645  
FXUS01 KWBC 221714  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION...CORRECTED  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1213 PM EST FRI DEC 22 2017  
 
VALID 00Z SAT DEC 23 2017 - 00Z MON DEC 25 2017  
   
..MODERATE RISK OF FLASH FLOODING ACROSS PORTIONS OF THE SOUTH
 
 
...ICY CONDITIONS/SNOW MAY IMPACT TRANSPORTATION ACROSS THE  
NORTHWEST AND FROM THE GREAT LAKES TO NEW ENGLAND...  
 
...BITTERLY COLD TEMPERATURES EXPECTED ACROSS THE NORTHERN PLAINS  
AND NORTHERN ROCKIES...  
 
A FRONTAL ZONE DROPPING THROUGH THE INTERMOUNTAIN WEST ALONG WITH  
A WAVE OF LOW PRESSURE APPROACHING FROM THE PACIFIC WILL PROMOTE  
COASTAL RAINS FOR WASHINGTON, OREGON, AND EVENTUALLY NORTHWEST  
CALIFORNIA WITH AREAS OF SNOW ACROSS THE CASCADES AND INTERIOR  
NORTHWEST AS WELL AS THE NORTHERN/CENTRAL ROCKIES OVER THE NEXT  
COUPLE OF DAYS.  
 
WIDESPREAD SHOWERS AND THUNDERSTORMS FROM THE ARKLATEX INTO THE  
LOWER/MIDDLE MISSISSIPPI VALLEY AND TENNESSEE VALLEY ARE DUE TO  
WARM, MOIST GULF AIR TRANSPORTS NORTH AHEAD OF A COLD FRONT. AIR  
WITHIN THE WARM SECTOR IS HIGH ENOUGH TO THREATEN RECORD HIGH  
TEMPERATURES ACROSS PORTIONS OF LOUISIANA AND MISSISSIPPI THIS  
AFTERNOON AND LEAD TO WARM . WITH AN EXPECTED SLOW EASTERN  
PROGRESSION WITH THIS SYSTEM, AN AXIS OF HIGHER RAINFALL AMOUNTS  
IS FORECAST TO SPAN FROM SOUTHERN ARKANSAS TO SOUTHERN KENTUCKY-  
INVOKING AN AREA WITH A MODERATE RISK FOR FLASH FLOODING AND A  
MARGINAL RISK OF SEVERE WEATHER TODAY. AS THE PRECIPITATION AND  
FRONT SHIFTS TO THE EAST ON SATURDAY THE AREA OF ELEVATED RISK  
WILL SETUP OVER THE EASTERN TENNESSEE VALLEY/CENTRAL APPALACHIANS.  
 
BY SATURDAY AFTERNOON, THE COLD FRONT QUICKLY MOVES TOWARD THE  
EAST COAST. RAINFALL WILL STILL OCCUR ALONG AND AHEAD OF THE FRONT  
BY SATURDAY AFTERNOON ALBEIT NOT NEARLY AS HEAVY. A CLIPPER SYSTEM  
WILL DROP THROUGH THE NORTHERN AND CENTRAL PLAINS WHICH WILL  
REINFORCE COLD AIR OVER THE CENTRAL U.S. AND THE GREAT LAKES  
REGION. THIS DOES NOT BODE WELL FOR TRAVEL OVER THE NEXT FEW DAYS  
AS PRECIPITATION WILL LIKELY BE A MIX OF ICE AND SNOW FROM THE  
GREAT LAKES TO NEW ENGLAND. FREEZING RAIN ALONG WITH SNOW WILL  
SPREAD NORTHWARD ACROSS THE NORTHEAST TODAY AND INTO SATURDAY  
MORNING AS THE FRONTAL BOUNDARY LIFTS NORTH. PLEASE SEE WPC'S  
WINTER WEATHER PRODUCTS AND DISCUSSION FOR MORE INFORMATION  
PERTAINING TO THE WINTER WEATHER HAZARDS ASSOCIATED WITH THIS  
SYSTEM.  
 
ARCTIC AIR WILL SURGE SOUTHWARD ALONG THE NORTHERN ROCKIES AND  
INTO THE NORTHERN PLAINS IN THE WAKE OF THE COLD FRONT MOVING  
THROUGH THE SOUTHEAST AND A SECONDARY BOUNDARY DROPPING INTO THE  
NORTHERN PLAINS ON SUNDAY. TEMPERATURES ACROSS THIS SECTOR WILL  
PLUMMET INTO THE TEENS ABOVE ZERO, WHICH ON AVERAGE WILL BE 20  
DEGREES BELOW NORMAL FOR LATE DECEMBER, THOUGH NO RECORD LOWS OR  
RECORD COLD HIGH TEMPERATURES ARE ANTICIPATED UNTIL AT LEAST  
MONDAY.  
 
ROTH/CAMPBELL  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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