053
FXUS02 KWBC 251817
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
211 PM EDT SUN MAY 25 2008
VALID 12Z WED MAY 28 2008 - 12Z SUN JUN 01 2008
A DEAMPLIFICATION PROCESS IS PLACE ACROSS CONUS AS SEEN BY MODELS
AND ENSEMBLES. A LARGE SCALE MEAN TROF WILL PERSIST ACROSS THE
EPAC COASTAL REGION THRU THE PERIOD. DOWNSTREAM PLAINS RIDGING
WILL FLATTEN AFTER A TROF/FRONT EXITS THE EAST COAST DAY 3. A WEAK
MEAN TROF WILL PERSIST ALONG THE EAST COAST FOR THE NEXT WEEK. PAC
SHORTWAVE ENERGY EXITING THE WRN TROF WILL TRAVERSE THE COUNTRY
REACHING THE GREAT LAKES REGION DAY 6 SAT. THERE ARE SOME TIMING
DIFFERENCES...A MATTER OF ABOUT 6 HRS WITH THE OP GFS BEING
FASTEST. OVERALL MODELS ARE IN GOOD AGREEMENT. ENSEMBLE MEANS OF
BOTH GFS AND ECMWF ARE A BIT SLOWER THAN OP MODELS WITH LOW
PRESSURE COMING THRU AND OUT OF THE PLAINS DAYS 5-7. HI RES OP
MODELS WHEN IN AGREEMENT ARE USUALLY SUPERIOR TO THE ENS MEANS.
UPDATED HPC BLEND..DAYS 3 AND 4 WED/THU ECMWF/GFS. DAYS 5-7
FRI-SUN ECMWF AND ECMWF ENS MEAN.
AFTN 12Z GFS IS MUCH WEAKER AND CONSIDERABLY FARTHER OFFSHORE WITH
THE CLOSED LOW OFF THE PAC COAST FROM DAY 4 ONWARD AND RESULTS IN
A SLOWER EJECTION OF A SHORTWAVE COMING ACROSS THE NRN PLAINS INTO
THE GREAT LAKES REGION BY THE END OF THE PERIOD. THIS SOLUTION IS
CLOSER TO AND WWD OF THE 00Z GFS ENS MEANS. NEW 12Z CMC REMAINS
CONTINUITY WITH ITS OLDER RUN AS DOES UKMET.
CMC/ECMWF/GFS ALL CONT THEIR PERSISTENT TREND TOWARDS TROPICAL
CYCLOGENESIS NEAR YUCATAN MID PERIOD AS MODELS BUILD UPPER LEVEL
RIDGING WITH LOW WIND SHEAR OVER CENTRAL AMERICA/WEST CARRIBEAN.
HPC POSITIONING IS A MODEL/ENSEMBLE MEAN LOCATIONAL AND PRESSURE
AVERAGE.
ROSENSTEIN
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