PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
830 AM EDT THU MAR 18 2010

30-DAY OUTLOOK DISCUSSION FOR APRIL 2010

EL NINO CONDITIONS CONTINUE ACROSS THE EQUATORIAL PACIFIC OCEAN WITH SEA 
SURFACE TEMPERATURE (SST) DEPARTURES OF +1.0 DEGREE C OR GREATER ACROSS MUCH OF 
THE CENTRAL PACIFIC. OCEAN SUB-SURFACE TEMPERATURE ANOMALIES ALSO REMAIN 
POSITIVE FROM THE SURFACE TO A DEPTH OF APPROXIMATELY 130 M EAST OF THE 
DATELINE ALONG THE EQUATOR ACROSS THE PACIFIC, THEREFORE EL NINO CONDITIONS ARE 
EXPECTED TO CONTINUE EASILY THROUGH APRIL 2010.

CURRENT ATMOSPHERIC CONDITIONS IN THE TROPICS ARE CONSISTENT WITH EL NINO. 
ENHANCED TROPICAL CONVECTION ACROSS THE PACIFIC OCEAN NEAR THE DATE LINE IS 
EVIDENT AS WELL AS ANOMALOUS LOW-LEVEL WESTERLY WIND ANOMALIES ACROSS PORTIONS 
OF THE WEST-CENTRAL PACIFIC DURING THE PAST 30 DAYS. BASED ON THE 
AFOREMENTIONED OCEANIC AND ATMOSPHERIC CONDITIONS, EL NINO REMAINS A FACTOR IN 
THE APRIL 2010 MONTHLY OUTLOOK FOR THE US. 

WE NEED TO POINT OUT THAT THE ENSO IMPACT DEPENDS ON SEASON. WE MAY SEE 
CONTINUED EL NINO TYPE FORCING IN THE TROPICS AND A DIRECT OR DELAYED 
ATMOSPHERIC RESPONSE IN THE MID-LATITUDE FOR APRIL, BUT LESS SO THAN IN MARCH. 
SOME ENSO IMPACTS OVER THE US EXPERIENCED DURING LAST WINTER MAY CARRY OVER IN 
LAGGED FASHION INTO APRIL AND LATER THROUGH SOIL MOISTURE ANOMALIES, AS WELL AS 
BY WIDESPREAD NEGATIVE SST ANOMALIES IN THE GULF OF MEXICO AND SOUTHWEST 
ATLANTIC.

BOTH STATISTICAL AND DYNAMICAL FORECAST TOOLS WERE CONSIDERED FOR THE OUTLOOK 
ALTHOUGH THE STATISTICAL TOOLS MAY HAVE LITTLE SIGNAL FOR A PERIOD AS SHORT AS 
MONTH. THE CFS INDICATES A STRONG EL NINO PATTERN THAT IS QUITE CONSISTENT WITH 
EL NINO COMPOSITES. WE AMENDED THE ENSO COMPOSITES IN AREAS WHERE STRONG SOIL 
MOISTURE ANOMALIES MAY IMPACT APRIL TEMPERATURE. THIS WOULD BE MAINLY IN STATES 
WHERE VEGETATION IS GREENING, I.E. ACROSS THE SOUTH, NOT IN THE DAKOTAS

THE APRIL OUTLOOK FAVORS ENHANCED CHANCES FOR BELOW-AVERAGE TEMPERATURES ACROSS 
PARTS OF THE SOUTH-CENTRAL AND SOUTHEAST U.S. INTO THE SOUTHERN MID-ATLANTIC 
AND AN ENHANCED LIKELIHOOD FOR ABOVE-NORMAL TEMPERATURES FOR MUCH OF ALASKA, 
THE PACIFIC NORTHWEST AND PARTS OF THE GREAT LAKES. ABOVE-MEDIAN PRECIPITATION 
IS FAVORED FOR SOME OF THE SOUTHERN TIER OF THE U.S. FROM ARIZONA ACROSS THE 
SOUTH TO EASTERN TEXAS AND ALSO FLORIDA. ELEVATED CHANCES FOR BELOW-MEDIAN 
PRECIPITATION ARE INDICATED FOR THE PACIFIC NORTHWEST AND PARTS OF THE GREAT 
LAKES.

  
 


FORECASTER: HUUG VAN DEN DOOL

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

AN UPDATED MONTHLY OUTLOOK... FOR APR WILL BE ISSUED ON WED MARCH 31 2010

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

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