PROGNOSTIC DISCUSSION FOR LONG-LEAD OUTLOOKS
CLIMATE PREDICTION CENTER NCEP
NATIONAL WEATHER SERVICE  WASHINGTON DC
3 PM EDT THURSDAY MAY 16 2002
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     SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS

THIS SET OF OUTLOOKS ARE AFFECTED BY THREE MAIN FACTORS - SOIL MOISTURE - EL 
NINO - AND TREND.  THE OUTLOOK FOR JUNE-JULY-AUGUST 2002 CALLS FOR ABOVE NORMAL 
PRECIPITATION FROM THE WESTERN OHIO VALLEY TO THE CENTRAL GREAT PLAINS - BASED 
ON THE EXPECTED EFFECT OF ON-GOING VERY WET SOILS IN THAT REGION.  TEMPERATURES 
IN THAT REGION ARE ALSO EXPECTED TO BE MORE MODERATE THAN THEY MIGHT OTHERWISE 
BE - ON AVERAGE.  ON THE OTHER HAND - WET SOILS IN THE REGION COULD CONTRIBUTE 
TO MORE SEVERE HEAT WAVE CONDITIONS WHEN ABNORMALLY WARM TEMPERATURES DO OCCUR 
BY ACTING AS A SOURCE OF MOISTURE WHICH ENHANCES THE HUMIDITY.  IMPACTS OF WET 
SOILS COULD CONTINUE INTO JULY-AUGUST-SEPTEMBER BUT INDICATIONS ARE NOT 
SUFFICIENTLY STRONG TO WARRANT ANOMALIES ON THE MAP.
  
THE TEMPERATURE OUTLOOK IN THE CENTRAL CONTINENTAL US IS UNCERTAIN - CALLING 
FOR CLIMATOLOGICAL PROBABILITIES THROUGHOUT THE MIDDLE OF THE LOWER 48 STATES.  
ABOVE NORMAL TEMPERATURES ARE EXPECTED FOR MUCH OF THE EAST - THE SOUTH - THE 
ROCKIES AND THE WEST.  THIS BASIC TEMPERATURE PATTERN IS EXPECTED TO HOLD FOR 
MUCH OF THE WARM SEASON.  THE OTHER CONSISTENT SUMMER FORECAST INDICATION IS 
FOR DRIER THAN NORMAL CONDITIONS IN THE NORTHWESTERN CONTINENTAL US.  
CLIMATOLOGICAL PROBABILITIES (UNCERTAIN CONDITIONS) ARE INDICATED FOR ALASKA. 

CURRENTLY THE TROPICAL PACIFIC OCEAN SURFACE TEMPERATURES ARE HOVERING JUST 
BELOW THE LEVEL OF A WEAK EL NINO.  WE EXPECT AT LEAST WEAK EL NINO CONDITIONS 
TO DEVELOP BY EARLY WINTER.  THE OUTLOOKS FOR THE COLD SEASON REFLECT THIS - 
SHOWING ABNORMALLY WARM AND DRY CONDTIONS FOR THE NORTHERN CONTINENTAL US AND
ABNORMALLY WET - AND IN SOME AREAS COLD - CONDTIONS IN THE SOUTH DURING WINTER.  

THE FORECAST REVERTS TO THE TREND - MAINLY WARMER THAN NORMAL TEMPERATURES 
AROUND THE MARGINS OF THE NATION - IN LATE SPRING AND SUMMER 2003. 

     BASIS AND SUMMARY OF THE CURRENT LONG-LEAD OUTLOOK
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THIS OUTLOOK REFLECTS THE EXPECTED U.S. CLIMATE ANOMALIES BASED ON THE LONG-TERM 
TREND AS ESTIMATED BY OCN - AND STATISTICALLY BASED RELATIONSHIPS BETWEEN RECENT 
OCEANIC AND ATMOSPHERIC CONDITIONS AND U.S. TEMPERATURE AND PRECIPITATION.
DYNAMICAL FORECASTS FROM GENERAL CIRCULATION MODELS WERE ALSO CONSIDERED FOR THE 
FIRST FOUR SEASONS. THE OUTLOOKS FOR OND 2002 THROUGH MAM 2003 ARE INFLUENCED BY 
THE ANTICIPATION OF THE DEVELOPMENT OF AN EL NINO EVENT BY OR BEFORE NEXT 
WINTER.

