UPDATE FOR 30-DAY OUTLOOK DISCUSSION FOR JANUARY 2005

[CaptinCrunch]

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

[misty]

So will this sub tropical jet eventually hit some colder air in the latter part of the month to give the southern states an ice storm, or do you think that the jet stream will move and we will have a ho-hum rest of winter.