US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 316 PM EST Tue Jan 18 2022 Valid Friday January 21 2022 - Tuesday January 25 2022 Hazards: - Heavy snow across portions of the Southeast, the Southern Appalachians, the Mid-Atlantic, and the Central Appalachians, Fri-Sat, Jan 21-Jan 22. - Freezing rain across portions of the Southeast, the Mid-Atlantic, the Southern Appalachians, and the Tennessee Valley, Fri-Sat, Jan 21-Jan 22. - Flooding occurring or imminent across portions of the Lower Mississippi Valley. - Much below normal temperatures across portions of the Central Plains, the Lower Mississippi Valley, the Tennessee Valley, the Middle Mississippi Valley, the Southeast, and the Southern Plains, Fri-Sun, Jan 21-Jan 23. - Much below normal temperatures across portions of the Central Plains, the Lower Mississippi Valley, the Tennessee Valley, the Great Lakes, the Middle Mississippi Valley, the Upper Mississippi Valley, the Southern Plains, and the Ohio Valley, Fri, Jan 21. - Much below normal temperatures across portions of the Central Plains, the Middle Mississippi Valley, the Great Lakes, the Upper Mississippi Valley, and the Northern Plains, Sun-Tue, Jan 23-Jan 25. - Much below normal temperatures across portions of the Northeast, the Central Appalachians, the Mid-Atlantic, the Southern Appalachians, the Great Lakes, and the Ohio Valley, Fri-Sat, Jan 21-Jan 22. - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Fri-Sat, Jan 21-Jan 22 and Mon, Jan 24. - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Sun-Mon, Jan 23-Jan 24. - High winds across portions of the Alaska Panhandle and mainland Alaska, Fri, Jan 21 and Mon, Jan 24. Detailed Summary: Overall, the medium range time period (Friday, January 21 to Tuesday, January 25) will feature upper-level ridging across the West Coast and troughing over the eastern United States. As a result, storm tracks will ride along the southern periphery of this trough and swing from the Northern Plains to the Southeast and East Coast, with finer details regarding these storm systems having rather high uncertainty. Below average temperatures will also be found throughout the Southern Plains and Eastern U.S., with above average temperatures likely for the West. Temperatures 10 to 20 degrees below average are expected throughout the Midwest, Great Lakes, Middle/Lower Mississippi Valley, Deep South, and Southern Plains on Friday. Cold air will linger into the weekend across the Southern Plains and Deep South, with freeze chances along the Gulf Coast. The Northeast and northern Mid-Atlantic will also be in for frigid cold on Friday and Saturday underneath a strong high pressure system. Widespread single digit and subzero lows are forecast here. Finally, another shot of cold air behind a reinforcing cold front will likely enter the Upper Midwest on Sunday as lows and associated wind chills dip well below zero, lingering into next week. ...Mid-Atlantic and Southeast from Friday, January 21 to Saturday, January 22... An arctic cold front progressing into the northern Gulf of Mexico and off the Southeast coastline later this week will set the stage for a potentially significant winter storm throughout parts of the Southeast and southern Mid-Atlantic into this weekend. Surface temperatures are expected to drop near/below freezing throughout eastern North Carolina, much of South Carolina, and northern Georgia. As a shortwave trough enters the Lower Ohio Valley on Friday, an area of low pressure is forecast to develop along the aforementioned frontal boundary off of coastal Carolina. This area of low pressure is to be positioned near the right entrance region of a potent jet streak over the northern Mi-Atlantic and southern New England, which will allow for strengthening. As a result, blossoming precipitation is expected to the north of the low pressure system and over an area experiencing subfreezing temperatures. A swath of heavy snow is most likely to occur from north-central North Carolina to southeast Virginia and the southern Delmarva Peninsula. Regardless of recent deterministic guidance trending more progressive with the system and limiting QPF over the northern Mid-Atlantic, there remains numerous ensemble members and synoptic support hinting at a farther north solution. Given the ridging downstream over the western Atlantic, it won't take much to steer a system closer to the coast and extend heavy snow as far north as an area from southern Pennsylvania to southern New England. Given the large uncertainty, the heavy snow area on the hazards chart today depicts where most guidance overlaps the highest chances for receiving greater than 4" of snow. However, it is important to note that changes to this forecast over the next few days are still likely. On the south side of the system, higher confidence for impactful freezing rain and sleet exists throughout northern Georgia, central and southern South Carolina, as well as eastern North Carolina. Dense cold air at the surface underneath warm air aloft will allow for an extended period of freezing rain from Friday to Saturday. In fact, it's appearing more and more likely that an area of widespread ice accretion greater than 0.25" is possible. This would imply maximum amounts up to 0.50" are not out of the question, particularly for areas in the highlighted region that reside in the Carolinas. This amount of ice would have the potential to create difficult travel conditions, as well as power outages and tree damage. ...Alaska... The North Pacific jet stream pattern features a deep upper trough southwest of the Aleutians and in the Bering Sea. Farther east, an amplifying ridge is forecast to anchor itself over the western coast of Canada and through the Alaskan Panhandle. On Friday, a powerful cyclone south of the Alaskan Peninsula will tap into rich subtropical moisture, leading to a robust Atmospheric River aimed directly at the South Central coast and the northern Panhandle. The southern Panhandle looks to receive heavy precipitation too, but lower elevation rainfall and mountain snowfall totals look to be significant, especially near Yakutat where ensemble guidance is anticipating the highest totals to occur. In addition, strong wind gusts along the coastline associated with a barrier jet are possible with gusts in excess of 50 knots possible on Friday. By Sunday, a separate low pressure system and Atmospheric River is expected to impact a similar region as the upper-level low unravels and moves into western Alaska. Additional gusty winds are possible here as well. Snell