Extended Forecast Discussion NWS Weather Prediction Center College Park MD 300 AM EDT Tue Mar 26 2019 Valid 12Z Fri Mar 29 2019 - 12Z Tue Apr 02 2019 ...Overview and Weather Highlights and Hazards... Dynamic upper trough energy is slated to punch inland over the West to the s-central Great Basin and Rockies by Friday. These southern stream height falls will then work eastward over the central and eastern states over the weekend, interacting with amplifying northern stream trough energies digging down from Canada. Plains cyclogenesis and subsequent movement through the MS Valley/Midwest may combine with a lead surge of deepening moisture/warmth from the Gulf of Mexico to fuel a period of enhanced rain/thunderstorms in those areas with ongoing flooding Friday into Saturday. There is also some risk of heavy snow Fri-Sun on the cooled northwest to northern periphery of the precipitation shield from the Northern/Central Rockies/Plains to the Midwest/Great Lakes then northern New England. ...Guidance Assessment/Preferences... Model and ensemble solutions seem reasonably well clustered Fri into Sat for mid-larger-scale features and a composite blend focuses less emphasis on the less predictable smaller scale features. This blend includes the latest GFS, ECMWF, UKMET, and Canadian that cluster well with the latest GEFS/ECMWF ensemble means during this time period. Forecast spread and run-run continuity issues become more problematic this weekend into early next week. This begins with questions about the degree of separation in the northern and southern streams, namely the manner in which a deep upper trough in east-central Canada phases with southern stream troughing traversing over the central CONUS. Recent ECMWF runs/ECMWF ensemble means show more stream phasing than recent GFS and to a lesser extent the FV3 and GEFS means. Preferred a blend of the GEFS/ECMWF ensemble means given uncertainty, but applied more weight to ECMWF ensembles for better continuity into Day 7. 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