PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
300PM EDT SATURDAY APR 30 2011

30-DAY OUTLOOK DISCUSSION FOR MAY 2011

LA NINA CONDITIONS ARE WEAKLY PRESENT ACROSS THE TROPICAL PACIFIC OCEAN BUT 
LAST WINTER'S EVENT IS WANING AND THE DIRECT IMPACT ON THE US SHOULD BE MINIMAL 
IN MAY. INDIRECT IMPACTS LIVE ON BECAUSE THIS WINTER'S EVENT HAS LEFT A STRONG  
IMPRINT IN TERMS OF DRY SOIL MOISTURE CONDITIONS ACROSS THE SOUTH AND GENERALLY 
WET CONDITIONS ACROSS THE NORTH. THESE LOWER BOUNDARY CONDITIONS OVER LAND 
WOULD CAUSE WARMTH ACROSS THE SOUTH AND COOLNESS ACROSS THE NORTH WHEN SOLAR 
RADIATION BECOMES MORE INTENSE, I.E. SPRING AND SUMMER. 

THE MAY 2011 TEMPERATURE AND PRECIPITATION OUTLOOKS AT LONG LEAD WERE BASED ON 
DYNAMICAL MODELS AS WELL AS CCA, SMLR, CAS AND OCN. THE END OF THE MONTH 
ADJUSTMENT TAKES INTO ACCOUNT THE NUMERICAL GUIDANCE FROM GFS AND CFS, AS WELL 
AS THE HPC DAY 1-5 QPF AND CPC 6-10 DAY AND WEEK 2 FORECASTS. THE MAIN CHANGE 
IS THE ADDITION OF ENHANCED CHANCES FOR ABOVE MEDIAN PRECIPITATION IN A STRIPE 
FROM EXTREME NE TEXAS TO SOUTHERN OHIO WHERE HEAVY PRECIPITATION IS PREDICTED 
IN THE SHORT RANGE (MAY 1-4). WE ALSO REDUCED THE CHANCES FOR ABOVE NORMAL 
TEMPERATURES IN THE SOUTH BECAUSE NUMERICAL GUIDANCE LOOKS QUITE COLD, BUT 
MODELS MAY BE OVERDOING THIS OVER THE EXCEEDINGLY DRY SOILS OF TEXAS ETC.

ENHANCED CHANCES FOR ABOVE NORMAL TEMPERATURE ARE EXPECTED ACROSS THE SOUTH, 
ESPECIALLY IN ARIZONA, NEW MEXICO AND TEXAS. PROBABILITIES FOR BELOW NORMAL 
TEMPERATURES ARE MODESTLY ENHANCED FROM WASHINGTON TO THE DAKOTAS, THEN ONWARD 
INTO THE MID-WEST. 

ENHANCED CHANCES FOR BELOW MEDIAN PRECIPITATION ARE EXPECTED IN MUCH OF THE 
SOUTHWEST WITH THE HIGHEST PROBABILITIES IN THE SAME AREAS (NEW MEXICO, ETC, 
... ) WHERE A WARM SIGNAL EXISTS.  PROBABILITIES FOR ABOVE MEDIAN PRECIPITATION 
ARE ENHANCED FROM THE NW PACIFIC TO THE DAKOTAS AND MINNESOTA, AND IN A 
SEPARATE AREA FROM EXTREME NE TEXAS TO SOUTHERN OHIO WITH THE HIGHEST 
PROBABILITIES IN CENTRAL ARKANSAS.

SIGNALS ARE CONFLICTING OR ABSENT ELSEWHERE, IN PARTICULAR IN THE EAST AND 
ALASKA.

WHERE THERE ARE NO CLEAR CLIMATE SIGNALS DURING THE FORECAST PERIOD, EQUAL 
CHANCES (EC) OF BELOW, NEAR, AND ABOVE NORMAL FOR TEMPERATURE AND BELOW, NEAR, 
AND ABOVE MEDIAN FOR PRECIPITATION ARE INDICATED.


FORECASTER: HUUG VAN DEN DOOL


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


THE NEXT MONTHLY OUTLOOK...FOR JUN ... WILL BE ISSUED ON THU MAY 19 2011


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

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