331  
FXUS02 KWBC 041554  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1152 AM EDT SAT AUG 04 2018  
 
VALID 12Z TUE AUG 07 2018 - 12Z SAT AUG 11 2018  
   
..MORE HOT TEMPERATURES FOR THE WEST
 
 
   
..PATTERN OVERVIEW AND GUIDANCE/PREDICTABILITY ASSESSMENT
 
 
AN UPPER HIGH IN THE WEST MAY BEGRUDGINGLY ABATE NEXT WEEKEND AS  
ERN PACIFIC UPPER TROUGH ENERGY LIFTS INTO BRITISH COLUMBIA.  
DOWNSTREAM, THE E-CENTRAL U.S. WILL EXPERIENCE ANOTHER UPPER  
TROUGH AMPLIFY AND SETTLE INTO THE REGION. MODEL AND ENSEMBLE MASS  
FIELD AND PRECIPITATION FORECAST CLUSTERING IS BETTER THAN NORMAL,  
BOLSTERING FORECAST CONFIDENCE. A COMPOSITE BLEND OF THE 06 UTC  
GFS/GEFS MEAN AND 00 UTC ECMWF/ECMWF ENSEMBLE MEAN SEEMS TO  
PROVIDE A GOOD BASIS FOR THESE FORECASTS INTO DAY5/THU. GUIDANCE  
SPREAD BECOMES MORE OF AN ISSUE THU-NEXT SAT WITH THE ECMWF MORE  
AMPLIFIED THAN RECENT GFS RUNS. RECENT FLOW HISTORY AND ENSEMBLES,  
ESPECIALLY THE ECMWF ENSEMBLES, SEEM TO BEST SUPPORT PATTERN  
EVOLUTION ON THE AMPLIFIED SIDE OF THE FULL ENVELOPE OF SOLUTIONS,  
BUT NOT AS AMPLIFIED AS THE LATEST ECMWF THAT ITSELF HAS TRENDED  
QUITE A BIT MORE AMPLIFIED/LESS PROGRESSIVE THAN RECENT PRIOR  
VERSIONS.  
   
..WEATHER HIGHLIGHTS AND HAZARDS
 
 
WITH THE UPPER LOW LINGERING OFFSHORE FOR MOST OF THE PERIOD,  
RIDGING WILL SUPPORT WELL ABOVE AVERAGE TEMPERATURES IN THE  
WEST/INTERIOR WEST. SOME RECORD HIGHS AND NUMEROUS RECORD WARM  
MINIMUMS ARE AGAIN LIKELY FOR THE DESERT SOUTHWEST, GREAT BASIN,  
AND INTERIOR NORTHWEST UNTIL HEIGHTS FALL AND THE FRONT PUSHES  
ASHORE IN ABOUT A WEEK. PRECIPITATION SHOULD BE CONFINED TO  
COASTAL/NORTHERN WASHINGTON AND THEN MAINLY ON THE UPPER DIFFUENT  
EAST SIDE OF THE UPPER HIGH OVER NM/CO EASTWARD TO THE SOUTHERN  
PLAINS.  
 
THE MEAN UPPER TROUGH SETTLING OVER THE E-CENTRAL TO SRN/ERN U.S.  
MEANWHILE RAISES THE CHANCE FOR PERIODS OF HEAVY CONVECTIVE  
PRECIPITATION THAT WILL FOCUS ALONG/AHEAD OF A WAVY SURFACE FRONT  
AND WITH WARM SECTOR MESO-BOUNDARIES. ACTIVITY WILL BE MAXIMIZED  
AS A SERIES OF LESS PREDICTABLE EMBEDDED SHORTWAVE IMPULSES  
INTERACT WITH POOLED DEEPENED MOISTURE AND INSTABILITY. AS THE  
FRONT SETTLES INTO THE SOUTH LATE NEXT WEEK, THE TYPICAL  
WARM/HUMID AIRMASS WILL SUPPORT ADDITIONAL CONVECTION/LOCALLY  
HEAVY RAINFALL.  
 
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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