Extended Forecast Discussion NWS Weather Prediction Center College Park MD 155 PM EST Tue Jan 04 2022 Valid 12Z Fri Jan 07 2022 - 12Z Tue Jan 11 2022 ...General Pattern Overview... The upper level pattern over the continental U.S. through the beginning of next week should remain fairly amplified but also progressive. A strong shortwave trough and associated nor'easter will exit the East Coast Friday, and this should give way to a Canadian surface high and cold weather settling across the east-central U.S. in the wake of the strong cold front. Inland progression of an early Friday Pacific Northwest system will bring a drier trend to that region as upper ridging builds over the West by Sunday-Monday. Meanwhile by the weekend the flow ahead of Plains low pressure and a trailing cold front will support an expanding area of rain from the Gulf Coast into at least the Tennessee Valley. Also another surge of arctic air will reach the north-central U.S. behind the system. ...Guidance/Predictability Assessment... There was reasonably good agreement for significant features in the 00Z-06Z models/ensembles. The large scale of the eastern trough by early next week suggests better than average predictability while there is some uncertainty with shortwaves that may try to move into/around the upper ridge building into the West. Details become somewhat ambiguous over and near the southwestern U.S. by the first half of next week as solutions diverge for what becomes of smaller-scale energy in the southernmost part of the upper trough crossing the West during the weekend as well as another feature that approaches from the Pacific. A blend of the latest operational models represented consensus ideas from Friday into Sunday and incorporating some weight of the 06Z GEFS/00Z ECMWF means along with the 06Z GFS and 00Z ECMWF/CMC reflected the continued large scale agreement while accounting for the uncertainty near the Southwest next week. The resulting forecast yielded good continuity. Guidance is finally better clustered for the deepening storm that tracks from off the New England coast into the Canadian Maritimes late this week. Today's GFS runs are stronger versus a number of prior runs while the consistently strong ECMWF has nudged its track a bit to the east over the past couple days. New guidance still shows various ideas for the weak shortwave energy that may linger over the Southwest by late weekend/early next week with the GFS still weakest/most progressive and 00Z ECMWF the most concentrated. The 00Z ECMWF's handling of that feature likely plays a role in its greater deflection of approaching Pacific energy versus what most other models and means show. 12Z ECMWF trends are favorable compared to other guidance. ...Hazards/Sensible Weather Highlights... After an active period of weather during the short range period across the Pacific Northwest, some lingering rain and mountain snow is still likely from northern California to western Washington, and snow for the Northern Rockies, on Friday. A drying trend should commence in time for the weekend across much of the West as high pressure builds back into the region. Meanwhile, an intensifying nor'easter off the New England Coast on Friday may produce some snow over eastern/northern New England in particular (amounts very sensitive to exact track) along with lingering snow showers over the rest of the Northeast. New England may see a brief period of brisk to strong winds behind this system. Gulf moisture ahead of a Plains cold front should spread rain and thunderstorms from the Lower Mississippi Valley into the Tennessee Valley/southern Appalachians this weekend with lesser amounts of rain extending farther north. Some locally moderate to heavy activity is possible but confidence in specifics is fairly low at this time. Areas from the upper Great Lakes into the Northeast could see wintry weather, either exclusively or before a changeover to rain. Parts of the Great Lakes may see lake effect snow behind the passing front. Temperatures will be quite cold across the central/northern Plains to the Upper Midwest on Friday with a large surface high of arctic origin governing the weather pattern for this region. Lows may be 20-30F below normal while highs 15-20F or so below normal may extend as far southeast as the Tennessee Valley and southern Appalachians. Expect some moderation of the severe cold over the Plains/Midwest on Saturday ahead of the next arctic surge that reaches into the northern tier states by Sunday-Monday. The second surge may not be quite as intense as its predecessor but temperatures could still be 15-25F below normal over some areas. From Friday into Sunday above normal temperatures will progress from the southern Plains into the Deep South with greatest anomalies of plus 20-25F possible at some locations for highs on Saturday and morning lows on Sunday. Seasonably cold conditions are likely west of the Continental Divide with readings generally within 10 degrees of climatological averages, though locally a little more than that on the warm side of normal for lows on Friday-Saturday. Rausch/Hamrick 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