Extended Forecast Discussion NWS Weather Prediction Center College Park MD 1047 AM 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