Extended Forecast Discussion NWS Weather Prediction Center College Park MD 255 AM EDT Wed Sep 18 2019 Valid 12Z Sat Sep 21 2019 - 12Z Wed Sep 25 2019 ...Imelda moisture offers a East-Central Plains to Midwest Heavy Rainfall Threat... ...Overview and Guidance Evaluation/Preferences... Models and ensembles offer a reasonably similar medium range flow evolution in a pattern with above average forecast confidence. The WPC medium range product suite was primarily derived from a composite blend of fairly well clustered guidance from the GFS/ECMWF/UKMET/Canadian, GEFS/ECMWF ensemble means and the National Blend of Models. This maintains excellent WPC continuity. ...Weather Highlights/Threats... Deep tropical moisture with the remains of Imelda will offer a significant threat of locally excessive rainfall into the weekend. Expected inland lifting/entrainment into the flow with approaching mid-latitude upper trough energy from the West and surface front proximity will likely then focus heavy convection/runoff issues with cell training from the east-central Plains to the Mid-MS Valley/Midwest. Meanwhile, an aforementioned upper trough will lift northeastward from the unsettled and cooled West/Rockies to the north-central U.S. This will support an organized convective focus with locally heavy downpours and a severe thunderstorm risk into Saturday as per SPC. Deepened lead moisture may also support some record high minimum temperatures. Upstream, upper low/trough energies will reload back into an again unsettled West/Southwest Sunday into next week with an initial precipitation swath over the Northwest then Great Basin. There is guidance uncertainty, but monsoonal rainfall/convection then into the Southwest/Southern Rockies may be enhanced early next week by an influx of tropical moisture well downstream of current Tropical Storm Lorena. 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