902  
FXUS02 KWBC 311601  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1200 PM EDT TUE OCT 31 2017  
 
VALID 12Z FRI NOV 03 2017 - 12Z TUE NOV 07 2017  
   
..COLDER AND STORMY FOR THE WEST
 
 
   
..GUIDANCE/UNCERTAINTY ASSESSMENT AND WEATHER/THREAT HIGHLIGHTS
 
 
THE 06 UTC GFS/GEFS AND 00 UTC ECMWF/ECMWF ENSEMBLES ARE  
REASONABLY WELL CLUSTERED THROUGH THE WEEKEND AND DEVELOP AN  
AMPLIFIED WRN US MEAN TROUGH WITH A PROLONGED PERIOD OF WIDESPREAD  
MODERATE TO TERRAIN ENHANCED PRECIPIATION AND LOWERING SNOW LEVEL  
THREAT. THE PATTERN OFFERS A STEADY FLOW OF LESS PREDICTABLE AND  
MODERATE PRECIPITATION FOCUSING IMPULSES THAT EJECT ENEWD OVER THE  
CENTRAL AND ERN US. THE PATTERN ALLOWS FOR SEVERAL COLD AIR  
SURGES. LEAD CANADIAN HIGH PRESSURE DIGS THROUGH THE CENTRAL THEN  
ERN US FRI-SUN AND AN UPSTREAM LOWER ATMOSPHERIC COOLING  
HIGH/RIDGE SHOULD DIG THROUGH THE WRN TO EAST-CENTRAL US SUN- NEXT  
TUE. THIS FURTHER SUPPORTS WRN US/ROCKIES HEAVY SNOWS AND OFFERS  
SOME DOWNSTREAM SNOW POTENTIAL OVER THE CENTRAL TO ERN US NRN TIER  
ALONG WITH LEAD WAVY FRONT ENHANCED WARM SECTOR  
RAINS/CONVECTION...MAINLY FROM THE MIDWEST TO THE S-CENTRAL US.  
 
THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM A  
COMPOSITE BLEND OF THESE GUIDANCE PIECES THROUGH SUNDAY. THE 00  
UTC ECMWF TRENDED FASTER ACROSS THE CONUS THAN PRIOR RUNS DAYS 6/7  
WITH ONLY LIMITED ENSEMBLE SUPPORT. ACCORDINGLY...HAVE DOWNPLAYED  
THAT SCENARIO FOR NOW TO MAINTAINS MAX WPC CONTINUITY.  
 
SCHICHTEL  
 

 
 
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