439  
FXUS01 KWBC 210747  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
246 AM EST WED NOV 21 2018  
 
VALID 12Z WED NOV 21 2018 - 12Z FRI NOV 23 2018  
 
...HEAVY RAIN POSSIBLE FOR PARTS OF CALIFORNIA AND THE PACIFIC  
NORTHWEST...  
 
...HEAVY SNOW POSSIBLE FOR THE SIERRAS/CASCADES AND PARTS OF THE  
NORTHERN/CENTRAL ROCKIES...  
 
...THERE IS A MARGINAL RISK WITH EMBEDDED SLIGHT RISK OF EXCESSIVE  
RAINFALL OVER PARTS OF CALIFORNIA  
 
...TEMPERATURES WILL BE 10 TO 25 DEGREES BELOW AVERAGE OVER THE  
NORTHEAST...  
 
A FRONT EXTENDING FROM THE LOWER GREAT LAKES TO THE MIDDLE  
MISSISSIPPI VALLEY THEN NORTHWESTWARD INTO THE NORTHERN HIGH  
PLAINS WILL MOVE SOUTHEASTWARD OFF THE MOST OF THE EASTERN  
SEABOARD BY THANKSGIVING EVENING. A STATIONARY FRONT WILL EXTEND  
FROM THE SOUTHEAST COAST NORTHWESTWARD TO THE NORTHERN HIGH PLAINS  
ON THANKSGIVING. THE SYSTEM WILL PRODUCE SNOW OVER THE GREAT  
LAKES INTO PARTS OF NORTHERN NEW ENGLAND THAT WILL MOVE OFF THE  
NORTHEAST COAST BY THANKSGIVING MORNING. IN THE WAKE OF THE STORM  
VERY COLD HIGH PRESSURE WILL SOUTHEASTWARD FROM WESTERN ONTARIO TO  
THE NORTHERN MID-ATLANTIC BY THANKSGIVING EVENING. TEMPERATURES  
WILL BE 10 TO 25 DEGREES BELOW AVERAGE FROM THE GREAT LAKES TO THE  
NORTHEAST AND MID-ATLANTIC STATES FROM THURSDAY EVENING INTO  
FRIDAY.  
 
MEANWHILE, UPPER-LEVEL ENERGY OVER THE NEW MEXICO/MEXICAN BORDER  
WILL MOVE EASTWARD TO THE SOUTHEAST BY THANKSGIVING EVENING. THE  
ENERGY WILL PRODUCE LIGHT RAIN OVER PARTS OF THE WESTERN GULF  
COAST THAT WILL EXPAND EASTWARD INTO PARTS OF THE CENTRAL GULF  
COAST BY THANKSGIVING MORNING BEFORE ENDING OVER THE  
WESTERN/CENTRAL GULF COAST BY AFTERNOON ON THANKSGIVING.  
 
AN IMPORTANT STORY, A DEEP UPPER-LEVEL TROUGH WILL MOVE ONSHORE  
OVER THE WEST COAST ON WEDNESDAY MOVING INLAND TO THE ROCKIES  
OVERNIGHT THURSDAY. RAIN WILL BEGIN TO DEVELOP ALONG THE WEST  
COAST ON WEDNESDAY MORNING AND MOVE INLAND TO THE NORTHERN/CENTRAL  
ROCKIES AND THE GREAT BASIN BY THANKSGIVING EVENING. THE RAIN  
WILL BE HEAVY OVER PARTS OF NORTHERN CALIFORNIA INTO THE PACIFIC  
NORTHWEST COAST THROUGH FRIDAY MORNING. HEAVY SNOW WILL DEVELOP  
OVER THE HIGHER ELEVATIONS OF THE SIERRAS AND THE CASCADES WITH  
HEAVY RAIN AT THE LOWEST ELEVATIONS. DUE TO THE HEAVY  
PRECIPITATION, A MARGINAL WITH EMBEDDED SLIGHT RISK OF EXCESSIVE  
RAINFALL IS ISSUED OVER CALIFORNIA FROM WEDNESDAY MORNING INTO  
FRIDAY MORNING. OVERNIGHT WEDNESDAY, RAIN AND HIGHER ELEVATION  
SNOW WILL DEVELOP OVER PARTS OF THE NORTHERN INTERMOUNTAIN REGION  
AND THE GREAT BASIN THAT WILL EXPAND INTO THE NORTHERN/CENTRAL  
ROCKIES OVERNIGHT THURSDAY.  
 
ZIEGENFELDER  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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