633  
FXUS02 KWBC 060659  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
158 AM EST WED MAR 6 2019  
 
VALID 12Z SAT MAR 9 2019 - 12Z WED MAR 13 2019  
   
..WEATHER PATTERN OVERVIEW
 
 
AN ACTIVE WEATHER PATTERN IS EXPECTED DURING MUCH OF THE MEDIUM  
RANGE PERIOD AS TWO LARGE SCALE TROUGHS ORIGINATING FROM THE  
PACIFIC LEAD TO SURFACE LOW DEVELOPMENT ACROSS THE CENTRAL U.S.  
AND MIDWEST STATES. THE FIRST STORM SYSTEM DEVELOPS AND  
INTENSIFIES ACROSS THE CENTRAL PLAINS AND UPPER MIDWEST THIS  
WEEKEND WITH SURFACE HIGH PRESSURE EXITING THE EAST COAST REGION.  
THE SECOND PACIFIC DISTURBANCE CROSSES THE DESERT SOUTHWEST ON  
MONDAY AND THEN UNDERGOES SECONDARY CYCLOGENESIS OVER THE WESTERN  
HIGH PLAINS BY THE END OF THE FORECAST PERIOD NEXT WEDNESDAY.  
 
   
..MODEL GUIDANCE EVALUATION AND PREFERENCES
 
 
THE AGREEMENT AMONG THE MODELS AND ENSEMBLES HAS CONTINUED TO  
IMPROVE ON THE SYNOPTIC SCALE FOR THE ENTIRE FORECAST PERIOD WITH  
THE MORE AMPLIFIED PATTERN THAT WILL BE IN PLACE, AND FORECAST  
CONFIDENCE IS ABOVE AVERAGE FOR THIS TIME PERIOD. THE ECMWF, GFS,  
FV3, AND THE EC AND GEFS MEAN INDICATE RATHER IMPRESSIVE CONSENSUS  
FOR A DAY 7 FORECAST REGARDING THE SECOND LOW TO AFFECT THE  
CENTRAL PART OF THE NATION, WITH THE CMC BEING THE EXCEPTION TO  
THIS BY HAVING THE LOW WELL TO THE SOUTH ACROSS TEXAS. THE CMC IS  
ALSO TO THE WEST OF THE MODEL CONSENSUS WITH THE WEEKEND STORM  
ACROSS THE UPPER MIDWEST. THERE HAS BEEN A SLIGHTLY FASTER TREND  
IN THE ENSEMBLE MEANS FOR THE WEEKEND STORM AND SLIGHTLY MORE  
AMPLIFIED WITH THE STORM SYSTEM EARLY-MID NEXT WEEK.  
 
TAKING ALL OF THESE FACTORS INTO ACCOUNT, THE FORECAST WAS  
PRIMARILY DERIVED FROM THE 12Z ECMWF/18Z FV3 AND GFS/12Z UKMET FOR  
THE FIRST THREE DAYS, AND THEN SLIGHTLY HIGHER PERCENTAGES OF THE  
EC AND GEFS MEANS WHILE STILL KEEPING A SIGNIFICANT PERCENTAGE OF  
THE DETERMINISTIC GFS AND ECMWF FOR THE SECOND HALF OF THE  
FORECAST PERIOD. THE WPC FORECAST IS VERY SIMILAR TO THE PREVIOUS  
FORECAST.  
 
   
..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 SHOULD 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 BY THE END  
OF THE FORECAST PERIOD AS THE TROUGH INDUCES ANOTHER SURFACE LOW  
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  
 
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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