC EL NINOS...LIKE THOSE IN 1963-64, 1968-69 AND 2002-03 ARE CHARACTERIZED BY SMALL SST ANOMALIES IN THE EASTERN PACIFIC AND ABNORMALLY WARM SSTS IN THE CENTRAL TROPICAL PACIFIC. THE U.S. TEMPERATURE RESPONSE TO THIS TYPE OF EL NINO IS USUALLY COLDER THAN NORMAL OVER THE SOUTHEAST AND A MUCH LESS RELIABLE HEAVY PRECIPITATION SIGNAL ACROSS THE SOUTHERN U.S. .. ESPECIALLY IN CALIFORNIA. . . . . . . . . SOME EL NINO RELATED INFLUENCE ON U.S. CLIMATE IS LIKELY FOR THE UPCOMING WINTER... AND A SLIGHT INCREASE IN THE ODDS IN FAVOR OF EL NINO IMPACTS ARE INDICATED IN THE LONG-LEAD OUTLOOKS BETWEEN OND 2004 AND MAM 2005. FOR LEAD TIME BEYOND MAM 2005 THE OUTLOOK PRIMARILY REFLECTS LONG TERM TEMPERATURE AND PRECIPITATION TRENDS. . . . . . . . . THE OUTLOOK FOR NDJ 2004 IS BASED ON INDICATIONS FROM WARMING TRENDS IN THE SOUTHWESTERN U.S... WITH ABOVE NORMAL TEMPERATURES ANTICIPATED IN THE WESTERN PART OF THE U.S. AND ALSO IN SOUTHERN ALASKA... AND ALSO FROM COMPOSITES ASSOCIATED WITH WEAK EL NINOS. AS THE SEASONS PROGRESS THROUGH WINTER... THE TEMPERATURE FORECASTS REFLECT EL NINO COMPOSITES IN COMBINATION WITH TRENDS AND INDICATIONS FROM OTHER TOOLS... ESPECIALLY THE NEWLY OPERATONAL NCEP CFS MODEL AND THE IRI MULTI-MODEL FORECASTS. TEMPERATURES IN THE SOUTHEASTERN U.S. ARE OFTEN COOLER DURING WEAK EL NINOS WITH WARM CENTRAL EQUATORIAL PACIFIC SSTS THAN FOR THEIR MODERATE AND STRONGER COUNTERPARTS WHOSE WARM SST ANOMALIES EXTEND TO THE COAST OF SOUTH AMERICA. THEY ALSO TEND TO BE COOLER WHEN TEMPERATURES OVER THE INDIAN OCEAN ARE NOT WELL ABOVE NORMAL AS THEY HAD BEEN UNTIL RECENTLY. THUS FORECASTS FOR THE EASTERN U.S. INCLUDE SOME INDICATIONS OF BELOW NORMAL TEMPERATURES OVER THE SOUTHEASTERN U.S. DURING THE WINTER SEASONS. FOLLOWING EL NINO COMPOSITES AND MANY OF THE MODEL INDICATIONS... TEMPERATURES OVER THE NORTHERN GREAT PLAINS ARE PREDICTED TO BE ABOVE NORMAL... BUT ONLY MARGINALLY ABOVE CLIMATOLOGICAL PROBABILITIES BECAUSE THIS AREA HAS OFTEN EXPERIENCED BELOW NORMAL TEMPERATURES WITH WEAK EL NINOS IN THE PAST. TEMPERATURES OVER THE NORTHWESTERN U.S. AND ALASKA ARE FORECAST TO BE ABOVE NORMAL TO REFLECT INCREASED CHANCES OF WARMER THAN NORMAL CONDITIONS IN EL NINO YEARS... AND ARE SUPPORTED BY MOST DYNAMICAL MODEL FORECASTS. FOR AMJ 2005 AND BEYOND THE FORECAST REFLECTS MAINLY TRENDS TOWARDS WARMER THAN NORMAL TEMPERATURES OVER MUCH OF THE WEST IN THE SPRING... INCLUDING THE SOUTH CENTRAL AND SOUTHEASTERN U.S. IN SUMMER... AND ABOVE NORMAL TEMPERATURES