PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
830 AM EDT THU APRIL 15 2004
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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. SSTS IN THE TROPICAL PACIFIC REMAIN BELOW THE THRESHOLD
REQUIRED TO PRODUCE ENSO IMPACTS ON THE US CLIMATE. IN FACT - SSTS IN THE
ENSO-RELEVANT REGION HAVE MOVED EVEN CLOSER TO NORMAL THAN THEY WERE LAST MONTH.
CLIMATE MODELS FROM NCEP - CDC - IRI AND ECMWF INDICATE CONTINUATION OF NEAR-
NEUTRAL TROPICAL SSTS AT LEAST THROUGH THE SUMMER. THESE MODELS ALL TEND TO
AGREE ON THE LIKELY OCCURRENCE OF A REGION OF ABNORMAL DRYNESS OVER THE SOUTH-
EASTERN US DURING MJJ. ANOTHER REGION OF ABNORMAL DRYNESS IS LIKELY OVER THE
NORTHWEST US DURING JAS AND ASO. EQUAL CHANCES IS GIVEN FOR THE THREE POSSIBLE
CATEGORIES OF PRECIPITATION (ABOVE - MEDIAN - BELOW) OVER ALASKA BEYOND JAS 2004
AND OVER THE CONUS BEYOND ASO 2004. RELATIVELY WARM CONDITIONS ARE LIKELY OVER
MUCH OF THE WEST - THE SOUTHWEST - SOUTHERN TEXAS - THE GULF COAST STATES AND
FLORIDA DURING MJJ THROUGH SON. REMAINING AREAS NOT MENTIONED HAVE EQUAL ODDS
FOR EACH OF THE THREE CATEGORIES OF TEMPERATURE AND PRECIPITATION.
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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
AS OF MID-APRIL WEEKLY AVERAGES OF SST SHOW TEMPERATURE ANOMLIES IN THE NEUTRAL
RANGE ACROSS MUCH OF THE TROPICAL PACIFIC - INCLUDING ALONG THE WEST COAST OF
SOUTH AMERICA. EXCEPTIONS INCLUDE A SMALL REGION OF 0.5 TO 1.0 DEGREE ANOMALIES
WEST OF ABOUT 145E - AND A SMALL REGION OF -0.5 TO -1.0 DEGREE ANOMALIES
BETWEEN ABOUT 130 AND 100W.
A 5-DAY MEAN TOGA-TAO DEPTH-LONGITUDE CROSS-SECTION SHOWS ABNORMALLY WARM WATER
- WITH ANOMALIES OF UP TO 2 C - CENTERED ABOUT 125 METERS BELOW THE SURFACE
WEST OF ABOUT 160W AND A REGION OF ABNORMALLY COLD WATER TO THE EAST OF 160W -
SLOPING UPWARD TOWARD THE EAST - FROM A DEPTH OF 125 METERS AT 160W (WITH 1 C
ANOMALIES) - TO A DEPTH OF 50 METERS (WITH -2 C ANOMALIES) BETWEEN 120W AND THE
SOUTH AMERICAN COAST. THIS ARRANGEMENT OF ANOMALIES MAKES FOR A LARGER-THAN-
AVERAGE TILT IN THE THERMOCLINE - FROM DEEPER THAN NORMAL IN THE WEST TO
SHALLOWER THAN NORMAL IN THE EAST.
THE TRADE WINDS HAVE AN ABNORMAL WESTERLY COMPONENT NEAR ABOUT 160E. ELSEWHERE
TRADE WINDS ARE CLOSE TO NORMAL. A BURST OF WESTERLY WINDS OVER THE FAR WESTERN
SECTION OF THE TROPICAL PACIFIC OCCURED DURING EARLY APRIL.
A REGION OF ENHANCED CONVECTION CURRENTLY RESIDES BETWEEN 145E AND THE DATELINE.
THIS REGION HAS SHIFTED EASTWARD OVER THE PAST MONTH. ELSEWHERE IN THE TROPICAL
PACIFIC OLR IS SUB-NORMAL.
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PROGNOSTIC DISCUSSION OF SST FORECASTS
FORECASTS FROM MULTIPLE MODELS GIVE A RANGE OF POSSIBLE FUTURE SST ANOMALIES IN
NINO 3.4 OF -0.3 TO +1.0 C FOR THE NEXT FEW SEASONS. THE CONSENSUS OF THE
MODEL SST FORECASTS FALLS WITHIN THE ENSO-NEUTRAL RANGE FROM THEN THROUGH NEXT
FALL. 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 REMAIN SLIGHTLY ABOVE ZERO THROUGH SPRING 2004 - WITH THE ODDS
FOR NEUTRAL CONDITIONS REACHING 85% IN MJJ - 80% IN JJA AND 75% IN JAS -
WHILE THE ODDS OF LA NINA ARE 10% IN MJJ - 15% IN JJA AND 20% IN JAS. THE
ODDS FOR EL NINO ARE A CONSTANT 5% IN MJJ - 5% IN JJA AND 5% IN JAS.
BY NEXT WINTER - THE CONSENSUS IS STILL WITHIN THE NEUTRAL RANGE. WE EXPECT
THAT TRANSIENT ATMOSPHERIC CIRCULATION PATTERNS WILL CONTINUE TO BE FORCED
PRIMARILY BY INTRA-SEASONALLY VARYING PHASES OF THE MJO.
PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOK
THE PRIMARY TOOLS USED IN THE MJJ THROUGH ASO FORECASTS WERE OCN AND CCA.
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. 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. ALSO - SOME CONSIDERATION WAS GIVEN TO COMPOSITE
OBSERVED TEMPERATURE AND PRECIPITATION ANOMALY PATTERNS OVER THE CONUS FOR PAST
CASES OF NEUTRAL SST PATTERNS OVER THE EQUATORIAL PACIFIC.
