PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD 300 PM EDT SAT MAR 31 2007 30-DAY OUTLOOK DISCUSSION FOR APRIL 2007 SEA SURFACE TEMPERATURE (SST) ANOMALIES IN THE CENTRAL AND EASTERN EQUATORIAL PACIFIC HAVE STEADILY DECREASED SINCE THE BEGINNING OF THE YEAR... WITH NEGATIVE ANOMALIES OBSERVED THROUGHOUT MOST OF MARCH BETWEEN 140W AND 100W. 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 140E AND 165E. THE EQUATORIAL UPPER-OCEAN HEAT CONTENT ACROSS THE CENTRAL AND EASTERN PACIFIC REACHED A MAXIMUM IN EARLY NOVEMBER... AND DECREASED RAPIDLY ... 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. IN ANY CASE... FORCING FROM THE TROPICAL PACIFIC IS NOT EXPECTED TO IMPACT THE CLIMATE OF THE U.S. DURING APRIL. THE TEMPERATURE OUTLOOK FOR APRIL CALLS FOR ABOVE NORMAL TEMPERATURES ACROSS MOST OF THE WESTERN THIRD OF THE LOWER 48 STATES... AND MOST OF MAINLAND ALASKA. THIS IS CONSISTENT WITH THE LATEST EXTENDED RANGE MODEL GUIDANCE... ALTHOUGH THE WARMTH OVER THE SOUTHWEST IS ALSO INDICATED BY THE OCN... CCA... AND CAS STATISTICAL TOOLS. THE RECENT CLIMATE FORECAST SYSTEM (CFS) RUNS HAVE SHOWN A PREFERENCE FOR RELATIVELY COLD CONDITIONS ACROSS THE NORTHERN ROCKIES - AND NORTHERN AND CENTRAL GREAT PLAINS... WHILE RECENT GFS EXTENDED RANGE MODEL GUIDANCE SUGGESTS COLDER THAN AVERAGE TEMPERATURES ACROSS THE GREAT LAKES AND NORTHEAST DURING THE 6-10 AND WEEK 2 PERIODS. IT REMAINS TO BE SEEN WHETHER OR NOT THIS COLD WEATHER LASTS LONG ENOUGH INTO APRIL TO DOMINATE THE ENTIRE MONTHS CLIMATE. ELSEWHERE... WHICH INCLUDES THE EASTERN CONUS - THE IMMEDIATE COASTLINE OF FAR SOUTHERN CALIFORNIA - THE ALASKA PANHANDLE - AND THE ALEUTIANS ... WEAK OR CONFLICTING SIGNALS AMONG THE TOOLS RESULTED IN A FORECAST OF EQUAL CHANCES OF ABOVE NORMAL... NEAR NORMAL... OR BELOW NORMAL TEMPERATURES. THE PRECIPITATION OUTLOOK FOR APRIL CALLS FOR ABOVE MEDIAN PRECIPITATION OVER CENTRAL AND EASTERN TEXAS AS WELL AS OVER WESTERN AND CENTRAL LOUISIANA. THIS IS BASED PRIMARILY ON SHORT AND MEDIUM RANGE MODEL GUIDANCE. BELOW MEDIAN AMOUNTS OF PRECIPITATION ARE EXPECTED OVER MUCH OF THE SOUTHWEST U.S... FLORIDA... AND SOUTHERN GEORGIA. THESE AREAS OF RELATIVE DRYNESS ARE ALSO CONSISTENT WITH EXTENDED RANGE MODEL GUIDANCE... ALTHOUGH THE DRYNESS OVER THE SOUTHWEST IS ALSO SUPPORTED BY THE OCN ... CCA AND CAS STATISTICAL TOOLS. THE RELATIVE DRYNESS ANTICIPATED OVER FLORIDA AND NEARBY SOUTHERN GEORGIA ALSO HAS SUPPORT FROM LONGER TERM TRENDS (OCN)... WITH APRIL TRADITIONALLY BEING A DRY TIME OF THE YEAR FOR THAT AREA. THE AREA OF RELATIVE WETNESS PREDICTED TWO WEEKS AGO OVER THE EASTERN DAKOTAS AND WESTERN MINNESOTA MAINLY ON THE BASIS OF STATISTICAL TOOLS HAS BEEN TAKEN OUT DUE TO MORE RECENT DYNAMICAL MODEL CONSIDERATIONS. ELSEWHERE... INCLUDING ALL OF ALASKA... THERE ARE WEAK AND/OR CONFLICTING PRECIPITATION SIGNALS... AND THE FORECAST IS FOR EQUAL CHANCES FOR ABOVE MEDIAN... NEAR MEDIAN... OR BELOW MEDIAN PRECIPITATION. FORECASTER: A ARTUSA NOTES - AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL PROBABILITIES) ARE NOW LABELED EC (EQUAL CHANCES). THE NEXT MONTHLY OUTLOOK... FOR MAY 2007... WILL BE ISSUED ON THU APR 19 2007 THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1971-2000 BASE PERIOD. $$