Extended Forecast Discussion NWS Weather Prediction Center College Park MD 200 AM EST Sat Jan 15 2022 Valid 12Z Tue Jan 18 2022 - 12Z Sat Jan 22 2022 ...Pattern Overview... Guidance overall agrees that a mean upper ridge will amplify off the West Coast mid-later next week. Downstream, this should force an increasingly dominant series of northern stream impulses dig down from Canada to carve out a large and central U.S. centered mean upper trough. ...Guidance/Predictability Assessment... The WPC forecast suite was mainly derived from a composite blend of reasonably well clustered solutions from the 18 UTC GFS and 12 UTC ECMWF/UKMET/Canadian days 3-5 (Tue-Thu) along with the 01 UTC NBM in a pattern with seemingly above normal predictability. WPC product continuity is well maintained. Forecast spread and model run to run consistency become a bit less manageable into days 6/7 (Fri-next Saturday). Prefer a composite of the larger scale compatible 18 UTC GEFS mean and 12 UTC NAEFS/ECMWF ensemble means to maintain max WPC product continuity beyond less predictable smaller scale embedded system detail. Overall, the resultant solution seems reasonable and a similar pattern amplification/evolution is depicted with composite of newer 12 UTC model and ensemble runs. ...Weather Highlights/Hazards... A significant winter storm is slated to exit still windy New England to the Canadian Maritimes by Tuesday as another organized low pressure system digs into the north-central U.S. Low development and subsequent track roughly eastward along the U.S./Canadian border into Wed/Thu will bring some snow to the Upper Midwest, Great Lakes then northern New England, with locally higher totals expected near typical lake enhancement areas as cold high pressure sweeps down across the central and eastern U.S. in the wake of the low. Guidance varies with potential focus, but suspect the wavy trailing cold front on the leading edge of this Arctic blast will gain at least modest moisture from the Gulf of Mexico to fuel an emerging area of precipitation over the Southeast that offers some later next week potential for overrunning snow/ice on the northern periphery of activity. The Canadian and some ensemble members are more robust with frontal/coastal wave amplitude and precipitation extent across the region and over the East Coast at these longer time periods. The main upper trough position is far enough West to not discount this possibility. Meanwhile, The West could see some light precipitation through the period, particularly over the Pacific Northwest and into the Northern Rockies as weakening systems cross the region, with mainly dry conditions elsewhere. 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