US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 726 PM EST Wed Jan 05 2022 Valid Sunday January 09 2022 - Thursday January 13 2022 Hazards: - Freezing rain and sleet across portions of the Central Appalachians and the Northeast, Sun, Jan 9. - Heavy rain across portions of the Southeast, the Southern Appalachians, the Lower Mississippi Valley, the Southern Plains, and the Tennessee Valley, Sat-Sun, Jan 8-Jan 9. - Heavy snow across portions of the Great Lakes, Sun-Mon, Jan 9-Jan 10. - Flooding possible across portions of the Southeast, the Mid-Atlantic, and the Pacific Northwest. - Flooding occurring or imminent across portions of the Pacific Northwest and the Ohio Valley. - Flooding likely across portions of the Pacific Northwest and the Ohio Valley. - Much below normal temperatures across portions of the Northern Plains and the Northern Rockies, Sat-Sun, Jan 8-Jan 9. - Much below normal temperatures across portions of the Northern Plains, the Upper Mississippi Valley, and the Great Lakes, Sun-Tue, Jan 9-Jan 11. - Much below normal temperatures across portions of the Great Lakes, Mon-Tues, Jan 10-Jan 11. - Much below normal temperatures across portions of the Northeast and the Great Lakes, Tue-Wed, Jan 11-Jan 12. - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Sat-Tue, Jan 8-Jan 12. - High winds across portions of the Alaska Panhandle and mainland Alaska, Sat-Sun, Jan 8-Jan 9. - Much below normal temperatures across portions of mainland Alaska, Sat-Sun, Jan 8-Jan 9. - Much below normal temperatures across portions of mainland Alaska, Sat, Jan 8. Detailed Summary: The synoptic scale pattern during the medium range (Sat, Jan. 8 - Wed, Jan. 12) will feature a handful of hazards across the Lower 48 that feature wintry conditions. The primary weather feature will be an amplifying upper trough diving southeast from Canada through the Northern Plains and Upper Midwest first, then into the Great Lakes and eventually the Northeast. Meanwhile, a ridging pattern aloft in the Southeast will help provide return southerly flow ahead of a storm system tracking south and east from the North-Central U.S. this weekend. Increased instability ahead of the storm system in the South may produce heavy rain in parts of the Deep South. It should also be noted that Farther north, a dome of high pressure on Saturday anchors cold/dry air over the Northeast and Mid-Atlantic into Sunday morning. Isentropic lift as warm air advection ahead of the approaching storm system sets the stage for an icy Sunday for parts of the Northeast. As of this afternoon, most global guidance keeps this high pressure progressive and entering the northwest Atlantic. This should limit the duration of the freezing rain and sleet potential, but should stick around in the Northeast longer, heavier ice accumulations could occur. For now, icy conditions are expected with impact to travel in affected areas. Behind the storm system tracking through the Great Lakes on Sunday is an Arctic intrusion of bitterly cold temperatures. Daily temperature anomalies from northern Montana to northern Minnesota are forecast to range between 15-25 degrees below normal with some areas as cold as 30 degrees below normal. The air-mass will moderate some as it reaches the Great Lakes but daily anomalies of roughly 15-20 degrees below normal between Jan 10-11 are a good bet, along with frigid wind chills. Meanwhile, the fresh injection of Arctic air passing over the open Great Lakes will turn on the lake effect snow machine throughout much of the Great Lakes. The coldest anomalies temps aloft are likely to be positioned downwind of Lakes Superior and Michigan, so chose to put a heavy snow area over parts of Michigan's U.P. and northern Michigan. A case could be made to add one downwind of Lakes Erie and Ontario too, but not all guidance was initially on board with a long enough duration event. A heavy snow area may be needed tomorrow should trends support significant lake effect snows in parts of northeast Ohio, northwest Pennsylvania, and northern New York for Jan 10-11. Lastly, while not on the map, will be watching out to Day 7 as an upper trough near Baja California moves east, bringing the chance for wet weather to the South Central U.S.. There are even some hints at the potential for icy conditions in the Mid-South but spread in ensemble guidance remains high across the board, so chose to leave out heavy rain or wintry hazards out to Day 7 for now. For Alaska, the North Pacific jet stream pattern becomes locked with a deep upper level cyclone in the north-central Pacific funneling rounds of subtropical moisture north towards the southern Alaska coast. This prolonged period of unsettled weather is supported by a blocking ridge of high pressure in northwest Russia and an emerging +PNA regime over western North America. This large scale pattern across the North Pacific is likely to result in a multi-day significant heavy precipitation event stretching from Kodiak Island on east down the Panhandle. The heaviest amounts are still most likely to occur Sunday into Monday and concentrate from the Kenai Peninsula eastward across southeastern Alaska. Precipitation will primarily be in the form of snow, though the surge of warmer air will allow for a changeover to rain across parts of the Panhandle and right along the immediate coast of south-central/southeastern Alaska. In addition to periods of heavy rain and snow, the presence of a strong pressure gradient between the Gulf of Alaska low and the expansive high pressure area from northwest Russia to the Arctic circle will result in strong winds. Easterly to southeasterly gusts up to 40-60 mph possible over the weekend along the coast and in the mountainous terrain. Meanwhile, much below normal temperatures will through the weekend for parts of southwestern Alaska, the Alaska Range/Denali Park, and eastern sections of the Yukon-Tanana Uplands. However, due to the strong southerly maritime flow courtesy of the North Pacific low, much milder air will stream inland for next week. Mullinax