PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK 
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
300 PM EST THU DEC 18 2003

30-DAY OUTLOOK DISCUSSION FOR JANUARY 2004
                                                                               .
SST ANOMALIES CURRENTLY AVERAGE AROUND .5 TO 1 DEGREE C ABOVE NORMAL IN THE 
EASTERN AND CENTRAL EQUATORIAL PACIFIC OCEAN... AND CLOSER TO PLUS 1 DEGREE C 
NEAR AND JUST WEST OF THE DATE LINE. THE VARIOUS STATISTICAL AND NUMERICAL 
MODELS FOR EQUATORIAL PACIFIC SSTS ARE EVENLY SPLIT BETWEEN THOSE PREDICTING A 
SLOW DRIFT TOWARD NORMAL CONDITIONS OR SLIGHTLY NEGATIVE ANOMALIES AND THOSE 
THAT PREDICT A SLIGHT INCREASE IN POSITIVE ANOMALIES.  THE CONSENSUS OPINION IS 
THAT SST ANOMALIES WILL REMAIN APPROXIMATELY STEADY AND THAT THE ENSO STATE IN 
JANUARY WILL BE BEST DESCRIBED AS EITHER NEUTRAL OR A VERY WEAK EL NINO.  IN 
ANY EVENT THE IMPACTS OF ENSO ON U.S. TEMPERATURE AND PRECIPITAION IN JANUARY 
IS EXPECTED TO BE VERY SMALL.  

THIS MONTHS NUMERICAL CLIMATE PREDICTION MODELS APPEAR TO BE MOST INFLUENCED
BY THE WARMER THAN NORMAL SSTS IN THE WESTERN PACIFIC WHICH FAVOR AN ANOMALOUS 
MEAN UPPER RIDGE OVER WESTERN NORTH AMERICA AND AN ANOMALOUSLY DEEP TROUGH IN 
THE EAST.  THIS CIRCULATION PATTERN WOULD MAKE MOST OF THE WESTERN HALF OF THE 
CONUS AND ALASKA WARMER THAN NORMAL... WITH COLDER THAN NORMAL TEMPERATURES IN 
MOST OF THE EASTERN U.S.  THE RELIABILITY OF THE MODELS IS NOT KNOWN IN THE 
ABSENCE OF A STRONG ENSO SIGNAL SO THE ANOMALY PATTERN PREDICTED BY THE MODELS 
IS  REFLECTED ONLY WHERE THERE IS SUPPORT FROM OTHER TOOLS.  THUS... BELOW 
NORMAL TEMPERATURES ARE INDICATED ONLY FOR THE SOUTHEASTERN AND GULF COAST 
STATES...  SUPPORTED BY CCA AND SCREENING REGRESSION FORECASTS.  ABOVE NORMAL 
TEMPERATURES ARE INDICATED MAINLY FOR THE SOUTHWEST U.S. WITH SUPPORT FROM ALL 
TOOLS... ESPECIALLY OCN.  ALASKAN TEMPERATURES ARE EXPECTED TO AVERAGE 
ABOVE NORMAL IN THE EASTERN PART OF THE STATE.  ABOVE NORMAL TEMPERATURES ARE 
INDICATED IN THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY MAINLY DUE TO 
TRENDS AND THE CCA FORECAST... BUT MAY RESULT FROM THE EXPECTED CIRCULATION 
PATTERN INDICATED BY THE MODELS DUE TO MILD PACIFIC AIR ENTERING WESTERN 
CANADA AND CROSSING OVER THE WESTERN RIDGE INTO THE NORTH-CENTRAL STATES.   

THE MODELS CONTINUE TO INDICATE ABNORMALLY DRY CONDITIONS IN FLORIDA AND 
SURROUNDING AREAS.  THIS SIGNAL IS REMARKABLY PREVALENT AMONG DIFFERENT 
CLIMATE MODELS - AND ALSO APPEARS IN THE STATISTICAL TOOLS AS WELL SUCH AS CCA
AND SCREENING REGRESSION FORECASTS.  THE FORECAST IS ONLY MARGINALLY DIFFERENT 
FROM CLIMATOLOGICAL PROBABILITIES... HOWEVER... DUE TO THE POSSIBILITY OF WEAK 
ENSO CONDITIONS WHICH FAVOR ABOVE MEDIAN PRECIPITATION IN THE REGION.  THE 
MODELS PREDICT BELOW MEDIAN PRECIPITATION FOR MUCH OF THE SOUTHWESTERN U.S...
BUT SINCE MODEL RESULTS ARE FOR THREE-MONTH PERIODS AND PRECIPITATION TOTALS 
FOR A MONTHLY PERIOD IN THAT AREA OFTEN DEPEND ON ONLY ONE OR TWO SYNOPTIC 
EVENTS... THE PRECIPIATION OUTCOME IS CLOSE TO EQUAL CHANCES IN THE SOUTHWEST.
OVER THE EASTERN PACIFIC... THE MAIN BAND OF WESTERLIES IS EXPECTED TO BE 
DISPLACED SLIGHTLY NORTH OF NORMAL... FAVORING ABOVE MEDIAN PRECIPITATION IN 
THE ALASKAN PANHANDLE.  THERE ARE NO RELIABLE INDICATIONS FOR JANUARY 
PRECIPITATION ELSEWHERE.    

FORECASTER: D. UNGER

NOTE - THIS CLIMATE OUTLOOK IS INTENDED FOR USE ONLY PRIOR TO THE START OF THE 
VALID PERIOD.  WITHIN THE VALID PERIOD OBSERVATIONS AND SHORT AND MEDIUM RANGE 
FORECASTS SHOULD BE CONSULTED.

NOTE -  AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL
PROBABILTIES) ARE NOW LABELED EC (EQUAL CHANCES).  
  
NOTE - THE NEXT 0.5 MONTH LEAD-TIME MONTHLY OUTLOOK WILL BE ISSUED 
THURSDAY JANUARY 15 2004.
  
NOTE - THE NEW 1971-2000 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE 
WITH THE MAY 17 2001 FORECAST RELEASE.


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