PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD 830 AM EST THU FEBRUARY 19 2004 . . . . . . . . SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS THE SEASONAL OUTLOOK REFLECTS THE PRESENCE OF LONG TERM TRENDS ON U.S. TEMPERATURE AND PRECIPITATION...STATISTICAL FORECAST TOOLS... WITH SOME INPUT FROM NUMERICAL MODELS DURING THE FIRST SEVERAL SEASONS... AND THE LIKELY CONTINUATION OF ENSO NEUTRAL CONDITIONS IN THE TROPICAL PACIFIC DURING THE NEXT SEVERAL MONTHS. WHILE SSTS ALONG THE EQUATOR REMAIN SLIGHLY WARMER THAN NORMAL OVER MUCH OF THE EQUATORIAL PACIFIC OCEAN... THEY REMAIN BELOW THE THRESHOLD TEMPERATURES REQUIRED TO PRODUCE SUBSTANTIAL IMPACTS ON U.S. CLIMATE ASSOCIATED WITH EL NINO. CLIMATE MODELS RUN AT NCEP AND OTHER CENTERS SUGGEST THAT THE UNUSUALLY WARM SSTS IN THE WESTERN EQUATORIAL PACIFIC MAY AN IMPACT ON U.S. TEMPERATURE AND PRECIPITAION... AND THESE IMPACTS ARE REFLECTED IN THE OUTLOOKS FOR MAM 2004. THERE IS LITTLE CONSENSUS AMONG CLIMATE MODELS FROM AMJ ONWARD... REFLECTING BOTH A WEAKER ASSOCIATION BETWEEN TROPICAL PACIFIC SSTS AND U.S. CLIMATE IN SPRINGTIME... AND A GREATER UNCERTAINTY IN THE STATE OF THE SSTS IN THE REGIONS IMPORTANT TO THE U.S. CLIMATE. THUS THE OUTLOOK FOR AMJ 2004 AND BEYOND PRIMARILY REFLECT DECADAL TRENDS IN U.S. TEMPERATURE AND PRECIPITATION. CURRENT INDICATIONS ARE THAT THE SSTS IN THE CENTRAL EQUATORIAL PACIFIC WILL REMAIN SLIGHTLY ABOVE NORMAL... BUT WILL STAY WITHIN THE ENSO NEUTRAL RANGE AT LEAST THROUGH THE SPRING AND SUMMER. THE OUTLOOK FOR MARCH THROUGH MAY 2004 CALLS FOR BETTER THAN AVERAGE ODDS OF ABOVE NORMAL TEMPERATURES OVER THE WESTERN STATES FROM OREGON SOUTHWARD THROUGH THE SOUTHWEST TO WEST TEXAS AND CENTRAL AND EASTERN ALASKA. THIS IS BOTH BY RECENT TRENDS AND THE CIRCULATION PATTERNS PREDICTED BY THE CLIMATE MODELS. LONG TERM TRENDS ALSO FAVOR A GREATER THAN AVERAGE CHANCE OF BELOW NORMAL TEMPERATURES IN THE NORTHERN PLAINS. THE CHANCE FOR BELOW-MEDIAN PRECIPITATION IS GREATER THAN AVERAGE OVER CALIFORNIA AND WESTERN NEVADA AND IN THE FLORIDA PENINSULA. . . . . . . . . . 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 SSTS ALONG THE EQUATOR IN THE EASTERN PACIFIC OCEAN BETWEEN THE DATE LINE AND THE SOUTH AMERICAN COAST ARE CURRENTLY WITHIN 0.5 DEGREES C OF AVERAGE. THERE HAS BEEN CONSIDERABLE VARIATION OVER THE PAST FEW MONTHS ASSOCIATED WITH STRONG MADDEN-JULIAN OSCILLATIONS. EQUATORIAL SSTS REMAIN ABOVE NORMAL WEST OF THE DATE LINE WITH ANOMALIES OF 1 DEGREE C EXTENDING WESTWARD TO ABOUT 150E. SUB-SURFACE TEMPERATURES ALONG THE EQUATOR REFLECT AN EASTWARD PROPAGATING OCEANIC KELVIN WAVE THAT HAS RESULTED IN ABOVE NORMAL SUB-SURFACE TEMPERATURES IN THE CENTRAL PACIFIC AND BELOW-NORMAL OCEANIC TEMPERATURES IN THE EASTERN PACIFIC. THE LARGE SCALE ATMOSPHERIC CIRCULATION... TRADE WINDS... AND CONVECTION IN THE TROPICAL PACIFIC HAVE SHOWN NO SIGNIFICANT TRENDS IN THE MEAN AND SHOW CONSIDERABLE WEEK TO WEEK VARIABILITY IN RESPONSE TO STRONG