Extended Forecast Discussion NWS Weather Prediction Center College Park MD 318 PM EST Wed Nov 06 2019 Valid 12Z Sat Nov 09 2019 - 12Z Wed Nov 13 2019 ...Strong Cold Front Includes Northern Tier to Northeast Snows Early Next Week... ...Pattern Overview and Guidance/Predictability Assessment... The larger scale flow pattern is expected to remain amplified into next week with 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 decent, but breaks down toward the midweek as troughs of uncertain timing push into the West Coast. The 00Z UKMET had strength/timing issues with the lead cold front and is excluded from the blend. The 00Z/06Z GFS are much slower than the 00Z ECMWF/CMC with the first trough pushing through the western ridge by Day 5. The preferences was toward the 00Z ECMWF/CMC into Day 5, then a strong switch to the 00Z ECENS/NAEFS means for Days 6/7 for pressures and fronts. ...Weather Highlights/Threats... An Arctic-sourced cold front pushes south from Canada, reinforcing the mean eastern trough, this weekend, bringing colder than normal temperatures for the eastern 3/4 of the CONUS. The center of the surface high pressure centers tracks south/southeast from the Canadian Prairies and across the center of the CONUS into the middle of next week. 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 resulting in upslope flow. The longwave upper flow pattern continues to suggest potential for low development off the East Coast early-mid next week, although there remains uncertainty in its coastal proximity and extent of potential wintry impacts. Guidance continues to show support for another threat of some heavy snow for the Northeast and vicinity. Jackson 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 - Heavy precipitation across portions of the Northeast, Tue, Nov 12. - Heavy rain across portions of the Western Gulf Coast, Mon, Nov 11. - Heavy snow across portions of the Upper Great Lakes, Mon, Nov 11. - Flooding possible across portions of the Lower Mississippi Valley and the Southern Plains. - Flooding occurring or imminent across portions of the Middle Mississippi Valley, the Lower Mississippi Valley, and the Northern Plains. - Flooding likely across portions of the Northern Plains. - Much below normal temperatures across much of the Central and Eastern U.S., Mon-Wed, Nov 11-Nov 13. - Much below normal temperatures across portions of the Mid-Atlantic, Sat, Nov 9. 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