     CURRENT ATMOSPHERIC AND OCEANIC CONDITIONS

PACIFIC SSTS ARE NOW AT LEAST 0.5 DEG C ABOVE NORMAL ALONG THE EQUATOR FROM
WEST OF THE INTERNATIONAL DATE LINE TO APPROXIMATELY 130W.  SUB-SURFACE PACIFIC 
OCEAN TEMPERATURES ALONG THE EQUATOR ARE MODESTLY WARMER THAN NORMAL AS WELL. SO 
FAR CONVECTION HAS BEEN ENHANCED MAINLY NEAR AND JUST WEST OF THE DATE LINE AND 
MOST ATMOSPHERIC INDICIES STILL INDICATE NEUTRAL ENSO CONDITIONS.  EXTRATROPICAL 
NORTH PACIFIC SSTS EAST OF THE DATELINE HAVE COOLED CONSIDERABLY DURING THE LAST 
MONTH. THERE ARE LARGE AREAS OF AT LEAST -1C ANOMALIES NEAR THE DATELINE AT 
20-40-N AND ALONG THE WEST COAST OF NORTH AMERICA.  SSTS IN THE VICINITY OF 
HAWAII HAVE ALSO DECLINED DURING THE LAST MONTH TO NEAR-NORMAL.   
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     PROGNOSTIC DISCUSSION OF SST FORECASTS

STATISTICAL AND DYNAMICAL PREDICTIONS OF NINO 3.4 SSTS ARE IN GOOD AGREEMENT
ON THE ENSO OUTLOOK FOR THE NEXT SEVERAL MONTHS TO YEAR. TWO OF THE THREE MAIN
TOOLS RUN AT NCEP FORECAST WEAK TO MODERATE WARM EPISODE (EL NINO) CONDITIONS
TO DEVELOP BY SUMMER (CCA AND THE NCEP NUMERICAL MODEL) - WHILE THE CONSTRUCTED
ANALOG (CA) METHOD KEEPS TEMPERATURES NEAR NORMAL THROUGH THE REMAINDER OF 2002. 
AT THIS POINT WE CAN PRACTICALLY RULE OUT A COLD EVENT. THE CA PREDICTION DOES
NOT ACCOUNT FOR THE SUB-SURFACE OBSERVATIONS WHICH HAVE CHANGED DRAMATICALLY IN 
THE LAST 6 MONTHS - WHICH MAY EXPLAIN ITS LACK OF RESPONSE TO RECENT CHANGES IN 
EQUATORIAL SSTS.

THE MOST RECENT OBSERVATIONS OF SSTS IN THE CENTRAL PACIFIC - ALONG WITH THE
SUB SURFACE STRUCTURE SUPPORTS THE ENSO PREDICTION TOOLS THAT FAVOR WARMER SSTS 
HENCE THE OFFICIAL FORECAST IS FOR A WARM ENSO EVENT TO CONTINUE TO DEVELOP. 
THUS THIS MONTHS OUTLOOK WILL FOLLOW THE FORECAST FROM THE NCEP MODEL AND CCA
AND NOT THE CA OR THE REGRESSION CONSOLIDATION FORECAST.  ABOVE NORMAL CENTRAL
EQUATORIAL PACIFIC SSTS ARE ALSO SUPPORTED BY NEARLY ALL MODELS RUN AT OTHER 
CLIMATE CENTERS.  THEREFORE CONFIDENCE IN AN AT LEAST MODEST WARM EVENT BY NEXT 
WINTER IS UP FROM LAST MONTH.  WE NOTE SOME MODEL RUNS ELSWHERE SHOWING A 
QUICKLY DEVELOPING WARM EVENT WITH A DEMISE BY FALL. THIS SCENARIO - WHILE 
POSSIBLE - IS NOT ADOPTED HERE.  THE OFFICIAL FORECAST IS FOR A WARM ENSO EVENT 
TO FURTHER DEVELOP IN THE NEXT 3-6 MONTHS AND PERSIST THROUGH NEXT WINTER.

     PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOK

THE STATISTICAL TOOLS ...CCA - OCN - SMLR... WERE CONSIDERED AT ALL LEAD TIMES. 
DYNAMICAL MODEL FORECASTS FROM NCEP AND OTHER FORECAST CENTERS WERE CONSULTED
FOR THE PERIOD JJA-SON 2002.  THE LARGE SCALE CIRCULATION PATTERNS ARE
ANTICIPATED TO REFLECT WARM ENSO CONDITIONS BY LATE SUMMER AT THE EARLIEST
AND INTO THE NEXT COOL SEASON - SO WARM EVENT COMPOSITES WERE CONSULTED FOR
SEASONS FROM OND 2002 THROUGH MAM 2003.
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     PROGNOSTIC DISCUSSION OF OUTLOOKS - JJA 2002 TO JJA 2003

TEMPERATURE:

VERY FEW CHANGES WERE MADE RELATIVE TO THE FORECASTS ISSUED ONE MONTH AGO. FOR
JJA WE ENHANCED THE REGION OF WET CONDITIONS EXPECTED IN THE CENTRAL US.  WE
ALSO ADDED AN EXPECTATION OF SUB-MEDIAN PRECIPITATION IN SOUTH TEXAS AND 
EXPANDED THE PREDICTED REGION OF ABNORMAL DRYNESS IN THE NORTHWEST.  
PRECIPITATION ANOMALIES OF SMALL SIZE HAVE BEEN ELIMINATED FROM THE OUTLOOKS
FOR ASO AND SON.  THE ONLY CHANGE IN THE REMAINING OUTLOOKS WAS TO REMOVE
THE SMALL-SCALE PRECIPITATION ANOMALY PREVIOUSLY PREDICTED IN THE NORTHWEST
IN AMJ 2003.  

