Extended Forecast Discussion NWS Weather Prediction Center College Park MD 200 AM EST Sun Nov 07 2021 Valid 12Z Wed Nov 10 2021 - 12Z Sun Nov 14 2021 ...Deep Midwest/Great Lakes Low mid-later week... ...Moisture Plume to focus into Pacific Northwest later week... ...Pattern Overview... Positive height anomalies over northern Canada and off the Southwest and Southeast U.S. will favor increased troughing over the central-eastern U.S. in an amplifying pattern. This favors a deepening central states cyclone that will lift northeastward through the Midwest/Great Lakes into Canada. Milder air over much of the Lower 48 will trend cooler with time as the trailing cold front sweeps eastward bringing a widespread swath of enhanced but overall progressive rains across the broad region along with some wrap-back snows across the Dakotas/Upper Midwest/Great Lakes and Northern Appalachians. Upstream, there is a growing guidance signal bringing a long fetch plume of Pacific moisture into the Pacific Northwest, especially later this week. Favorable flow should focus heavy rains and elevation snows over the Olympics and Cascades. ...Guidance/Predictability Assessment... Guidance continues to illustrate a reasonably similar larger scale pattern evolution, but with continued uncertainty in timing, track, and strength of the embedded systems including run to run continuity issues. Accordingly, the WPC medium range product suite was primarily derived from a composite blend of the latest GEFS/ECMWF ensemble means and the National Blend of Models that seem reasonably compatible. ...Weather/Hazards Highlights... Amplified upper troughing carving out over the central U.S. is slated to be sandwiched between upper ridges over the West Coast and East Coast amid the pattern transition. Cyclogenesis and frontogenesis will act to favor an emerging lead organized rainfall/convective pattern over the east-central U.S. Thursday as theta-e advection increases. Surface wave development could act to enhance rainfall along the front from the southern Appalachians northward. Backside cold air flow by next Friday also suggests potential for some snow over the Dakotas/Upper Midwest/Great Lakes/northern Appalachians as moisture feeds back around the developing/exiting main low. Temperatures will be near to above normal early in the week, with possible record highs ahead of the front, trending cooler by week's end especially into the Southeast. Please see WPC links below for all the details in graphical format. Upstream, there is a growing guidance signal bringing a long fetch plume of Pacific moisture into the Pacific Northwest, especially later this week. Favorable flow should focus heavy rains and elevation snows over the Olympics and Cascades. Schichtel 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