PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD 830 AM EDT THU JUNE 17 2004 . . . . . . . . SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS THE SEASONAL OUTLOOK REFLECTS PRIMARILY THE PRESENCE OF LONG TERM TRENDS ON U.S. TEMPERATURE AND PRECIPITATION...STATISTICAL FORECAST TOOLS...WITH LIMITED INPUT FROM NUMERICAL MODELS DURING THE FIRST SEVERAL SEASONS...ALL WITHIN THE CONTEXT OF THE LIKELY CONTINUATION OF ENSO-NEUTRAL CONDITIONS IN THE TROPICAL PACIFIC DURING THE NEXT SEVERAL MONTHS. SSTS IN THE TROPICAL PACIFIC REMAIN BELOW THE THRESHOLD REQUIRED TO PRODUCE SIGNIFICANT ENSO IMPACTS ON THE U.S. CLIMATE DURING THE SUMMER. MOST CLIMATE MODELS FROM NCEP - CDC - IRI AND ECMWF INDICATE CONTINUATION OF NEAR-NEUTRAL TROPICAL SSTS AT LEAST THROUGH THE SUMMER...AFTER WHICH THE SPREAD AMONG MODEL FORECASTS INCREASES. THE MAJORITY OF MODELS FAVOR POSITIVE SST ANOMALIES IN THE NINO 3.4 REGION BY THE UPCOMING COLD SEASON...BUT THE MAGNITUDE OF THE ANOMALIES ARE NOT ENOUGH TO SATISFY THE CRITERIA FOR AN EL NINO IN MANY CASES AND EVEN THE MODELS WITH THE LARGEST ANOMALIES ARE NOT FORECASTING A STRONG EL NINO. THE FORECASTS FOR JAS AND ASO 2004 FAVOR ABOVE NORMAL TEMPERATURES OVER MUCH OF THE WEST AND SOUTHWEST...AND AN AREA OF RELATIVE WAMRTH IN THE EAST THAT TENDS TO SHIFT NORTHWARD AND WEAKEN WITH TIME. SOME COOLER THAN NORMAL TEMPERATURES ARE EXPECTED FOR PORTIONS OF THE NORTH-CENTRAL AND SOUTH- CENTRAL STATES IN JAS DUE TO EXTREMELY WET GROUND PRESENTLY IN THOSE AREAS. A REGION OF ABNORMAL DRYNESS IS LIKELY DURING JAS OVER THE NORTHWEST U.S. FROM WASHINGTON AND OREGON EASTWARD AND SOUTHEASTWARD TO INCLUDE PARTS OF THE GREAT BASIN AND NORTHERN ROCKIES DURING JAS...AND THEN IN PARTS OF THE GREAT BASIN AND NORTHERN ROCKIES IN ASO. SOME PREFERENCE FOR ABOVE NORMAL TEMPERATURES IS INDICATED FOR PARTS OF THE SOUTH COAST OF ALASKA AND PARTS OF THE ALEUTIANS DURING JAS...BUT AFTER THAT EQUAL CHANCES ARE GIVEN FOR THE THREE POSSIBLE CATEGORIES FOR BOTH PRECIPITATION AND TEMPERATURE (ABOVE - NEAR MEDIAN OR NEAR NORMAL - BELOW) OVER ALASKA UNTIL FMA 2005. THE AUTUMN SEASONS OF SON AND OND HAVE THE WEAKEST SIGNALS FOR TEMPERATURE OF THE ENTIRE YEAR OVER THE CONUS ALTHOUGH THE TREND SIGNAL FOR ABOVE NORMAL TEMPERATURES CONTINUES FOR PORTIONS OF THE SOUTHWEST. THERE IS AN INDICATION FOR ABOVE MEDIAN PRECIPITATION OVER PARTS OF THE SOUTH-CENTRAL STATES IN OND THROUGH DJF AS WELL AS AN INDICATION FOR BELOW MEDIAN PRECIPITATION FOR SMALL PORTIONS OF THE CENTER OF THE NATION IN OND AND NDJ. DURING THE COMING WINTER AND FOLLOWING SPRING LONG-TERM TRENDS FAVOR ABOVE NORMAL TEMPERATURES CENTERED OVER THE MIDWEST DURING THE WINTER...REACHING MAXIMUM AREAL COVERAGE OF MUCH OF THE COUNTRY DURING JFM AND SETTLING INTO THE WEST AND SOUTHWEST FOR THE REMAINING SEASONS. MOST OF THESE SEASONS HAVE NO RELIABLE SIGNALS FOR PRECIPITATION. . . . . . . . . 