468  
FXUS01 KWBC 211950  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
249 PM EST WED NOV 21 2018  
 
VALID 00Z THU NOV 22 2018 - 00Z SAT NOV 24 2018  
 
...HEAVY RAIN LIKELY IN PARTS OF CALIFORNIA THROUGH FRIDAY WHICH  
COULD LEAD TO FLASH FLOODING, MUDSLIDES, AND DEBRIS FLOWS OVER  
RECENT BURN SCARS...  
 
...SIGNIFICANT SNOWFALL ACCUMULATIONS EXPECTED IN THE MOUNTAINS OF  
THE NORTHWEST AND CALIFORNIA...  
 
...UNSEASONABLY COLD TEMPERATURES WILL MOVE INTO THE NORTHEAST BY  
THURSDAY...  
 
A WET COUPLE OF DAYS IS IN STORE FOR MUCH OF THE WESTERN U.S. AS A  
SERIES OF UPPER LEVEL SYSTEMS MOVE THROUGH. HEAVY RAINFALL IS  
LIKELY TO CONTINUE THROUGH FRIDAY ACROSS PORTIONS OF CALIFORNIA  
AND THE PACIFIC NORTHWEST WITH RAIN REACHING INLAND ACROSS THE  
LOWER ELEVATIONS OF THE GREAT BASIN AND INTERMOUNTAIN WEST AS  
WELL. EXCESSIVE RAINFALL IS A CONCERN, ESPECIALLY ACROSS  
CALIFORNIA WHERE HEAVY RAINS OVER RECENT BURN SCARS MAY LEAD TO  
FLASH FLOODING, DEBRIS FLOWS, AND MUDSLIDES. WPC HAS HIGHLIGHTED  
MUCH OF THE REGION IN A MARGINAL TO SLIGHT RISK ON THE DAYS 1 AND  
2 EXCESSIVE RAINFALL OUTLOOKS AND FLASH FLOOD WATCHES ARE ALSO IN  
EFFECT ACROSS INTERIOR PORTIONS OF NORTHERN CALIFORNIA. IN  
ADDITION TO THE RAINFALL THREAT, HEAVY SNOWFALL IS LIKELY IN THE  
HIGHER TERRAIN OF THE CASCADES, SIERRAS, AND INTERMOUNTAIN WEST  
WHERE AS MUCH AS 2 TO 3 FEET IS POSSIBLE. WINTER STORM WARNINGS,  
WATCHES, AND ADVISORIES ARE IN EFFECT FOR SOME LOCATIONS.  
 
THE OTHER BIG WEATHER STORY IS THE ARCTIC CHILL EXPECTED TO MOVE  
OVER THE NORTHEAST U.S. JUST IN TIME FOR THANKSGIVING.  
TEMPERATURES ON THURSDAY AND FRIDAY WILL STRUGGLE TO GET OUT OF  
THE TEENS AND 20S ACROSS NEW ENGLAND AND THE 30S IN THE  
MID-ATLANTIC STATES, WITH WIND CHILLS MAKING IT FEEL EVEN COLDER.  
THESE VALUES ARE AS MUCH AS 20 TO 40 DEGREES BELOW NORMAL AND BOTH  
RECORD LOWS AND HIGHS COULD BE CHALLENGED OR BROKEN FOR DOZENS OF  
LOCATIONS. ON THE BACKSIDE OF THE COLD FRONT, HEAVY SNOW SQUALLS  
MAY CONTINUE THROUGH THIS EVENING FOR PARTS OF THE GREAT LAKES.  
 
A DEEP UPPER LEVEL TROUGH MOVING INTO THE CENTRAL U.S. ON FRIDAY  
WILL ALLOW FOR INCREASED RAIN CHANCES ALONG THE WESTERN AND  
CENTRAL GULF COAST AND INTO THE LOWER/MIDDLE MISSISSIPPI VALLEY.  
LOCALLY MODERATE TO HEAVY RAINFALL IS POSSIBLE, ESPECIALLY NEAR A  
DEVELOPING SURFACE LOW MOVING ALONG THE WESTERN GULF COAST ON  
FRIDAY.  
 
SANTORELLI  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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