Extended Forecast Discussion NWS Weather Prediction Center College Park MD 1059 PM EST Tue Nov 09 2021 Valid 12Z Sat Nov 13 2021 - 12Z Wed Nov 17 2021 ...Multiple rounds of precipitation into the Pacific Northwest into mid next week... ...Lake Effect/enhanced precipitation from this weekend through mid next week... ...Guidance/Predictability Assessment... The global guidance is in general agreement with the clustering and progression of the amplified trough that slowly progresses through the East into the Western Atlantic and a progressive trough moving into the West. While the 12z-18z GFS were a tad strong with a shortwave moving along the central US/Canadian border Monday into Tuesday, its overall pattern merges back towards the consensus mid next week. The WPC medium range product suite was primarily derived from a blend of deterministic and ensemble mean guidance along with the National Blend of Models. ...Pattern Overview and Weather/Hazards Highlights... An amplified trough will pass slowly through the eastern CONUS, periodically reinforced by shortwaves rounding its southwest side. Its associated cold fronts sweep across the East Friday into Saturday Enhanced lake effect snows are expected from the Upper Midwest/Great Lakes and into the northern Appalachians/Northeast. Temperatures should be generally around 10F below average for portions of the East Saturday through Tuesday. Moderation in the East is expected on Wednesday as low pressure moves across central Canada, with its cold front moving into the Upper Midwest, and the surface ridge axis slides towards the Southeast coast. For the Pacific Northwest, a long fetch of Pacific moisture with moderate to heavy rainfall will stream onshore Sunday into Wednesday resulting in rain in valleys and snow in the highest peaks. Overall, favorable flow should focus heavy rains and elevation snows over the Olympics and Cascades, as is usually the case. Until the Western trough moves into the area next Tuesday and Wednesday, temperatures are expected to be 10-15F above average before nudging slightly below average in the Northern Continental Divide on Wednesday. Roth Hazards: - Heavy rain across portions of the Mid-Atlantic, the Northeast, and the Pacific Northwest, Fri, Nov 12. - Heavy snow across portions of the Pacific Northwest and the Northern Great Basin, Fri, Nov 12. - High winds across portions of the Central Plains, the Middle Mississippi Valley, the Upper Mississippi Valley, and the Northern Plains, Fri, Nov 12. Additional 3-7 Day Hazard information can be found on the WPC medium range hazards outlook 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