US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 319 PM EST Thu Jan 06 2022 Valid Sunday January 09 2022 - Thursday January 13 2022 Hazards: - Heavy rain across portions of the Lower Mississippi Valley and the Southern Plains, Wed-Thu, Jan 12-Jan 13. - Heavy rain across portions of the Southeast, the Lower Mississippi Valley, the Southern Appalachians, the Ohio Valley, and the Tennessee Valley, Sun, Jan 9. - Heavy snow across portions of the Northeast and the Great Lakes, Sun-Mon, Jan 9-Jan 10. - Freezing rain across portions of the Great Lakes, the Mid-Atlantic, the Northeast, the Central Appalachians, and the Ohio Valley, Sun, Jan 9. - Much below normal temperatures across portions of the Northern Plains and the Northern Rockies, Sun, Jan 9. - Much below normal temperatures across portions of the Middle Mississippi Valley, the Great Lakes, the Upper Mississippi Valley, and the Northern Plains, Sun-Tue, Jan 9-Jan 11. - Much below normal temperatures across portions of the Middle Mississippi Valley, the Great Lakes, and the Upper Mississippi Valley, Mon-Tue, Jan 10-Jan 11. - Much below normal temperatures across portions of the Mid-Atlantic, the Northeast, and the Great Lakes, Tue-Wed, Jan 11-Jan 12. - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Sun-Tue, Jan 9-Jan 11 and Thu, Jan 13. - Heavy precipitation across portions of mainland Alaska, Sun, Jan 9. - High winds across portions of the Alaska Panhandle and mainland Alaska, Sun, Jan 9. - Much below normal temperatures across portions of mainland Alaska, Sun, Jan 9. Detailed Summary: The synoptic scale pattern during the medium range (Sun, Jan. 9 - Thurs, Jan. 13) features a handful of hazards across the Lower 48 that feature wintry conditions. The primary weather maker is an amplifying upper trough diving southeast 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 interior Northeast. Most global guidance remains in agreement that this high pressure system remains progressive as it enters the northwest Atlantic. This should limit the duration of the freezing rain and sleet, thus keeping totals from reaching crippling levels. However, should the CAD signature stick around in the Northeast longer than anticipated, heavier ice accumulations could occur. For now, icy conditions are expected with impact to travel by road and air within the highlighted region. Most guidance suggests anywhere from a glaze to as much as 0.20" of ice accumulation is possible. 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 still likely, 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. Recent trends in global models showed an increasing signal for intense lake effect snow bands downwind of Lake Ontario so have gone ahead and issued a heavy snow area for parts of Upstate New York. Lake effect snow showers should also occur downwind of Lake Erie, but the signal was not as evident there so chose to leave it off the chart at this time. Lastly, an upper trough near Baja California moving east looks to tap into subtropical moisture and generate areas of heavy rainfall in 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 with uncertainty as to how much low level cold sticks around into the middle of next week. Have chosen to leave out heavy rain or wintry hazards out to Day 7 for this southern system for now. In Alaska, the North Pacific jet stream pattern goes into a type of atmospheric gridlock as a deep upper level cyclone in the north-central Pacific funnels 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 blocking pattern across the North Pacific is likely to result in a multi-day significant heavy precipitation event stretching from Kodiak Island on Sunday on east down the Panhandle through the first half of the week. The heaviest amounts are still forecast to occur Sunday into Monday and concentrate from the Kenai Peninsula eastward across southeastern Alaska. Precipitation will primarily be in the form of snow with totals being measured in feet in the higher elevations. Meanwhile, a 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 Sunday along the coast and in the mountainous terrain. There are hints in ensemble guidance of another storm system arriving directing an Atmospheric River into the south-central Alaska coast on Day 7, but plenty of model spread remains. Exact totals and location of heaviest amounts are low confidence at this time. Meanwhile, much below normal temperatures will stick around one more day along the Alaska Range/Denali Park and across 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