EXTENDING INTO THE FALL OVER SOUTH FLORIDA AND THE SOUTHWESTERN U.S. . . . . . . . . PRECIPITATION FOR NDJ 2004 REFLECTS EXPECTATIONS ASSOCIATED WITH WEAK EL NINO CONDITIONS... WHICH ARE TYPICALLY DRIER THAN MODERATE AND ESPECIALLY STRONG EL NINOS ACROSS THE U.S. BOTH THE WET SIGNAL OVER THE SOUTHERN PLAINS AND THE DRY SIGNAL OVER THE OHIO VALLEY ARE OFTEN ASSOCIATED WITH WEAK EL NINOS. THE WINTER-TIME PRECIPITATION PATTERN OF GENERALLY WET CONDITIONS ACROSS THE SOUTHERN U.S. AND DRY CONDITIONS IN THE PACIFIC NORTHWEST AND THE OHIO VALLEY REFLECT CLASSICAL EL NINO CONDITIONS... ALTHOUGH WITH LESS CONFIDENCE THAN WOULD BE GIVEN IN A STRONGER EVENT. THE PRECIPITATION OUTLOOK OVER FLORIDA DURING THE EARLY AND MID WINTER IS LEFT AT EC... AS ALL MODEL FORECASTS ARE INDICATING DRIER THAN NORMAL CONDITIONS... WHICH IS CONTRARY TO THE EXPECTED EL NINO IMPACT. THE DRIER THAN NORMAL MODEL FORECAST IS POSSIBLY ASSOCIATED WITH COOLER THAN NORMAL SSTS THAT CURRENTLY SURROUND FLORIDA. THE PRECIPITATION FORECAST FOR THE SOUTHWESTERN U.S. FAVORS AN INCREASING CHANCE OF ABOVE NORMAL PRECIPITATION DURING LATE WINTER AND ESPECIALLY DURING THE EARLY SPRING. FROM AMJ 2005 THROUGH NDJ 2005 THE OUTLOOK REFLECTS PRECIPITATION TRENDS... WHICH ARE GENERALLY MODEST IN SIZE. DRY CONDITIONS ARE INDICATED OVER PARTS OF THE GREAT BASIN IN JAS AND ASO. TRENDS HINTING AT BELOW MEDIAN PRECIPITATION OVER THE UPPER RIO GRANDE VALLEY FOR ASO AND SON AND ABOVE MEDIAN PRECIPITATION IN FLORIDA FOR THE SEASONS JAS THROUGH SON 2005 AND OVER EASTERN TEXAS FOR OND AND NDJ WERE ALSO FOLLOWED. . . . . . . . . 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 CURRENT OCEANIC AND ATMOSPHERIC CONDITIONS INDICATE THAT WEAK EL NINO CONDITIONS NOW EXIST IN THE CENTRAL TROPICAL PACIFIC. NOAAS DEFINITION OF EL NINO CONDITIONS REQUIRES THAT 3-MONTH RUNNING MEAN SST ANOMALIES IN THE NINO 3.4 REGION - BETWEEN 120W TO 170W AND WITHIN 5 DEGREES OF THE EQUATOR - EXCEED +0.5 DEGREES CELSIUS. TO BE CLASSIFIED AS AN EVENT - THIS MINIMUM CRITERION MUST BE MET FOR AT LEAST 5 CONSECUTIVE MONTHS. THE MOST RECENT WEEKLY MEAN SHOWS THAT SSTS ARE MORE THAN 1 C ABOVE NORMAL ALONG AND NEAR THE EQUATOR FROM 160E TO 135W. SSTS ALONG AND JUST SOUTH OF THE EQUATOR NOW AVERAGE WITHIN AROUND 0.5 DEGREE C OF NORMAL FROM JUST OFF THE SOUTH AMERICAN COAST TO AROUND 125W. SUB-SURFACE OCEAN TEMPERATURES ALONG THE EQUATOR ARE SUBSTANTIALLY ABOVE NORMAL OVER MOST OF THE EAST-CENTRAL PACIFIC FROM THE SURFACE TO OVER 150 METERS