INTRASEASONAL ACTIVITY. . . . . . . . . PROGNOSTIC DISCUSSION OF SST FORECASTS FORECASTS FROM STATISTICAL AND NUMERICAL MODELS FOR SSTS IN THE TROPICAL PACIFIC MOSTLY INDICATE THAT SSTS WILL REMAIN WARMER THAN NORMAL IN THE NEXT FEW SEASONS. THERE IS CONSIDERABLE SPREAD AMONG THE TOOLS... WITH SOME MODELS PREDICTING SSTS IN THE NINO 3.4 REGION EDGING UPWARD TO PRODUCE A WEAK WARM EVENT... WHILE OTHERS PREDICT THAT ANOMALIES WILL SLOWLY DIMINISH TOWARD ZERO. A CONSOLIDATION FORECAST OF NCEP SST MODELS INDICATES THAT NINO 3.4 TEMPERATURE ANOMALIES WILL DECREASE TO NEAR ZERO AND REMAIN THERE THROUGH THE FALL AND WINTER. NINO 3.4 PREDICTABILITY FROM WINTER INTO SPRING AND SUMMER IS LOW... AND INDIVIDUAL SOLUTIONS FOR THIS SUMMERS NINO 3.4 SSTS RANGE FROM VERY SLIGHTLY BELOW NORMAL TO A WEAK WARM EVENT WITH ANOMALIES AROUND 1 DEGREE C. CONSENSUS SUGGETS NEUTRAL ENSO CONDITIONS WILL CONTINUE THROUGH LATE 2004... WITH NO CONSENSUS FOR EITHER WARM OR COLD EPISODE CONDITIONS NEXT WINTER. TO SEE THESE FORECASTS GO TO: http://www.cpc.ncep.noaa.gov/products/predictions /90day/tools/briefing/index.pri.html PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOK THE STATISTICAL TOOLS...CCA - OCN - SMLR...WERE CONSULTED AT ALL LEAD TIMES. DYNAMICAL MODEL FORECASTS FROM NCEP AND OTHER FORECAST CENTERS WERE EXAMINED FOR THE PERIOD MAM 2004 THROUGH JJA 2004 AND A CONSENSUS OF THESE TOOLS WAS USED IN PREPARING THE FORECASTS FOR THESE SEASONS. ALSO - SOME CONSIDERATION OF COMPOSITE OBSERVED TEMPERATURE AND PRECIPITATION ANOMALY PATTERNS OVER THE CONUS FOR PAST CASES OF NEUTRAL NINO 3.4 SSTS WERE CONSIDERED IN PREPARING THE FORECASTS FOR THE FIRST FEW LEADS. THE PRIMARY TOOLS USED IN THE MAM THROUGH JJA FORECASTS WERE OCN AND CCA... TWO-TIER FORECASTS FROM SIX MODELS PROVIDED BY CDC... DYNAMICAL MULTI-MODEL ENSEMBLES FROM IRI AND DYNAMICAL MODEL FORECASTS FROM THE NCEP ENVIRONMENTAL MODELING CENTER FOR THE TEMPERATURE FORECASTS... WITH MORE EMPHASIS PLACED ON THE DYNAMICAL MODELS FOR THE PRECIPITATION OUTLOOKS. . . . . . . . . PROGNOSTIC DISCUSSION OF OUTLOOKS - MAM 2004 TO MAM 2005 TEMPERATURE: THE CIRCULATION PATTERN PREDICTED FOR MAM AND AMJ 2004 BY A CONSENSUS OF CLIMATE MODELS FAVORS WARMER THAN NORMAL TEMPERATURES IN THE WESTERN U.S. AND ALASKA. RECENT TEMPERATURE TRENDS ALSO FAVOR ABOVE NORMAL TEMPERATURES ACROSS MOST OF THE WEST AND CENTRAL AND EASTERN ALASKA. A COMPOSITE OF PAST CASES FOR TREND ADJUSTED ENSO-NEUTRAL CONDITIONS SUGGEST AN INCREASE IN THE ODDS OF BELOW NORMAL TEMPERATURES IN PORTIONS OF THE NORTHERN PLAINS DURING MAM 2004... WHICH IS ALSO INDICATED BY THE OCN AND CCA TEMPERATURE TOOLS. THE OUTLOOK FROM AMJ AND MJJ 2004 IS DERIVED MAINLY FROM CCA AND OCN AND FEATURES BETTER THAN AVERAGE CHANCES FOR ABOVE NORMAL TEMPERATURES THROUGH MUCH OF THE WESTERN U.S... SOUTHERN FLORIDA AND ALASKA. THE CCA AND OCN ALSO INDICATED AREAS OF BELOW NORMAL TEMPERATURES DURING BOTH SEASONS IN THE NORTHERN PLAINS. BETTER THAN AVERAGE CHANCES