TEMPERATURES FOR OND 2002 THROUGH MAM 2003 REFLECT THE INFLUENCE OF TRENDS AND 
AN ANTICIPATED MATURE EL NINO EVENT COMBINED. PROBABILITY ANOMALIES ARE MODEST 
SINCE THE STRENGTH OF THE WARM EVENT REMAINS UNCERTAIN AT THIS TIME. IN THE
ABSENCE OF TRENDS THE WINTERTIME TEMPERATURES THROUGHOUT MUCH OF THE SOUTHERN 
U.S. TEND TO BE BELOW NORMAL IN A WARM ENSO EVENT.  HOWEVER A WARMING TREND
ACROSS MUCH OF THE SOUTH MODERATES THE EL NINO SIGNAL.  THE ENSO SIGNAL FOR
BELOW NORMAL IS STRONG ENOUGH RELATIVE TO THE TREND TO FAVOR BELOW NORMAL
TEMPERATURES ONLY OVER FLORIDA NEXT WINTER AND SPRING.  A WARM EVENT IS
ASSOCIATED WITH NEAR TO BELOW NORMAL TEMPERATURES ALONG THE GULF COAST AND
TEXAS.  UNCERTAINTY IN THE STRENGTH OF THE WARM EVENT PREVENTS A CLEAR
DETERMINATION OF THE CATEGORICAL FORECAST THERE - LEAVING THE ODDS CLOSE TO
CLIMATOLOGY IN MOST OF THE GULF COAST AND TEXAS REGION.  OCN - WITH VARYING
AMOUNTS OF SUPPORT FROM CCA AND SMLR - INDICATES WARMER THAN NORMAL
TEMPERATURES FOR MOST SEASONS IN THE SOUTHWEST U.S.  HOWEVER THE OCN WARM
SIGNAL IN THE SOUTHWEST FOR OND - DJF WAS NULLIFIED BY INDICATIONS FOR COLD
AS SEEN IN ENSO COMPOSITES - HENCE A CL FORECAST.

FOR ALASKA ANY SIGNALS SHOWN ARE FOR WARM ARE BASED ON OCN MAINLY. IN MANY
CASES - INCLUDING THE FIRST LEAD JJA - CCA AND OCN CONFLICT AND WE OPTED FOR CL. 

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PRECIPITATION:

BELOW MEDIAN PRECIPITATION IS FAVORED IN THE PACIFIC NORTHWEST IN JJA DUE TO
LONG-TERM TRENDS - CCA AND DYNAMICAL MODEL FORECASTS.  LARGE PORTIONS OF THE 
NATION HAVE DRY INITIAL SOIL MOISTURE CONDITIONS - A MAJOR CONCERN.  CONSTRUCTED 
ANALOG SOIL MOISTURE FORECASTS INDICATE A STRONG IMPACT OF BOTH THE DRY 
CONDITIONS IN SOUTH TEXAS AND THE ROCKIES AND THE WET CONDITIONS IN THE CENTRAL 
US.  CA WAS THE BASIS FOR THE JJA FORECAST OF BELOW-MEDIAN PRECIPITATION IN 
SOUTH TEXAS AND ABOVE-MEDIAN IN THE CENTRAL US.  THE JAS FORECAST OF ABNORMAL
DRYNESS IS FROM CCA - OCN AND CA.
  
A WET AREA FORECAST OVER FLORIDA FROM LATE FALL INTO WINTER THE ABOVE MEDIAN FOR 
FLORIDA IS FROM EL NINO COMPOSITES.  THE BELOW MEDIAN PRECIPITATION FORECAST IN 
THE PACIFIC NORTHWEST IN OND AND THE NORTHERN ROCKIES AND NORTHERN HIGH PLAINS 
FROM NDJ 2002 THROUGH FMA 2003 ARE ALSO BASED ON EL NINO WITH SOME SUPPORT FROM 
OCN.  BEGINNING IN OND 2002 AND CONTINUING THROUGH MAM 2003 EXTENSIVE AREAS OF 
ABOVE MEDIAN PRECIPITATION WITH MODEST PROBABILITIES ARE FORECAST ACROSS THE 
SOUTHERN PART OF THE NATION DUE TO EXPECTED EL NINO CONDITIONS.  THE BELOW MEDIAN 
PRECIPITATION PREDICTION FOR THE NORTH CENTRAL STATES AND THE OHIO VALLEY FROM 
JFM 2003 THROUGH MAM 2003 IS ALSO DUE TO EXPECTED EL NINO INFLUENCES. 

THERE ARE NO RELIABLE FORECAST INDICATIONS FOR ALASKA PRECIPITATION TO DEPART
FROM CLIMATOLOGICAL PROBABILITIES DURING ANY OF THE LEADS AT THIS TIME. 

FORECASTERS: ED OLENIC AND A. J. WAGNER
  
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/MULTI-SEASON/
13_SEASONAL_OUTLOOKS/TOOLS  (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 THURSDAY JUNE 13 2002.

1971-2000 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 17 2001
FORECAST RELEASE.

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