US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 305 PM EST Mon Feb 24 2020 Valid Thursday February 27 2020 - Monday March 02 2020 Hazards: - Heavy precipitation across portions of the Pacific Northwest and the Northern Great Basin, Sat, Feb 29. - Heavy rain across portions of the Middle Mississippi Valley, the Lower Mississippi Valley, and the Southern Plains, Mon, Mar 2. - Heavy snow across portions of the Northeast and the Great Lakes, Thu-Fri, Feb 27-Feb 28. - Heavy snow across portions of the Northeast, Thu, Feb 27. - Flooding possible across portions of the Southeast. - Flooding occurring or imminent across portions of the Lower Mississippi Valley, the Tennessee Valley, the Middle Mississippi Valley, the Southern Appalachians, the Southeast, the Southern Plains, and the Ohio Valley. - Flooding likely across portions of the Southeast. - Much below normal temperatures across portions of the Central Appalachians, the Northern Plains, the Tennessee Valley, the Middle Mississippi Valley, the Southern Appalachians, the Upper Mississippi Valley, the Great Lakes, and the Ohio Valley, Thu-Sat, Feb 27-Feb 29. - Much below normal temperatures across portions of the Southeast, Thu-Fri, Feb 27-Feb 28. - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Thu, Feb 27. - High winds across portions of mainland Alaska and the Aleutians, Sat-Sun, Feb 29-Mar 1. - Much below normal temperatures across portions of mainland Alaska, Thu-Mon, Feb 27-Mar 2. - Much below normal temperatures across portions of far northern mainland Alaska, Thu-Fri, Feb 27-Feb 28. Detailed Summary: A potent Midwest and Great Lakes snowstorm in the short range will track into northern New England Thursday morning. Heavy snow will fall over the region with the highest totals focused in the northern Appalachians. Snow totals in excess of a foot are possible in central Maine and New Hampshire on Thursday. On the backside of the storm, brisk and cold westerly winds flowing over Lakes Ontario and Erie will lead to bands of lake effect snow over portions of western Pennsylvania and New York. Lake effect snows will persist through Friday and may even linger into the first half of Saturday. In wake of the short range winter storm, bitterly cold temperatures will spread throughout the Midwest, the Lower Great Lakes, and Ohio Valley Thursday and into Friday. Below normal temperatures will likely linger across the Ohio Valley into Saturday morning. Much below normal temperatures will also extend into the Southeast with the coldest departures focused in southern Georgia and most of Florida. Morning low temperatures may dip below freezing in parts of southern Georgia and north-central Florida both Friday and Saturday mornings. In the West, a shortwave trough is forecast to track into the Pacific Northwest this weekend sending a stream of precipitation over much of Washington, northern Oregon, and northern Idaho. The heaviest precipitation amounts are currently expected to accumulate in the Olympics and Cascades. While lower elevations receive rain, the higher elevations can expect mountain snow with accumulations in excess of 8 inches possible. By Sunday, an amplifying upper-level trough is forecast to dig into the Southwest and slowly inch towards the Southern Plains early next week. Deterministic model guidance does contain a range of sensible weather outcomes the first half of the week due to differences in the depth, speed, and position of this upper-level trough. That said, ensemble guidance is steadfast in the likelihood of an anomalous trough in the Southwest that should promote the opportunity for heavy rain and thunderstorms across the South-Central U.S. and into the mid-Mississippi Valley the first half of next week. Due to recent heavy rainfall and subsequent overly saturated soil, there is also the potential for additional flooding in the Mississippi Valley next week. Over Alaska, a prolonged stretch of frigid temperatures will engulf much of the mainland late week, through the weekend, and into the first half of next week. Thursday will be a wet one in the Panhandle thanks to a storm system in the Gulf of Alaska that will slam into the Panhandle coast. Higher elevations can expect heavy snow while the valleys and coastal areas see periods of rain. To the west, a powerful and highly anomalous surface low pressure system is expected to develop and track towards the western Aleutians late Friday and into Saturday. In addition to heavy showers and rough seas, strong winds will be a concern with wind speeds in excess of 50 knots possible across much of the Aleutians to kick start the weekend. Mullinax