822  
FXUS02 KWBC 141552  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1151 AM EDT SUN APR 14 2019  
 
VALID 12Z WED APR 17 2019 - 12Z SUN APR 21 2019  
 
...YET ANOTHER MAJOR SPRING STORM MID-LATE WEEK WILL PACK A HEAVY  
RAINFALL AND SEVERE WEATHER THREAT FOR THE CENTRAL TO EASTERN  
U.S...  
   
..OVERVIEW
 
 
POTENT UPPER LEVEL LOW WILL EXIT THE FOUR CORNERS REGION WEDNESDAY  
AND WORK ITS WAY EASTWARD/NORTHEASTWARD AS RIDGING BUILDS IN THE  
WESTERN ATLANTIC. THIS WILL LEAD TO A DYNAMIC SPRING STORM AGAIN  
FOR THE CENTRAL STATES WITH RAIN, SEVERE WEATHER, AND SOME  
NORTHERN FRINGE SNOW. RIDGING WILL ALSO PUSH INTO THE WEST  
COAST,TO BE PARTIALLY REPLACED BY AN UPPER LOW TRACKING INTO  
SOUTHERN CA INTO SATURDAY AND SHEARING OVER THE SOUTHWEST TO THE  
SOUTHERN PLAINS NEXT SUNDAY WITH LITTLE FANFARE. THE SYSTEM IS  
KICKED OUT AS MORE UNSETTLING/WETTER PACIFIC TROUGH ENERGIES AND  
HEIGHT FALLS DIG BACK UPSTREAM AND INLAND ACROSS THE WEST COAST.  
 
   
..GUIDANCE PREFERENCES
 
 
06 UTC GFS/GEFS AND 00 UTC ECMWF/ECMWF ENSEMBLE FORECASTS NOW  
CLUSTER EXTREMELY WELL AND MAINTAIN GOOD CONTINUITY DAYS 3-7. WPC  
PROGS WERE MAINLY DERIVED FROM A COMPOSITE BLEND OF THESE GUIDANCE  
PIECES. GREATER WEIGHTING WAS APPLIED TO THE DETERMINISTIC MODELS  
FOR EXTRA DETAIL CONSISTENT WITH A PATTERN WITH SEEMINGLY ABOVE  
NORMAL PREDICTABILITY. HOWEVER, IT REMAINS A BIT LESS CERTAIN THE  
EXTENT THE SOUTHERN PORTION OF THE UPPER TROUGH REMAINS SEPARATED  
FROM THE FLOW TO THE NORTH. THE 00 UTC UKMET AND ESPECIALLY THE 00  
UTC CANADIAN DELAY STREAM PHASING COMPARED TO THE GFS/ECMWF,  
PERHAPS SLOWING THE SYSTEM DOWN MORE BY THE WEEKEND.  
 
   
..WEATHER HIGHLIGHTS/THREATS
 
 
SIGNIFICANT PRECIPITATION WILL AGAIN INCREASE INTO WEDNESDAY AND  
SPREAD FROM THE MISSISSIPPI/MISSOURI VALLEYS THROUGH THE EAST AS  
LOW PRESSURE STRENGTHENS OVER THE PLAINS AND CORN BELT. MULTI-INCH  
RAINFALL TOTALS WITH LOCAL FLOODING ARE PROBABLE (ENHANCED IN  
EMBEDDED CONVECTION) BOTH ALONG/AHEAD OF THE FRONT AND TO THE  
NORTH/NORTHEAST OF THE SURFACE LOW. CONSULT SPC FOR THE LATEST ON  
THE SEVERE WEATHER RISK. MILD TEMPERATURES WILL PRECEDE THE FRONT  
(10-15F ABOVE AVERAGE) TO BE REPLACED BY COOLER THAN AVERAGE  
TEMPERATURES AFTER ITS PASSAGE. UPSTREAM, THE NORTHWEST WILL SEE A  
FRONT WITH MODEST PRECIPITATION PUSH THROUGH THE REGION FRIDAY AND  
THE WEEKEND, REACHING THE UPPER MIDWEST AND STRETCHED BACK TO CA.  
 
FRACASSO/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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