PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD 830 AM EDT THU MAY 19 2005 SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS CURRENT OBSERVATIONS INDICATE THAT THE WEAK WARM EPISODE CONDITIONS (EL NINO) THAT HAVE PREVAILED OVER THE EQUATORIAL PACIFIC SINCE JJA 2004 HAVE ENDED. A TEMPORARY INCREASE IN BOTH SURFACE AND SUBSURFACE TEMPERATURES IN THE VICINITY OF THE EQUATOR DURING LATE APRIL AND EARLY MAY WAS DUE TO THE ARRIVAL OF A STRONG KELVIN WAVE IN THE EASTERN PACIFIC... BUT THE MOST RECENT OBSERVATIONS SHOW THAT SSTS ARE RETURNING RAPIDLY TO NORMAL OVER THE EASTERN EQUATORIAL PACIFIC WITH ONLY ONE SMALL AREA OF SST ANOMALIES GREATER THAN 1.0 DEGREE CELSIUS REMAINING NEAR 105W. ELSEWHERE PACIFIC EQUATORIAL SSTS ARE GENERALLY 0.5 DEGREES C OR LESS ABOVE NORMAL. A CONSENSUS OF SEA SURFACE TEMPERATURE (SST) PREDICTION TOOLS INDICATES THAT ENSO-NEUTRAL CONDITIONS WILL PREVAIL THROUGH THE SUMMER AND INTO THE FALL... ALTHOUGH THE CONSENSUS INDICATES THE POSSIBILITY OF A WARMING TO BORDERLINE WEAK WARM EVENT (EL NINO) CONDITIONS BY NEXT WINTER. THEREFORE ENSO COMPOSITES WERE NOT STRONGLY USED FOR ANY OF THE OUTLOOKS PRESENTED HERE... AND ANY INFLUENCES ON THE CLIMATE DURING THE NEXT SEVERAL SEASONS FROM THE EQUATORIAL PACIFIC ARE EXPECTED TO BE PRIMARILY FROM VARIABLE MJO ACTIVITY THAT DOES NOT PRODUCE USEFUL SEASONAL CLIMATE SIGNALS. . . . . . . . . THE OUTLOOKS FOR JJA 2005 THROUGH ASO 2005 ARE BASED ON A WIDE ARRAY OF FORECAST TOOLS INCLUDING DYNAMICAL AND STATISTICAL TOOLS. ONLY MINIMAL CONSIDERATION WAS GIVEN TO THE CFS MODEL... SINCE IT AGAIN APPEARS TO HAVE A COOL AND WET BIAS IN ITS FORECASTS FOR THE SUMMER AND FALL SEASONS. OTHER AVAILABLE DYNAMICAL MODELS INCLUDE THE IRI MULTI-MODEL ENSEMBLE... THE CDC STATISTICAL ENSEMBLE RENDERING OF THE RESPONSE OF SIX MODELS TO SST FORECASTS AND THE SCRIPPS COUPLED MODEL FORECAST. ALL OF THESE MODELS PREDICT REGIONS OF ABOVE NORMAL PRECIPITATION IN PARTS OF THE PACIFIC NORTHWEST AND/OR NORTHERN PLAINS... AND RELATIVELY DRY CONDITIONS IN THE SOUTHEAST DURING THE SUMMER SEASONS. CONSISTENT WITH THESE INDICATIONS FOR THE PRECIPITATION... MOST OF THE MODELS INDICATE COOL WEATHER... CENTERED EITHER IN THE GREAT BASIN OR NORTHERN GREAT PLAINS... AND ABOVE NORMAL TEMPERATURES OVER MUCH OF THE SOUTHERN AND EASTERN PARTS OF THE NATION. SEVERAL OF THE STATISTICAL TOOLS... INCLUDING THE CONSTRUCTED ANALOG BASED ON SOIL MOISTURE CONSIDERATIONS... OCN ... AND THE ENSEMBLE CCA... ARE CONSISTENT WITH MANY OF THE MODEL FORECASTS. EXCEPTIONS ARE THAT THE