PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD 300 PM EST WED FEB 28 2007 30-DAY OUTLOOK DISCUSSION FOR MARCH 2007 SEA SURFACE TEMPERATURE (SST) ANOMALIES IN THE CENTRAL EQUATORIAL PACIFIC HAVE STEADILY DECREASED SINCE THE BEGINNING OF THE YEAR... WITH NEGATIVE ANOMALIES OBSERVED BY THE END OF FEBRUARY BETWEEN 145W AND 110W. THIS RAPID DECREASE OF THE SST ANOMALIES HAS SIGNALED A RETURN TO NEAR-NEUTRAL ENSO CONDITIONS... AFTER A RATHER SHORT PERIOD OF EL NINO CONDITIONS THAT BEGAN EARLY LAST FALL. ABOVE NORMAL SSTS ACROSS THE EQUATORIAL PACIFIC WERE ONLY OBSERVED BETWEEN 160E AND 170W AND IN THE EXTREME EASTERN PACIFIC. THE EQUATORIAL UPPER-OCEAN HEAT CONTENT ACROSS THE CENTRAL AND EASTERN PACIFIC REACHED A MAXIMUM IN EARLY NOVEMBER... AND DECREASED RAPIDLY SINCE THEN... BECOMING NEGATIVE DURING THE MIDDLE OF JANUARY FOR THE FIRST TIME SINCE APRIL 2006. THE LOW LEVEL (850-HPA) EQUATORIAL EASTERLIES HAVE GENERALLY BEEN ENHANCED SINCE THE MIDDLE OF DECEMBER... CONTRIBUTING TO THE RATHER RAPID AND EARLY DEMISE OF THIS EL NINO EPISODE. THE SUB-SURFACE OCEAN TEMPERATURE ANOMALIES ACROSS THE CENTRAL AND EASTERN PACIFIC COMBINED WITH THE PERSISTENT ENHANCED LOW LEVEL EASTERLY WINDS INDICATE A POSSIBLE TRANSITION TO LA NINA CONDITIONS DURING THE NEXT FEW MONTHS. HOWEVER FORCING FROM THE TROPICAL PACIFIC IS NOT EXPECTED TO IMPACT THE CLIMATE OF THE U.S. DURING MARCH. THE UPDATED TEMPERATURE OUTLOOK FOR MARCH FAVORS ABOVE NORMAL TEMPERATURES ACROSS MUCH OF THE WESTERN PART OF THE NATION... EXCEPT FOR THE PACIFIC NORTHWEST... SOUTHERN CALIFORNIA AND EXTREME SOUTHERN ARIZONA. THIS IS BASED LARGELY ON LONG TERM TRENDS ALTHOUGH THERE IS PRETTY GOOD AGREEMENT AMONG ALL THE STATISTICAL TOOLS... CCA... SMLR... AND OCN... WHICH ALL FAVOR ABOVE NORMAL TEMPERATURES ACROSS PARTS OF THE WEST. INDICATIONS FROM VARIOUS DYNAMICAL MODEL SOLUTIONS ALSO FAVOR ABOVE NORMAL TEMPERATURES IN MUCH OF THE REGION DURING BOTH THE WEEK 1 AND WEEK 2 PERIODS. MODEL SOLUTIONS ALSO FAVOR WELL BELOW NORMAL TEMPERATURES IN MUCH OF ALASKA DURING THE NEXT 2 WEEKS... ENHANCING THE PROBABILITY THAT MARCH TEMPERATURES WILL AVERAGE BELOW NORMAL ACROSS MUCH OF THE STATE. THE STATISTICAL TOOLS GIVE NO STRONG INDICATIONS OF ABOVE OR BELOW NORMAL TEMPERATURES IN EITHER THE CENTRAL OR EASTERN PART OF THE COUNTRY... WHILE THE INDICATIONS FOR THE FIRST HALF OF THE MONTH ARE MIXED... WITH BELOW NORMAL TEMPERATURES EXPECTED EARLY FOLLOWED BY ABOVE NORMAL TEMPERATURES DURING WEEK 2. FOR THAT REASON... THE OUTLOOK IN THOSE REGIONS HAS EQUAL CHANCES OF ABOVE NORMAL... NEAR NORMAL... OR BELOW NORMAL TEMPERATURES DURING MARCH. THE PRECIPITATION OUTLOOK FOR MARCH FAVORS ABOVE MEDIAN PRECIPITATION OVER THE PACIFIC NORTHWEST AND OVER THE WESTERN GREAT LAKES. THIS IS INDICATED IN FORECASTS FOR THE FIRST FEW DAYS OF THE MONTH AND IS ALSO FAVORED IN BOTH THE 6-10 AND 8-14 DAY FORECASTS. THE LONG LEAD MONTHLY FORECAST HAD FAVORED ABOVE NORMAL PRECIPITATION IN THE SOUTHERN PLAINS... BUT THIS FORECAST WAS CHANGED TO EQUAL CHANCES DUE TO EXPECTATIONS OF A DRY FIRST HALF OF THE MONTH. DRIER-THAN-MEDIAN PRECIPITATION IS ANTICIPATED OVER SOUTHERN AND CENTRAL CALIFORNIA... ARIZONA... THE SOUTHERN HALF OF NEVADA... SOUTHERN UTAH AND WESTERN NEW MEXICO. THIS IS INDICATED IN BOTH THE CFS AND SMLR AND IS ALSO EVIDENT IN FORECASTS FROM THE SHORTER RANGE DYNAMICAL MODELS. DRIER THAN MEDIAN CONDITIONS ARE ALSO ANTICIPATED FOR MUCH OF ALASKA... AS THE UPSTREAM RIDGE FORECAST IN THE DYNAMICAL MODELS FAVORS BELOW-MEDIAN PRECIPITATION... AT LEAST DURING THE FIRST HALF OF THE MONTH. ELSEWHERE THERE ARE NO STRONG INDICATIONS FOR EITHER ABOVE OR BELOW MEDIAN PRECIPITATION AND THE FORECAST IS FOR EQUAL CHANCES FOR ABOVE NORMAL... NEAR NORMAL... OR BELOW NORMAL PRECIPITATION. FORECASTER: M HALPERT NOTES - AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL PROBABILITIES) ARE NOW LABELED EC (EQUAL CHANCES). THE NEXT MONTHLY OUTLOOK... FOR APRIL 2007... WILL BE ISSUED ON THU MAR 15 2007 THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1971-2000 BASE PERIOD. $$