895
FXUS07 KWBC 211337
PMD30D
PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
830 AM EST THU FEB 21 2008
30-DAY OUTLOOK DISCUSSION FOR MARCH 2008
STRONG LA NINA CONDITIONS CONTINUE TO DOMINATE THE TROPICAL PACIFIC... WITH
WELL BELOW AVERAGE SEA SURFACE TEMPERATURES (SSTS) OBSERVED ACROSS THE CENTRAL
AND EASTERN EQUATORIAL PACIFIC. SSTS MORE THAN 2 DEG CELSIUS BELOW AVERAGE
WERE OBSERVED BETWEEN 175E AND 120W AND THE NINO 3.4 REGION INDEX VALUE HAS
BEEN NEAR -2.0 FOR THE PAST MONTH. IN ADDITION THE LOW LEVEL EQUATORIAL
EASTERLY WINDS HAVE BEEN STRONGER THAN AVERAGE ACROSS THE CENTRAL EQUATORIAL
PACIFIC... STRONGER THAN AVERAGE UPPER LEVEL WESTERLY WINDS HAVE BEEN
OBSERVED... AND CONVECTION HAS BEEN SUPPRESSED OVER THE CENTRAL PACIFIC.
COLLECTIVELY, THESE ATMOSPHERIC AND OCEANIC CONDITIONS ARE CONSISTENT WITH
STRONG LA NINA CONDITIONS. SST FORECASTS FROM THE CFS AND A SUITE OF OTHER
STATISTICAL AND DYNAMICAL MODELS INDICATE THAT LA NINA SHOULD REMAIN STRONG OR
MODERATE THROUGH MARCH AND INTO THE SPRING. THEREFORE, THE MARCH TEMPERATURE
AND PRECIPITATION FORECASTS ARE BASED STRONGLY ON LA NINA COMPOSITES FOR THE
FEBRUARY - APRIL SEASON. INTRASEASONAL (MJO) ACTIVITY HAS BEEN RATHER
PERSISTENT SINCE MID-NOVEMBER, AND HAS MODULATED LA NINA IMPACTS ACROSS THE
CONUS AT VARIOUS TIME DURING THE WINTER. THIS MAY CONTINUE THROUGH MARCH...
AND THIS POTENTIAL IS REFLECTED MAINLY IN THE PRECIPITATION FORECAST WITH LOWER
PROBABILITIES THAN MIGHT OTHERWISE BE EXPECTED GIVEN THE STRENGTH OF THE
ONGOING LA NINA.
THE TEMPERATURE OUTLOOK FOR MARCH FAVORS ABOVE AVERAGE TEMPERATURES ACROSS MOST
OF THE SOUTH FROM ARIZONA EASTWARD... ACROSS THE SOUTHERN AND CENTRAL PLAINS...
AND ALONG THE EASTERN SEABOARD FROM FLORIDA NORTHWARD THROUGH THE MID-ATLANTIC.
BELOW-AVERAGE TEMPERATURES ARE MOST LIKELY IN THE PACIFIC NORTHWEST AND IN
SOUTHERN CALIFORNIA AND ALSO IN SOUTHERN ALASKA AND THE ALASKAN PANHANDLE. THE
OBSERVED BELOW-AVERAGE SSTS ALONG THE CALIFORNIA COAST FAVOR A CONTINUATION OF
BELOW AVERAGE TEMPERATURES IN SOUTHERN CALIFORNIA. THE TEMPERATURE FORECAST
OVER THE REST OF THE CONUS AND ALASKA IS CONSISTENT WITH OBSERVATIONS FROM
PREVIOUS STRONG LA NINA EPISODES. THE TEMPERATURE FORECAST IN THESE REGIONS IS
ALSO SUPPORTED BY THE SMLR AND THE CCA, AS WELL AS FORECASTS FROM THE CFS.
THE PRECIPITATION FORECAST FOR MARCH LARGELY REFLECTS THE FEBRUARY - APRIL LA
NINA COMPOSITE, WHICH INDICATES MEAN DRY CONDITIONS ACROSS THE ENTIRE SOUTHERN
U.S. WITH AN EXTENSION UP INTO THE CENTRAL PLAINS AND WETTER THAN AVERAGE
CONDITIONS IN THE PACIFIC NORTHWEST AND IN THE OHIO AND TENNESSEE VALLEYS.
PROBABILITIES IN THE SOUTHWEST ARE LOWER THAN MIGHT TYPICALLY BE EXPECTED
DURING A STRONG LA NINA DUE TO THE UNPREDICTABILITY OF THE MJO. DRIER THAN
AVERAGE CONDITIONS ARE ALSO FAVORED IN SOUTHERN ALASKA... AS INDICATED BY THE
CFS AND THE CCA.
FORECASTER: MIKE HALPERT
NOTES: AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL
PROBABILITIES) ARE NOW LABELED AS EC (EQUAL CHANCES).
AN UPDATED MONTHLY OUTLOOK... FOR MAR WILL BE ISSUED ON FRI FEBRUARY 29 2008
THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1971-2000 BASE PERIOD.
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