US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 309 PM EST Thu Jan 9 2020 Valid Sunday January 12 2020 - Thursday January 16 2020 Hazards: - Heavy precipitation across portions of western Washington, Sun-Mon, Jan 12-Jan 13. - Heavy precipitation across portions of the Northeast, Sun, Jan 12. - Heavy rain across portions of California and the Pacific Northwest, Tue-Thu, Jan 14-Jan 16. - Heavy rain across portions of the Southeast, the Mid-Atlantic, the Southern Appalachians, and the Tennessee Valley, Sun-Tue, Jan 12-Jan 14. - Heavy snow across portions of California, the Central Great Basin, the Pacific Northwest, and the Northern Great Basin, Tue-Thu, Jan 14-Jan 16. - Heavy snow across portions of the Central Great Basin, the Pacific Northwest, the Northern Rockies, and the Northern Great Basin, Sun-Mon, Jan 12-Jan 13. - Heavy snow across portions of the Central Rockies, the Central Great Basin, the Northern Rockies, the Northern Great Basin, and the Northern Plains, Sun-Tue, Jan 12-Jan 14. - Heavy snow across portions of the Northeast, Sun, Jan 12. - Flooding possible across portions of the Lower Mississippi Valley, the Tennessee Valley, the Southern Plains, the Middle Mississippi Valley, the Great Lakes, and the Ohio Valley. - Flooding occurring or imminent across portions of the Lower Mississippi Valley, the Pacific Northwest, and the Northern Plains. - Much below normal temperatures across portions of the Northern Plains and the Northern Rockies, Sun-Mon, Jan 12-Jan 13. - Much below normal temperatures across portions of the Upper Mississippi Valley, the Northern Plains, and the Northern Rockies, Tue-Thu, Jan 14-Jan 16. - Much below normal temperatures across portions of mainland Alaska, Sun, Jan 12. - Much below normal temperatures across portions of the Alaska Panhandle, Sun-Tue, Jan 12-Jan 14. Detailed Summary: The strong weekend storm system that will be affecting a large portion of the central and eastern U.S. will still be ongoing across much of the Northeast at the beginning of the forecast period Sunday morning. As the surface low lifts northward into eastern Canada, a swath of moderate to heavy snow still appears likely across northern Maine and a transition zone of sleet and freezing rain across central portions of New England before ending Sunday night. The southern portion of the cold front is expected to stall across the Deep South and Gulf Coast region going into the beginning of next week and then slowly lift northward as a warm front. There will likely be an enhanced swath of heavy rainfall extending from the Florida Peninsula to eastern North Carolina through Tuesday. Additional rainfall going into mid-week also appears likely, but the timing and intensity of this rainfall is in question and therefore we are holding off on delineating a second heavy rain area at this juncture. Across the northwestern U.S., a parade of multiple storm systems will keep the weather pattern unsettled going into next week. The heaviest rainfall is expected across northwest California and western Oregon, where several inches of rain appears likely. This will equate to heavy snow for the Cascades, and over the northern Intermountain region, the main slug of moisture associated with these systems will bring heavy snows to some of the higher elevations through mid-week and especially so for the northern Rockies. Across Montana and then over the Dakotas, a bitterly cold arctic air mass will gradually be settling southward over the region. Temperatures are expected to average up to 20-35 degrees below normal across central and northern Montana by Monday. The frigid air mass should spread southeastward to the Dakotas by Tuesday and into Wednesday. There are differences in the model guidance on the eastward extent of the arctic airmass, and therefore additional revisions to the much below normal temperature areas will likely be warranted in future updates. Subzero high temperatures are currently expected across northern Montana and into North Dakota, and lows dropping into the minus 20s. Across Alaska, much below normal temperatures are forecast to continue across east-central portions of the mainland Interior through the weekend and then moderate by the beginning of next week. Much of the Panhandle region should also experience colder than average temperatures through early in the week as the arctic air spills over the Canadian Rockies and is slower to erode. Hamrick