DEPTH... WITH THE AXIS OF MAXIMUM ANOMALIES SLOPING UPWARDS FROM AROUND 150 METERS DEPTH IN THE CENTRAL PACIFIC TO 50 METERS DEPTH OVER THE EASTERN PACIFIC NEAR 110W. VERY LITTLE BELOW NORMAL WATER REMAINS AT ANY DEPTH OVER THE EASTERN PACIFIC. SO FAR THERE ARE FEW SIGNS OF ANY ANOMALOUS CONVECTION ASSOCIATED WITH THE WARM SSTS AND TRADE WINDS CONTNUE TO BE INFLUENCED BY INTRASEASONAL ACTIVITY. THE SOI HAS BEEN CONSISTENTLY NEGATIVE SINCE JUNE 2004... INDICATING SOME ATMOSPHERIC IMPACT FROM THE ABOVE NORMAL SSTS. . . . . . . . . PROGNOSTIC DISCUSSION OF SST FORECASTS A CONSOLIDATION FORECAST OF IN-HOUSE TOOLS INDICATES THAT NINO 3.4 SST ANOMALIES WILL REMAIN CLOSE TO THE SEPTEMBER AVERAGE OF ABOUT +.7 C FROM EARLY FALL THROUGH THE WINTER SEASON INTO SPRING BEFORE SLOWLY DECREASING IN THE LATE SPRING AND SUMMER MONTHS OF 2005. ENSEMBLE PREDICTIONS FROM THE NEW CFS MODEL... AND STATISTICAL PREDICTIONS FROM CCA... CA... AND THE MKV MODEL PREDICT THE NINO 3.4 SSTS ANOMALIES IN AN ENVELOPE BETWEEN +0.3 AND +1.2 DEGREES C THROUGH MAM 2005... WITH MOST BETWEEN 0.5 AND 1.0 DEG C MOST MODELS PREDICT THE POSITIVE SST ANOMALIES IN DJF 2004-05 TO BE RESTRICTED TO A RELATIVELY NARROW AREA MAINLY IN THE CENTRAL PACIFIC. THE MAJORITY OF MODELS PREDICT ABOVE NORMAL SSTS TO EXTEND TO THE SOUTH AMERICAN COAST BY DJF... ALTHOUGH NONE PREDICT THE EXTENSIVE AREAS OF WELL ABOVE NORMAL SSTS IN THE PACIFIC NEAR THE SOUTH AMERICAN COAST ASSOCIATED WITH STRONG WARM EVENTS. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOK NCEPS NEW CLIMATE FORECAST SYSTEM (CFS) - WHICH BECAME OPERATONAL ON AUGUST 24 2004 - WAS A MAJOR CONTRIBUTOR TO THIS OUTLOOK FOR THE OUTLOOKS THROUGH AMJ2005. ALSO CONSIDERED WERE EL NINO COMPOSITES BASED ON WEAK AND MODERATE EVENTS FOR NDJ 2004 TO MAM 2005 OUTLOOKS... A TWO-TIER FORECASTING SYSTEM BASED ON SIX MODELS FROM CDC AND DYNAMICAL MULTI-MODEL ENSEMBLES FROM IRI THROUGH FMA 2005. CCA... OCN AND SMLR GUIDANCE WERE CONSULTED FOR ALL LEAD TIMES. ANY EL NINO IMPACTS WILL DEPEND CRITICALLY ON THE EVOLUTION OF THE SSTS IN THE EASTERN PACIFIC AND THE COUPLING BETWEEN THE ATMOSPHERE AND SST ANOMALIES. THE MODEST PROBABILITIES ASSOCIATED WITH THESE OUTLOOKS... PARTICULARLY FOR PRECIPITATION ... SHOW REGIONS WHERE THERE IS A CHANCE FOR ENSO IMPACTS. . . . . . . . . PROGNOSTIC DISCUSSION OF OUTLOOKS - NDJ 2004 TO NDJ 2005 TEMPERATURE: FOR NDJ 2004 THE CFS MODEL INDICATES ENHANCED LIKELIHOOD OF ABOVE NORMAL TEMPERATURES IN THE NORTHWEST... WHILE THE