Extended Forecast Discussion NWS Weather Prediction Center College Park MD 234 AM EDT Fri Oct 16 2020 Valid 12Z Mon Oct 19 2020 - 12Z Fri Oct 23 2020 ...Guidance Evaluation/Preferences... Guidance offers a well clustered larger scale forecast envelope through medium range time scales. This pattern will be highlighted by a broad upper trough over much of the lower 48, save lingering ridging over the Southeast. Deepest upper troughing/height falls should focus over the Rockies and north-central states. However, there is high forecast spread with the timing of smaller scale impulses progressing through the flow and weather focusing surface systems. To mitigate, the WPC medium range product suite was mainly based from a blend of the more compatible 12 UTC GEFS/ECMWF ensemble means and the 01 UTC National Blend of Models. ...Weather/Hazard Highlights... An uncertain series of wavy frontal systems with modest moisture will focus periods of light to moderate precipitation from the Northwest/Rockies and north-central U.S./Midwest to the Northeast. Post-frontal Canadian air surges will dig through the Northwest/Great Basin/central U.S. and to a lesser extent the East/Southeast. Temperature profiles favor periods of snow for the Cascades and northern Rockies to the Dakotas. Meanwhile, protracted easterly fetch favors some lingering Gulf Coast/FL showers that may lift/enhance later next week with potential/gradual flow amplification. Schichtel 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