Extended Forecast Discussion NWS Weather Prediction Center College Park MD 201 AM EST Mon Feb 01 2021 Valid 12Z Thu Feb 04 2021 - 12Z Mon Feb 08 2021 ...Midweek Southwest U.S. system to progress to the Plains/Midwest/Northeast later week followed by arctic outbreak by weekend... ...Guidance/Predictability Assessment... ...Weather/Threats Highlights... The low ejection of a stormy lead cyclone into the Canadian Maritimes will allow some areas along or offshore coastal New England to have lingering brisk winds into Thursday. Upper troughing driving through the Southwest/Rockies will produce a swath of terrain enhanced snows into Thursday. System ejection into the Plains still offers additional northern stream trough phasing uncertainties and a complex frontal structure, but suspect that a deepening low will organize and lift to the Great Lakes into Friday. Enhanced snows are expected near and to the north of the main cyclone track from the windy Midwest/Great Lakes to the Northeast. Meanwhile to the south, leading warm air advection and return Gulf moisture will combine with favorable dynamics and forcing to fuel an expanding but progressive area of moderate rain/convection from the east-central U.S. through the Eastern Seaboard. Upstream, expect a swath of heavy terrain snows are forecast from the Northwest to the north-central Rockies late week with a series of potent shortwaves that subsequently dig into an emerging/amplified central U.S. upper trough position this weekend. This will act to drive a frigid arctic airmass fully southward through the central then eastern U.S.. Interaction with a lingering wavy front trailing from the aforementioned lead system over the East may favor piedmont/coastal rains and inland snows from the OH Valley/Appalachians to the Northeast. 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