527
FXUS01 KWBC 222037
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
336 PM EST SUN NOV 22 2009
VALID 00Z MON NOV 23 2009 - 12Z TUE NOV 24 2009
A STRONG AND QUICK MOVING UPPER LEVEL TROUGH AND COLD FRONT WHICH
MOVED INTO THE PACIFIC NORTHWEST THIS MORNING WILL BE ONE OF TWO
SIGNIFICANT WEATHER MAKERS OVER THE LOWER 48 DURING THE SHORT TERM
FORECAST PERIOD. WESTERLY ONSHORE FLOW BEHIND THE FRONT WILL
CONTINUE TO PRODUCE COASTAL RAIN AND INLAND SNOW FROM THE PACIFIC
NORTHWEST TO THE CENTRAL AND NORTHERN ROCKIES AS SNOW LEVELS
TEMPORARILY DROP. TOTALS ARE NOT EXPECTED TO BE SIGNIFICANT FOR
THE REGION THOUGH ISOLATED HEAVY SNOWFALL IS POSSIBLE ESPECIALLY
IN THE NORTHERN CASCADES. A RATHER LARGE DOME OF HIGH PRESSURE
WILL BUILD INTO THE WEST BEHIND THE FRONT TONIGHT BRINGING THE
SHOWERS TO AN END EXCEPT FOR A SECOND FRONTAL SYSTEM TO CLIP THE
PACIFIC NORTHWEST WITH A BIT OF RAIN AND SNOW TOMORROW INTO
TUESDAY. THE BULK OF THE SYSTEMS PRECIPITATION WILL END UP IN
CANADA HOWEVER AS A PATTERN SHIFT TAKES PLACE ACROSS THE LOWER 48
TO MORE UPPER RIDGING IN THE WEST.
THE UPPER LEVEL LOW IS EXPECTED TO EMERGE OVER THE CENTRAL PLAINS
TOMORROW... LIKELY PRODUCING SOME WET SNOW OVER PORTIONS OF THE
CENTRAL PLAINS AS A SURFACE LOW DEVELOPS AND MOISTURE IS WRAPPED
AROUND THE LOW INTO THE COLDER AIR. THE WESTERN PORTION OF A
STATIONARY FRONT IN THE GULF OF MEXICO WILL HOLD THE BEST MOISTURE
WELL TO THE SOUTH THOUGH DYNAMICS ASSOCIATED WITH THE STRONG UPPER
LOW COULD PRODUCE SOME LOCALLY HEAVY RAINFALL MONDAY NIGHT FROM
EASTERN NEBRASKA INTO WESTERN IDAHO. COLD AIR BEHIND THE FRONT
WILL SWEEP DOWN THROUGH THE SOUTHERN PLAINS LEAVING TEXAS AND
OKLAHOMA MUCH COOLER ON TUESDAY AFTER A WARM SUNDAY AND MONDAY.
OVER THE EAST... PERIODS OF STEADY RAIN FALLING OVER THE SOUTHEAST
THIS AFTERNOON SHOULD BEGIN TO MOVE UP THE EAST COAST TONIGHT AS
REDEVELOPMENT OF A SURFACE LOW TAKES PLACE OFF THE SOUTH CAROLINA
COAST. THE AREA OF LOW PRESSURE IS FORECAST TO TRACK NORTHEASTWARD
TOMORROW AND TUESDAY BRINGING CLOUDS AND RAIN TO MUCH OF THE
EASTERN SEABOARD. STRONG HIGH PRESSURE TO THE NORTH WILL LIKELY
ALLOW FOR A STRONG PRESSURE GRADIENT AND BREEZY WINDS TO AFFECT
COASTAL NEW ENGLAND AS THE LOW MOVES NORTH TOMORROW AFTERNOON...
LASTING THOUGH MUCH OF TUESDAY.
OTTO
GRAPHIC AVAILABLE AT WWW.HPC.NCEP.NOAA.GOV
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