Extended Forecast Discussion NWS Weather Prediction Center College Park MD 402 PM EST Tue Nov 09 2021 Valid 12Z Fri Nov 12 2021 - 12Z Tue Nov 16 2021 ...Robust Midwest/Great Lakes Low into later this week... ...Multiple rounds of precipitation into the Pacific Northwest later this week... ...Pattern Overview and Weather/Hazards Highlights... During the extended period, an amplified trough will pass from central to eastern CONUS by the weekend as a robust surface low lifts northeastward through the Midwest/Great Lakes into eastern Canada. The associated cold front will sweep across the East and will provide focus for a concentrated area of moderate to locally heavy rainfall as moisture from the Gulf and western Mid-Atlantic converge near the front. The speed of the front may limit the severity of runoff and the flooding potential; however, the most promising area for this will be over the favored terrain of interior New England. Enhanced wrap-around then lake effect snows are expected from the Upper Midwest/Great Lakes and into the northern Appalachians/Northeast. Another potent shortwave/surface low pressure system is expected for the the Midwest and Great Lakes later in the period, bringing another blast of cold air that will favor snow across the region. For the Pacific Northwest, a long fetch of Pacific moisture will stream onshore into Saturday resulting in rain in the lower levels and snow in the highest peaks. Additional enhanced precipitation is expected as embedded shortwaves enter the region later this period. Overall, favorable flow should focus heavy rains and elevation snows over the Olympics and Cascades. ...Guidance/Predictability Assessment... The global guidance is in fairly good agreement with the clustering and progression of the amplified trough that passes over the eastern U.S. In maintaining consistency, the WPC medium range product suite was primarily derived from a composite blend of best clustered guidance from the GFS/ECMWF and GEFS/ECMWF ensemble means along with the National Blend of Models. Campbell 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