THE IMPACT OF OCN AND CCA IS VISIBLE IN THE SOUTHERN AND WESTERN US AND IN
ALASKA JFM THROUGH AMJ TEMPERATURE FORECASTS AND TO A LESSER EXTENT IN THE
PRECIPITATION FORECASTS FOR THESE SAME SEASONS. CCA AND OCN ARE THE ONLY TOOLS
USED BEYOND THE FOURTH LEAD. THE CONSTRUCTED ANALOG FORECAST AND THE ENSEMBLE
CCA BOTH PREDICTED COLD IN THE WEST AND WARM IN THE EAST. CA ALSO PREDICTED
ABNORMAL WETNESS IN TEXAS. THESE TOOLS - THOUGH OF GREAT INTEREST - WERE NOT
USED AS PRIMARY INPUTS - THOUGH PROBABILITIES OF ABOVE NORMAL TEMPERATURE IN
TEXAS WERE REDUCED COMPARED WITH LAST MONTHS FORECAST IN ACNOWLEDGMENT OF THE
CA AND ECCA FORECASTS.
BECAUSE THE STATUS OF ENSO IS NEUTRAL AND WE ARE IN THE SPRING BARRIER PERIOD -
FORECASTS FROM THE DYNAMICAL MODELS ARE NOT THE MAIN INPUTS TO THIS FORECAST.
ONE EXCEPTION IS THE PRECIPITATION FORECAST FOR MJJ IN THE SOUTHEAST - WHERE
A STRONG CONSENSUS AMONG DYNAMICAL MODELS AND THE CCA FORECAST FROM CDC
PROMPT A FORECAST FOR ENHANCED LIKELIHOOD OF SUB-MEDIAN PRECIPITATION.
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PROGNOSTIC DISCUSSION OF OUTLOOKS - MJJ 2005 TO MJJ 2006
TEMPERATURE: CCA AND OCN ARE THE MAIN TOOLS USED HERE.
FOR MJJ 2005 CCA AND OCN INDICATE ABOVE NORMAL TEMPERATURES FOR MUCH OF ALASKA
- THE COASTAL NORTHWEST AND SECTIONS OF THE SOUTHERN U.S. FROM CALIFORNIA TO
THE SOUTHEAST. THIS OVERALL WARM - AND LARGELY TREND - SIGNAL FADES FROM
ALASKA IN JJA 2004 THROUGH MAM 2005 BUT RETURNS IN AMJ AND MJJ 2005. OVER THE
CONTINENTAL U.S. THE EXCESS WARMTH EXPANDS IN JJA TO BECOME CONTINUOUS ALONG
THE WEST COAST - AND TO COVER ALL OF THE SOUTHWEST - THE SOUTHERN GREAT PLAINS
- THE SOUTH AND THE OHIO AND MISSISSIPPI VALLEYS. IN JAS THE EXCESS WARMTH -
REMAINS IN THESE AREAS - SHRINKING IN SIZE AND LIKELIHOOD IN THE EAST AND
GETTING MORE LIKELY AND LARGER IN AREA - IN THE WEST. BY ASO ABNORMAL WARMTH
COVERS CENTRAL AND SOUTHERN SECTIONS OF THE WEST - THE ROCKIES AND WESTERN
SECTIONS OF THE CENTRAL AND SOUTHERN GREAT PLAINS - AS WELL AS SOUTHERN FLORIDA.
BY SON THE TREND FOR ABNORMAL WARMTH RETREATS TO A SMALL SECTION OF THE INTERIOR
SOUTHWEST CENTERED ON ARIZONA - SOUTHERN FLORIDA ALSO REMAINS IN THE ABOVE
NORMAL CLASS. THE CCA-OCN SIGNAL FADES TO EC 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. IN DJF THIS REGION GETS COMPANY FROM THE
NORTHEAST - THE GREAT LAKES THE OHIO VALLEY AND TENNESSEE AND EASTERN SECTIONS
OF THE NORTHERN AND CENTRAL GREAT PLAINS. THE CCA-OCN SIGNAL PEAKS IN JFM 2005
- WHEN MUCH OF THE NATION IS LIKELY TO HAVE ABOVE NORMAL TEMPERATURES THAN IN
ANY OTHER SEASON. CCA-OCN INDICATES ABNORMAL WARMTH ONLY IN THE WEST IN
FMA AND MAM AND IN THE WEST AND SOUTHERN ALASKA IN AMJ 2005. IN THE FINAL
LEAD - MJJ 2005 - THE CCA-OCN COMBINED TOOL INDICATES ENHANCED LIKELIHOOD FOR
ABNROMAL WARMTH IN THE SOUTHEAST - SECTIONS OF THE INTERIOR SOUTHWEST AND
TEXAS - COASTAL SECTIONS OF THE NORTHWEST AND IN SOUTHERN ALASKA.
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PRECIPITATION:
A CONSENSUS OF MODELS INDICATES AN ENHANCED LIKELIHOOD OF SUB-MEDIAN
PRECIPITATION IN THE SOUTHEAST IN MJJ. IN JAS AND ASO OCN AND CCA INDICATE
ENHANCED LIKELIHOOD OF SUB-MEDIAN PRECIPITATION IN SECTIONS OF THE NORTHWEST.
ELSEWHERE AND FOR OTHER SEASONS NOT MENTIONED EC IS INDICATED.
NOTE - AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL
PROBABILITIES) ARE NOW LABELED EC (EQUAL CHANCES).
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FORECASTER: E. OLENIC
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.
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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 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.
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.
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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 MAY 20 2004.
1971-2000 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 17 2001
FORECAST RELEASE.
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