IRI MULTI-MODEL ENSEMBLE PREDICTION TILTS THE ODDS TOWARD ABOVE NORMAL TEMPERATURES FOR THE EDGES OF THE WESTERN U.S. AND MOST OF ALASKA. OCN INDICATES ABOVE NORMAL TEMPERATURES OVER THE SOUTHWESTERN U.S. FOR NDJ 2004. AS THE SEASONS PROGRESS TOWARD WINTER... ABOVE NORMAL TEMPERATURES ARE LIKELY TO EXPAND OVER THE WESTERN AND NORTHWESTERN PORTIONS OF THE U.S. AND COVER MOST OF THE WEST AND THE ROCKY MOUNTAIN REGIONS. THIS PATTERN ALSO AGREES WITH CFS MODEL AND ENSO COMPOSITES. THE CFS MODEL PREDICTS INCREASED ODDS FOR BELOW TEMPERATURES IN THE SOUTHERN AND EASTERN U.S. THROUGH MAM 2005. THESE ARE SUPPORTED BY WEAK EL NINO COMPOSITES. HOWEVER... IN VIEW OF STRONG WARMING TRENDS IN RECENT YEARS... AND CONTRARY INDICATIONS FROM CCA... THE OUTLOOK FOR THE NORTHEAST WAS LEFT AT EC FOR THE REGION NORTH OF NEW YORK WITH A SLIGHT INCREASE IN PROBABILITIES FAVORING BELOW NORMAL TEMPERATURES IN THE REST OF THE NORTHEAST AND THE MID ATLANTIC COAST STATES. GREATER THAN AVERAGE ODDS FOR BELOW NORMAL TEMPERATURES WERE FORECAST FOR PORTIONS OF THE SOUTHEASTERN U.S. FOR DJF AND JFM 2005 TO REFLECT WEAK EL NINO COMPOSITES... THE CFS MODEL FORECAST... AND INDICATIONS FROM CCA THAT THE GULF COAST WILL LIKELY BE COOLER THAN AVERAGE. THESE TOOLS CONSISTENTLY INDICATE ENHANCED ODDS FOR COLDER THAN NORMAL TEMPERATURES FOR MOST OF TEXAS FOR NDJ 2004 THROUGH MAM 2005. FOR AMJ 2005 AND BEYOND THE TEMPERATURE FORECAST MAINLY REFLECTS TRENDS WHICH ENHANCE THE ODDS OF WARMER THAN NORMAL TEMPERATURES IN MUCH OF THE WEST AND ALASKA... EXTENDING ACROSS THE SOUTHERN U.S. IN THE SUMMER MONTHS. THIS SIGNAL SHRINKS IN LATE SUMMER AND RETREATS TO THE SOUTHWESTERN U.S. AND SOUTHERN FLORIDA BY FALL 2005. . . . . . . . . PRECIPITATION: FOR NDJ THROUGH JFM THERE IS AN ELEVATED CHANCE OF A WARM ENSO-LIKE PRECIPITATION ANOMALY PATTERN... EXCEPT OVER FLORIDA. PROBABILITIES ARE STILL RELATIVELY LOW SINCE WEAK EL NINOS RAISE THE UNCERTAINTY ASSOCIATED WITH IMPACTS OVER THE U.S. THE LOW RELIABILITY OF THE SIGNAL IS ALSO SUGGESTED BY A LACK OF CONSENSUS AMONG TOOLS... WITH THE CFS MODEL NOT SHOWING MUCH ABOVE MEDIAN PRECIPITATION IN THE SOUTHERN PART OF THE COUNTRY UNTIL FMA AND MAM 2005. SINCE THIS WILL MOST LIKELY BE AT LEAST A WEAK WARM EVENT... THESE SLIGHT INDICATIONS FROM VARIOUS TOOLS WERE COMBINED TO FORM A COHERANT PATTERN SIMILAR TO A WARM ENSO EVENT COMPOSITE FOR THE WINTER AND SPRING. THE CFS SHOWS DRY CONDITIONS IN THE OHIO VALLEY BY LATE WINTER AND SPRING 2005. THE MOST PROBLEMATIC