637  
FXUS01 KWBC 152030  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
329 PM EST FRI DEC 15 2017  
 
VALID 00Z SAT DEC 16 2017 - 00Z MON DEC 18 2017  
   
..HEAVY SNOW POSSIBLE OVER THE NORTHERN CASCADES
 
 
...HEAVY LAKE EFFECT SNOW POSSIBLE DOWNWIND FROM LAKES ERIE AND  
ONTARIO...  
 
...SNOW POSSIBLE OVER THE NORTHERN ROCKIES AND PARTS OF SOUTHERN  
NEW ENGLAND COAST...  
 
UPPER-LEVEL ENERGY OVER PENSILVANIA WILL MOVE EASTWARD OUT OVER  
THE WESTERN ATLANTIC BY SATURDAY MORNING. THE ENERGY WILL AID IN  
PRODUCING LIGHT SNOW OVER PARTS OF THE NORTHERN MID-ATLANTIC COAST  
AND SOUTHERN NEW ENGLAND COAST THAT WILL END OVERNIGHT FRIDAY. IN  
ADDITION, ANOTHER AREA OF UPPER-LEVEL ENERGY OVER LAKES SUPERIOR  
WILL, LIKEWISE, MOVE EASTWARD OUT OVER THE WESTERN ATLANTIC BY  
SATURDAY EVENING. THE ENERGY WILL AID IN PRODUCING LAKE EFFECT  
SNOW DOWNWIND FROM THE GREAT LAKES ENDING BY SATURDAY EVENING.  
ADDITIONALLY, A FRONT OVER THE NORTHERN PLAINS INTO THE UPPER  
GREAT LAKES WILL ALSO AID IN DEVELOPING LIGHT SNOW NEAR THE  
BOUNDARY THAT WILL LIFT NORTHWARD INTO WESTERN ONTARIO BY LATE  
SATURDAY EVENING.  
 
MEANWHILE, A STRONG UPPER-LEVEL TROUGH MOVING ONSHORE OVER THE  
WEST COAST WILL MOVE SOUTHEASTWARD TO THE NORTHERN  
ROCKIES/SOUTHWEST BY SUNDAY. THE ENERGY WILL AID IN PRODUCING  
COASTAL RAIN AND HIGHER ELEVATION SNOW OVER THE PACIFIC NORTHWEST  
THROUGH SATURDAY MORNING. OVERNIGHT FRIDAY, SNOW WILL DEVELOP  
OVER PARTS OF THE NORTHERN INTERMOUNTAIN REGION/NORTHERN ROCKIES  
EXPANDING INTO THE GREAT BASIN AND STREAMING OUT INTO PARTS OF THE  
NORTHERN/CENTRAL PLAINS ON SATURDAY. THE SNOW WILL BEGIN TO WANE  
ON SUNDAY MORNING OVER THE AREA. A FRONT WILL APPROACH THE  
PACIFIC NORTHWEST SATURDAY AFTERNOON INTO SUNDAY THAT WILL AID IN  
PRODUCING COASTAL RAIN AND HIGHER ELEVATION SNOW ON SATURDAY  
AFTERNOON INTO SUNDAY.  
 
FURTHERMORE, AS THE UPPER-LEVEL ENERGY MOVES INTO THE SOUTHWEST ON  
SATURDAY NIGHT INTO SUNDAY. MOISTURE FROM THE PACIFIC WILL MOVE  
INTO THE SOUTHWEST THAT WILL AID IN PRODUCING HIGHER ELEVATION  
SNOW AND LOWER ELEVATION RAIN OVERNIGHT SATURDAY INTO SUNDAY.  
ELSEWHERE, AN UPPER-LEVEL LOW OVER WEST-CENTRAL MEXICAN COAST WILL  
WEAKEN AND MOVE NORTHEASTWARD INTO THE SOUTHERN PLAINS/LOWER  
MISSISSIPPI VALLEY BY SUNDAY. MOISTURE FROM THE WESTERN GULF OF  
MEXICO WILL START TO FLOW NORTHWARD OVER THE WESTERN GULF COAST BY  
EARLY SATURDAY MORNING THAT WILL STRENGTHEN MOVING INTO THE  
LOWER/MIDDLE MISSISSIPPI VALLEY AND THE TENNESSEE VALLEY BY  
SUNDAY. RAIN WILL DEVELOP OVER PARTS OF THE WESTERN/CENTRAL GULF  
COAST BY FRIDAY EVENING THAT WILL MOSTLY COME TO AN END OVERNIGHT  
FRIDAY. ON SATURDAY AS THE MOISTURE MOVES OVER THE SOUTHERN  
PLAINS, RAIN WILL DEVELOP OVER SOUTHERN TEXAS THAT WILL EXPAND AND  
MOVE NORTHEASTWARD INTO THE LOWER MISSISSIPPI VALLEY OVERNIGHT  
SATURDAY INTO SUNDAY.  
 
ZIEGENFELDER  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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