038  
FXUS02 KWBC 080655  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
254 AM EDT SUN JUL 08 2018  
 
VALID 12Z WED JUL 11 2018 - 12Z SUN JUL 15 2018  
   
..PATTERN OVERVIEW/GUIDANCE EVALUATION/PREFERENCES
 
 
MODEL GUIDANCE THIS EVENING IS IN EXCELLENT AGREEMENT ON THE  
GENERAL EVOLUTION OF THE SYNOPTIC PATTERN ACROSS NORTH AMERICA  
THROUGH NEXT WEEKEND. AN UPPER-LEVEL TROUGH MOVING INTO THE  
NORTHEAST EARLY IN THE WEEK IS FORECAST TO LIFT TOWARD  
SOUTHEASTERN CANADA BY MIDWEEK. THIS WILL BRING A COLD FRONT  
THROUGH THE NORTHEAST INTO MUCH OF THE MID-ATLANTIC AND HELP  
ACCELERATE WHAT IS STILL TROPICAL DEPRESSION THREE OFF THE NORTH  
CAROLINA COAST TOWARD THE NORTHEAST. THE UKMET HAS BEEN  
ADVERTISING THE STORM TO LINGER A BIT LONGER OFF THE SOUTHEAST  
U.S. COAST BEFORE ACCELERATING IT JUST OFF OR ACROSS COASTAL NEW  
ENGLAND AROUND THE DAY 4-5 TIME FRAME. THIS SCENARIO HAS BEEN  
DISCOUNTED. CONSULT NHC PRODUCTS FOR LATEST INFORMATION ON T.D.  
THREE.  
 
AS THE UPPER TROUGH LIFTS OUT OF THE NORTHEAST, MODELS ARE IN  
UNANIMOUS AGREEMENT THAT THE WARM SUBTROPICAL HIGH WILL  
REESTABLISH AND ANCHOR ITSELF OVER THE CENTRAL PLAINS WITH A  
SLIGHT TENDENCY OF EXTENDING A RIDGE WESTWARD INTO THE WESTERN  
U.S. THROUGH NEXT WEEKEND. MEANWHILE, A COUPLE OF SHORTWAVE  
TROUGHS ARE INDICATED TO TRAVERSE WESTERN CANADA JUST NORTH OF THE  
U.S.-CANADIAN BORDER. DESPITE THEIR RELATIVELY FAST ZONAL  
MOVEMENT, MODELS ARE IN EXCELLENT AGREEMENT ON THEIR SPEEDS OF  
MOTION AND AMPLITUDES. THE ASSOCIATED COLD FRONTS WILL LIKELY  
MOVE ACROSS THE NORTHERN TIER STATES THROUGH THE MEDIUM-RANGE  
PERIOD.  
 
THEREFORE, THE EVENING WPC MEDIUM-RANGE GRID PACKAGE WAS A  
CONSENSUS OF THE 12Z AND 18Z GFS TOGETHER WITH THE 12Z ECMWF WITH  
MORE OF THE 12Z GEFS MEAN AND 12Z EC ENSEMBLE MEAN INCLUDED TOWARD  
DAYS 6 AND 7. THE 12Z GEFS WAS CHOSEN INSTEAD OF THE 18Z GEFS DUE  
TO BETTER AGREEMENT WITH THE 00Z EC MEAN ON THE SURFACE FEATURES  
IN CENTRAL CANADA. THEIR U.S. SURFACE FEATURES ARE IN EXCELLENT  
AGREEMENT HOWEVER.  
   
..WEATHER THREATS/HIGHLIGHTS
 
 
WITH THE SUBTROPICAL HIGH FORECAST TO REESTABLISH OVER THE CENTRAL  
U.S., TEMPERATURES ARE EXPECTED TO REMAIN ABOVE AVERAGE ACROSS THE  
REGION THROUGH NEXT WEEKEND. FARTHER NORTH ACROSS THE NORTHERN  
TIER INTO THE NORTHEAST AND MID-ATLANTIC, PERIODIC COLD FRONTAL  
PASSAGES WILL BRING OCCASIONAL BREAKS IN THE HEAT AND HUMIDITY  
ALONG WITH PASSING SHOWERS AND THUNDERSTORMS. SOUTH OF THE CENTER  
OF THE SUBTROPICAL HIGH, AN ACTIVE MONSOONAL FLOW REGIME SHOULD  
KEEP TEMPERATURES BELOW NORMAL WITH SHOWERS AND THUNDERSTORMS  
LIKELY ACROSS THE FOUR CORNERS REGION. OVER THE WESTERN U.S.,  
EXPECT WELL ABOVE NORMAL READINGS TO PERSIST ACROSS THE INTERIOR  
PACIFIC NORTHWEST THROUGHOUT THE END OF THE WEEK WITH TRIPLE-DIGIT  
HEAT MOST LIKELY ON THURSDAY. MEANWHILE, A GOOD CHANCE OF SHOWERS  
AND THUNDERSTORMS CAN BE EXPECTED TO PERSIST ACROSS THE SOUTHEAST  
U.S., FLORIDA AND ALONG THE GULF COAST THROUGH THIS WEEK, KEEPING  
TEMPERATURES NEAR OR SLIGHTLY COOLER THAN NORMAL.  
 
KONG  
 
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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