821
FXUS02 KWBC 161638
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
1238 PM EDT MON JUN 16 2008
VALID 12Z THU JUN 19 2008 - 12Z MON JUN 23 2008
PRELIMINARY UPDATE...
THE 00Z GEFS MEAN AND ECMWF ENSEMBLE MEAN HANDLE THE PATTERN
ACROSS THE NATION QUITE SIMILARLY DURING THE NEXT WEEK...SHOWING A
RIDGE WEST OF THE MISSISSIPPI AND A TROUGH TO THE EAST. THE
DETERMINISTIC GFS CLOSES OFF A MID LEVEL LOW OVER THE SOUTHEAST
DAYS 6 AND 7...WITH THE ECMWF SENDING MOST OF THE FRESH HEIGHT
FALLS INTO THE MID ATLANTIC REGION. MEANS FROM BOTH MODELING
CENTERS TAKE A MIDDLE GROUND...AND THAT COMPROMISE WAS REFLECTED
IN THE UPDATED FRONTS AND PRESSURES FORECAST FROM DAY 5 ONWARD.
THE GFS WAS A SHARP OUTLIER WITH THE SHORT WAVE TROUGH APPROACHING
THE PACIFIC NORTHWEST EARLY IN THE PERIOD...EVEN COMPARED WITH ITS
ENSEMBLE MEAN...SO CHOSE THE DETAILS OF THE DETERMINISTIC ECMWF
FOR THE FIRST TWO DAYS OF THE FORECAST...WHICH IS IN LINE WITH
BOTH THE GEFS AND ECMWF ENSEMBLE MEANS.
FINAL...
THE 12Z GFS IS SLOWER AND LESS VIGOROUS THAN ITS 00Z RUN WITH THE
SHORT WAVE BRUSHING THE PACIFIC NORTHWEST DAYS 3 AND 4...MORE IN
HARMONY WITH THE 00Z ECMWF...THOUGH STILL ON THE AMPLIFIED SIDE OF
THE GUIDANCE. THE GFS HAS ALSO TRENDED AWAY FROM ITS DEEP CLOSED
LOW OVER THE SOUTHERN APPALACHIANS AT THE END OF THE
PERIOD...CLOSER TO THE ENSEMBLE MEAN PRODUCTS USED FOR THE UPDATE
PACKAGE.
MOST OF THE PRECIPITATION DURING THE MEDIUM RANGE SHOULD OCCUR
ALONG THE BAROCLINIC EDGE OF THE EASTERN TROUGH...FROM THE LOWER
MISSISSIPPI VALLEY TO THE SOUTHEAST COAST...AND WEST OF THE
CASCADES...WHERE ENOUGH ENERGY SHOULD WRING OUT THE MARITIME POLAR
AIRMASS STRENGTHENING OVER THE REGION TO KEEP THE WEATHER
UNSETTLED.
CISCO
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