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 THE MOST RECENT WEEKLY MEAN AVERAGE OF SST ANOMALIES SHOWS THAT SEA SURFACE TEMPERATURES ARE SLIGHTLY ABOVE NORMAL ACROSS MUCH OF THE TROPICAL PACIFIC. THE EXCEPTION IS AN AREA OF NEGATIVE SST ANOMALIES EXTENDING FROM THE COAST OF PERU WEST TO ABOUT 115W. RECENT 5-DAY MEAN TOGA-TAO DEPTH-LONGITUDE CROSS-SECTIONS SHOW ABNORMALLY WARM WATER...WITH ANOMALIES OF UP TO 1.5 C... BETWEEN THE SURFACE AND ABOUT 100 M DEPTH...BUT WITH A POOL OF NEGATIVE TEMPERATURE ANOMALIES OF MORE THAN -2.0 C CENTERED NEAR 150W AT A DEPTH OF ABOUT 150 M. THE TRADE WINDS HAVE BEEN MOSTLY STRONGER THAN NORMAL DURING THE PAST MONTH IN THE VICINITY OF THE DATELINE. A BURST OF WESTERLY WINDS THAT OCCURRRED OVER THE FAR WESTERN TROPICAL PACIFIC DURING EARLY APRIL IS PROBABLY THE CAUSE OF THE RECENT WARMING OF WATER AT THE SURFACE OVER THE EAST-CENTRAL PACIFIC...AS A KELVIN WAVE HAS SHOALED. OUTGOING LONG-WAVE RADIAION (OLR) MAPS FROM SATELLITE OBSERVATIONS SHOW THAT RECENTLY MOST ACTIVE CONVECTION HAS MOVED OFF THE EQUATOR IN THE INDIAN AND PACIFIC OCEANS EXCEPT BETWEEN ABOUT 130E AND 170E. ELSEWHERE IN THE TROPICAL PACIFIC OLR ANOMALIES ARE GENERALLY POSITIVE. . . . . . . . . PROGNOSTIC DISCUSSION OF SST FORECASTS FORECASTS FROM MULTIPLE MODELS GIVE A RANGE OF POSSIBLE FUTURE SST ANOMALIES IN NINO 3.4 OF -0.5 TO +1.0 C THROUGH SON WITH A FAIRLY EVEN SPLIT BETWEEN THOSE WHICH ARE BELOW AND ABOVE 0.5 C...THE BOUNDARY BETWEEN NEUTRAL AND A WEAK WARM EVENT...BY EARLY WINTER...WITH SIGNIFICANT UNCERTAINTY. TO SEE THESE FORECASTS GO TO: http:// www.cpc.ncep.noaa.gov/products/predictions/90day/tools/briefing/index.pri.html A CONSOLIDATION FORECAST OF IN-HOUSE TOOLS INDICATES THAT NINO 3.4 SST ANOMALIES WILL RISE FROM ITS CURRENT SLIGHTLY POSITIVE VALUES TO SLIGHTLY BELOW THE +0.5 C THRESHOLD FROM ASO THROUGH NDJ AND THEN DECLINE SLOWLY THEREAFTER. THE PROBABILITY SPREAD FOR COLD - NEUTRAL - OR WARM ENSO CONDITIONS INCREASES WITH THE GREATEST LIKELIHOOD SHIFTING FROM NEAR NORMAL IN LATE SUMMER TO ABOUT EQUAL CHANCES FOR NEUTRAL OR WARM ENSO CONDITIONS BY FALL AND A SHIFT TO BETTER