Extended Forecast Discussion NWS Weather Prediction Center College Park MD 153 PM EST Fri Nov 20 2020 Valid 12Z Mon Nov 23 2020 - 12Z Fri Nov 27 2020 ...Overview and Guidance Evaluation... The latest runs of the models and their ensemble means have shown improvement with the degree of spread within the wave that crosses through the central U.S. into the East. The preferred blend for this issuance leaned a little heavier with the 00Z ECWMF through time but also included the 00Z CMC/ECWMF ensemble mean and the 06Z GFS. There are still some uncertainties to work out in the coming days. ...Sensible Weather and Hazards... Scattered to widespread precipitation is expected to organize over portions of the Plains and the Mississippi/Tennessee/Ohio Valleys before moving into the Southeast and Mid-Atlantic regions. Most of the precipitation should fall as rain, but northern portions of the moisture shield should contain some snow and wintry mix. For Tuesday-Thursday, there is an increasing signal for a separated southern stream shortwave trough/low aloft and surface low pressure system to produce an episode of meaningful precipitation from the Southern Rockies/Plains northeastward through the East, Expect some snow will be possible this period from the upper Midwest to the upper Great Lakes under more northern stream impulse influence. Over the Northwest, it remains the case that progressive but energetic flow aloft will promote a wet period as a series of fronts approach/reach the region. There is good continuity for persistence of rain and higher elevation snow with highest totals over Coastal and Cascade Ranges and a secondary maximum into the Rockies. The supporting trough energies aloft early next weak may be followed by more flow separated/amplified systems mid-later next week that could dig organized precipitation into California, the Great Basin and then the Southwest. Campbell/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