PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
300 PM EST THU NOV 30 2006

30-DAY OUTLOOK DISCUSSION FOR DECEMBER 2006

THE SST ANOMALIES ALONG THE EQUATOR IN THE CENTRAL AND EASTERN PACIFIC OCEAN 
ARE MORE THAN 1 DEGREE C ABOVE NORMAL FROM ABOUT 170E TO THE SOUTH AMERICAN 
COAST... WITH ANOMALIES OF MORE THAN 2 DEGREES C IN SOME PLACES.  SUB-SURFACE 
OCEAN TEMPERATURES REMAIN WELL ABOVE NORMAL THROUGHOUT THE EASTERN AND CENTRAL 
EQUATORIAL PACIFIC... WHICH WILL HELP TO MAINTAIN ABOVE NORMAL SSTS IN ALL ENSO 
SENSITIVE REGIONS.  RECENT RUNS OF THE CFS MODEL PREDICT SST ANOMALIES IN THE 
NINO 3.4 REGION OF AROUND +1.0 DEGREES C THROUGH THE MONTH OF DECEMBER.  THE 
SST ANOMALIES HAVE INCREASED SLIGHTLY SINCE MID-NOVEMBER IN THE CENTRAL PACIFIC 
ENSO REGIONS INDICATING A STRENGTHENING OF EL NINO CONDITIONS.  THIS 
STRENGTHENING WAS ANTICIPATED IN THE ENSO REGION SST FORECASTS AVAILABLE IN 
MID-NOVEMBER... SO DIFFERENCES BETWEEN THIS UPDATE AND THE OUTLOOK ISSUED 
EARLIER IN THE MONTH REFLECT ONLY THE SHORT TERM CIRCULATION PATTERNS PREDICTED 
BY THE GFS MODEL IN THE FIRST HALF OF DECEMBER.    

THE SHORT TERM CIRCULATION PATTERN EXPECTED IN THE FIRST WEEK OF DECEMBER WILL 
FAVOR BELOW NORMAL TEMPERATURES AND SOMEWHAT DRY CONDITIONS OVER MUCH OF THE 
CONUS.  THIS IS EXPECTED TO EVOLVE INTO A CIRCULATION PATTERN MORE TYPICAL OF 
EL NINO EVENTS BY THE SECOND WEEK OF THE MONTH.  EL NINO IS NORMALLY ASSOCIATED 
WITH WARM TEMPERATURES IN THE NORTHERN GREAT PLAINS AND THE GREAT LAKES REGION 
IN DECEMBER.  THE COLD START OF THE MONTH DIMINISHES THE CONFIDENCE IN THIS 
SIGNAL SLIGHTLY... HOWEVER THE EXTENDED RANGE FORECAST OF AN UPPER LEVEL RIDGE 
DEVELOPING IN WESTERN NORTH AMERICA IN THE SECOND WEEK OF DECEMBER TOGETHER 
WITH THE EL NINO TELECONNECTIONS SHOULD FAVOR ABOVE NORMAL TEMPERATURES FROM 
THE NORTHERN ROCKIES TO THE WESTERN GREAT LAKES.  A COLD START TO THE MONTH... 
AND EL NINO TELECONNECTIONS SHOULD FAVOR BELOW NORMAL TEMPERATURES IN THE 
VICINITY OF TEXAS.  CONFIDENCE IN THE ALASKAN PREDICTION FOR ABOVE NORMAL 
TEMPERATURES ISSUED EARLIER IN THE MONTH IS GREATLY REDUCED BY THE PREDICTION 
OF A TROUGH OVER THE ALUETIAN ISLANDS AND WESTERN PART OF THE STATE BY THE 
SECOND WEEK OF THE MONTH.  THE CFS MODEL HAS ALSO BACKED OFF ON ITS EARLIER 
PREDICTION OF ABOVE NORMAL TEMPERATURES FOR ALASKA... SO IN SPITE OF A WARM 
START... THERE ARE ABOUT EQUAL CHANCES FOR THE MONTHLY MEAN TEMPERATURES TO BE 
OBSERVED IN THE THREE CLASSES... ABOVE... NEAR... OR BELOW NORMAL IN MUCH OF 
ALASKA... EXCEPT IN EASTERN SECTIONS OF THE STATE WHICH IS ANTICIPATED TO BE 
CLOSER TO THE MEAN UPPER LEVEL RIDGE.  

THE UPPER LEVEL CIRCULATION PATTERN EXPECTED IN THE FIRST HALF OF DECEMBER 
CALLS FOR AN ACTIVE STORM TRACK IN THE NORTH PACIFIC... WHICH FAVORS ABOVE 
MEDIAN PRECIPITATION AMOUNTS IN THE ALASKAN PANHANDLE AND PARTS OF THE ALASKAN 
SOUTH COAST.  THERE ARE HINTS OF A SOUTHERN JET IN THE GFS EXTENDED RANGE 
PREDICTIONS... WHICH TOGETHER WITH THE 500-HPA RIDGE PREDICTED OVER WESTERN 
NORTH AMERICA COMPLIMENTS THE EXPECTED EL NINO SIGNALS FOR EARLY WINTER IN 
NORTH AMERICA.  THUS... BELOW MEDIAN PRECIPITATION AMOUNTS ARE EXPECTED FROM 
THE NORTHERN ROCKIES TO THE GREAT LAKES... AND ABOVE MEDIAN PRECIPITATION IS 
EXPECTED IN THE SOUTHERN CONUS FROM SOUTHERN CALIFORNIA TO THE WESTERN GULF OF 
MEXICO... AND ALSO IN SOUTHERN FLORIDA.   

FORECASTER: D. UNGER

NOTES - AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL 
PROBABILITIES) ARE NOW LABELED EC (EQUAL CHANCES).

THE NEXT MONTHLY OUTLOOK... FOR JANUARY 2007... WILL BE ISSUED ON THU DEC 21 
2006

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

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