Extended Forecast Discussion NWS Weather Prediction Center College Park MD 147 AM EST Sat Nov 21 2020 Valid 12Z Tue Nov 24 2020 - 12Z Sat Nov 28 2020 ...Overview and Guidance Evaluation... The WPC medium range product suite was primarily derived from a guidance blend of the 18 UTC GFS/GEFS mean, the 12 UTC ECMWF/ECMWF ensemble mean and the 01 UTC National Blend of Models. Applied most blend weighting to the 12 UTC ECMWF that offers more southern stream system separation that seems in line with recent guidance trends and continuity. The 00 UTC GFS is now more progressive, but the 00 UTC ECMWF/UKMET/Canadian are trending slower, bolstering forecast confidence. ...Sensible Weather and Hazards... There is a decent guidance signal that a separated southern stream shortwave trough/low aloft and surface low pressure system will produce a swath of meaningful precipitation from the Southern Plains/Mid-Lower MS Valley northeastward through the East Coast Tue-Thu. Expect moderate precipitation including some snow will also be possible this period from the Upper Midwest to the Upper Great Lakes to New England under more northern stream system 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 week 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. Downstream progression and system genesis may support strong convection/heavier rains starting over the south-central U.S. heading into next weekend. 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