PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
300 PM EDT MON APR 30 2007

30-DAY OUTLOOK DISCUSSION FOR MAY 2007

SEA SURFACE TEMPERATURES (SSTS) REMAIN AT ENSO-NEUTRAL LEVELS IN THE NINO 3.4 
REGION (120W TO 170W, +/- 5 N, S), AND ARE EXPECTED TO REMAIN NEAR THERE DURING 
MAY, SO ENSO IS NOT AN EXPLICIT FACTOR IN THIS FORECAST.  THIS ZERO-LEAD 
FORECAST FOR MAY IS BASED ON 1) SHORT-AND EXTENDED-RANGE PRECIPITATION 
FORECASTS, 2) EXTENDED-RANGE (6-10-, 8-14-DAY) AVERAGE TEMPERATURE FORECASTS, 
AND 3) FORECASTS OF 30-DAY AVERAGE TEMPERATURE AND TOTAL PRECIPITATION FROM 
NCEP'S CLIMATE FORECAST SYSTEM (CFS) MODEL.  

SHORT-RANGE QUANTITATIVE PRECIPITATION FORECASTS FROM THE HYDROMETEOROLOGICAL 
PREDICTION CENTER INDICATE A HEAVY PRECIPITATION EVENT CENTERED ON NORTH TEXAS 
AND OKLAHOMA DURING THE FIRST 5 DAYS OF MAY.  THIS EVENT HAS APPEARED IN 
FORECAST MODELS FOR MORE THAN A WEEK, AND APPEARS TO BE WELL-SUPPORTED, AND IS 
INCLUDED IN THIS FORECAST FOR MAY.  EXTENDED-RANGE FORECASTS INDICATE 
ABOVE-MEDIAN RAINFALL FROM OKLAHOMA NORTHWARD TO MINNESOTA, THE DAKOTAS, 
MONTANA, WYOMING AND UTAH AND NORTHWESTERN COLORADO.  EXTENDED RANGE FORECASTS 
ALSO INDICATE SUB-MEDIAN RAINFALL FROM THE OHIO VALLEY NORTHEASTWARD INTO NEW 
ENGLAND.  THE MOST STRONGLY INDICATED PORTIONS OF THESE FORECASTS ARE INCLUDED 
IN THE MAY FORECAST.  FINALLY, THE CFS AGREES WITH THESE SHORTER-RANGE 
INDICATIONS OVER SECTIONS OF MONTANA AND NORTH DAKOTA.  IT ALSO INDICATES 
SUB-MEDIAN AVERAGE MAY RAINFALL OVER SECTIONS OF THE SOUTHEAST.

THE CFS FOREAST FOR ALASKA GIVES STRONG INDICATIONS OF ABOVE-NORMAL 
TEMEPERATURE OVER ALASKA.  THE CFS ALSO INDICATES BELOW-NORMAL TEMPERATURES 
OVER THE NORTHWEST, AND ABOVE-NORMAL TEMPERATURES IN THE SOUTHWEST.  EXTENDED 
RANGE FORECASTS AGREE WITH THE CFS IN THE NORTHWEST, BUT NOT IN THE SOUTHWEST, 
WHERE THEY GIVE WEAK INDICATIONS OF ABOVE-NORMAL TEMPERATURES.  THE COMPROMISE 
IN THE MAY FORECAST IS TO PREDICT BELOW-NORMAL TEMPERATURES IN THE NORTHWEST 
AND A SMALL REGION OF ABOVE-NORMAL TEMPERATURES OVER MAINLY CENTRAL AND 
SOUTHERN CALIFORNIA, WITH THE EXCEPTION OF EC IN SOUTHERN-MOST COASTAL AREAS, 
WHERE COOL TEMPERATURES HAVE APPEARED IN RECENT DAYS. 

FORECASTER: EDWARD OLENIC


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

THE NEXT MONTHLY OUTLOOK... FOR JUNE 2007... WILL BE ISSUED ON THU MAY 17 2007

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

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