FOR ABOVE NORMAL TEMPERATURES ARE ALSO FAVORED ACROSS THE SOUTH DURING MJJ. THE OUTLOOK FOR JJA 2004 AND BEYOND IS BASED MOSTLY ON CCA AND OCN AND FAVORS WARMER THAN NORMAL TEMPERATURES OVER THE SOUTHWEST DURING ALL LEAD TIMES... EXTENDING TO INCLUDE MUCH OF THE SOUTHERN AND SOUTHEASTERN U.S. IN THE SUMMER. THE FORECAST FOR THE WINTER OF 2004-2005 REFLECTS REGIONAL TEMPERATURE TRENDS... SINCE THE ENSO STATE FOR THAT TIME IS UNCERTAIN. . . . . . . . . PRECIPITATION: THE STATISTICAL TOOLS GIVE VERY WEAK INDICATIONS FOR ANOMALOUS PRECIPITATION DURING MAM. THEREFORE THE MAM PRECIPITATION FORECAST IS BASED ENTIRELY ON THE DYNAMIC MODELS AND THE CDC TWO-TIER FORECASTS... WHICH SUGGEST BELOW MEDIAN PRECIPITATION FOR MOST OF CALIFORNIA AND WESTERN NEVADA... AND FOR THE FLORIDA PENINSULA. MOST OF THE DYNAMICAL TOOLS WERE IN GOOD AGREEMENT OF THESE FEATURES. OCN GIVES INDICATIONS FOR ENHANCED CHANCES OF ABOVE MEDIAN PRECIPITATION FOR THE PACIFIC NORTHWEST IN AMJ TO MJJ 2004...WHILE THE IRI MULTI-MODEL FORECAST GIVES A CONTINUED SIGNAL FOR BELOW-NORMAL PRECIPITATION OVER FLORIDA. THERE WERE FEW RELIABLE PRECIPITATION SIGNALS FOR JJA THROUGH SON 2004 - WITH THE EXCEPTION OF DRY CONDITIONS FORECAST FOR PORTIONS OF THE FAR WEST DURING JAS AND ASO AND FOR ENHANCED CHANCES OF ABOVE MEDIAN PRECIPITATION CENTERED OVER WESTERN NEBRASKA IN SON AND OND INDICATED BY OCN. OCN ALSO INDICATES ELEVATED CHANCES OF ABOVE MEDIAN PRECIPITATION AMOUNTS OVER SOUTHERN FLORIDA FROM JAS TO SON 2004. CHANCES FOR BELOW MEDIAN PRECIPITATION FROM NDJ THROUGH JFM OVER MONTANA AND NORTHERN WYOMING ARE FROM THE OCN TOOL. INDICATIONS FOR ABOVE MEDIAN PRECIPITATION IN THE SOUTHERN PLAINS AND TEXAS ARE ALSO FROM TRENDS. 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. CDC - CLIMATE DIAGNOSTIC CENTER. A NOAA ENVIRONMENTAL RESEARCH AND DEVELOPMENT FACILITY. http://www.cdc.noaa.gov CLIMATOLOGY - THE 30-YEAR AVERAGE OF A VARIABLE - LIKE TEMPERATURE - AT A GIVEN LOCATION AND TIME OF YEAR. . . . . . . . . CONUS - CONTERMINOUS UNITED STATES CONVECTION - A PROCESS WHEREBY AIR BECOMES BUOYANT RELATIVE TO ITS SURROUNDINGS AND BEGINS TO RISE IN A CONCENTRATED COLUMN - WHILE THE SURROUNDINGS SUBSIDE OVER A MUCH LARGER AREA. THE TERM IS OFTEN USED TO DESCRIBE THE OCCURENCE OF DEEP CUMULUS CONVECTION IN THE TROPICAL OCEANS. CPC - CLIMATE PREDICTION CENTER. A NOAA FACILITY WHICH PRODUCES OPERATIONAL PREDICTIONS FOR 6-10-, 8-14-DAYS, MONTHLY AND SEASONAL TIME FRAMES. http://www.cpc.ncep.noaa.gov DATELINE - A HYPOTHETICAL LINE APPROXIMATELY ALONG THE 180TH MERIDIAN DESIGNATED AS THE PLACE WHERE EACH CALENDAR DAY BEGINS. 