060  
FXUS02 KWBC 031431  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1030 AM EDT FRI AUG 03 2018  
 
VALID 12Z MON AUG 06 2018 - 12Z FRI AUG 10 2018  
   
..OVERVIEW AND GUIDANCE/UNCERTAINTY ASSESSMENT
 
 
PATTERN NEXT WEEK WILL FEATURE A STRONG UPPER HIGH OVER THE  
SOUTHWEST AND RESURGENT TROUGHING IN THE EASTERN HALF OF THE LOWER  
48. AN UPPER LOW WELL OFF THE PACIFIC NORTHWEST COAST WILL ONLY  
SLOWLY MOVE TOWARD BRITISH COLUMBIA BY THE END OF NEXT WEEK. THERE  
IS GROWING DISCORD IN THE GUIDANCE SUITE, WITH THE 00Z CANADIAN  
BECOMING QUITE THE OUTLIER IN THE CENTRAL PACIFIC WHICH LED TO  
DOWNSTREAM PROBLEMS FROM WEDNESDAY ONWARD ACROSS THE  
NORTHWEST/WESTERN CANADA. THE 00Z UKMET APPEARS TO HAVE ISSUES  
WITH FRONTAL PLACEMENT IN THE CENTRAL PLAINS ON TUESDAY.  
OTHERWISE, THE 06Z GFS AND 00Z ECMWF FIT THEIR MEANS SOLUTIONS  
WELL AND ARE AGREEABLE.  
 
FOR THE PRESSURES, 500 HPA HEIGHTS, AND WINDS, USED A COMPROMISE  
OF THE 00Z CANADIAN/06Z GFS/00Z ECMWF FOR TUESDAY, BEFORE  
SWITCHING TO A BLEND OF THE 00Z UKMET/00Z CANADIAN/06Z GFS/00Z  
ECMWF FOR WEDNESDAY. FOR THURSDAY AND NEXT FRIDAY, USED A  
COMBINATION OF THE 06Z GFS/00Z ECMWF/00Z NAEFS MEAN/00Z ECMWF  
ENSEMBLE MEAN SOLUTIONS. THIS LED TO GOOD CONTINUITY WITH NIGHT  
SHIFT PRESSURES/FRONTS. THE DEW POINT, CLOUD, WEATHER,  
TEMPERATURE, AND PRECIPITATION CHANCE GRIDS USE A MORE EVEN BLEND  
OF THE DETERMINISTIC/ENSEMBLE MEAN GUIDANCE THROUGH THE PERIOD.  
THE DAYS 4-5 QPF WILL LIKELY BE BASED ON A BLEND OF THE 00Z ECMWF,  
06Z GFS, 00Z CANADIAN, 00Z UKMET, AND 12Z NATIONAL BLEND OF  
MODELS. THE DAYS 6-7 QPF WILL LIKELY BE COMPOSED OF A BLEND OF  
THE 00Z ECMWF, 06Z GFS, AND THE 12Z NATIONAL BLEND OF MODELS  
OUTPUT. SHOULD THE 12Z GFS PROVE USEFUL MASS FIELD-WISE, IT TOO  
COULD BE INCLUDED IN THE QPF PREFERENCE.  
 
   
..WEATHER HIGHLIGHTS/THREATS
 
 
WITH THE UPPER LOW LINGERING OFFSHORE, RIDGING WILL SUPPORT WELL  
ABOVE AVERAGE TEMPERATURES IN THE WEST/INTERIOR WEST. RANDOM  
RECORD HIGHS (INCLUDING MORE NUMEROUS RECORD WARM MINIMUMS) ARE  
AGAIN LIKELY FOR THE DESERT SOUTHWEST, WITH THE GREAT BASIN  
GETTING IN ON THE ACT ON THURSDAY.  
 
THE EAST WILL SEE ONE DAY OF WELL ABOVE AVERAGE TEMPERATURES ON  
MONDAY (A COUPLE RECORD HIGHS AND MORE NUMEROUS HIGH MINIMA  
POSSIBLE AROUND NYC) BEFORE AN UPPER TROUGH DIGS/BROADENS ACROSS  
THE EAST AND THE FRONT PUSHES EASTWARD, RAISING THE CHANCE FOR  
PRECIPITATION. PRECIPITATION WILL FOCUS ALONG/AHEAD OF THE FRONT  
THAT WILL PUSH OUT OF THE HIGH PLAINS/GREAT LAKES EARLY IN THE  
WEEK AND THEN INTO THE SOUTHEAST FROM WED-FRI. WARM/HUMID AIRMASS  
WILL SUPPORT SCATTERED CONVECTION WITH LOCALLY HEAVY RAINFALL.  
 
ROTH/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  

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page