492
FXUS01 KWBC 160751
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
350 AM EDT WED SEP 16 2009
VALID 12Z WED SEP 16 2009 - 00Z FRI SEP 18 2009
THE LARGE SCALE PATTERN WILL CONTINUE TO SHOW ONLY MINOR CHANGES
OVER THE NEXT SEVERAL DAYS WITH A DEEP TROF SLOWLY APPROACHING
WESTERN CANADA AND THE PAC NW COAST..WHILE GENERALLY LOW HEIGHTS
ARE MAINTAINED ACROSS EASTERN CANADA INTO THE NE U.S. IN
BETWEEN...AN UPPER RIDGE BUILDING ACRS THE NORTHERN PLAINS INTO
THE NRN ROCKIES WILL ESSENTIALLY BLOCK ANY SIGNIFICANT MOVEMENT TO
THE PERSISTENT CUTOFF LOW NEAR THE ARKLATEX REGION..WHICH HAS
BROUGHT HEAVY TO EXCESSIVE RAINS TO PARTS OF THE SOUTHERN U.S.
OVER THE PAST SEVERAL DAYS. AS A RESULT..MORE WET WEATHER IS IN
STORE ACROSS THE SOUTH NEXT 2 DAYS..WITH THE MORE NUMEROUS SHOWERS
AND THUNDERSTORMS OCCURRING NEAR THE VERTICALLY STACKED LOW
CIRCULATION. A COLD FRONT SURGING SOUTHWARD ACROSS THE MID
ATLANTIC REGION AND SOUTHERN OH VALLEY WILL BEGIN TO INTERACT WITH
THE CUT OFF LOW CIRCULATION LATER WED THRU THUR AS MOIST SOUTHERLY
FLOW EAST OF THE CIRCULATION OVERRUNS THE COOL RIDGE OF HIGH
PRESSURE..BRINGING INCREASING RAINS TO PARTS OF THE CENTRAL AND
SOUTHERN APPALACHIANS..ESPECIALLY THE EASTERN SLOPES. HIGH
PRESSURE BUILDING ACROSS THE NORTHEAST WILL BRING SOME PLEASANTLY
COOL WEATHER TO PARTS OF THE NORTHEAST THE NEXT TWO DAYS ALONG
WITH THE THREAT OF FROST/FREEZE CONDITIONS TO SOME OF THE MORE
NORTHERN LOCATIONS.
IN THE WEST..A WEAKER CUT OFF LOW WILL SINK SLOWLY SOUTHWARD
ACROSS THE 4 CORNERS REGION OVER THE NEXT 2 DAYS. MOISTURE MAINLY
EAST OF THE CIRCULATION WILL BE TAPPED BY DAYTIME HEATING TO
PRODUCE SCATTERED SHOWERS AND THUNDERSTORMS..MOST NUMEROUS ACROSS
PORTIONS OF NEW MEXICO AND SOUTHERN CO. NORTHWEST OF THIS
AREA..THE DEEP TROF OF LOW PRESSURE OFF THE PAC NW COAST..WILL
HELP PUSH A COLD FRONT INLAND LATER WED ACRS THE PAC NW REGION
ACCOMPANIED BY A NARROW BAND OF MAINLY POST FRONTAL SHOWERS. WITH
MOST OF THE SUPPORTING ENERGY LIFTING RAPIDLY INTO WESTERN
CANADA...THE BULK OF THE HEAVIER RAINS WITH THIS SYSTEM WILL OCCUR
NORTH OF THE U.S./CANADIAN BORDER. RESIDUAL SHOWERS HOWEVER WILL
CONTINUE TO SPREAD EASTWARD WITH THE FRONT AS IT MAKES ITS WAY
INTO THE NORTHERN INTERMOUNTAIN REGION ON THUR.
SULLIVAN
GRAPHICS AVAILABLE AT WWW.HPC.NCEP.NOAA.GOV
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