241  
FXUS02 KWBC 250511  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
110 AM EDT MON SEP 25 2017  
 
VALID 12Z THU SEP 28 2017 - 12Z MON OCT 02 2017  
 
A PROGRESSIVE PATTERN WILL RETURN TO THE CONUS THIS WEEKEND AS THE  
BLOCKINESS IN THE SHORT TERM UNRAVELS. THE ENSEMBLES HAVE BEEN  
FAIRLY CONSISTENT ON TELEGRAPHING THE BREAKDOWN OF THE PATTERN BUT  
THE UPSTREAM FLOW OUT OF THE PACIFIC THIS WEEKEND REMAINS SHROUDED  
IN UNCERTAINTY. A COLD FRONT WILL PUSH OFF THE EAST COAST ON  
THURSDAY AND HELP PUSH HURRICANE MARIA OUT TO SEA AS A SECONDARY  
FRONT USHERS IN MUCH COOLER AIR TO THE CENTRAL/EASTERN STATES. THE  
WEST WILL SEE A PACIFIC FRONT CRUISE THROUGH THE NORTHWEST CORNER  
OF THE CONUS AS HEIGHTS LOWER AND THE RIDGE MOVES EASTWARD. THIS  
WILL BRING AN INCREASED CHANCE OF RAIN TO THE CENTRAL PLAINS LATER  
THIS WEEKEND INTO MONDAY. THE COLD FRONT WILL STALL ACROSS FLORIDA  
BY THE END OF THE WEEKEND WHICH WILL MAINTAIN THE CHANCE FOR  
WIDESPREAD SHOWERS THERE. 12Z GFS/ECMWF OFFERED A REASONABLE  
STARTING POINT BUT SWITCHED TO THE 18Z RUNS OF EACH DUE TO THE  
BETTER CLUSTERING (ESP IN THE GREAT LAKES WITH THE SECONDARY  
FRONT) WITH THE 12Z ECMWF/ECENS MEAN. BY NEXT SUN/MON, ENSEMBLES  
HAVE SHOWN LITTLE CONSISTENCY OUT OF THE NORTHEASTERN PACIFIC  
WHICH MAY BE COMPRISED OF LOW-AMPLITUDE AND LOW-PREDICTABILITY  
SHORT WAVES.  
 
FRACASSO  
 

 
 
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