Extended Forecast Discussion NWS Weather Prediction Center College Park MD 159 AM EST Wed Nov 06 2019 Valid 12Z Sat Nov 09 2019 - 12Z Wed Nov 13 2019 ...Central/Eastern U.S Winterization includes Northern Tier to Northeast Snows... ...Pattern Overview and Guidance/Predictability Assessment... The larger scale flow pattern is expected to remain amplified this weekend into next midweek and feature aloft a U.S. West Coast to Alaska ridge and downstream trough over the central/eastern CONUS. Overall, forecast confidence in the large scale pattern is above average, and a favored blend of the latest GFS/ECMWF, GEFS/ECMWF ensemble means and NBM provides a good starting point for the Day 3-7 product suite. ...Weather Highlights/Threats... To the west of the Rockies expect mainly warm and dry conditions. One exception may be with some modest Pacific moisture/precipitation that may work into the West Coast mean upper ridge position, especially into favored terrain of the Pacific Northwest. The downstream pattern under a mean upper trough laden with embedded shortwave impulses favors periodic reinforcement of colder than normal temperatures from the Rockies and Central U.S. to the East as post-frontal surface high pressure centers track south/southeast from Canada. A lead airmass will cross the central/eastern states by Sat with a fairly broad coverage of temperatures 10-20F below normal that could produce a few record cold values. Then by Sun-Wed an even colder surge with highs 15-25F below normal is expected to spread across the central and eastern U.S. that may produce more widespread record cold temperatures. A lead weekend clipper system and trailing cold cyclonic flow will bring mostly snow to the Great Lakes/Northeast with snows prolonged into next week by lake effect. Meanwhile, locations along the eastern slopes of the northern-central Rockies will see periods of enhanced snows as the trailing Arctic front digs southward. The longwave upper flow pattern then suggests potential for coastal low development offshore the East Coast early-mid next week, although there is considerable uncertainty in its coastal proximity and extent of potential wintery impacts. Guidance trends show increased support for another threat of some heavy snow for the Northeast and vicinity. 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