Extended Forecast Discussion NWS Weather Prediction Center College Park MD 300 AM EDT Mon Apr 27 2020 Valid 12Z Thu Apr 30 2020 - 12Z Mon May 04 2020 ...Much above normal temperatures spread from the West to the Plains late week... ...Stormy weather to progress across the eastern U.S. late week... ...Pattern Overview and Guidance/Predictability Assessment... Pacific trough energies will work inland across the West Coast later this week and nudge an amplified upper ridge out of the West/Rockies to over the central U.S. This will be contrasted with an upper trough/closed low moving across the eastern U.S. where a moderately strong low pressure system is forecast. Guidance solutions have converged on a more common overall solution, bolstering forecast confidence. Well upstream, there is a growing guidance signal for amplified eastern Pacific troughing to work more robustly over the Northwest next weekend, reaching the Rockies in a week. The WPC medium range product suite was mainly derived from a blend of reasonably well clustered guidance of the GFS/ECMWF/UKMET days 3-5 (Thu-Sat) and then the ECMWF and GEFS/ECMWF ensemble means days 6/7. The ECMWF seems the best fit with these ensemble means at these longer time frames. This solution maintains good WPC continuity and acts to mitigate the less certain smaller scale weather features and interactions. ...Weather/Hazard Highlights... An amplified mid-upper level trough/closed low and well-organized surface low will track from the Great Lakes/OH Valley to the Northeast Thu-Sat. A trailing frontal system will sweep across the eastern U.S. mainly Thu along with a swath of moderately heavy rainfall/strong thunderstorms. Coastal low redevelopment may enhance Northeast rainfall and offshore maritime hazards as the entire system moves away into the Canadian Maritimes later weekend. An upper ridge upstream will meanwhile support much above normal temperatures to include a risk of record maximum/minimum temperature values from the Southwest to through the Great Basin/Rockies/Plains. Temperatures will cool in the wake of the exiting upper ridge as upstream Pacific systems work into the West. This will support light to moderate precipitation, but could then support some organized weekend convection downstream over the north-central states. An uncertain chance of rain/some strong thunderstorms should then increase eastward through the Ohio Valley/central Appalachians later next weekend into Mon with system approach. 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