001  
FXUS02 KWBC 271535  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1034 AM EST MON NOV 27 2017  
 
VALID 12Z THU NOV 30 2017 - 12Z MON DEC 04 2017  
 
...GUIDANCE/UNCERTAINTY ASSESSMENT AND PATTERN  
HIGHLIGHTS/THREATS...  
 
THE LATEST MODELS AND ENSEMBLES ARE WELL CLUSTERED WITH THE LARGER  
SCALE WEATHER IMPACTING SYSTEMS FOR THE NEXT WEEK. THIS BOLSTERS  
FORECAST CONFIDENCE TO ABOVE NORMAL LEVELS OVERALL.  
ACCORDINGLY...THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY  
DERIVED FROM A COMPOSITE BLEND OF THE 06 UTC GFS/GEFS AND 00 UTC  
ECMWF/ECMWF ENSEMBLE MEAN.  
 
A DYNAMIC LEAD MID-UPPER LEVEL TROUGH SWEEPS ACROSS THE UPPER  
MIDWEST AND GREAT LAKES WITH MODEST PCPN THU AS A COOLING COLD  
FRONT PROGRESSES ACROSS THE EAST-CENTRAL STATES. THE MAIN SYSTEM  
WORKS ACROSS THE NERN US AND CANADIAN MARITIMES FRI INTO SAT WITH  
AN ATTENDANT SURFACE LOW THAT WILL OFFER POTENTIAL FOR TRIPLE  
POINT REDEVELOPMENT JUST OFFSHORE THAT WOULD ENHANCE PCPN  
POTENTIAL AND WINDS...INCLUDING SOME SNOWS ON THE COOLED NRN  
PERIPHERY OF THE OVERALL PCPN SHIELD.  
 
UPSTREAM...STORMY CONDITIONS RETURN IN ERNEST FROM THE ERN PACIFIC  
INTO THE WEST COAST AND INLAND OVER THE WRN STATES THIS WEEKEND AS  
AN AMPLIFIED AND COOLING MID-UPPER LEVEL TROUGH AND WAVY FRONTAL  
SYSTEM DIGS INLAND...REACHING THE CENTRAL US BY NEXT MON. EXPECT  
WIDESPREAD PCPN TO SWEEP ACROSS THE WEST WITH HEAVIEST RAINS/WINDS  
SPREADING DOWN FROM THE NWRN US INTO CA. THIS PATTERN WILL ALSO  
FAVOR THE POTENTIAL FOR HEAVY SNOWS THAT WILL NOT BE LIMITED BY  
WILL MOST STRONGLY FOCUS OVER ELEVATED TERRAIN AS THE SYSTEM  
SPREADS FROM THE SIERRA AND INTERMOUNTAIN WEST INTO THE ROCKIES.  
EXPECT PCPN WILL THEN BREAKOUT ACROSS THE CENTRAL US WITH SYSTEM  
APPROACH AND INCREASED MOISTURE INFLOW WITH TIME.  
 
SCHICHTEL  
 

 
 
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