676  
FXUS02 KWBC 151600  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1200 PM EDT WED MAY 15 2019  
 
VALID 12Z SAT MAY 18 2019 - 12Z WED MAY 22 2019  
   
..GUIDANCE/PREDICTABILITY ASSESSMENT
 
 
THE 06 UTC GFS/FV3 AND 00 UTC ECMWF/UKMET/CANADIAN OFFER GOOD  
FORECAST CLUSTERING THIS WEEKEND. DESPITE SOME COMMON LONGER TERM  
MODEL SIMILARITIES, FORECAST CONFIDENCE NEXT WEEK REMAINS BELOW  
NORMAL DUE TO LESS THAN STELLAR CONTINUITY ISSUES. ACCORDINGLY,  
THE WPC PRODUCT SUITE PRIMARILY WAS DERIVED FROM A COMPOSITE MODEL  
SOLUTION THIS WEEKEND BEFORE QUICKLY TRANSITIONING TO MORE  
COMPATABLE 06 UTC GEFS MEAN AND 00 UTC ECMWF ENSEMBLE MEAN INTO  
EARLY NEXT WEEK AMID GROWING FORECAST SPREAD....GUIDANCE  
ASSESSMENT AND WEATHER HIGHLIGHTS/THREATS...  
   
..WEATHER HIGHLIGHTS AND HAZARDS
 
 
MODEL AND ENSEMBLE SOLUTIONS CONTINUE TO SHOW ABOVE NORMAL  
FORECAST SPREAD WITH RESPECT TO NORTHEASTERN U.S./MID-ATLANTIC  
FLOW THROUGH THIS WEEKEND AS A SERIES OF POTENT CANADIAN UPPER  
SYSTEMS PROGRESS WITHIN AN ENERGETIC NORTHERN STREAM. FAVOR A  
COMPOSITE.  
 
UPSTREAM, A DYNAMIC MID-UPPER LEVEL TROUGH WILL LIFT NORTHEASTWARD  
FROM THE SOUTHERN ROCKIES TO THE CENTRAL THEN NORTHEASTERN U.S.  
SAT-TUE. THIS SYSTEM WILL SPAWN SURFACE SYSTEM/LOW GENESIS WITH  
LEAD MOISTURE INFLOW AND INSTABILITY PROVIDING THE FOUNDATION FOR  
A THREAT OF HEAVY CONVECTION/RAINFALL AND SEVERE WEATHER AS PER  
SPC. UNDERNEATH, A GRADUALLY WEAKENING CLOSED LOW/CONVECTION WILL  
WEAKEN OVER THE EASTERN GULF OF MEXICO.  
 
THERE REMAINS A STRONG SIGNAL THAT PACIFIC FLOW WILL BRING ANOTHER  
ROUND OF STRONG HEIGHT FALLS AND WIDESPREAD PRECIPITATION/TERRAIN  
ENHANCED SNOWS TO THE WEST LATER THIS WEEKEND INTO EARLY-MID NEXT  
WEEK BEFORE EJECTING OVER THE CENTRAL U.S. FURTHER UPSTREAM, THERE  
IS A STILL UNCERTAIN GUIDANCE SIGNAL TO DEVELOP A DEEPER LOW IN  
THE EASTERN PACIFIC EARLY NEXT WEEK THAT OFFERS POTENTIAL TO REACH  
CA AND THE GREAT BASIN/SOUTHWEST AGAIN EARLY NEXT WEEK ALONG WITH  
RENEWED UNSETTLED WEATHER/PRECIPITATION.  
 
SCHICHTEL  
 
ADDITIONAL 3-7 DAY HAZARDS INFORMATION CAN BE FOUND ON THE WPC  
MEDIUM RANGE HAZARDS CHART AT:  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP  
 
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION, WINTER WEATHER OUTLOOK PROBABILITIES  
AND HEAT INDICES ARE 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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