AREA IS IN THE SOUTHWESTERN U.S. AND SOUTHERN CALIFORNIA. WHILE THE CHANCE OF ABOVE MEDIAN PRECIPITATION IN THIS AREA INCREASES SLIGHTLY FOR WEAK EL NINOS... PROBABILITY SHIFTS WERE INDICATED FOR LATE WINTER THROUGH SPRING. AFTER THE EL NINO-RELATED SIGNALS DIE AWAY IN THE SPRING EC IS INDICATED DUE TO LACK OF ANY SIGNIFICANT SIGNALS EXCEPT FOR TREND-RELATED INDICATIONS FOR BELOW MEDIAN PRECIPITATION IN THE GREAT BASIN AND PORTIONS OF THE SOUTHWEST IN SUMMER...AND ABOVE MEDIAN PRECIPITATION IN SOUTHERN FLORIDA FROM JAS THROUGH SON 2005 AND IN EASTERN TEXAS FOR OND AND NDJ 2005. NOTE - AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL PROBABILITIES) ARE NOW LABELED EC (EQUAL CHANCES). . . . . . . . . FORECASTER: M. HALPERT GLOSSARY AND DEFINITIONS: ANALOG (NATURAL ANALOG) - A WEATHER MAP THAT RESEMBLES ANOTHER WEATHER MAP - USUALLY FROM DIFFERENT YEARS BUT THE SAME SEASON IN THE HISTORICAL RECORD. THE CRITERION FOR SELECTING AN ANALOG IS OFTEN THE PATTERN CORRELATION BETWEEN THE MAPS. TWO MAPS WILL JUST BEGIN TO RESEMBLE EACH OTHER TO THE HUMAN EYE AT A PATTERN CORRELATION OF ABOUT 40%. TO BE USEFUL - ANALOGS NEED TO HAVE MUCH HIGHER CORRELATIONS TO THE ORIGINAL MAP THAN THAT - 80% OR MORE. ANALOGS ARE INCREASINGLY DIFFICULT TO FIND AS THE GEOGRAPHIC REGION BEING COMPARED INCREASES IN SIZE. PERFECT ANALOGS TO THE ENTIRE NORTHERN HEMISPHERE SIMPLY DO NOT EXIST - FOR PRACTICAL PURPOSES. THIS IS WHY SIMPLE ANALOG FORECAST METHODS DO NOT WORK VERY WELL. ANNUAL CYCLE - AT MOST LOCATIONS THE CLIMATE STATE VARIABLES - T - P - SST- WIND - AND OTHERS DISPLAY A REGULAR VARIATION WHICH FOLLOWS THAT OF THE ELEVATION OF THE SUN IN THE SKY. A GRAPH OF THE 30 YEAR AVERAGE OF A VARIABLE FOR EACH DAY OF THE YEAR VERSUS DATE SHOWS A WAVE-FORM WHICH - FOR T AT DES MOINES FOR EXAMPLE - RANGES SMOOTHLY FROM LOWEST VALUES IN THE WINTER TO HIGHEST VALUES IN THE SUMMER. ANOMALY - THE ARITHMETIC DIFFERENCE BETWEEN THE VALUE OF A VARIABLE AT A GIVEN PLACE AND TIME AND THE LONG-TERM AVERAGE (USUALLY 30 YEARS) FOR THE LOCATION AND TIME OF YEAR. AO - ARCTIC OSCILLATION - A MEASURE OF THE DIFFERENCE IN PRESSURE (AT SEA LEVEL) OR 500-HPA HEIGHT (IN THE MIDDLE TROPOSPHERE) BETWEEN THE NORTHERN POLAR REGION AND MIDDLE LATITUDES. WHEN PRESSURES AND HEIGHTS ARE ABOVE (BELOW) NORMAL AT HIGH LATITUDES AND BELOW (ABOVE) NORMAL AT MIDDLE LATITUDES - THE AO IS DEFINED AS NEGATIVE (POSITIVE) AND IS ASSOCIATED WITH BELOW (ABOVE) NORMAL TEMPERATURES OVER MIDDLE LATITUDES - INCLUDING