830
FXUS07 KWBC 151330
PMD30D
PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
830 AM EDT THU MAY 15 2008
30-DAY OUTLOOK DISCUSSION FOR JUNE 2008
THE MAGNITUDE OF NEGATIVE SEA SURFACE TEMPERATURE (SST) ANOMALIES ALONG THE
EQUATOR IN THE EAST CENTRAL PACIFIC OCEAN HAVE DIMINISHED CONSIDERABLY IN THE
PAST MONTH. SSTS IN THE NINO 3.4 REGION (BETWEEN 5 N AND 5 S, AND 170W AND
120W) ARE CURRENTLY ABOUT .8 DEGREES C BELOW NORMAL. THE ATMOSPHERIC
CIRCULATION THROUGHOUT THE TROPICAL PACIFIC OCEAN CONTINUES TO REFLECT LA NINA
CONDITIONS, WITH ENHANCED LOW LEVEL EASTERLIES ALONG THE EQUATOR, AND
SUPPRESSED CONVECTION IN THE CENTRAL EQUATORIAL PACIFIC. MOST NUMERICAL AND
STATISTICAL MODELS FOR SSTS FORECASTS CONTINUED TO WEAKEN SST ANOMALIES IN THE
NINO 3.4 REGION OVER THE NEXT FEW MONTHS. THUS LA NINA IS EXPECTED TO HAVE
NEGLIGIBLE IMPACT ON U.S. TEMPERATURES AND PRECIPITATION IN JUNE.
INTRASEASONAL (MJO) ACTIVITY CONTINUES TO BE WEAK AND IS NOT EXPECTED HAVE A
SIGNIFICANT INFLUENCE ON THIS MONTHLY FORECAST.
SSTS ALONG THE WESTERN COAST OF NORTH AMERICA ARE BELOW NORMAL AND ARE EXPECTED
TO FAVOR BELOW NORMAL AIR TEMPERATURES ALONG IMMEDIATE COASTAL AREAS FROM THE
ALASKAN PANHANDLE TO SOUTHERN CALIFORNIA. THE CFS, CCA, AND OCN INDICATE ABOVE
NORMAL TEMPERATURES IN THE SOUTHWESTERN U.S. AND THE GREAT BASIN. THE CFS
SUGGESTS ELEVATED CHANCES OF A LONG WAVE UPPER LEVEL RIDGE JUST OFF THE WEST
COAST WITH A TROUGH IN THE EAST. THIS ALSO FAVORS ABOVE NORMAL TEMPERATURES
OVER INTERIOR PORTIONS OF THE WEST. SEVERAL TOOLS INDICATE BELOW NORMAL
TEMPERATURES IN THE EAST-CENTRAL PART OF THE NATION. SOIL MOISTURE IS MUCH
ABOVE NORMAL FROM THE UPPER MISSISSIPPI VALLEY TO THE TENNESSEE AND OHIO RIVER
VALLEYS, WHICH FAVORS BELOW NORMAL TEMPERATURES DUE TO INCREASED EVAPORATIVE
COOLING. THIS, COMBINED WITH SOME INDICATIONS FROM THE CFS FOR INCREASED
CHANCES OF BELOW NORMAL UPPER LEVEL HEIGHTS SUGGEST INCREASED CHANCES FOR BELOW
NORMAL TEMPERATURES IN PARTS OF THE EAST-CENTRAL CONUS. ABOVE NORMAL
TEMPERATURES ARE EXPECTED IN PORTIONS OF NORTHERN AND CENTRAL ALASKA DUE TO
TEMPERATURE TRENDS AS INDICATED BY OCN.
LOCAL SOIL MOISTURE CONDITIONS ARE ASSOCIATED WITH INCREASED CHANCES FOR ABOVE
MEDIAN RAINFALL FOR THE UPPER MISSISSIPPI AND PORTIONS OF THE OHIO RIVER
VALLEYS. THIS IS ALSO WEAKLY INDICATED IN CFS FORECASTS FOR ABOVE MEDIAN
PRECIPITATION IN THE AREA. DRY CONDITIONS ARE FORECAST FOR THE NORTHERN
ROCKIES AND NORTHERN GREAT BASIN BY THE CFS MODEL, AND ALSO THE CAS SOIL
MOISTURE ANALOG TOOL. THIS IS FURTHER SUPPORTED BY SEASONAL FORECASTS FOR DRY
CONDITIONS IN THE AREA DURING JUNE-AUGUST FROM CCA, SMLR, AND OCN.
FORECASTER: DAVID UNGER
NOTES: AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL
PROBABILITIES) ARE NOW LABELED AS EC (EQUAL CHANCES).
AN UPDATED MONTHLY OUTLOOK... FOR JUN WILL BE ISSUED ON SAT MAY 31 2008
THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1971-2000 BASE PERIOD.
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