PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK 
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
300 PM EST FRI DEC 31 2004

UPDATE FOR 30-DAY OUTLOOK DISCUSSION FOR JANUARY 2005
                                                                               .
SSTS ALONG THE EQUATOR IN THE PACIFIC ARE CURRENTLY MORE THAN 1 DEGREE C ABOVE 
NORMAL FROM ABOUT 160E TO 150W LONGITUDE AND CLOSE TO 1 DEGREE C ABOVE NORMAL
FROM 150W TO JUST OFF THE SOUTH AMERICAN COAST.  SST ANOMALIES IN THE ENSO 
SENSITIVE REGIONS OF THE PACIFIC ARE VERY SIMILAR TO THEIR VALUES IN MID-
DECEMBER... THUS THE CHANGES INDICATED ON THIS UPDATE REFLECT THE INFLUENCE OF 
SHORT-TERM CIRCULATION ANOMALIES PREDICTED IN THE FIRST HALF OF THE MONTH... 
AND NOT ANY CHANGE IN THE ANTICIPATED ENSO FORCING.  JANUARY 2005 BEGINS WITH
A PERSISTENT UPPER LEVEL CIRCULATION PATTERN FEATURING A STRONG RIDGE IN THE 
GULF OF ALASKA... A DEEP TROUGH IN THE WESTERN U.S. AND A RIDGE OVER THE 
EASTERN PART OF THE COUNTRY.  AN ENHANCED SUBTROPICAL JET IS PREDICTED FOR THE 
FIRST PART OF THE MONTH OVER THE NORTH PACIFIC AND INTO THE CALIFORNIA COAST.  

THE ENHANCED SUBTROPICAL JET WILL MAKE CONDITIONS FAVORABLE FOR PRECIPITATION 
IN CALIFORNIA AND MUCH OF THE SOUTHWEST.  EL NINO CONDITIONS ALSO FAVOR AN 
ENERGETIC SOUTHERLY JET... ALTHOUGH USUALLY LATER IN THE WINTER.  WHILE THE 
WEAK EL NINO CONDITIONS CURRENTLY OBSERVED ARE EXPECTED TO HAVE ONLY A SLIGHT 
IMPACT ON THE CIRCULATION OVER THE U.S... THE ACTIVE SOUTHERN JET EXPECTED FOR 
EARLY JANUARY WILL HELP STRENGTHEN CHANCES FOR ABOVE MEDIAN PRECIPITATION 
ACROSS MUCH OF THE SOUTHERN U.S.  PRECIPITATION AMOUNTS EXPECTED IN THE FIRST 
HALF OF JANUARY IN FLORIDA ARE LIGHT SO THE OUTLOOK THERE WAS REVISED TO 
INDICATE EQUAL CHANCES RATHER THAN ABOVE MEDIAN AS WOULD BE EXPECTED IN A 
STRONGER EL NINO.   AN ACTIVE STORM TRACK AND HEAVY PRECIPITATION IS PREDICTED 
IN EARLY JANUARY OVER THE LOWER MISSISSIPPI AND OHIO RIVER VALLEYS... WITH 
FORECAST PRECIPITATION AMOUNTS IN THE FIRST WEEK OF JANUARY EXCEEDING MONTHLY 
NORMALS IN THE LOWER OHIO VALLEY.  

TEMPERATURES EXPECTED IN THE FIRST TWO WEEKS OF JANUARY CONFLICT WITH THOSE 
NORMALLY EXPECTED IN WEAK WARM ENSO EVENTS.  MUCH OF THE EASTERN U.S. WILL 
BEGIN THE MONTH WITH TEMPERATURES AVERAGING MUCH ABOVE NORMAL... WHILE BELOW 
NORMAL TEMPERATURES ARE EXPECTED IN MUCH OF THE WEST... ESPECIALLY IN THE 
NORTHERN ROCKIES.  THE COLD START OF THE MONTH IN THE WEST REQUIRES A 
SUBSTANTIAL REVISION IN THE 30-DAY TEMPERATURE OUTLOOK... WITH TEMPERATURES 
NOW EXPECTED TO BE MORE IN LINE WITH CLIMATOLOGY OVER MUCH OF THE WEST... AND 
BELOW NORMAL TEMPERATURES FAVORED IN PARTS OF NORTHERN ROCKIES INTO THE 
PACIFIC NORTHWEST.  WARMER THAN NORMAL TEMPERATURES EARLY IN JANUARY IN THE 
EASTERN U.S. WILL INCREASE THE CHANCES THAT THE MONTHLY AVERAGES THERE WILL BE 
WARMER THAN NORMAL.  ALASKAN TEMPERATURES ARE EXPECTED TO AVERAGE ABOVE NORMAL 
IN EARLY JANUARY... AND ARE IN ROUGH AGREEMENT WITH THE OUTLOOK ISSUED IN MID-
DECEMBER EXCEPT ALONG THE PANHANDLE WHERE COOLER THAN NORMAL TEMPERATURES 
EARLY ON FORCED A DOWNWARD REVISION IN MONTHLY MEAN TEMPERATURES EXPECTED 
THERE.

FORECASTER: D. UNGER


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 JAN 20 2005.
  
THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1971-2000 BASE PERIOD.


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