599  
FXUS02 KWBC 090700  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
300 AM EDT MON JUL 09 2018  
 
VALID 12Z THU JUL 12 2018 - 12Z MON JUL 16 2018  
 
...PATTERN OVERVIEW/GUIDANCE EVALUATION/PREFERENCES WITH WEATHER  
HIGHLIGHTS...  
 
LATEST MODELS AND ENSEMBLES THIS EVENING SHOW BETTER THAN AVERAGE  
AGREEMENT ON THE EVOLUTION OF THE SYNOPTIC PATTERN ACROSS NORTH  
AMERICA THROUGH THE MEDIUM RANGE PERIOD. A MID- AND UPPER-LEVEL  
TROUGH LIFTING OUT OF THE NORTHEAST WILL BRING ANOTHER SHOT OF  
COOL AIR INTO THE NORTHEAST LATE THIS WEEK WHILE PLAYING A KEY  
ROLE IN STEERING TROPICAL CYCLONE CHRIS NORTHEASTWARD AT SOME  
DISTANCE OFF THE NEW ENGLAND COAST ON THURSDAY. THE UKMET  
CONTINUES TO BE THE OUTLIER BY BRINGING THE STORM VERY CLOSE TO  
NEW ENGLAND. THIS SCENARIO IS CONSIDERED TO BE OF LOW  
PROBABILITY. CONSULT NHC PRODUCTS FOR LATEST INFORMATION ON CHRIS.  
 
MEANWHILE, A SUBTROPICAL HIGH WILL ANCHOR ITSELF OVER THE CENTRAL  
PLAINS LATE THIS WEEK AS A COUPLE OF MID-LATITUDE SHORTWAVE  
TROUGHS MOVE ACROSS WESTERN CANADA JUST NORTH OF THE  
U.S.-CANADIAN BORDER. MODELS AGREE THAT THE FIRST SHORTWAVE WILL  
BRING A COLD FRONT ACROSS THE NORTHERN PLAINS INTO THE GREAT LAKES  
WHERE THUNDERSTORMS COULD BECOME STRONG WEDNESDAY AND THURSDAY.  
ANOTHER FRONT IS FORECAST TO FORM IN THE PACIFIC NORTHWEST AND  
THEN MOVE INTO THE NORTHERN PLAINS IN THE WEEKEND WITH SCATTERED  
SHOWERS AND THUNDERSTORMS.  
 
FROM THE SOUTHEASTERN U.S. WESTWARD ALONG THE GULF COAST, A  
DISSIPATING FRONT WILL KEEP A GOOD CHANCE OF SHOWERS AND  
THUNDERSTORMS IN THE VICINITY THROUGH THE WEEKEND. MONSOONAL  
MOISTURE WILL LINGER ACROSS THE FOUR CORNERS AREA WHERE LOCALLY  
HEAVY DOWNPOURS WILL BE POSSIBLE THROUGH EARLY NEXT WEEK.  
 
MEANWHILE, TRIPLE-DIGIT HEAT IS FORECAST FOR THE INTERIOR SECTIONS  
OF THE PACIFIC NORTHWEST INTO THE INTERMOUNTAIN REGION AS WELL AS  
INTERIOR CALIFORNIA THROUGH THE WEEKEND, AS COOL AIR FILTERS INTO  
THE NORTHERN PLAINS BEHIND THE SECOND COLD FRONT.  
 
GIVEN THE BETTER THAN AVERAGE AGREEMENT IN THE LATEST GUIDANCE,  
THE LATEST WPC FORECAST BLEND UTILIZED A MAJORITY WEIGHT OF  
OPERATIONAL MODELS (18Z GFS AND 12Z ECMWF/CMC) VERSUS 18Z  
GEFS/ECMWF MEANS THROUGH DAY 5 FRI AND THEN TRENDED TOWARD AN EVEN  
MODEL/ENSEMBLE BLEND AMONG GFS/ECMWF RUNS AND THEIR MEANS.  
 
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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