334  
FXUS01 KWBC 291945  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
245 PM EST FRI DEC 29 2017  
 
VALID 00Z SAT DEC 30 2017 - 00Z MON JAN 01 2018  
 
...REINFORCING SHOT OF BITTER COLD ARCTIC AIR TO BRING  
TEMPERATURES TO NEAR OR BELOW ZERO ACROSS MUCH OF THE NORTHERN  
PLAINS THIS WEEKEND...  
 
...MODERATE TO HEAVY LAKE EFFECT SNOWS WILL CONTINUE DOWNWIND OF  
THE GREAT LAKES...  
 
...HEAVY SNOWFALL LIKELY INTO SATURDAY ACROSS THE HIGHER TERRAIN  
OF THE NORTHWEST...  
 
THE DOMINATING WEATHER STORY AS WE HEAD INTO THE WEEKEND CONTINUES  
TO BE THE COLD AIR MASS PERSISTING ACROSS MUCH OF THE COUNTRY EAST  
OF THE ROCKIES WITH AFTERNOON HIGH TEMPERATURES OF 5 TO 10 DEGREES  
BELOW NORMAL. MEANWHILE, A CLIPPER TYPE OF SYSTEM IS EXPECTED TO  
SEND A SWATH OF LIGHT SNOW FROM THE MIDWEST THIS EVENING, INTO THE  
NORTHERN MID-ATLANTIC ON SATURDAY WITH ONLY LIGHT ACCUMULATIONS  
EXPECTED. ACROSS THE GREAT LAKES, WESTERLY FLOW ON THE BACKSIDE OF  
THIS SYSTEM WILL ALLOW FOR MODERATE TO HEAVY LAKE EFFECT SNOWS TO  
CONTINUE DOWNWIND OF THE LAKES WITH LOCALIZED TOTALS OF 6 TO 12+  
INCHES POSSIBLE. IN THE WAKE OF THIS COLD FRONT THOUGH, ANOTHER  
REINFORCING SHOT OF VERY COLD ARCTIC AIR FROM CANADA WILL DROP  
INTO THE NORTHERN PLAINS BY SATURDAY. THIS WILL BRING DAYTIME HIGH  
TEMPERATURES PLUNGING TO NEAR OR BELOW ZERO READINGS THIS WEEKEND,  
WHICH IS 30 TO 40 DEGREES BELOW NORMAL FOR THIS TIME OF THE YEAR.  
THIS AIR MASS WILL SPREAD EASTWARD ON SUNDAY WITH PARTS OF THE  
NORTHEAST AND MID-ATLANTIC EXPECTED TO BE NEAR 20 DEGREES BELOW  
AVERAGE.  
 
OUT WEST, HEAVY SNOWFALL WILL CONTINUE TONIGHT AND INTO SATURDAY  
ACROSS THE NORTHERN INTERMOUNTAIN WEST AND THE NORTHERN PLAINS AS  
UPPER LEVEL ENERGY MOVES THROUGH IN THE FLOW ALOFT. WINTER STORM  
WARNINGS AND WINTER WEATHER ADVISORIES ARE IN EFFECT WITH  
ADDITIONAL SNOWFALL ACCUMULATIONS OF 1 TO 2 FEET POSSIBLE IN THE  
HIGHEST TERRAIN. THE HEAVY RAINFALL ACROSS COASTAL REGIONS OF THE  
PACIFIC NORTHWEST SHOULD COME TO AN END THIS EVENING AS THE  
ASSOCIATED COLD FRONT MOVES ONSHORE.  
 
FINALLY, A DEVELOPING WAVE OF LOW PRESSURE IN THE WESTERN GULF OF  
MEXICO WILL BRING LIGHT RAIN INTO EASTERN TEXAS TONIGHT AND  
SPREADING INTO THE LOWER MISSISSIPPI VALLEY AND CENTRAL GULF  
STATES BY SUNDAY. SOME MIXED PRECIPITATION OR FREEZING RAIN WILL  
ALSO BE POSSIBLE ON THE NORTHERN EDGE OF THE MOISTURE SHIELD FROM  
NORTHERN TEXAS TO CENTRAL MISSISSIPPI AND ALABAMA.  
 
SANTORELLI  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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