395  
FXUS02 KWBC 041604  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1204 PM EDT WED JUL 04 2018  
 
VALID 12Z SAT JUL 07 2018 - 12Z WED JUL 11 2018  
   
..WEATHER THREATS/HIGHLIGHTS.
 
 
AN UPPER HIGH WILL CONTINUE TO DOMINATE THE LOWER 48 THIS COMING  
WEEKEND INTO THE MIDDLE OF NEXT WEEK. TROUGHS OVER THE NORTHWEST  
AND NORTHEAST FLATTEN WITH TIME AS A MORE ZONAL FLOW TAKES SHAPE  
ALONG THE US/CANADIAN BORDER AS HEIGHTS BECOME ABOVE AVERAGE COAST  
TO COAST. A MODERATING FRONT IN THE EAST WILL SINK INTO THE  
SOUTHEAST THIS WEEKEND AND DISSIPATE NEXT WEEK AS WESTERN NORTH  
AMERICAN FRONTS SHIFT DOWNSTREAM ACROSS THE NORTHERN PLAINS, UPPER  
MIDWEST/GREAT LAKES AND NORTHEAST ALONG WITH THUNDERSTORM FOCUS  
AND LOCAL SEVERE STORM THREAT AS PER SPC.  
 
THE SOUTHWEST OFFERS POTENTIAL FOR RECORD WARMTH IN THIS PATTERN,  
ESPECIALLY THIS SATURDAY IN SOUTHERN CALIFORNIA WHERE MAXIMUM  
TEMPERATURES IN THE 90S ARE LIKELY TO THE COAST AND WELL INTO THE  
100S INLAND. RECORD HIGH MINIMUM TEMPERATURES ALSO THREATEN  
SOUTHERN CALIFORNIA TO SOUTHERN ARIZONA THIS WEEKEND, INCLUDING  
PHOENIX.  
   
..GUIDANCE EVALUATION/PREFERENCES
 
 
THE 06 UTC GFS/GEFS, 00 UTC ECMWF, AND 00 UTC NAEFS/ECMWF/CANADIAN  
ENSEMBLES CLUSTER REASONABLY WELL WITH FLOW EVOLUTION DAYS 3-7.  
THE BIGGEST GUIDANCE CONTINUITY CHANGE COMPARED TO YESTERDAY IS  
THAT LATEST GUIDANCE IS NOW MORE AMPLIFIED AND LESS PROGRESSIVE  
WITH DOWNSTREAM SHORTWAVE ENERGY EJECTION FROM A MEAN POSITION OFF  
THE PACIFIC NORTHWEST. THIS ADJUSTMENT SEEMS TO MAKE SENSE  
CONSIDERING THE TRACK OF A DEEPENED EXTRATROPICAL LOW ASSOCIATED  
WITH THE REMNANTS OF CURRENT WEST PACIFIC TROPICAL STORM PRAPIROON  
TOWARD ALASKA WOULD SUPPORT THIS TREND TO AMPLIFY FLOW DOWNSTREAM  
INTO THE CONUS.  
 
FRACASSO/SCHICHTEL  
 
WPC MEDIUM RANGE 500 MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION, WINTER WEATHER OUTLOOK PROBABILITIES  
AND HEAT INDEXES ARE FOUND AT:  
 
HTTP://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST500_WBG.GIF  
HTTP://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST_WBG_CONUS.GIF  
HTTP://WWW.WPC.NCEP.NOAA.GOV/5KM_GRIDS/5KM_GRIDSBODY.HTML  
HTTP://WWW.WPC.NCEP.NOAA.GOV/QPF/DAY4-7.SHTML  
HTTP://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4  
HTTP://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML  
 

 
 
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