742  
FXUS01 KWBC 221244  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
744 AM EST THU NOV 22 2018  
 
VALID 12Z THU NOV 22 2018 - 12Z SAT NOV 24 2018  
 
...HEAVY RAIN LIKELY IN PARTS OF CALIFORNIA THROUGH SATURDAY WHICH  
COULD LEAD TO FLASH FLOODING, MUDSLIDES, AND DEBRIS FLOWS OVER  
RECENT BURN SCARS...  
 
...HEAVY SNOW POSSIBLE FOR THE SIERRAS/CASCADES AND PARTS OF THE  
HIGHER ELEVATIONS OF THE GREAT BASIN/NORTHERN INTERMOUNTAIN REGION  
AS WELL AS THE NORTHERN/CENTRAL ROCKIES...  
 
...TEMPERATURES WILL BE 20 TO 35 DEGREES BELOW AVERAGE FROM THE  
GREAT LAKES/MID-ATLANTIC INTO THE NORTHEAST...  
 
A DEEP UPPER-LEVEL TROUGH OVER THE WEST COAST WILL MOVE INLAND TO  
THE MISSISSIPPI VALLEY BY SATURDAY NIGHT. THE SYSTEM WILL PRODUCE  
RAIN AND HIGHER ELEVATION SNOW OVER PARTS OF THE PACIFIC  
NORTHWEST/CALIFORNIA INTO NORTHERN INTERMOUNTAIN REGION/GREAT  
BASIN ON THANKSGIVING. THE RAIN WILL END OVER SOUTHERN CALIFORNIA  
BY THURSDAY EVENING AS THE SNOW AND LOWER ELEVATION RAIN EXPANDS  
INTO PARTS THE NORTHERN/CENTRAL ROCKIES AND CONTINUE OVER THE  
REGION INTO SATURDAY. THE RAIN WILL BE HEAVY OVER  
NORTHERN/CENTRAL CALIFORNIA WITH HEAVY SNOW OVER THE  
CASCADES/SIERRAS, NORTHERN INTERMOUNTAIN REGION/GREAT BASIN, AND  
NORTHERN/CENTRAL ROCKIES, LIKEWISE, THROUGH SATURDAY.  
 
MEANWHILE, A VERY COLD AREA OF HIGH PRESSURE OVER THE GREAT LAKES  
WILL MOVE SOUTHEASTWARD OFF THE MID-ATLANTIC COAST BY FRIDAY  
EVENING. TEMPERATURES WILL BE 20 TO 35 DEGREES BELOW AVERAGE FROM  
THE GREAT LAKES/MID-ATLANTIC INTO THE NORTHEAST, WITH TEMPERATURES  
BEGINNING TO MODERATE BY FRIDAY EVENING. AS THE AFOREMENTIONED  
UPPER-LEVEL TROUGH MOVES OUT OF THE ROCKIES, MOISTURE FROM THE  
WESTERN GULF OF MEXICO WILL MOVE NORTHWARD OVER THE PLAINS INTO  
THE UPPER MISSISSIPPI VALLEY/UPPER GREAT LAKES BY FRIDAY EVENING.  
BY FRIDAY AFTERNOON, RAIN WILL DEVELOP OVER PARTS OF THE UPPER  
MISSISSIPPI VALLEY SOUTHWARD TO THE WESTERN GULF COAST. THE RAIN  
WILL EXPAND INTO THE GREAT LAKES/OHIO VALLEY AND THE  
CENTRAL/SOUTHERN APPALACHIANS AS WELL AS INTO PARTS OF THE  
SOUTHEAST/EASTERN GULF COAST. OVERNIGHT FRIDAY, AREAS OF  
RAIN/FREEZING RAIN WILL DEVELOP OVER PARTS OF THE CENTRAL/SOUTHERN  
APPALACHIANS. IN ADDITION, SNOW WILL DEVELOP OVER PARTS OF THE  
UPPER MISSISSIPPI VALLEY OVERNIGHT FRIDAY, TOO. ADDITIONALLY,  
EASTERLY FLOW OFF THE ATLANTIC WILL AID IN STREAMING MOISTURE  
INLAND OVER PARTS OF SOUTHEAST BY THURSDAY EVENING. THE MOISTURE  
WILL AID IN PRODUCING SHOWERS AND THUNDERSTORMS OVER PARTS OF  
FLORIDA OVERNIGHT THURSDAY INTO FRIDAY EVENING.  
 
ZIEGENFELDER  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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