962  
FXUS02 KWBC 061958  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
257 PM EST WED MAR 06 2019  
 
VALID 12Z SAT MAR 09 2019 - 12Z WED MAR 13 2019  
   
..WEATHER PATTERN OVERVIEW
 
 
A STORMY WEATHER PATTERN PERSISTS THROUGH MEDIUM RANGE TIME SCALES  
AS TWO LARGE SCALE MID-UPPER LEVEL TROUGHS/HEIGHT FALLS  
ORIGINATING FROM THE PACIFIC LEAD TO DEEP SURFACE LOW DEVELOPMENT  
OVER THE CENTRAL U.S. AND MIDWEST STATES. THE FIRST STORM SYSTEM  
DEVELOPS AND INTENSIFIES ACROSS THE CENTRAL PLAINS AND UPPER  
MIDWEST THIS WEEKEND AS SURFACE HIGH PRESSURE ERODES THE EAST. A  
SECOND PACIFIC STORM CROSSES THE DESERT SOUTHWEST TUE, WITH  
PLAINS/MIDWEST STORM GENESIS BY WED.  
 
   
..GUIDANCE AND UNCERTAINTY ASSESSEMENT
 
 
MODEL AND ENSEMBLE FORECAST CLUSTERING IS QUITE GOOD FOR MUCH OF  
THE FORECAST PERIOD WITH A MORE AMPLIFIED PATTERN IN PLACE AND  
FORECAST PREDICTABILITY REMAINS ABOVE AVERAGE. THE GFS,FV3,ECMWF,  
CANADIAN AND THE GEFS/NAEFS/ECMWF ENSEMBLE MEANS INDICATE RATHER  
IMPRESSIVE CONSENSUS INTO DAY 6/TUE AND A COMPOSITE SOLUTION SEEMS  
REASONABLE. TIMING ISSUES ARE EVIDENT WITH THE SECOND MAIN SYSTEM  
ENERGING FROM THE SOUTHWEST INTO THE PLAINS/MIDWEST IN ABOUT A  
WEEK. PREFER A SLIGHTLY LESS PROGRESSIVE THAN CONCENSUS SOLUTION  
GIVEN FLOW AMPLITUDE, MORE IN LINE WITH RECENT ECMWF/CANADIAN AND  
ECMWF/NAEFS ENSEMBLE MEANS. THIS SOLUTION MAINTAINS GOOD WPC  
CONTINUITY. HOWEVER, THE MORE PROGRESSIVE GFS/GEFS SOLUTIONS ARE  
PLAUSIBLE GIVEN POTENTIAL KICKER UPSTREAM SHORTWAVE APPROACH DAY 7  
TO THE PACIFIC NORTHWEST THAT COULD ACT TO DECREASE SYSTEM  
WAVELENGTH SPACING.  
 
   
..WEATHER HIGHLIGHTS AND HAZARDS
 
 
WIDESPREAD RAIN AND THUNDERSTORMS ARE EXPECTED TO DEVELOP FROM THE  
GULF COAST TO THE OHIO VALLEY AND SOUTHERN APPALACHIANS ON  
SATURDAY AND INTO EARLY SUNDAY AS A RICH SUPPLY OF GULF MOISTURE  
SURGES NORTHWARD AHEAD OF A STRONG COLD FRONT FROM THE MIDWEST  
SURFACE LOW. THE HEAVIEST RAINFALL IS LIKELY FROM EASTERN TEXAS TO  
THE SOUTHERN APPALACHIANS, WHERE A GENERAL 1 TO 2 INCHES OF RAIN  
IS LIKELY THAT MAY LEAD TO SOME LOCAL FLOODING ISSUES BASED ON THE  
CURRENT FORECAST. HOWEVER, THE PROGRESSIVE NATURE OF THE EVENT  
WOULD LIMIT THE DURATION OF THE HEAVIEST RAIN. DEPENDING ON WHERE  
THE SURFACE LOW TRACKS, A CORRIDOR OF BLIZZARD CONDITIONS IS  
BECOMING INCREASINGLY LIKELY ACROSS PARTS OF THE UPPER MIDWEST,  
INCLUDING PARTS OF THE DAKOTAS. ANOTHER FACET TO THIS LOW PRESSURE  
SYSTEM WILL BE THE POTENTIAL FOR SEVERE THUNDERSTORMS TO DEVELOP  
IN THE WARM SECTOR, AND THIS IS SOMETHING THAT THE STORM  
PREDICTION CENTER IS CURRENTLY MONITORING.  
 
UPSTREAM, THE PATTERN AGAIN FAVORS AN AMPLIFIED MID-UPPER LEVEL  
TROUGH DEVELOPING OFF THE WEST COAST THIS WEEKEND. THIS WILL  
SUPPORT ANOTHER ROUND OF PRECIPITATION OVER THE SOUTHWESTERN U.S.  
AS THE TROUGH MOVES INLAND ON MONDAY. ADDITIONAL WIDESPREAD RAIN  
MAY THEN DEVELOP ACROSS THE CENTRAL AND SOUTHERN PLAINS THROUGH  
THE MISSISSIPPI VALLEY/MIDWEST IN ABOUT A WEEK AS THE TROUGH  
INDUCES ANOTHER DEEPENING SURFACE LOW/STORM EAST OF THE ROCKIES.  
THERE IS ALSO THE POTENTIAL FOR SEVERE WEATHER WITH THIS STORM  
SYSTEM, AND DETAILS ON THIS WILL BECOME MORE EVIDENT IN THE  
UPCOMING DAYS.  
 
D. HAMRICK/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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