Extended Forecast Discussion NWS Weather Prediction Center College Park MD 408 PM EDT Thu Apr 11 2019 Valid 12Z Sun Apr 14 2019 - 12Z Thu Apr 18 2019 ...Two major spring storms offer a heavy rainfall/flooding threat from the mid-lower Mississippi Valley to the Ohio Valley this weekend and again through next midweek along with a risk of severe weather over the South... ...Weather Highlights/Hazards and Guidance/Predictability Assessment... A highly dynamic mid-upper trough/height falls and coupled upper jet support across the southern Plains through the mid-lower MS/OH Valleys this weekend, bringing widespread heavy rains with potential of excessive rainfall and flash flooding as deep moisture (1.5+ S.D. above normal) is pulled inland from the Gulf of Mexico. There is also a risk of severe warm sector convection over the South as per SPC. The potent low and enhanced but progressive precipittaion will track over the Northeast Monday where there is some threat of onset northern New England snow/ice. There will also be rains/convection along and ahead of a trailing cold front moving across the South, East and offshore into the Gulf of Mexico and western Atlantic. The 00 UTC GFS/ECMWF/GEFS/ECMWF ensemble mean solutions are well clustered in a pattern with above normal predictability. Meanwhile upstream, models and ensembles still agree to bring potent mid-upper level troughing/ample height falls/frontal precipitation into the West Coast Sunday. The southern stream upper trough is reinforced over the Great Basin and Rockies Monday/Tuesday to emerge over the Plains midweek then east-central U.S. by Thursday. Height falls should induce Plains cyclogenesis with a renewed return flow of deepening Gulf moisture and ascent leading to enhanced rainfall in eastern OK/TX extending downstream into the mid-lower MS to Ohio Valleys. Given a similar cyclone track/intensity and support profile/upper level trough track, similar areas hit by rain this weekend are expected to receive a repeat heavy rain and strong to severe threat. The 00 UTC GFS/ECMWF/GEFS/ECMWF ensemble mean solutions are well clustered in a pattern with much above normal predictability considering this longer timeframe. Schichtel Hazards: - Heavy precipitation across portions of the Pacific Northwest and the Northern Great Basin, Sun-Tue, Apr 14-Apr 16. - Heavy precipitation across portions of the Pacific Northwest, the Northern Rockies, and the Northern Great Basin, Sun-Mon, Apr 14-Apr 15. - Heavy precipitation across portions of the Northeast, the Central Great Basin, the Northern Plains, the Northern Rockies, the Central Rockies, and the Northern Great Basin, Mon-Tue, Apr 15-Apr 16. - Heavy precipitation across portions of the Central Rockies and the Central Plains, Wed-Thu, Apr 17-Apr 18. - Heavy rain across portions of the Lower Mississippi Valley, the Central Appalachians, the Tennessee Valley, the Great Lakes, the Middle Mississippi Valley, the Mid-Atlantic, the Southern Appalachians, the Southeast, the Southern Plains, and the Ohio Valley, Tue-Thu, Apr 16-Apr 18. - Heavy rain across portions of the Southeast, the Mid-Atlantic, the Southern Appalachians, and the Tennessee Valley, Sun-Mon, Apr 14-Apr 15. - Heavy rain across portions of the Great Lakes, the Mid-Atlantic, the Northeast, the Central Appalachians, and the Ohio Valley, Mon-Tue, Apr 15-Apr 16. - Severe weather across portions of the Southeast, the Mid-Atlantic, the Lower Mississippi Valley, the Southern Appalachians, and the Tennessee Valley, Sun, Apr 14. - Flooding possible across portions of the Middle Mississippi Valley, the Great Lakes, the Upper Mississippi Valley, and the Northern Plains. - Flooding occurring or imminent across portions of the Lower Mississippi Valley, the Northern Plains, the Tennessee Valley, the Northern Great Basin, the Middle Mississippi Valley, the Upper Mississippi Valley, the Pacific Northwest, and the Ohio Valley. - Flooding likely across portions of the Upper Mississippi Valley and the Northern Plains. - Much below normal temperatures across portions of the Southern Rockies, the Central Rockies, the Southern Plains, and the Central Plains, Sun, Apr 14. 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