INDICATIONS FOR BELOW NORMAL TEMPERATURES OVER THE GREAT BASIN AND PARTS OF THE PACIFIC NORTHWEST FROM THE CAS AND MANY OF THE MODELS ARE AT ODDS WITH STRONG STATISTICAL SIGNALS FROM OCN AND CCA FOR ABOVE NORMAL TEMPERATURES OVER MUCH OF THE WEST... ESPECIALLY IN THE INTERIOR SOUTHWEST. HOWEVER... A CIRCULATION PATTERN THAT FEATURES STRONGER THAN NORMAL WESTERLIES BRINGING ACTIVE SHORT WAVES WITH OCCASIONAL PRECIPITATION AND COOL WEATHER INTO THE PACIFIC NORTHWEST IS CONSISTENT WITH A WEAK SUMMER MONSOON THAT WOULD FAVOR WARMER AND DRIER THAN NORMAL WEATHER IN THE INTERIOR SOUTHWEST. . . . . . . . . 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 WITH THE EXCEPTION OF A RECENT TEMPORARY WARMING DUE TO THE ARRIVAL OF A KEVIN WAVE IN THE EASTERN PACIFIC... SST ANOMALIES ALONG THE EQUATOR IN THE PACIFIC HAVE DECREASED SINCE THE BEGINNING OF THE YEAR... WITH DEPARTURES OF MORE THAN 0.5 DEGREES C ABOVE NORMAL OBSERVED ONLY BETWEEN 160E AND 180W AND IN RELATIVELY SMALL PATCHES CENTERED NEAR 150W... 130W AND 105W BY THE MIDDLE OF MAY. SINCE THE BEGINNING OF THE YEAR THE ENSO SST INDICES HAVE DECREASED ACROSS THE CENTRAL PACIFIC... WITH VALUES IN NINO 4... NINO 3.4... AND NINO 3 ALL WITHIN 0.5 DEGREES CELSIUS OF NORMAL AROUND MID-APRIL. IN RECENT WEEKS THE ARRIVAL OF THE KELVIN WAVE OVER THE EASTERN PACIFIC HAS CAUSED SSTS TO INCREASE MARKEDLY OVER THE EASTERN PACIFIC... BY AS MUCH AS 2 DEGREES C IN THE NINO 1 + 2 REGION. HOWEVER... AS THE KELVIN WAVE IS NOW SHOALING AND WEAKENING OVER THE EASTERN PACIFIC... A RESUMPTION OF THE USUAL UPWELLING IN IS WAKE HAS LED TO A DECREASE IN POSITIVE SST ANOMALIES OVER THE CENTRAL PACIFIC... AND IN THE MOST RECENT WEEK SST ANOMALIES HAVE ALSO DECREASED OVER THE EASTERN PACIFIC. THE TOTAL HEAT CONTENT OF THE EQUATORIAL PACIFIC HAS DECREASED IN THE WAKE OF THIS KELVIN WAVE. RECENT CONVECTIVE ACTIVITY OVER THE INDIAN OCEAN AND WESTERN PACIFIC HAS BEEN DOMINATED BY INTRASEASONAL VARIABILITY... AND EXPECTATIONS ARE THAT NEAR-NEUTRAL ENSO CONDITIONS WILL PERSIST THROUGH THE BOREAL SUMMER INTO THE FALL. . . . . . . . . PROGNOSTIC DISCUSSION OF SST FORECASTS THE CONSENSUS OF SEVERAL MODELS USED AT CPC SHOWS SEASONAL MEAN NINO 3.4 SST ANOMALIES REMAINING CLOSE TO THEIR MOST RECENT (FMA) AVERAGE OF ABOUT +0.3 C UNTIL LATE SUMMER OR EARLY FALL... RISING TO ABOUT +0.5 C DURING THE LATE FALL AND WINTER SEASONS OF 2005-06. PREDICTIONS FROM THE CA AND CFS MODELS KEEP THE SST ANOMALIES NEAR 0 DEGREES C... WHILE THE VALUES FROM THE MARKOV MODEL ARE NEAR THE CONSENSUS.... WHICH WOULD