CHANCES OF WARM BY EARLY NEXT SPRING. THE FORECAST REMAINS UNCERTAIN...BUT THERE IS LITTLE EXPECTATION FOR A COLD EVENT TO DEVELOP. SINCE WEAK WARM EVENTS DO NOT EXERT STRONG FORCING ON THE ATMOSPHERE...SHOULD ONE DEVELOP...WE EXPECT THAT TRANSIENT ATMOSPHERIC CIRCULATION PATTERNS WILL CONTINUE TO BE FORCED PRIMARILY BY INTRA-SEASONALLY VARYING PHASES OF THE MJO...AND THE HIGHER LATITUDE PATTERNS WILL BE DETERMINED BY VARYING PHASES OF THE AO AND NAO THAT ARE NOT CURRENTLY PREDICTABLE AT SEASONAL RANGES. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOK THE PRIMARY TOOLS USED IN THE JAS THROUGH SON FORECASTS WERE OCN...CCA...AND SMLR. CONSULTED - BUT NOT USED SIGNIFICANTLY - WERE TWO-TIER FORECASTS FROM SIX MODELS PROVIDED BY CDC - DYNAMICAL MULTI-MODEL ENSEMBLES FROM IRI AND DYNAMICAL MODEL FORECASTS FROM NCEPS ENVIRONMENTAL MODELING CENTER...SINCE THE MODELS GAVE A WIDE RANGE OF OFTEN CONFLICTING INDICATIONS...AND HAVE LITTLE A PRIORI SKILL DURING ENSO NEUTRAL CONDITIONS. CCA AND OCN TEMPERATURE FORECASTS WERE OFTEN CONSIDERED TOGETHER AS A CONSOLIDATION OF THESE TWO TOOLS AND WERE USED FOR THOSE AREAS AND PROJECTION TIMES WHERE THEY HAD USEFUL STATISTICAL SIGNIFICANCE. THE CONSTRUCTED ANALOG TECHNIQUE USING SOIL MOISTURE (CAS) WAS CONSDIERED AS IT DOES BEST DURING THE WARM SEASON. IT CONFIRMED THE AREAS OF DRYNESS PREDICTED FOR PORTIONS OF THE WEST FROM OCN AND CCA...AND WAS THE MAIN TOOL USED TO FORECAST BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE NORTH- CENTRAL AND SOUTH-CENTRAL STATES IN JAS...WITH SOME SUPPORT FROM THE SMLR TOOL. THE IMPACT OF OCN AND CCA IS VISIBLE IN THE WARMTH PREDICTED OVER THE SOUTHERN AND WESTERN U.S. FROM JFM THROUGH JJA 2005 FOR THE TEMPERATURE FORECASTS. CCA AND OCN ARE THE ONLY TOOLS USED BEYOND THE FOURTH LEAD. THERE WERE FEW SIGNIFICANT INDICATIONS FOR MAKING OTHER THAN AN EQUAL CHANCES FORECAST FOR PRECIPITATION AT THE LONGER LEADS. . . . . . . . . PROGNOSTIC DISCUSSION OF OUTLOOKS - JAS 2004 TO JAS 2005 TEMPERATURE: CCA AND OCN ARE THE MAIN TOOLS USED HERE. FOR JAS 2004 CCA AND OCN HAVE SOME INDICATIONS FOR ABOVE NORMAL TEMPERATURES FOR THE SOUTH COAST AND PANHANDLE OF ALASKA...AND STRONGER INDICATIONS OF ABOVE NORMAL TEMPERATURES FOR THE PACIFIC NORTHWEST AND MUCH OF THE SOUTHWESTERN U.S. FROM CALIFORNIA TO THE SOUTHERN HALF OF THE HIGH PLAINS. ALTHOUGH THESE TOOLS ALSO HAVE AT LEAST WEAK INDICATIONS FOR ABOVE NORMAL TEMPERATURES FOR MOST OF THE CONUS...BELOW NORMAL WAS PREDICTED FOR PORTIONS OF THE NORTH-CENTRAL