778  
FXUS02 KWBC 101611  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1211 PM EDT FRI AUG 10 2018  
 
VALID 12Z MON AUG 13 2018 - 12Z FRI AUG 17 2018  
   
..PATTERN OVERVIEW AND GUIDANCE/PREDICTABILITY ASSESSMENT
 
 
A PAIR OF CLOSED MID-UPPER LOWS CENTERED NEAR THE CENTRAL  
APPALACHIANS AND SOUTHERN HIGH PLAINS INTO EARLY NEXT WEEK WILL  
ACT TO FOCUS A HEAVY PRECIPITATION THREAT. BOTH FEATURES ARE  
EXPECTED TO GRADUALLY EVOLVE INTO OPEN WAVES WITH GRADUAL  
NORTHEASTWARD MIGRATION MID-LATER WEEK AS A POTENTIALLY AMPIFIED  
NEW TROUGH/LOW DIGS INTO THE NORTH-CENTRAL STATES/MIDWEST. OPTED  
TO LEAN ON AN AMPLIFIED SOLUTION GIVEN RECENT FLOW HISTORY AND AS  
FURTHER SUPPORTED BY THE ENTRAINMENT OF THE EXTRATROPICAL  
LOW/REMNANTS OF EX-TYPHOON SHANSHAN FROM THE NORTHERN PACIFIC TO  
CANADA. FLOW AMPLITUDE ON THE MORE AMPLIFIED SIDE OF THE FULL  
ENVELOPE OF FORECAST SOLUTIONS IS MOST CHAMPIONED BY THE 00 UTC  
ECMWF AND GEFS/ECMWF ENSEMBLES. OVER THE DESERT SOUTHWEST/FOUR  
CORNERS REGION, MODELS SHOW A RETURN OF A WARMING 594-DM MID-LEVEL  
RIDGE MID-LATER NEXT WEEK.  
 
ACCORDINGLY, THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY  
DERIVED FROM A COMPOSITE BLEND OF THE 00 UTC ECMWF AND GEFS/ECMWF  
ENSEMBLES. GUIDANCE SPREAD AND PREDICTABILITY SEEM NEAR TO  
SLIGHTLY BETTER THAN NORMAL.  
   
..WEATHER HIGHLIGHTS AND HAZARDS
 
 
THE MOST FOCUSED AREAS OF HEAVY RAINFALL WILL LINGER NEAR/AHEAD OF  
SLOW TO EJECT CLOSED LOWS OVER THE MID-ATLANTIC/NORTHEAST AND BACK  
IN THE SOUTH-CENTRAL U.S, TO BE FOLLOWED BY AN UPSTREAM KICKER  
MOVING INTO THE NORTH-CENTRAL STATES/MIDWEST. THE MAIN EXCESSIVE  
RAINFALL THREAT MAY FURTHER FOCUS ALONG ASSOCIATED/WAVY FRONTS  
THAT WILL POOL DEPEENED MOISTURE AND TAP INSTABILITY. MEANWHILE,  
DECENT DAILY CHANCES FOR MONSOONAL THUNDERSTORMS SHOULD DEVELOP  
OVER THE DESERT SOUTHWEST AND THE SOUTH-CENTRAL GREAT  
BASIN/ROCKIES.  
 
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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