438  
FXUS02 KWBC 050627  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
227 AM EDT SUN AUG 05 2018  
 
VALID 12Z WED AUG 08 2018 - 12Z SUN AUG 12 2018  
   
..CONTINUED HOT FOR MUCH OF THE WEST
 
 
   
..PATTERN OVERVIEW AND GUIDANCE/PREDICTABILITY ASSESSMENT
 
 
AN UPPER LOW WELL WEST OF THE PACIFIC NORTHWEST WILL MOVE INTO  
BRITISH COLUMBIA AND WEAKEN LATER THIS WEEK AS THE UPPER HIGH OVER  
THE SOUTHWEST ATTEMPTS TO HOLD IN PLACE. DOWNSTREAM IN THE EAST,  
TROUGHING WILL SETTLE INTO THE REGION. A BLEND OF THE RECENT  
12Z/18Z MODELS OFFERED A GOOD STARTING POINT, BUT THE 12Z ECMWF  
WAS NOTABLY SLOWER THAN THE CONSENSUS WITH THE PACIFIC UPPER LOW  
AND WAS DROPPED FROM THE PREFERENCE BY FRIDAY IN FAVOR OF ITS  
ENSEMBLE MEAN. THE 12Z CANADIAN AND 12Z/18Z GFS SERVED AS SOME  
DETAIL TO THE FORECAST FOR NEXT WEEKEND AS THE SYSTEM DRAGS A COLD  
FRONT INTO THE INTERIOR NORTHWEST.  
 
   
..WEATHER HIGHLIGHTS AND HAZARDS
 
 
WELL ABOVE AVERAGE TEMPERATURES ARE FORECAST FOR MUCH OF THE CONUS  
WEST OF THE DIVIDE EXCEPT FOR MONTANA WHICH WILL PUSH EAST. SOME  
RECORD HIGHS AND NUMEROUS RECORD WARM MINIMUMS ARE LIKELY FOR THE  
DESERT SOUTHWEST, GREAT BASIN, AND INTERIOR NORTHWEST UNTIL  
HEIGHTS FALL AND THE FRONT PUSHES ASHORE BY THE WEEKEND.  
PRECIPITATION SHOULD BE CONFINED TO COASTAL/NORTHERN WASHINGTON  
AND THEN MAINLY ON THE UPPER DIFFLUENT EASTERN SIDE OF THE UPPER  
HIGH OVER NM/CO EASTWARD TO THE SOUTHERN PLAINS.  
 
EASTERN TROUGHING WILL SUPPORT PERIODS OF HEAVY CONVECTIVE  
PRECIPITATION THAT WILL FOCUS ALONG/AHEAD OF A WAVY SURFACE FRONT  
AND CO-DRIVEN BY WARM SECTOR MESO-BOUNDARIES. SHORTWAVES AND WEAK  
SURFACE BOUNDARIES WILL BRIEFLY INCREASE COVERAGE OF RAIN/STORMS  
THROUGH THE GREAT LAKES AND NORTHEAST. AS THE FRONT LINGERS IN THE  
SOUTH LATER IN THE WEEK, THE TYPICAL WARM/HUMID AIRMASS WILL  
SUPPORT ADDITIONAL CONVECTION AND LOCALLY HEAVY RAINFALL.  
 
FRACASSO  
 
WPC MEDIUM RANGE 500 MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION, WINTER WEATHER OUTLOOK PROBABILITIES  
AND HEAT INDEXES ARE FOUND AT:  
 
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST500_WBG.GIF  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST_WBG_CONUS.GIF  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/5KM_GRIDS/5KM_GRIDSBODY.HTML  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/DAY4-7.SHTML  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML  
 

 
 
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