916  
FXUS02 KWBC 101319  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
918 AM EDT SUN MAR 10 2019  
 
VALID 12Z WED MAR 13 2019 - 12Z SUN MAR 17 2019  
 
...HEAVY SNOW/WIND THREAT FOR THE NORTH-CENTRAL U.S. WEDNESDAY AND  
THURSDAY...  
 
...HEAVY RAIN/STRONG THUNDERSTORM THREAT FROM THE SOUTH-CENTRAL  
PLAINS/MS VALLEY TO THE MID-SOUTH/SOUTHEAST WEDNESDAY TO FRIDAY...  
 
   
..OVERVIEW
 
 
AN AMPLIFIED FLOW PATTERN WILL REMAIN QUITE ACTIVE WED/THU AS  
ANOTHER CENTRAL U.S. SYSTEM HEADS TOWARD THE GREAT LAKES WITH A  
POTPOURRI OF WEATHER THREATS TYPICAL OF A ROBUST LATE WINTER/EARLY  
SPRING STORM. THIS WILL SPREAD A LARGE AREA OF POTENTIALLY HEAVY  
RAIN/SEVERE CONVECTION AND RUNOFF THREAT FROM THE CENTRAL/SOUTHERN  
PLAINS THROUGH THE MID-SOUTH/SOUTHEAST AS MARGINALLY COLD AIR TO  
THE NORTH SUPPORTS A HEAVY SNOW/WIND THREAT FOR THE NORTH-CENTRAL  
ROCKIES/PLAINS AND UPPER MIDWEST. BY NEXT WEEKEND, THE PATTERN  
APPEARS MUCH QUIETER WITH HIGH PRESSURE FORECAST TO DOMINATE THE  
WESTERN/CENTRAL PARTS OF THE LOWER 48 AS BROAD TROUGHING LINGERS  
IN THE EAST WITH MOST UNSETTLED FLOW OVER A COOLED NORTHEAST AND  
WET FLORIDA NEAR A STALLED TRAILING FRONT.  
   
..GUIDANCE AND UNCERTAINTY ASSESSMENT
 
 
DETERMINISTIC AND ENSEMBLE GUIDANCE REMAIN UNUSUALLY WELL  
CLUSTERED INTO NEXT WEEKEND AND A COMPOSITE BLEND SEEMS TO OFFER A  
VERY REASONABLE FORECAST THAT MAINTAINS EXCELLENT WPC CONTINUITY.  
PREDICTABILITY IN THIS PATTERN IS QUITE HIGH.  
   
..WEATHER HIGHLIGHTS AND HAZARDS
 
 
THE MAIN SYSTEM OF INTEREST IN THE MEDIUM RANGE WILL LIFT OUT OF  
SOUTHEASTERN CO WED MORNING AS PRECIPITATION EXPANDS IN COVERAGE  
EASTWARD, FOCUSED FROM EASTERN PORTIONS OF THE SOUTHERN/CENTRAL  
PLAINS AND MID-LOWER MS VALLEY TO THE TN VALLEY WED. THIS WILL  
INCLUDE A RISK OF SEVERE WEATHER GIVEN HEIGHT FALLS/JET  
DYNAMICS/DIFFLUENCE ALOFT AND LOWER ATMOSPHERIC  
INFLOW/CONVERGENCE. TO THE EAST, A LEAD FRONTAL BOUNDARY WILL LIFT  
NORTHWARD AS A WARM FRONT AND BRING WIDESPREAD RAINS AND EMBEDDED  
CONVECTION TO AL/GA/TN/KY THEN SOUTH-CENTRAL APPALACHIANS THU/FRI.  
TO THE NORTH, ENOUGH COLD AIR WILL SUPPORT HEAVY SNOW ON THE  
NORTHWEST/NORTH SIDE OF THE SURFACE LOW THAT WILL OCCUR WITH  
STRONG WINDS (POSSIBLE BLIZZARD CONDITIONS). HEAVY COLD RAINS WILL  
FALL TO THE SOUTHEAST OF THE SURFACE LOW OVER SOME AREAS THAT WILL  
HAVE RECEIVED SIGNIFICANT SNOW IN THE SHORT TERM (I.E. ND/SD/MN  
INTERSECTION). THE SURFACE LOW WILL DEPART THROUGH SOUTHERN CANADA  
FRIDAY AS COLDER AIR IS DRAGGED IN BEHIND IT ACROSS THE GREAT  
LAKES, ENHANCING LAKE-EFFECT SNOWS. THIS ACTIVITY MAY BE  
REINFORCED WITH WEEKEND APPROACH OF SHORTWAVE ENERGY DIGGING WELL  
TO THE LEE OF AN AMPLIFYING WESTERN CANADIAN UPPER RIDGE.  
 
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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