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 - EL NINO/SOUTHERN OSCILLATION FORCED OR FORCING - GENERALLY REFERS TO WARM OCEAN SURFACE TEMPERATURES IN THE TROPICAL OCEANS WHICH SUCCESSIVELY INFLUENCE THE STRENGTH OF TROPICAL CUMULUS CONVECTION - THE TROPICAL LARGE-SCALE ATMOSPHERIC CIRCULATION - THE JET STREAMS AND FINALLY - THE MIDDLE LATITUDE CIRCULATION. GCM - GENERAL CIRCULATION MODEL - A GENERIC TERM APPLIED TO GLOBAL DYNAMICAL MODELS. IRI - INTERNATIONAL RESEARCH INSTITUTE FOR CLIMATE PREDICTION - A NOAA-FUNDED NON-GOVERNMENTAL ORGANIZATION WHICH PREPARES INTERNATIONAL CLIMATE FORECASTS. http://iri.columbia.edu 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 OSCILLA- TION - 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. OLR - OUTGOING LONGWAVE RADIATION (HEAT) WHICH IS OBSERVED BY SATELLITE. IN THE TROPICS - LOWER THAN AVERAGE OLR INDICATES ENHANCED DEEP CUMULUS CLOUDS AND RAIN (SATELLITE IS SEEING COLD CLOUD TOPS) - WHILE HIGHER THAN AVERAGE OLR INDICATES AN ABNORMAL ABSENCE OF CLOUDS AND RAIN (SATELLITE IS SEEING WARM LOW LAYERS (SHALLOW CLOUDS) OF THE ATMOSPHERE OR THE SURFACE). 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. SIGNAL - THAT PART OF THE VARIATION OF THE ENVIRONMENT WHICH CORRESPONDS TO A REAL - PHYSICAL PHENOMENON. WHEN THE SIGNAL IS LARGE - ITS SIGNATURE STANDS OUT ABOVE THE REMAINDER TO THE VARIATION OF THE ENVIRONMENT - CALLED THE NOISE. SIGNAL IS SOMETIMES PREDICTABLE. NOISE IS NOT. THE RELATIONSHIP BETWEEN SIGNAL AND NOISE IS EXPRESSED AS A NUMBER - CALLED THE SIGNAL-TO-NOISE RATIO OR S/N. WHEN S/N IS GREATER THAN 1 - SIGNAL IS LARGER THAN NOISE - AND THE SIGNATURE OF THE DISTURBANCE CAUSING THE SIGNAL CAN BE SEEN. WHEN S/N IS LESS THAN 1 WE HAVE NO HOPE OF SEEING OR PREDICTING THE DISTURBANCE. 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. SPREAD - A MEASURE OF THE VARIATION - OR AGREEMENT AMONG MODEL FORECASTS WHICH ARE VALID AT THE SAME TIME. LARGE SPREAD INDICATES POOR AGREEMENT. SMALL SPREAD GENERALLY INDICATES GOOD AGREEMENT AMONG FORECASTS. SST - SEA SURFACE TEMPERATURE STATISTICAL PREDICTIONS - PREDICTIONS BASED MAINLY ON LARGE OBSERVATIONAL DATA SETS. CCA - OCN - SMLR - CAS - CA ARE EXAMPLES OF THESE. TAO - TROPICAL OCEAN-ATMOSPHERE PROJECT. A SOURCE OF REAL-TIME OBSERVATIONS OF THE STATUS OF THE TROPICAL PACIFIC. DEVELOPED AND MAINTAINED BY THE PACIFIC MARINE ENVIRONMENTAL LABORATORY (PMEL) - A NOAA FACILITY. http://www.pmel.noaa.gov 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. UPPER AIR HEIGHT PATTERN - A PATTERN FORMED BY THE CONTOURS WHICH MAP THE TOPOGRAPHY OF THE HEIGHT ABOVE SEA LEVEL OF A SURFACE ALONG WHICH THE PRESSURE IS EVERYWHERE THE SAME. THE LINES ON THIS MAP FORM A SERIES OF UNDULATING BUT MORE OR LESS CIRCULAR SHAPES WHICH ARE CONCENTRIC ABOUT THE POLES AND WHICH RESEMBLE A CROSS SECTION OF AN ONION. WELL ABOVE THE GROUND THE WIND BLOWS PARALLEL TO THE CONTOURS WITH LOW PRESSURE TO THE NORTH (SOUTH) IN THE NORTHERN (SOUTHERN) HEMISPHERE - GENERALLY FROM WEST TO EAST - WITH SPEED PROPORTIONAL TO THE SLOPE OF THE SURFACE. THE CLOSER (FARTHER APART) THE CONTOURS ARE TOGETHER (THE STEEPER (SHALLOWER) THE SLOPE) THE FASTER (SLOWER) THE WIND SPEED. 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 MAR 18 2004. THESE OUTLOOKS ARE BASED ON DEPARTURES FROM 1971-2000 AVERAGES. $$