THE CONUS. CA - CONSTRUCTED ANALOG - A LINEAR COMBINATION OF PAST OBSERVED ANOMALY PATTERNS SUCH THAT THE COMBINATION IS AS CLOSE AS DESIRED TO THE INITIAL STATE. A FORECAST IS OBTAINED BY PERSISTING THE WEIGHTS ASSIGNED TO EACH YEAR IN THE HISTORICAL RECORD AND LINEARLY COMBINING THE STATES FOLLOWING THE INITIAL TIME IN THE HISTORICAL YEARS. CAS - CONSTRUCTED ANALOG SOIL MOISTURE PREDICTION TECHNIQUE. CCA - CANONICAL CORRELATION ANALYSIS - A TECHNIQUE WHICH PREDICTS THE STATUS OF U.S. T AND P FOR SOME FUTURE TARGET SEASON USING THE MOST RECENT 4 NON- OVERLAPPING SEASONAL OBSERVATIONS OF TROPICAL PACIFIC SST - CIRCULATION AND U.S. T OR P TO CHARACTERIZE THE RECENT BEHAVIOR OF THE CLIMATE - AND PAST OBSERVATIONS TO PLACE RECENT BEHAVIOR INTO A HISTORICAL CONTEXT. CLIMATOLOGY - THE 30-YEAR AVERAGE OF A VARIABLE - LIKE TEMPERATURE - AT A GIVEN LOCATION AND TIME OF YEAR. . . . . . . . . CONUS - CONTERMINOUS UNITED STATES DYNAMICAL MODEL - A PREDICTION METHOD WHICH USES EQUATIONS DESCRIBING THE PHYSICAL BEHAVIOR OF A SYSTEM AND A COMPREHENSIVE SET OF CURRENT OBSERVATIONS OF THE VALUES OF THE VARIABLES DESCRIBING THE CURRENT STATE OF THE SYSTEM (INITIAL CONDITIONS) TO PREDICT THE VALUES OF THOSE VARIABLES A SHORT TIME-STEP IN THE FUTURE. THOSE VALUES ARE - IN TURN - USED AS THE INITIAL CONDITIONS FOR A SUBSEQUENT PREDICTION - AND SO ON - UNTIL THE DESIRED FUTURE PREDICTION TIME IS REACHED. EASTERLY WIND - WIND BLOWING FROM EAST TO WEST. EC - EQUAL CHANCES - THE PROBABILITY OF THE MOST LIKELY CATEGORY CANNOT BE DETERMINED AND THE EXPECTED LIKELIHOODS OF ABOVE - NORMAL AND BELOW DO NOT DIFFER FROM THEIR CLIMATOLOGICAL ODDS OF 33 1/3% EACH. EC REPLACES CL. EL NINO - THE WARM PHASE OF THE ENSO CYCLE ENSO - ACRONYM FOR EL NINO/SOUTHERN OSCILLATION GCM - GENERAL CIRCULATION MODEL - A GENERIC TERM APPLIED TO GLOBAL DYNAMICAL MODELS. ITCZ - INTERTROPICAL CONVERGENCE ZONE - A LINE WHERE THE SOUTHEASTERLY AND NORTHEASTERLY TRADE WINDS CONVERGE - CHARACTERIZED BY ENHANCED CONVECTION. IT MAY BE IN EITHER THE NORTHERN OR SOUTHERN HEMISPHERE - AND OCCASIONALLY A DOUBLE ITCZ MAY BE SEEN IN BOTH HEMISPHERES NOT FAR FROM THE EQUATOR. LA NINA - THE COLD PHASE OF THE ENSO CYCLE MJO - MADDEN-JULIAN OSCILLATION - ALSO CALLED TROPICAL INTRA-SEASONAL OSCILLATION - A DISTURBANCE IN TROPICAL CONVECTION - PRECIPITATION - WIND AND PRESSURE. MJO PRECIPITATION AND CLOUDINESS ARE ENHANCED ONLY IN REGIONS WHERE SSTS ARE VERY WARM - E.G. INDIAN OCEAN AND WEST PACIFIC. THE PRESSURE