341  
FXUS02 KWBC 051554  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1153 AM EDT SUN AUG 05 2018  
 
VALID 12Z WED AUG 08 2018 - 12Z SUN AUG 12 2018  
   
..STILL HOT FOR MUCH OF THE WEST THIS WEEK
 
 
   
..PATTERN OVERVIEW AND GUIDANCE/PREDICTABILITY ASSESSMENT
 
 
THE LARGER SCALE PATTERN EVOLUTION SEEMS FAIRLY WELL ESTABLLISHED  
IN GUIDANCE. AN UPPER LOW WELL WEST OF THE PACIFIC NORTHWEST WILL  
MOVE INTO BRITISH COLUMBIA AND WEAKEN LATER THIS WEEK AS THE UPPER  
HIGH CENTERED OVER THE GREAT BASIN/SOUTHWEST ATTEMPTS TO HOLD IN  
PLACE. DOWNSTREAM OVER THE EAST-CENTRAL U.S., MID-UPPER LEVEL  
TROUGHING WILL SETTLE INTO THE REGION. FORECAST SPREAD IS  
MANAGEABLE OVER THE NEXT WEEK. A COMPOSITE MODEL AND ENSEMBLE  
SOLUTION SEEMS A REASONABLE STARTING POINT INTO DAY5/FRIDAY. GIVEN  
INCREASING FORECAST SPREAD, PREFER AN ENSEMBLE BASED SOLUTION  
HEADING INTO NEXT WEEKEND AND THE SLIGHTLY MORE AMPLIFIED 00 UTC  
ECMWF ENSEMBLES COMPARED TO GEFS/NAEFS SEEM A BETTER FIT WITH  
RECENT GUIDANCE TRENDS AND FLOW HISTORY.  
 
   
..WEATHER HIGHLIGHTS AND HAZARDS
 
 
WELL ABOVE AVERAGE TEMPERATURES ARE FORECAST FOR MUCH OF THE WEST.  
SOME RECORD HIGHS AND NUMEROUS RECORD WARM MINIMUMS ARE LIKELY FOR  
THE DESERT SOUTHWEST, GREAT BASIN, AND INTERIOR NORTHWEST UNTIL  
HEIGHTS FALL AND A FRONT PUSHES ASHORE NEXT WEEKEND. LIGHT  
PRECIPITATION WILL BE CONFINED TO COASTAL/NORTHERN WASHINGTON WITH  
HEAVIER CONVECTIVE POTENTIAL IN THE DEEPER MOISTURE ON THE UPPER  
DIFFLUENT EASTERN SIDE OF THE UPPER HIGH FROM NM/CO/AZ EASTWARD TO  
THE SOUTHERN PLAINS.  
 
EAST-CENTRAL MEAN TROUGHING WILL SOME SEPARATION/LONGEVITY WILL  
MEANWHILE SUPPORT PERIODS OF HEAVY CONVECTIVE PRECIPITATION THAT  
WILL FOCUS ALONG/AHEAD OF WAVY SURFACE FRONTS 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 INTO THE U.S.  
SOUTHERN TIER AND MID-ATLANTIC LATER IN THE WEEK, THE WARM/HUMID  
AIRMASS WILL SUPPORT CONVECTION AND LOCALLY HEAVY RAINFALL.  
 
FRACASSO/SCHICHTEL  
 
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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