670  
FXUS01 KWBC 212046  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
345 PM EST TUE NOV 21 2017  
 
VALID 00Z WED NOV 22 2017 - 00Z FRI NOV 24 2017  
   
..HEAVY RAIN POSSIBLE OVER THE PACIFIC NORTHWEST
 
 
   
..RAIN CHANGING TO SNOW OVER PARTS OF THE LOWER GREAT LAKES
 
 
A FRONT EXTENDING FROM THE LOWER GREAT LAKES ROUGHLY SOUTHWESTWARD  
TO THE LOWER MISSISSIPPI VALLEY/SOUTHERN PLAINS WILL MOVE EAST AND  
SOUTHWARD TO OFF THE EASTERN SEABOARD AND THE GULF COAST BY  
WEDNESDAY. AN AREA OF RAIN AND SNOW OVER PARTS OF THE GREAT LAKES  
WILL MOVE EASTWARD INTO NORTHERN NEW ENGLAND BY WEDNESDAY EVENING  
AND INTO CANADA BY LATE WEDNESDAY NIGHT. IN THE WAKE OF THE  
FRONT, LAKE EFFECT SNOW WILL DEVELOP FOR A SHORT TIME OVER PARTS  
OF THE UPPER GREAT LAKES ON TUESDAY EVENING, ENDING BY WEDNESDAY  
AFTERNOON.  
 
MEANWHILE, AREAS OF DISORGANIZED UPPER-LEVEL ENERGY OVER THE  
SOUTHEAST AND THE SOUTHERN PLAINS WILL AID IN PRODUCING SHOWERS  
AND THUNDERSTORMS OVER PARTS OF THE WESTERN/EASTERN GULF COAST AND  
PARTS OF THE SOUTHEAST THROUGH WEDNESDAY MORNING. THE FIRST  
BUNDLE OF ENERGY WILL MOVE OFF THE SOUTHEAST COAST OVERNIGHT  
TUESDAY INDUCING AN AREA OF LOW PRESSURE OFF THE CAROLINA COAST  
JUST AHEAD OF THE COLD FRONT. THE LOW WILL BECOME A WAVE OF LOW  
PRESSURE ALONG THE FRONT OVER THE WESTERN ATLANTIC THAT WILL MOVE  
NORTHEASTWARD INTO THE CANADIAN MARITIMES OVERNIGHT WEDNESDAY.  
OVERNIGHT TUESDAY, THE ENERGY WILL DEVELOP RAIN OVER PARTS OF THE  
CAROLINAS INTO THE MID-ATLANTIC THAT WILL MOVE NORTHWARD INTO  
SOUTHERN NEW ENGLAND BY WEDNESDAY MORNING AND INTO NORTHERN NEW  
ENGLAND BY WEDNESDAY AFTERNOON. THE RAIN WILL MOVE OFF THE NEW  
ENGLAND COAST BY WEDNESDAY EVENING. THE SECOND ARE OF UPPER-LEVEL  
ENERGY WILL MOVE TO THE EASTERN GULF COAST AND, LIKEWISE, DEVELOP  
A WAVE OF LOW PRESSURE ALONG THE BOUNDARY OVER THE EASTERN GULF OF  
MEXICO OVERNIGHT WEDNESDAY INTO THURSDAY. THE ENERGY WILL PRODUCE  
SHOWERS AND THUNDERSTORMS OVER PARTS OF FLORIDA WEDNESDAY EVENING  
INTO THURSDAY, THANKSGIVING.  
 
ELSEWHERE, A PLUME OF MOISTURE FROM THE PACIFIC WILL STREAM INTO  
THE PACIFIC NORTHWEST THAT WILL CONTINUE UNTIL THURSDSAY,  
THANKSGIVING, AS THE AXIS OF MOISTURE MOVES SOUTHWARD INTO  
NORTHERN CALIFORNIA ALSO ON THANKSGIVING. THE MOISTURE WILL AID  
IN PRODUCING RAIN OVER PARTS OF THE PACIFIC NORTHWEST EASTWARD  
INTO PARTS OF THE NORTHERN ROCKIES THROUGH THURSDAY, THANKSGIVING.  
IN ADDITION, RAIN WILL MOVE INTO PARTS OF NORTHERN CALIFORNIA  
COAST OVERNIGHT WEDNESDAY INTO THANKSGIVING. FURTHERNMORE, A FAST  
MOVING AREA OF LOW PRESSURE OVER THE NORTHERN HIGH PLAINS  
WEDNESDAY MORNING, WILL MOVE EASTWARD TO THE UPPER GREAT LAKES BY  
THANKSGIVING MORNING, THURSDAY. AN AREA OF LIGHT SNOW WILL  
DEVELOP OVER PARTS OF THE UPPER MISSISSIPPI VALLEY/NORTHERN PLAINS  
ON WEDNESDAY AFTERNOON THAT WILL MOVE TO THE UPPER GREAT LAKES BY  
THURSDAY MORNING, THANKSGIVING.  
 
ZIEGENFELDER  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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