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000 FXUS01 KWBC 232009 PMDSPD SHORT RANGE FORECAST DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 308 PM EST MON NOV 23 2009 VALID 00Z TUE NOV 24 2009 - 12Z WED NOV 25 2009 A SHOWERY PATTERN IS SHAPING UP ACROSS THE U.S. THIS WEEK. THREE SEPARATE FRONTAL SYSTEMS ARE WREAKING HAVOC ON THE PACIFIC NORTHWEST...CENTRAL PLAINS AND UPPER MISSISSIPPI VALLEY...AND THE NORTH AND CENTRAL ATLANTIC COAST. STRONG MID AND UPPER-LEVEL ENERGY PROVIDE THE DRIVING FORCE FOR THIS THANKSGIVING WEEK`S WEATHER. AN OCCLUDED SYSTEM IS MAKING ITS WAY INLAND ALONG THE CANADIAN PACIFIC COAST. AS THE DAY PROGRESSES THE FRONT WILL DROP SOUTH AND EASTWARD AHEAD OF HIGH PRESSURE BUILDING INTO SOUTHWESTERN CANADA...PUSHING SNOW SHOWERS INTO THE NORTHERN ROCKIES. PRECIPITATION WILL REMAIN SHOWERY IN NATURE...WITH SOME HEAVIER SNOW OCCURRING IN THE HIGHEST ELEVATIONS. THE STRONG DOME OF HIGH PRESSURE SITUATED OVER THE DESERT SOUTH WEST WILL ENSURE THAT THE PRECIPITATION ASSOCIATED WITH THIS PACIFIC SYSTEM STAYS TO THE NORTH...LEAVING THE SKY CLEAR OVER THE SOUTHWESTERN U.S. MEANWHILE...THE MIDDLE OF THE COUNTRY WILL RECEIVE THE HIGHEST PRECIPITATION AMOUNTS THIS WEEK. A COLD FRONT...CURRENTLY STRETCHED FROM MINNESOTA SOUTH SOUTHWESTWARD INTO NEW MEXICO...IS EXPECTED TO MOVE SLOWLY TO THE EAST. OVERNIGHT TONIGHT AN INCREASE IN MID-LEVEL ENERGY WILL CAUSE THE SOUTHERN PORTION OF THE FRONT TO INTENSIFY...BRINGING MODERATE RAIN TO THE MIDDLE MISSISSIPPI VALLEY. AS THE LOW PRESSURE IN THIS AREA CONTINUES TO DEEPEN...WIND SPEEDS WILL INCREASE AND THE SWATH OF PRECIPITATION WILL EXPAND. BY THURSDAY SCATTERED PRECIPITATION CAN BE EXPECTED ACROSS MUCH OF THE EASTERN HALF OF THE COUNTRY. COLLINS GRAPHIC AVAILABLE AT WWW.HPC.NCEP.NOAA.GOV $$
