251  
FXUS01 KWBC 211929  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
229 PM EST THU DEC 21 2017  
 
VALID 00Z FRI DEC 22 2017 - 00Z SUN DEC 24 2017  
 
...THERE IS A MODERATE RISK OF FLASH FLOODING ACROSS PORTIONS OF  
THE SOUTH...  
 
...ICY CONDITIONS ALONG WITH SNOW MAY OCCUR ALONG THE GREAT LAKES  
AND NEW ENGLAND...  
 
..BITTERLY COLD TEMPERATURES EXPECTED ACROSS THE NORTHERN PLAINS  
AND NORTHERN ROCKIES...  
 
A FRONTAL SYSTEM MOVING INTO THE PLAINS IS EXPECTED TO MOVE ACROSS  
THE SOUTHERN PLAINS AND INTO THE MISSISSIPPI VALLEY BY FRIDAY  
MORNING. SHOWERS AND THUNDERSTORMS AHEAD OF THE FRONT ALONG  
SOUTHEAST TEXAS CAN BE EXPECTED LATER TONIGHT AND INTO EARLY HOURS  
OF FRIDAY AS DEEP SOUTHERLY FLOW TRANSPORTS MOISTURE FROM THE GULF  
OF MEXICO AHEAD OF THIS FRONT COLD FRONT. HOWEVER, BY FRIDAY, A  
FLASH FLOODING EVENT COULD UNFOLD FROM PARTS OF THE LOWER  
MISSISSIPPI VALLEY TO THE TENNESSEE VALLEY BY FRIDAY AFTERNOON.  
HEAVY RAINFALL WILL SET UP ALONG THE FRONT IN THE LOWER  
MISSISSIPPI VALLEY BY EARLY AFTERNOON. THESE THUNDERSTORMS WILL BE  
VERY SLOW MOVING--ALLOWING FOR AN INCREASING POTENTIAL OF FLASH  
FLOODING. THE AXIS OF HEAVY RAINFALL WILL SHIFT TO THE WESTERN  
PORTIONS OF THE TENNESSEE VALLEY BY EARLY HOURS OF SATURDAY  
MORNING. A MODERATE RISK OF FLASH FLOODING IS IN PLACE FROM THE  
LOWER MISSISSIPPI VALLEY TO THE TENNESSEE VALLEY ON FRIDAY AS A  
RESULT. 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.  
 
AHEAD OF THE SYSTEM THAT WILL GIVE WAY TO FLASH FLOODING IN THE  
SOUTHERN PORTIONS OF THE U.S., IT WILL ALSO BRING WINTER  
PRECIPITATION NORTH OF IT. SNOW IS EXPECTED ALONG THE NORTHERN  
PORTIONS OF THE GREAT LAKES ON FRIDAY MORNING--WITH ICY CONDITIONS  
POSSIBLE NEAR THE RAIN/SNOW LINE. FREEZING RAIN ALONG WITH SNOW  
WILL SPREAD NORTHWARD ACROSS THE NORTHEAST THROUGHOUT FRIDAY AND  
INTO SATURDAY MORNING AS THE FRONTAL BOUNDARY LIFTS NORTH. THE ICY  
CONDITIONS CAN BE EXPECTED ESPECIALLY IN NEW ENGLAND. PLEASE SEE  
WPC'S WINTER WEATHER PRODUCTS AND DISCUSSION FOR MORE INFORMATION  
PERTAINING TO THE WINTER WEATHER HAZARDS ASSOCIATED WITH THIS  
SYSTEM.  
 
AS AN ARCTIC HIGH PRESSURE DIVES ACROSS THE NORTHERN PLAINS AND  
NORTHERN ROCKIES ON FRIDAY, BITTER COLD TEMPERATURES WILL FOLLOW.  
EXPECT HIGH TEMPERATURES TO BE IN THE TEENS ON SATURDAY--WHICH IS  
ABOUT 20 DEGREES BELOW AVERAGE FOR THIS TIME OF YEAR. AHEAD OF  
THE COLD FRONT PRESSING EASTWARD FROM THE PLAINS TO THE EAST  
COAST--HIGH TEMPERATURES WILL BE ABOUT 15 DEGREES ABOVE NORMAL.  
 
REINHART  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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