456  
FXUS02 KWBC 080701  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
200 AM EST THU MAR 08 2018  
 
VALID 12Z SUN MAR 11 2018 - 12Z THU MAR 15 2018  
   
..ANOTHER MAJOR ERN US COASTAL STORM THREAT EARLY NEXT WEEK
 
   
..A WET PATTERN FOR THE WEST COAST BY NEXT MIDWEEK
 
 
...PATTERN AND GUIDANCE/PREDICTABILITY ASSESSMENT AND  
WEATHER/THREATS HIGHLIGHTS...  
 
GUIDANCE AGREES TO DEVELOP QUITE AN AMPLIFIED FLOW PATTERN ALOFT  
NEXT WEEK OVER THE LOWER 48 TO BE HIGHLIGHTED BY A RIDGE OVER THE  
ROCKIES SANDWICHED BETWEEN AN EXPANSIVE CLOSED LOW JUST OFF THE  
WEST COAST AND AN ERN U.S. TROUGH.  
 
A FAVORABLE INLAND MOISTURE SURGE WILL FUEL MODERATE TO HEAVY  
PRECIPITATION AROUND A DEVELOPING SYSTEM CENTERED OVER THE  
MID-SOUTH AND SOUTHEAST SUNDAY. HEAVIEST PRECIPITATION SHOULD  
SHIFT ACROSS THE APPALACHIANS TO THE MID-ATLANTIC THEN NERN US AND  
MARITIME INTERESTS INTO MON/TUE WITH AN AXIS DEPENEDENT ON ANOTHER  
POTENTIALLY SIGNIFICANT COASTAL STORM GENESIS AND TRACK. SNOW IS  
EXPECTED WITHIN THE NWRN PERIPHERY OF THE ORGANIZING PRECIPITATION  
SHIELD. GUIDANCE SUPPORT FOR THIS TYPE OF SYSTEM EVOLUTION IS NOW  
BETTER SUPPORTED BY LATEST GUIDANCE...BUT RECENT  
ECMWF/UKMET/CANADIAN MODEL VARIANCE IS NOT EASILY FORGOTTEN  
DESPITE MUCH MORE RUN TO RUN CONSISTENT GFS/GEFS ENSEMBLE  
GUIDANCE.  
 
OVER THE WEST...THERE REMAINS A STRONG SIGNAL FOR A SWATH OF  
ORGANIZED PRECIPITATION ACROSS CA AND THE SOUTHWEST/SRN ROCKIES  
SUN INTO MON AS AN ANOMALOUS SURGE OF PACIFIC MOISTURE MOVES  
INLAND OVER THE REGION WITHIN SRN STREAM FLOW. SPECIFICS ARE  
UNCERTAIN...BUT THERE IS A GOOD OVERALL SIGNAL FOR MODERATE TO  
HEAVIER PRECIPITATION TO SHIFT BACK TO THE PACIFIC NW/CA AND THEN  
GRADUALLY WORK INLAND ALONG WITH COOLING TO THE INTERMOUNTAIN WEST  
TUE-THU AS A LEAD FRONT AND HEIGHT FALLS FROM AN EXPANSIVE ERN  
PACIFIC CLOSED LOW/TROUGH DEEPENS/NUDGES TOWARD THE WEST COAST.  
 
ACCORDINGLY...WPC MEDIUM RANGE GUIDANCE WAS PRIMARILY DERIVED FROM  
AN ENSEMBLE MEAN FORECAST APPROACH WITH STRONGEST WEIGHTING  
APPLIED TO THE GEFS MEAN FOR CONSISTENCY. WPC SURFACE FRONTAL  
PROGS...QPF...WINTER WEATHER PROBABILITIES AND OTHER WEATHER  
INFORMATION CAN BE FOUND AT:  
 
WWW.WPC.NCEP.NOAA.GOV/#PAGE=MED  
WWW.WPC.NCEP.NOAA.GOV/#PAGE=QPF  
WWW.WPC.NCEP.NOAA.GOV/#PAGE=WWX  
 
SCHICHTEL  
 

 
 
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