912
FXUS02 KWBC 031937
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
336 PM EDT THU SEP 03 2009
VALID 12Z SUN SEP 06 2009 - 12Z THU SEP 10 2009
THE LONGWAVE PATTERN IS PROGRESSIVE AT HIGH LATITUDES. HOWEVER
FLOW WILL BE WEAK OVER THE CONTINENTAL CONUS AT MID LATITUDES
UNTIL PACIFIC ENERGY BEGINS TO RE-ESTABLISH FLOW OVER THE NW
PORTION OF THE NATION BY THE MIDDLE OF NEXT WEEK.
FINAL GRAPHICS REMAINED UNCHANGED FROM THE UPDATED PRELIM. THE NEW
12Z/03 DETERMINISTIC ECMWF HAD EXCELLENT CONTINUITY THRU DAY 6
WITH ITS PRIOR 00Z/03 RUN....AND WAS STILL GOOD ON DAY 7. IT
TRENDED A BIT SLOWER IN PROGRESSING AN UPPER RIDGE ACROSS ERN
CANADA BY DAY 7.
THE NEW 12Z GFS STILL HAVING PROBLEMS WITH THE PATTERN OVER NE
NOAM DAYS 5-7. IT LOOKS TOO AMPLIFIED OVER NE CANANDA COMPARED TO
THE ECMWF AND ITS ENSEMBLE MEAN. ALSO...WE ARE DISREGARDING THE
GFS REVIVAL OF TS ERICA TRACKING SLOWLY NWD OFF THE E COAST DAYS
6-7. THE THE NEW 12Z/03 CANADIAN AT DAYS 5-6 WAS MORE CONSISTENT
WITH OUT UPDATED PRELIM BLEND ON ALL THE MAIN
FEATURES...ESPECIALLY OVER NE NOAM.
THE PRECIPITATION DURING THIS PERIOD WILL BE CHARACTERIZED BY SOME
MONSOONAL ACTIVITY OVER THE CENTRAL CENTRAL/SRN
ROCKIES/INTERMOUNTAIN REGIONS...WITH MOISTURE CLEARING OUT OF MUCH
OF THAT REGION BY WED/THU DAYS 6-7 AS UPPER FLOW BECOMES MORE
WESTERLY IN THE WAKE OF A TROF PASSAGE.FARTHER E....THE PRECIP
PATTERN LARGELY REPRESENTS ALMOST DAILY SCTD CONVECTIVE ACTIVITY
IN THE SRN PLAINS STATES THAT WILL EXTEND NE INTO AN AREA OF
FAIRLY HIGH VORT VALUES/LINGERING INSTABILITY IN THE OH VLY. WHILE
THE FLOW ALOFT ALONG THE ERN SEABOARD SHOULD BE SW MUCH OF THE
PERIOD...THE OH VLY ACTIVITY SHOULD REMAIN SEPARATED FROM THE DEEP
TROPICAL MOISTURE ALONG THE GULF STREAM EXCEPT FROM FL NE ALONG
THE IMMEDIATE GA/CAROLINA COASTS. THIS WILL LEAVE A PRECIP MINIMUM
FROM THE CAROLINA PIEDMONT INTO SRN NEW ENG.
FLOOD
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