US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 242 PM EST Fri Jan 17 2020 Valid Monday January 20 2020 - Friday January 24 2020 Hazards: - Heavy precipitation across portions of California and the Pacific Northwest, Tue-Wed, Jan 21-Jan 22. - Heavy precipitation across portions of the Central Plains, the Middle Mississippi Valley, the Southern Plains, and the Ohio Valley, Thu-Fri, Jan 23-Jan 24. - Heavy rain across portions of the Central and Southern Plains, the Lower and Middle Mississippi Valley, the Tennessee Valley, the Southeast, and the Ohio Valley, Thu-Fri, Jan 23-Jan 24. - Heavy snow across portions of the Central Great Basin and California, Tue-Wed, Jan 21-Jan 22. - Flooding possible across portions of the Central Plains, the Tennessee Valley, the Great Lakes, the Middle Mississippi Valley, the Southeast, the Southern Plains, and the Ohio Valley. - Flooding occurring or imminent across portions of the Lower and Middle Mississippi Valley, the Northern Plains, the Tennessee Valley, the Southeast, the Great Lakes, and the Ohio Valley. - Flooding likely across portions of the Middle Mississippi Valley. - Much below normal temperatures across portions of the Central Plains, the Northern Plains, the Middle and Upper Mississippi Valley, the Great Lakes, and the Ohio Valley, Mon-Tue, Jan 20-Jan 21. - High significant wave heights for coastal portions of California and the Pacific Northwest, Tue, Jan 21. - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Mon-Tue, Jan 20-Jan 21. - Much below normal temperatures across portions of mainland Alaska, Mon, Jan 20. Detailed Summary: A strong and cold dome of high pressure over the Northern Plains/Midwest early week will produce bitterly cold temperatures across these regions along with frigid wind chills. Look for daily low temperatures to plunge below zero on Monday and Tuesday in the Upper Mississippi Valley. Daily low temperature anomalies will average nearly 15 degrees below normal both days with high temperatures anomalies ranging between 20 to 25 degrees below normal. As high pressure drifts southeast, southerly return flow will usher in milder temperatures by mid-week. Cold temperatures associated with this dome of high pressure will reach parts of the Deep South by Tuesday and Wednesday but conditions will not to be as anomalously cold as was observed in the Midwest. The East Coast can also expect colder but not excessively colder temperatures, despite wind chills that could be sub-zero in parts of the Northeast Tuesday morning. An upper-level trough in the northeast Pacific will track into the Northwest and British Columbia on Tuesday leading to heavy precipitation in northern California and southwest Oregon. Higher elevations can expect heavy snow while lower elevations will likely deal with heavy rain. The northern Sierra Nevada will witness heavy snow Tuesday and into Tuesday night with totals that could cause problematic travel conditions. The Pacific Northwest coastline could also contend with high surf on Tuesday as the system approaches the region. As the trough tracks into the Intermountain West, model guidance disagrees as to the amplitude, position, and timing of the trough once it reaches the Plains mid-week. While there is uncertainty as to the evolution and track of the developing surface low in the south-central Plains, the longwave pattern supports a feed of Gulf of Mexico moisture funneling north into the Southern Plains and Lower Mississippi Valley. On the north side of storm system, a combination of snow and wintry mix could develop from the central Rockies to the Midwest. Potential hazards include the potential for flooding in the Southern Plains and Lower Mississippi Valley, plus potential disruptive winter weather in the Central Plains and Midwest. In Alaska, below normal temperatures are expected to continue for the lower elevations of the mainland through Monday. After Monday, temperatures will gradually modify the remainder of the week. A storm system in the Gulf of Alaska is likely to affect the Panhandle and potentially along the Gulf of Alaska coast Monday and into Tuesday. Guidance shows a combination of lower elevation rainfall and heavy mountain snow from the Panhandle on north and west to far southern coast. Mullinax