756  
FXUS01 KWBC 202034  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
333 PM EST WED DEC 20 2017  
 
VALID 00Z THU DEC 21 2017 - 00Z SAT DEC 23 2017  
   
..HEAVY SNOW OVER PARTS OF THE CENTRAL ROCKIES
 
 
...SNOW POSSIBLE FROM PARTS OF THE NORTHERN PLAINS ACROSS THE  
GREAT LAKES INTO THE NORTHEAST...  
 
...HEAVY RAIN POSSIBLE OVER PARTS OF THE LOWER MISSISSIPPI  
VALLEY/TENNESSEE VALLEY...  
 
STRONG STORM OVER GREAT BASIN/CENTRAL PLAINS WILL LIFT  
NORTHEASTWARD TO THE OHIO VALLEY BY FRIDAY. THE SYSTEM WILL  
PRODUCE COASTAL RAIN AND HIGHER ELEVATION SNOW OVER PARTS OF THE  
PACIFIC NORTHWEST WITH SNOW OVER PARTS OF THE NORTHERN  
INTERMOUNTAIN REGION/NORTHERN ROCKIES AND THE GREAT BASIN. THE  
RAIN AND SNOW WILL COME TO AN END OVER THE PACIFIC  
NORTHWEST/NORTHERN INTERMOUNTAIN REGION OVERNIGHT WEDNESDAY. IN  
ADDITION, SNOW OVER THE NORTHERN PLAINS WILL SPREAD INTO THE UPPER  
GREAT LAKES ALSO OVERNIGHT WEDNESDAY AS SNOW MOVES INTO THE  
CENTRAL ROCKIES ENDING OVERNIGHT THURSDAY. ON THURSDAY, SNOW AND  
SOME RAIN WILL DEVELOP OVER PARTS OF THE NORTHERN/CENTRAL PLAINS  
INTO THE UPPER GREAT LAKES. THE SNOW WILL ALSO END OVER CENTRAL  
PLAINS/UPPER MISSISSIPPI VALLEY OVERNIGHT THURSDAY, TOO.  
 
OVERNIGHT THURSDAY, SNOW WILL MOVE INTO THE NORTHEAST WHILE RAIN  
MOVES INTO PARTS OF THE OHIO VALLEY AND PARTS OF THE NORTHERN  
MID-ATLANTIC BY FRIDAY MORNING. THE ASSOCIATED WARM FRONT WILL BE  
DAMMED AGAINST THE APPALACHIANS THURSDAY AFTERNOON INTO FRIDAY.  
WITH THE DAMMING, THERE IS A RISK OF RAIN/FREEZING RAIN DEVELOPING  
OVER PARTS OF THE LOWER GREAT LAKES/NORTHERN APPALACHIANS ALSO  
OVERNIGHT THURSDAY INTO FRIDAY. ADDITIONALLY, AS THE ASSOCIATED  
COLD FRONT MOVES FROM THE PLAINS INTO PARTS OF THE MISSISSIPPI  
VALLEY, MOISTURE FROM THE GULF OF MEXICO WILL FLOW NORTHEASTWARD  
OVER THE SOUTHERN PLAINS INTO THE LOWER MISSISSIPPI/TENNESSEE  
VALLEYS ON THURSDAY AFTERNOON INTO FRIDAY. LIKEWISE, OVERNIGHT  
THURSDAY INTO FRIDAY, SHOWERS AND THUNDERSTORMS WILL DEVELOP OVER  
PARTS OF THE SOUTHERN PLAINS INTO THE LOWER MISSISSIPPI/TENNESSEE  
VALLEYS.  
 
MEANWHILE, UPPER-LEVEL ENERGY OVER THE SOUTHERN  
APPALACHIANS/SOUTHEAST WILL MOVE EASTWARD OUT OVER THE WESTERN  
ATLANTIC WEDNESDAY EVENING INTO THURSDAY MORNING. THE SYSTEM WILL  
PRODUCE RAIN AND THUNDERSTORMS OVER PARTS OF THE SOUTHERN OHIO  
VALLEY, TENNESSEE VALLEY, SOUTHERN MID-ATLANTIC, SOUTHEAST AND  
EASTERN GULF COAST THAT WILL MOVE EASTWARD OFF THE SOUTHEAST COAST  
BY THURSDAY MORNING INTO AFTERNOON. ELSEWHERE, A FRONT WILL MOVE  
SOUTHWARD FROM WESTERN CANADA INTO THE NORTHERN PLAINS TO THE  
PACIFIC NORTHWEST OVERNIGHT THURSDAY INTO FRIDAY. LIGHT SNOW WILL  
DEVELOP OVER PARTS OF THE NORTHERN PLAINS TO THE NORTHERN  
INTERMOUNTAIN REGION THURSDAY EVENING INTO FRIDAY.  
 
ZIEGENFELDER  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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