Extended Forecast Discussion NWS Weather Prediction Center College Park MD 157 PM EST Mon Feb 24 2020 Valid 12Z Thu Feb 27 2020 - 12Z Mon Mar 02 2020 ...Overview and Guidance/Predictability Assessment... An amplified mid-upper level pattern highlighted later this week by a ridge over the West and a trough over the East will shift eastward over the weekend in a rather quiet pattern. An exiting system at the short range/medium range interface (Thu) will continue to slowly move into Quebec and Atlantic Canada Fri-Sat. Well upstream, a potent Pacific system will move into WA/OR Saturday. There is a growing guidance signal and forecaster confidence to dig this system sharply through the cooling West/Southwest Sun into Mon in a separating southern stream flow split. Plains cyclogenesis and frontogensis early next week offers an emerging precipitation threat as Gulf moisture returns inland into the wettened mid-lower MS Valley and vicinity. There is also some risk for snow/ice on the northern periphery of the expanding precipitation shield. Overall, a WPC composite blend of the generally compatable GFS/ECMWF and GEFS/ECMWF ensemble means seems to produce a good forecast starting point through medium range time scales consistent with predictability. ...Weather/Hazard Highlights... An exiting deep lead low will support lingering heavy snow over northern New England Thu. Wrap-around flow over the Great Lakes will also support a several day period of snow focused downwind of Lakes Ontario and Erie. Accumulations could be significant for the Tug Hill Plateau. There may also be room for clipper low snows Friday for the OH Valley/Appalachians, but guidance is quite varied. Temperatures trend much cooler behind these systems, generally for a couple days, before rebounding toward average. By contrast, the West will see generally mild/warm days Thu-Sat with some potential record highs in California. Dry conditions Thu into Friday will be replaced by increasing coverage of light to terrain enhanced rain/snow with potent system development/passage. Temperatures will trend cooler as the system moves in, pushing the milder air east of the Rockies next week. Schichtel 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 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