680  
FXUS01 KWBC 192001  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
301 PM EST TUE DEC 19 2017  
 
VALID 00Z WED DEC 20 2017 - 00Z FRI DEC 22 2017  
   
..HEAVY SNOW POSSIBLE OVER THE SOUTHERN CASCADES
 
 
...SNOW OVER THE NORTHERN/CENTRAL ROCKIES, NORTHERN PLAINS, AND  
GREAT LAKES...  
 
...HEAVY RAIN POSSIBLE OVER PARTS OF THE LOWER MISSISSIPPI VALLEY  
INTO THE TENNESSEE VALLEY/SOUTHERN APPALACHIANS...  
 
UPPER-LEVEL ENERGY OVER TEXAS WILL MOVE EASTWARD OFF THE SOUTHERN  
MID-ATLANTIC COAST BY EARLY THURSDAY MORNING. MOISTURE FROM THE  
WESTERN GULF OF MEXICO WILL MOVE INLAND OVER THE WESTERN GULF  
COAST/LOWER MISSISSIPPI VALLEY AND INTO PARTS OF THE SOUTHEAST  
THROUGH WEDNESDAY EVENING. RAIN AND THUNDERSTORMS WILL DEVELOP  
OVER PARTS OF THE SOUTHERN PLAINS INTO THE LOWER MISSISSIPPI  
VALLEY/TENNESSEE VALLEY THAT WILL EXPAND EASTWARD INTO THE  
SOUTHERN MID-ATLANTIC BY WEDNESDAY MORNING. THE RAIN AND  
THUNDERSTORMS WILL COME TO AN END WEST TO EAST STARTING WEDNESDAY  
MORNING INTO THURSDAY.  
 
MEANWHILE, A STRONG UPPER-LEVEL TROUGH OVER THE NORTHWEST WILL  
MOVE SOUTHEAST TO THE GREAT BASIN/SOUTHWEST BY THURSDAY. THE  
ENERGY WILL AID IN PRODUCING RAIN AND HIGHER ELEVATION SNOW OVER  
THE PACIFIC NORTHWEST AND SNOW OVER THE NORTHERN INTERMOUNTAIN  
REGION/NORTHERN ROCKIES. OVERNIGHT TUESDAY, RAIN AND HIGHER  
ELEVATION SNOW WILL EXPAND INTO PARTS OF NORTHERN CALIFORNIA AND  
CENTRAL CALIFORNIA BY WEDNESDAY AFTERNOON. SNOW WILL ALSO EXPAND  
INTO THE GREAT BASIN AND THE NORTHERN HIGH PLAINS ALSO OVERNIGHT  
TUESDAY.  
 
MORE TO FOLLOW  
 
ZIEGENFELDER  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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