050  
FXUS02 KWBC 160658  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
257 AM EDT SAT JUN 16 2018  
 
VALID 12Z TUE JUN 19 2018 - 12Z SAT JUN 23 2018  
 
...GUIDANCE/PREDICTABILLITY ASSESSMENT AND  
 
MODELS AND ENSEMBLES OFFER A REASONABLY SIMILAR LARGER SCALE  
PATTERN EVOLUTION OVER THE NEXT WEEK IN AN ACTIVE WEATHER PATTERN,  
BUT SMALL-MID SCALE EMBEDDED FEATURES STILL OFFER QUITE OF BIT OF  
FORECAST SPREAD. GUIDANCE TO VARIOUS DEGREES HAS TRENDED TO A  
FASTER EJECTION OF AMPLIFIED SHORT RANGE MID-UPPER LEVEL TROUGHING  
FROM THE WEST INTO THE N-CENTRAL U.S. MID-LATE NEXT WEEK, THIS  
OCCURS AS KICKER FLOW EMERGES UPSTREAM FROM THE EASTERN PACIFIC  
INTO THE NORTHWEST. PREFER A SOLUTION IN BETWEEN THE GFS/ECMWF AND  
THEIR ENSEMBLES WHOSE LESS PROGRESSION SOLUTION THAN THE UKMET AND  
CANADIAN SEEMS MORE REASONABLE GIVEN THE INITIAL SLOW AND  
AMPLIFIED NATURE OF THE OVERALL PATTERN. THIS INCLUDES A HOT AND  
HUMID DOWNSTREAM RIDGE OVER THE EAST/SOUTHEAST WHOSE NORTHERN  
PERIPHERY IS ERODED BY PERSISTENT NRN STREAM CYCLONIC FLOW ALOFT  
FROM CENTRAL CANADA TO THE NORTHEAST U.S.  
 
OVERALL, THE WPC MEDIUM RANGE PRODUCT SUITE WAS MAINLY DERIVED  
FROM A COMPOSITE BLEND OF THE LATEST GFS/GEFS AND ECMWF/ECMWF  
ENSEMBLE MEAN ALONG WITH WPC CONTINUITY. THIS SOLUTION MAINTAINS  
GOOD WPC CONTINUITY AND ACTS TO DE-EMPHASIZE LESS PREDICTABLE  
SMALLER SCALE FORECAST COMPONENTS WHOSE HEAVY CONVECTIVE FOCUS  
REMAINS HIGHLY UNCERTAIN.  
   
..WEATHER HIGHLLIGHTS/THREATS
 
 
THIS WILL OVERALL LAY DOWN A LONG STANDING AND WAVY FRONTAL  
BOUNDARY ROUGHLY FROM THE ROCKIES AND CENTRAL PLAINS/MS VALLEY  
THAT SLOWLY SINKS ACROSS THE OH VALLEY AND MID-ATLANTIC NEXT WEEK.  
PERIODS OF LOCALLY EXCESSIVE CONVECTION WILL FOCUS IN/NEAR THIS  
BAROCLINIC ZONE AND IN THE WARM SECTOR AIDED BY EARLY PERIOD  
TROPICAL MOISTURE INFUX FROM THE GULF OF MEXICO. WPC MEDIUM RANGE  
QPF SHOWS HEAVIEST POTENTIAL OVER THE TX COAST WITH POTENTIAL  
TROPICAL WAVE/DISTURBANCE INFLUENCE AND SPILLING  
EAST-SOUTHEASTWARD ACROSS THE CENTRAL PLAINS AS NORTHWARD FLOWING  
MOISTURE AND LLJ ENERGY/INSTABILITY INTERSECT/TRAIN NEAR THE WAVY  
FRONT AND CONVECTIVELY DRIVEN MESO-BOUNDARIES.  
 
SCHICHTEL  
 
WPC MEDIUM RANGE FORECASTS OF 500 MB HEIGHTS, SURFACE SYSTEMS,  
WEATHER GRIDS, QUANTITATIVE PRECIPITATION, AND WINTER WEATHER  
OUTLOOK PROBABILITIES CAN BE 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  
 

 
 
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