PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD 830 AM EST THU NOV 19 2009 30-DAY OUTLOOK DISCUSSION FOR DECEMBER 2009 EL NINO CONTINUED TO STRENGTHEN DURING THE MONTH OF OCTOBER AND INTO EARLY NOVEMBER. SEA SURFACE TEMPERATURES (SSTS) IN THE PACIFIC OCEAN ARE NOW MORE THAN 1.5 DEG. C ABOVE NORMAL ALONG THE EQUATOR FROM 170 E TO 120 W LONGITUDE, WITH ANOMALIES CLOSE TO 2 DEG. C FROM NEAR THE DATE LINE TO 130W. SUB-SURFACE OCEAN TEMPERATURES IN THE EASTERN EQUATORIAL PACIFIC OCEAN ARE WELL ABOVE NORMAL. THE AVERAGE HEAT CONTENT OF THE UPPER 300 METERS HAS BEEN STEADY IN RECENT MONTHS AFTER HAVING RETREATED SLIGHTLY FROM THEIR PEAK VALUES IN LATE SUMMER. ATMOSPHERIC CONDITIONS OVER THE TROPICAL PACIFIC ARE CONSISTENT WITH EL NINO, WITH LOW LEVEL WESTERLY WIND ANOMALIES AND UPPER LEVEL EASTERLY WIND ANOMALIES OBSERVED IN OCTOBER AND EARLY NOVEMBER. THE MEAN ATMOSPHERIC CONVECTION FOR OCTOBER 2009 WAS ENHANCED IN THE WEST-CENTRAL EQUATORIAL PACIFIC AND SUPPRESSED OVER INDONESIA. THESE INDICATORS ARE SUGGESTIVE OF A MODERATE EL NINO EVENT. MOST MODELS PREDICT THAT THE EL NINO INTENSITY WILL REMAIN MODERATE THROUGH DECEMBER. THE MADDEN-JULIAN OSCILLATION (MJO) HAS BEEN QUITE ACTIVE IN THE PAST FEW WEEKS. THE MJO IS EXPECTED TO COMPLICATE THE ATMOSPHERIC EL NINO TELECONNECTIONS DURING THE MONTH OF DECEMBER. SPECIFICALLY, THE CHANCE OF ABOVE MEDIAN PRECIPITATION AMOUNTS IS ELEVATED ALONG THE WEST COAST OF THE CONUS AS A RESULT OF THE INFLUENCE OF THE MJO EXPECTED IN THE EARLY PART OF DECEMBER. THE TEMPERATURE OUTLOOK FOR DECEMBER IS MOSTLY BASED ON THE CFS MODEL FORECAST AND EL NINO COMPOSITES FOR NDJ. INCREASED CHANCES OF ABOVE NORMAL TEMPERATURES ARE INDICATED FOR THE WESTERN U.S. EXCEPT FOR PARTS OF THE SOUTHWEST AND SOUTHERN ROCKIES DUE TO AN UPPER LEVEL RIDGE EXPECTED OVER WESTERN NORTH AMERICA ASSOCIATED WITH EL NINO. EL NINO TELECONNECTIONS FAVOR BELOW NORMAL TEMPERATURES NEAR TEXAS AND PORTIONS OF THE WESTERN GULF STATES. THE CFS INDICATES BELOW NORMAL TEMPERATURES THROUGHOUT MOST OF THE SOUTHEASTERN U.S., HOWEVER, ENSO COMPOSITES SUGGESTING BELOW NORMAL TEMPERATURES ARE LESS CONVINCING ALONG THE EASTERN GULF THAN THE WESTERN GULF SO EC IS INDICATED FOR MUCH OF THE SOUTHEAST AND EASTERN U.S. ABOVE NORMAL TEMPERATURES ARE FAVORED FOR MUCH OF THE CENTRAL AND EASTERN PARTS OF ALASKA INCLUDING THE PANHANDLE. THE PRECIPITATION FORECAST IS CONSISTENT WITH ENSO COMPOSITES WITH SOME REVISIONS DUE TO THE CFS MODEL FORECASTS AND AN ACTIVE MJO. EL NINO USUALLY INCREASES THE CHANCES OF ABOVE MEDIAN PRECIPITATION AMOUNTS FOR SOUTHERN CALIFORNIA. AN ACTIVE MJO IN THE PHASE PREDICTED IN EARLY DECEMBER INCREASES CHANCES FOR ENHANCED PRECIPITATION AMOUNTS FARTHER NORTH ALONG THE COAST THAN NORMALLY EXPECTED IN EL NINO, SO ELEVATED CHANCES FOR ABOVE MEDIAN PRECIPITATION AMOUNTS FOR THIS DECEMBER EXTEND TO SOUTHERN OREGON. THE MJO RELATED ACTIVITY FAVORS WET CONDITIONS IN THE PACIFIC NORTHWEST, CONTRADICTING THE DRY CONDITIONS USUALLY FAVORED IN EL NINO DECEMBERS RESULTING IN A FORECAST FOR EQUAL CHANCES FOR BELOW, NEAR, OR ABOVE MEDIAN PRECIPITATION AMOUNTS FOR COASTAL AREAS IN WASHINGTON STATE AND NORTHERN OREGON. THE CFS INDICATES ABOVE MEDIAN PRECIPITATION ALONG THE ALASKAN PANHANDLE. THE CFS PREDICTS DRY CONDITIONS FOR MUCH OF THE WESTERN U.S., HOWEVER, WITH THE UNCERTAINTY DUE TO MJO AND GENERALLY WEAK ENSO PRECIPITATION TELECONNECTIONS IN THE EARLY PART OF THE WINTER SEASON, PROBABILITIES FOR BELOW MEDIAN PRECIPITATION ARE ONLY SIGNIFICANTLY ENHANCED FOR THE NORTHERN ROCKIES WHERE THE ENSO SIGNAL FOR DRY IS STRONGEST. AN ENHANCED SOUTHERN JET IN ASSOCIATED WITH EL NINO IS EXPECTED TO ELEVATE CHANCES FOR ABOVE MEDIAN PRECIPITATION AMOUNTS ALONG THE GULF COAST FROM TEXAS THROUGH FLORIDA. THE CFS FORECASTS FOR ENHANCED PRECIPITATION IN FLORIDA ARE DISTINCTLY LESS CERTAIN THAN FOR THE WESTERN GULF, SO HIGHEST PROBABILITIES ARE FOR INDICATED FOR SOUTHERN TEXAS. FORECASTER: DAVID UNGER NOTES: AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL PROBABILITIES) ARE NOW LABELED AS EC (EQUAL CHANCES). AN UPDATED MONTHLY OUTLOOK... FOR DEC WILL BE ISSUED ON MON NOVEMBER 30 2009 THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1971-2000 BASE PERIOD. $$