Extended Forecast Discussion NWS Weather Prediction Center College Park MD 146 AM EST Mon Nov 23 2020 Valid 12Z Thu Nov 26 2020 - 12Z Mon Nov 30 2020 ...Overview and Guidance Evaluation... The WPC medium range product suite was derived from a blend of well clustered guidance from the 12 UTC ECMWF, Canadian and ECMWF ensembles in a pattern with seemingly above average forecast predictability. This blend offers an overall solution on the more amplified/less progressive side of the full envelope of guidance. The 12 UTC UKMET was even more amplified, but the 12/18 UTC GFS/GEFS remain more progressive/less amplified as per known bias. WPC product continuity is well maintained with the aforementioned blend strategy. Newer 00 UTC guidance seems to generally be maintaining prior respective run trends. ...Sensible Weather and Hazards... A separated southern stream shortwave trough/low aloft and well-organized surface low pressure/frontal system will produce a progressive and wide swath of moderate rainfall that reaches New England by Thu before exiting with approach of an amplified northern stream trough from the Upper Midwest/Great Lakes. Meanwhile, trough/closing low energies aloft in an emerging/separating southern stream are slated to dig down through the West along with some terrain enhanced snows for the south-central Great Basin/Rockies then southern High Plains Thu into Fri. Potent system ejection and downstream cyclogenesis/frontogenesis along with increasingly deep return moisture from the Gulf of Mexico should promote and expanding area of enhanced to locally heavy rainfall Fri and the weekend across the South, lifting up through the OH Valley, Appalachians and Eastern Seaboard Sun and next Mon. Meanwhile, expect significant post-frontal cooling far southward through the central to eastern U.S. as Canadian high pressure digs across the region. Cooled temperatures and potential stream phasing to the lee of development of an amplifying/warming Rockies upper ridge may favor some wrap-back snows from the Great Lakes to northern New England on the northwestern periphery of the main precipitation shield. Rockies ridge amplification occurs in response to approach of an amplifying upper trough digging southward from the Gulf of Alaska that itself would favor renewed Northwest precipitation next Mon. 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