AND WIND DISTURBANCE ASSOCIATED WITH MJO IS OBSERVED TO MOVE FROM WEST TO EAST COMPLETELY AROUND THE GLOBAL TROPICS IN ABOUT 30 TO 60 DAYS. NAO - NORTH ATLANTIC OSCILLATION TELECONNECTION PATTERN - WHICH MAY BE CONSIDERED AS THE ATLANTIC HALF OF THE AO. NOTE THAT THE STATUS OF THE AO/NAO AND OTHER SLOWLY VARYING CIRCULATION MODES - WHILE VERY IMPORTANT IN DETERMINING THE TEMPERATURE AND PRECIPITATION REGIMES OVER THE U.S. - ARE UNPREDICTABLE BEYOND A WEEK OR TWO AHEAD AT BEST BY CURRENT TECHNOLOGY AND ARE NOT EXPLICITLY INCLUDED IN OUR FORECAST PROCESS AS RELIABLE PREDICTORS. NORTHERLY WIND - WIND BLOWING FROM NORTH TO SOUTH. OCN - OPTIMAL CLIMATE NORMALS - A FORECAST BASED ON PERSISTING THE AVERAGE OF THE LAST 10 YEARS FOR TEMPERATURE AND THE LAST 15 YEARS FOR PRECIPITATION. PNA - PACIFIC NORTH AMERICAN TELECONNECTION PATTERN. QBO - QUASI-BIENNIAL OSCILLATION - AN OSCILLATION OF THE WIND IN THE LOWER STRATOSPHERE BETWEEN EASTERLY AND WESTERLY WHICH REVERSES ON A NEARLY- 2 YEAR TIME SCALE. QBO IS ONE OF THE MOST REGULAR OSCILLATIONS KNOWN. SMLR - SCREENING MULTIPLE LINEAR REGRESSION - A TECHNIQUE WHICH SELECTS THE BEST SET OF PREDICTORS - FITTING THEM TO THE OBSERVATIONS TO CREATE EQUATIONS WHICH CAN BE USED TO MAKE PREDICTIONS. SOUTHERLY WIND - WIND BLOWING FROM SOUTH TO NORTH. STATISTICAL PREDICTIONS - PREDICTIONS BASED MAINLY ON LARGE OBSERVATIONAL DATA SETS. CCA - OCN - SMLR - CAS - CA ARE EXAMPLES OF THESE. TELECONNECTIONS - THESE GIVE THE HISTORICAL RELATIONSHIP BETWEEN A GIVEN POINT AND ALL OTHER POINTS OVER A LARGE AREA - LIKE THE NORTHERN HEMISPHERE - FOR A GIVEN TIME OF THE YEAR. THE POINTS ON THE MAP USUALLY CONSIST OF A SET OF MORE OR LESS EVENLY SPACED LOCATIONS CALLED GRID POINTS. TREND - AT A GIVEN LOCATION AND TIME OF YEAR - THE DIFFERENCE BETWEEN THE AVERAGE OF THE MOST RECENT 10 (15) YEARS OF OBSERVATIONS OF T (P) AND THE CLIMATOLOGY. WESTERLY WIND - WIND BLOWING FROM WEST TO EAST. ZONAL FLOW PATTERN - OCCURS WHEN 500-HPA CONTOURS LIE IN AN EAST-WEST DIRECTION PARALLEL TO LATITUDE CIRCLES WITH NEARLY PURE WEST-TO-EAST FLOW. -------------------------------------------------------------------------------- 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 LOWER CASE LETTERS) NOTES - THESE CLIMATE OUTLOOKS ARE INTENDED FOR USE PRIOR TO THE START OF THEIR VALID PERIODS. 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 NOVEMBER 18 2004. 1971-2000 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 17 2001 FORECAST RELEASE. $$