AND SOUTH-CENTRAL STATES IN JAS BECAUSE OF A STRONG OPPOSING SIGNAL FOR BELOW NORMAL TEMPERATURES IN CAS DUE TO RECENT HEAVY PRECIPITATION. EAST OF THE MISSISSIPPI RIVER MOST AREAS ALSO HAD INDICATIONS FOR WARMTH FROM CCA AND/OR OCN...ALTHOUGH THE SIGNALS WERE SOMEWHAT WEAK AND THE LOCATIONS WHERE THE SIGNAL WAS STRONGEST WERE NOT ALL COINCIDENT. THE OVERALL WARM...AND LARGELY TREND...SIGNAL FADES FROM ALASKA IN ASO 2004 THROUGH JFM 2005. OVER THE CONUS THE EXCESS WARMTH REMAINS IN PLACE OVER MUCH OF THE WEST IN ASO 2004...BUT THE AREA OF ABOVE NORMAL TEMPERATURES PREDICTED OVER THE EAST WEAKENS AND SHIFTS NORTHWARD DURING THIS SEASON. BY SON THE TREND FOR ABNORMAL WARMTH RETREATS TO A SMALL SECTION OF THE INTERIOR SOUTHWEST CENTERED ON ARIZONA WHILE SOUTHERN FLORIDA REMAINS IN THE ABOVE NORMAL CATEGORY. THE CCA-OCN SIGNAL FADES TO EC ALMOST EVERYWHERE BY OND WHEN THE SKILL OF CCA AND OCN ARE AT THEIR ANNUAL MINIMUM. THE SIGNAL BEGINS TO REBOUND IN NDJ IN THE CORE OF THE SOUTHWEST...AND BY DJF THIS REGION GETS COMPANY FROM THE EASTERN GREAT PLAINS TO PARTS OF THE NORTHEAST. THE CCA-OCN SIGNAL PEAKS IN JFM 2005 WHEN MORE OF THE NATION IS LIKELY TO HAVE ABOVE NORMAL TEMPERATURES THAN IN ANY OTHER SEASON. CCA-OCN INDICATES ABNORMAL WARMTH MAINLY IN THE WEST FROM FMA THROUGH AMJ. BY THE FINAL TWO LEADS...JJA AND JAS 2005... THE OCN TOOL AGAIN INDICATES ENHANCED LIKELIHOOD FOR ABNORMAL WARMTH FOR PARTS OF THE EAST AND GULF COAST...AND DURING AMJ IN SOUTHERN ALASKA AND MJJ IN SOUTHERN AND WESTERN ALASKA. . . . . . . . . PRECIPITATION: THERE IS A LIKELIHOOD OF SUB-MEDIAN PRECIPITATION FOR JAS AND ASO 2004 FROM OCN AND CCA FOR VARIOUS PARTS OF THE NORTHWEST AND THE GREAT BASIN. AN ENHANCED LIKELIHOOD OF ABOVE MEDIAN PRECIPITATION IS EXPECTED IN PARTS OF THE SOUTH- CENTRAL U.S. FOR SOME OF THE FALL AND WINTER SEASONS...ALONG WITH INDICATIONS FOR SUB-MEDIAN PRECIPITATION OVER PORTIONS OF THE MIDWEST DURING OND 2004 AND NDJ 2004-2005. CCA-OCN TOOL GIVES AN INDICATION OF ABOVE MEDIAN PRECIPITATION FOR THE NORTHERN CALIFORNIA COAST AND PORTIONS OF OREGON FOR MJJ 2005. ELSEWHERE AND FOR OTHER SEASONS NOT MENTIONED EC IS INDICATED DUE TO LACK OF ANY SIGNIFICANT SIGNALS. NOTE - AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL PROBABILITIES) ARE NOW LABELED EC (EQUAL CHANCES). . . . . . . . . FORECASTER: R. MARTIN 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 JULY 15 2004. 1971-2000 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 17 2001 FORECAST RELEASE. $$