353  
FXUS01 KWBC 160612  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
111 AM EST SAT DEC 16 2017  
 
VALID 12Z SAT DEC 16 2017 - 12Z MON DEC 18 2017  
   
..PATTERN CHANGE EXPECTED OVER THE WEEKEND
 
 
THE PERSISTENT WESTERN RIDGE AND EASTERN U.S. TROUGH OVER THE PAST  
WEEK IS NOW IN THE PROCESS OF CHANGING AS A STRONG UPPER LEVEL  
TROUGH AND SHORTWAVE DISTURBANCE OVER THE WEST BREAKS DOWN THE  
RIDGE AND FLATTENS THE EASTERN TROUGH. THIS TROUGH IS EXPECTED TO  
AMPLIFY OVER THE ROCKY MOUNTAINS DURING THE WEEKEND AND INCREASE  
THE CHANCE OF SNOW FOR THIS REGION THROUGH MONDAY. AFTER AN  
EXTENDED PERIOD OF DRY WEATHER, ACCUMULATING SNOW IS LIKELY FOR  
PARTS OF THE ROCKIES OVER THE NEXT FEW DAYS IN RESPONSE TO A  
DEVELOPING SURFACE LOW OVER THE FOUR-CORNERS REGION AND SHORTWAVE  
ENERGY ALOFT. THERE WILL LIKELY BE A DECREASE IN THE AMOUNT OF  
LAKE EFFECT SNOW WITH LESS COLD AIR ADVECTION OVER THE GREAT LAKES.  
 
WARM AND DRY CONDITIONS ARE EXPECTED FOR FLORIDA AND THE LOWER  
ELEVATIONS OF THE DESERT SOUTHWEST AND INTO CENTRAL AND SOUTHERN  
CALIFORNIA THIS WEEKEND. FIRE WEATHER CONCERNS WILL STILL EXIST  
ACROSS PARTS OF CALIFORNIA OWING TO THE DRY CONDITIONS AND GUSTY  
WINDS. ABOVE NORMAL TEMPERATURES ARE EXPECTED ACROSS THE CENTRAL  
PLAINS ON SATURDAY BEFORE COLDER WEATHER ARRIVES ON SUNDAY BEHIND  
A COLD FRONT. ON THE OTHER END OF THE TEMPERATURE SPECTRUM WILL  
BE THE NORTHERN ROCKIES AND NORTHERN NEW ENGLAND, WHERE READINGS  
WILL REMAIN QUITE CHILLY WITH SUB-FREEZING HIGH TEMPERATURES  
EXPECTED. AFTER A THUNDERSTORM DROUGHT ACROSS THE NATION, SOME  
LIGHTNING AND THUNDER WILL BE POSSIBLE FROM SOUTHERN TEXAS TO THE  
CENTRAL GULF COAST THIS WEEKEND. DEEPER MOISTURE RETURNING  
NORTHWARD FROM THE GULF OF MEXICO AHEAD OF A FRONT COULD FUEL THE  
DEVELOPMENT OF SOME SCATTERED STORMS, ALONG WITH LOCALLY HEAVY  
RAINFALL AT TIMES.  
 
D. HAMRICK  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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