HAVE BEEN VERY CLOSE TO EXACTLY NEUTRAL EXCEPT FOR THE PREDICTION BY CCA WHICH WAS AN OUTLIER ON THE WARM SIDE BY LATE FALL 2005. THIS HINT THAT SST ANOMALIES COULD BE AT LEAST APPROACHING THE BOUNDARY BETWEEN NEAR-NEUTRAL AND WEAK EL NINO CONDITIONS IS TAKEN WITH A GRAIN OF SALT SINCE AT THE CURRENT TIME OF YEAR THE SKILL OF FORECASTS OF PACIFIC EQUATORIAL SST ARE STILL NEAR THEIR MINIMUM. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS THE OUTLOOK FOR JJA 2005 THROUGH ASO 2005 IS BASED ON THE MULTI-MODEL ENSEMBLE FROM IRI... THE SCRIPPS MODEL AND STATISTICAL TOOLS... INCLUDING CCA... SMLR AND OCN. CAS AND ECCA WERE ALSO USED FOR JJA. OCN AND CCA ARE THE PRIMARY TOOLS USED FROM SON 2005 THROUGH JJA 2006. TEMPERATURE FORECASTS FROM THE TOOLS WERE MODIFIED SLIGHTLY FOR THE UPCOMING JJA 2005 SEASON IN COASTAL REGIONS THAT HAVE HAD STRONGLY PERSISTENT LOCAL SST ANOMALIES... TOWARDS COOLER ALONG THE EAST GULF AND SOUTH ATLANTIC COASTS AND WARMER ALONG PARTS OF THE PACIFIC COAST. . . . . . . . . PROGNOSTIC DISCUSSION OF OUTLOOKS - JJA 2005 TO JJA 2006 TEMPERATURE: FOR JJA THERE IS A STRONG CONSENSUS AMONG TOOLS FOR BELOW NORMAL TEMPERATURES IN A REGION CENTERED OVER THE NORTHERN GREAT PLAINS AND UPPER MISSISSIPPI VALLEY... AND FOR WARM ANOMALIES IN THE SOUTHWEST... ALONG THE PACIFIC NORTHWEST COAST AND IN INTERIOR SECTIONS OF THE SOUTHEAST. ALTHOUGH MOST MODELS AND STATISTICAL TOOLS INCLUDE FLORIDA AND THE SOUTHEASTERN COASTS IN THE AREAS WHERE ABOVE NORMAL TEMPERATURES ARE INDICATED... THE LOCAL CLIMATE AT COASTAL LOCATIONS MAY BE PRIMARILY INFLUENCED BY THE BELOW NORMAL SST ANOMALIES THAT ARE EXPECTED TO PERSIST WELL INTO THE SUMMER. EXCEPT FOR SOME HINTS FROM DYNAMICAL MODELS AND CAS FOR THE GREAT LAKES AND NORTHEAST... INDICATIONS FOR BELOW NORMAL TEMPERATURES FADE FOR THE REST OF THE YEAR... BUT WARM ANOMALIES ARE PREDICTED TO CONTINUE FOR MUCH OF THE WEST AND ALSO IN PARTS OF THE SOUTHEAST THROUGH ASO. CONSISTENTLY STRONG INDICATIONS FROM TRENDS FAVOR PERSISTENTLY ABOVE NORMAL TEMPERATURES IN THE SOUTHWEST DURING ALL SEASONS... BUT THESE ARE AT THEIR WEAKEST DURING OND WHEN THE AREA OF WARMTH IS SHOWN AT ITS SMALLEST. FROM SON 2005 THROUGH JJA 2006 OCN AND CCA ARE THE MAIN FORECAST TOOLS USED AND REFLECT PRIMARILY THE INFLUENCE OF TRENDS. NOTABLY... ALASKA IS PREDICTED TO HAVE ABOVE NORMAL TEMPERATURES FROM DJF 2005-2006 THROUGH JJA 2006. THE EASTERN BOUNDARY OF THE AREA OF PREDICTED RELATIVE WARMTH WAS SHIFTED WESTWARD FROM WHERE CCA AND OCN ALONE WOULD PLACE IT... TO NEAR THE APPALACHIANS