896  
FXUS01 KWBC 150559  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1258 AM EST FRI DEC 15 2017  
 
VALID 12Z FRI DEC 15 2017 - 12Z SUN DEC 17 2017  
   
..PATTERN CHANGE EXPECTED OVER THE WEEKEND
 
 
THE WEATHER PATTERN OVER THE CONTINENTAL U.S. WILL INITIALLY BE  
FEATURED WITH A BROAD EASTERN U.S. TROUGH AND A RIDGE CENTERED  
NEAR THE WEST COAST. AN UPPER LEVEL PATTERN CHANGE IS LIKELY BY  
SUNDAY AS MULTIPLE DISTURBANCES ALOFT BREAK DOWN THE WESTERN U.S.  
RIDGE AND MORE OF A ZONAL FLOW PATTERN RETURNS TO THE EASTERN  
STATES. A TROUGH IS EXPECTED TO AMPLIFY OVER THE ROCKY MOUNTAINS  
DURING THE WEEKEND AND INCREASE THE CHANCE OF SNOW FOR THIS  
REGION. AFTER AN EXTENDED PERIOD OF DRY WEATHER, WIDESPREAD  
ACCUMULATING SNOW IS LIKELY FOR THE CENTRAL AND ESPECIALLY THE  
NORTHERN ROCKIES OVER THE NEXT FEW DAYS IN RESPONSE TO A  
DEVELOPING SURFACE LOW OVER THE FOUR-CORNERS REGION AND SHORTWAVE  
ENERGY ALOFT. LAKE EFFECT SNOW IS ALSO EXPECTED DOWNWIND OF THE  
GREAT LAKES AT TIMES.  
 
WARM AND DRY CONDITIONS ARE EXPECTED FOR FLORIDA AND ESPECIALLY  
THE LOWER ELEVATIONS OF THE DESERT SOUTHWEST AND INTO CENTRAL AND  
SOUTHERN CALIFORNIA. FIRE WEATHER CONCERNS WILL STILL EXIST  
ACROSS PARTS OF CALIFORNIA OWING TO THE DRY CONDITIONS AND GUSTY  
WINDS. ON THE OTHER END OF THE TEMPERATURE SPECTRUM WILL BE  
NORTHERN MINNESOTA AND NORTHERN NEW ENGLAND, WHERE READINGS WILL  
REMAIN QUITE CHILLY WITH HIGHS IN THE TEENS AND 20S.  
THUNDERSTORMS ARE NOT EXPECTED ACROSS THE CONTINENTAL U.S. UNTIL  
SATURDAY, WHEN MOISTURE RETURNING NORTHWARD FROM THE GULF OF  
MEXICO AHEAD OF A FRONT COULD FUEL THE DEVELOPMENT OF SOME  
SCATTERED STORMS FOR SOUTHEAST TEXAS AND LOUISIANA.  
 
D. HAMRICK  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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