130
FXUS02 KWBC 201814
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
213 PM EDT FRI JUN 20 2008
VALID 12Z MON JUN 23 2008 - 12Z FRI JUN 27 2008
PRELIMINARY UPDATE...
WITH THE ADVENT OF THE FULL 00Z MODEL SUITE...CHOSE THE
DETERMINISTIC ECMWF TO CONSTRUCT THE MANUAL FRONTS AND PRESSURES
FOR DAYS 3 THROUGH 5...WITH A GRADUAL BLEND TOWARD THE ECMWF
ENSEMBLE MEAN THEREAFTER TO REFLECT THE UNCERTAINTIES INHERENT AT
THAT TIME RANGE. THE 00Z DETERMINISTIC GFS WAS A PROGRESSIVE
OUTLIER WITH THE SYSTEM DEPARTING THE EAST COAST DAY 5 AMONG THE
ECMWF...THE ECMWF ENSEMBLE MEAN...AND THE GEFS MEAN. BY DAYS 6
AND 7...THE GEFS MEAN BECOMES THE OUTLIER OVER THE PACIFIC
NORTHWEST WITH THE UNSEASONABLY DEEP TROUGH IT INDICATES OVER THE
REGION. BOTH THE GFS AND THE GEFS MEAN SHOW MORE COOLING OVER NEW
ENGLAND AT THE END OF THE PERIOD THAN EITHER THE ECMWF OR ITS
MEAN...AND ARE SUSPECT THERE DUE TO THEIR RESPECTIVE
ISSUES...DOWNSTREAM OVER THE ATLANTIC IN THE CASE OF THE
DETERMINISTIC GFS...AND UPSTREAM OVER THE PACIFIC NORTHWEST IN THE
CASE OF THE GEFS MEAN.
FINAL...
MADE NO CHANGES TO THE UPDATE PACKAGE FOR THE FINAL ISSUANCE. THE
12Z GFS HAS DISTINGUISHED ITSELF FURTHER FROM THE GLOBAL MODEL
PACK WITH AN EVEN SPEEDIER DEPARTURE OF THE SYSTEM OFF THE EAST
COAST LATE DAY 4 INTO DAY 5...AND MORE MID LEVEL CONFLUENCE AND
ASSOCIATED SURFACE COOLING OVER NEW ENGLAND BY THE BEGINNING OF
DAY 6. THE 12Z GEFS MEAN DOES NOT AGREE ON EITHER ACCOUNT...AND
ITSELF HAS BACKED OFF FROM ITS ANOMALOUSLY LOW HEIGHTS OVER THE
NORTHWEST DAY 7 DEPICTED ON THE 00Z RUN.
THE OVERALL PATTERN IS A DRY ONE FOR THE NATION...WITH MOST OF THE
ACTION COURTESY OF MESOSCALE CONVECTIVE SYSTEMS GLIDING
SOUTHEASTWARD THROUGH THE PLAINS AND MISSISSIPPI VALLEY.
CISCO
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