DURING THE WINTER SEASONS... SINCE THE CONSTRUCTED ANALOGS BASED ON THE CONSENSUS FORECAST OF BORDERLINE EL NINO CONDTIONS FOR THESE SEASONS ACTUALLY FAVORED BELOW NORMAL TEMPERATURES IN THE SOUTHEAST. RECENT COLD SEASONS HAVE ALSO HAD INCREASINGLY EXTENDED PERIODS OF NEGATIVE PHASE NAO AND AO... WHICH TEND TO COUNTERACT LONGER-TERM TRENDS FOR ABOVE NORMAL WINTERTIME TEMPERATURES OVER MUCH OF THE EASTERN AND CENTRAL CONUS. . . . . . . . . PRECIPITATION: FOR JJA THERE IS A STRONG CONSENSUS AMONG TOOLS FOR ABOVE NORMAL PRECIPITATION FROM THE PACIFIC NORTHWEST THROUGH THE NORTHERN ROCKIES INTO THE NORTHERN GREAT PLAINS. BELOW NORMAL PRECIPITATION IS EXPECTED FOR FLORIDA AND THE SOUTHEAST COASTAL AREAS FOLLOWING A CONSENSUS OF MOST OF THE MODELS AND THE EXPECTED SUPPRESSIVE EFFECTS ON CONVECTION OF BELOW NORMAL SSTS THAT MAY PERSIST WELL INTO THE SUMMER. SEVERAL STATISTICAL TOOLS STRONGLY INDICATE BELOW MEDIAN PRECIPITATION FOR THE WESTERN PLATEAU REGION DURING JAS... WHILE RELATIVE DRYNESS IS LIKELY TO PERSIST IN THE AREAS AFFECTED BY THE MONSOON. WET ANOMALIES ARE INTRODUCED IN THE SOUTHEAST ALONG THE ATLANTIC COAST BEGINNING WITH JAS DUE TO THE EXPECTED CONTINUATION OF ENHANCED TROPICAL ACTIVITY WHICH HAS INCREASED SINCE 1995 DUE TO A LONG TERM TREND IN ATLANTIC TROPICAL ACTIVITY. OCN IS BEGINNING TO SHOW THIS TREND OVER PARTS OF FLORIDA. THE AREAS OF ABOVE MEDIAN PRECIPITATION FORECAST OVER EAST TEXAS AND THE SOUTHERN PLAINS FROM OND 2005 THROUGH DJF 2005-06 COME FROM OCN. THERE ARE NO STRONG TRENDS EVIDENT ANYWHERE ACROSS THE COUNTRY AFTER DJF 2005-06... AND IN THE ABSENCE OF ANY CLEAR-CUT INDICATIONS FROM ENSO... THE PRECIPITATION MAPS FOR JFM THROUGH JJA 2006 ARE LEFT WITH EC EVERYWHERE. NOTE - AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL PROBABILITIES) ARE NOW LABELED EC (EQUAL CHANCES). . . . . . . . . FORECASTER: A. J. WAGNER 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. CFS - CLIMATE FORECAST SYSTEM - A FULLY-COUPLED OCEAN-ATMOSPHERE FORECAST SYSTEM WHICH USES NO ADJUSTMENTS TO OCEAN-ATMOSPHERE FLUXES IN POST- PROCESSING (A ONE-TIER SYSTEM) DEVELOPED AT THE NATIONAL CENTERS FOR ENVIRONMENTAL PREDICTION. 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. ECCA - ENSEMBLE CCA. A MULTI-VARIATE STATISTICAL FORECAST BASED ON THE PAST PERFORMANCE OF THE CFS MODEL FORECAST USING THE MOST RECENT FORECAST AS THE PREDICTOR. 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 JUNE 16 2005. 1971-2000 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 17 2001 FORECAST RELEASE. $$