855  
FXUS02 KWBC 061612  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1212 PM EDT FRI JUL 06 2018  
 
VALID 12Z MON JUL 09 2018 - 12Z FRI JUL 13 2018  
   
..TROPICAL SYSTEMS BECOMING MORE THREATENING
 
 
...WEATHER THREATS/HIGHLIGHTS AND GUIDANCE  
EVALUATION/PREFERENCES...  
 
TROPICAL SYSTEM ACTIVITY IS QUICKLY ESCALLATING OVER THE ATLANTIC  
BASIN. THE NHC SHOWS HURRICANE BERYL OVER THE TROPICAL ATLANTIC  
WHOSE FORECAST THREATENS THE EASTERN CARIBBEAN AND VICINITY, WITH  
LATTER NEXT WEEK RESIDUAL MOISTURE POSSIBLY WORKING INTO FLORIDA.  
NHC ALSO CONTINUES TO FOLLOW A DISTURBANCE OFF THE SOUTHEASTERN  
U.S. THAT OFFERS DEVELOPMENT POTENTIAL. WPC PROGS SHOW A  
COORDINATED TRACK FOR THIS LATTER SYSTEM WITH THE ASSUMPTION OF  
FURTHER DEVELOPMENT AND TRACK OFF THE EAST COAST. RECENT UKMET  
RUNS VANGUARDED THE POSSIBILLITY FOR THIS LOW TO NOT BE PICKED UP  
BY NRN STREAM TROUGH PASSAGE UNTIL AFTER A PERIOD OF DEVELOPMENT  
IN SLOW STEERING CURRENTS OFF THE COASTAL CAROLINAS. LATEST GFS  
AND ECMWF RUNS HAVE NOW TRENDED TOWARD THIS IDEA OF WAITING FOR  
MID-UPPER LEVEL TROUGH ENERGY DIGGING THROUGH THE NORTHEAST NEXT  
MIDWEEK TO INTERACT WITH THE SYSTEM. THE GFS OFFERS A  
DEEPER/CLOSER TO THE COAST TRACK OFF THE EASTERN SEABOARD THAN  
NHC/WPC DEPICTIONS, WITH THE ECMWF/CMC FURTHER OFFSHORE.  
 
OTHERWISE, AN UPPER HIGH WILL DOMINATE MUCH OF THE LOWER 48 NEXT  
WEEK. MEAN TROUGHS EXTENDING DOWN INTO THE NORTHWEST AND NORTHEAST  
FLATTEN THEN RE-AMPLIFY AGAIN ALONG THE US/CANADIAN BORDER.  
HEIGHTS WILL BECOME ABOVE AVERAGE COAST TO COAST WHICH SUPPORTS  
NEAR TO ABOVE AVERAGE TEMPERATURES OVER MOST AREAS OUTSIDE THE  
SOUTHERN TIER. A MODERATING FRONT IN THE EAST WILL 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 WILL SEE ENHANCED MONSOONAL MOISTURE AROUND THE  
UPPER HIGH REALIZED AS PRECIPITATION INITIALLY OVER THE HIGHER  
TERRAIN AND THEN INTO SOME OF THE LOWER DESERTS.  
 
THE WPC MEDIUM RANGE PRODUCT SUITE WAS MAINLY DERIVED FROM A BLEND  
OF REASONABLY CLUSTERED GUIDANCE FROM THE 06 UTC GEFS MEAN AND 00  
UTC NAEFS/ECMWF ENSEMBLE MEANS THROUGH THE MEDIUM RANGE PERIOD.  
THE LATEST INDIVIDUAL MODELS WERE ALSO REASONABLY WELL CLUSTERED  
WITH ENSEMBLES OVER LAND, BUT HAVE BEEN MORE DIVERSE WITH TROPICAL  
BASED SYSTEMS. WHILE GUIDANCE IS COMING INTO BETTER AGREEMENT  
OFFSHORE AS WELL, INSTEAD PREFER TO BLEND THE ENSEMBLE MEANS  
EVERYWHERE AND MANUALLY INSERT CURRENT/POTENTIAL TROPICAL SYSTEMS  
AS PER COORDINATION BETWEEN WPC AND NHC.  
 
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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