US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 411 PM EDT Wed Mar 24 2021 Valid Saturday March 27 2021 - Wednesday March 31 2021 Hazards: - Heavy precipitation across portions of the Northeast, Sun, Mar 28. - Heavy rain across portions of the Lower Mississippi Valley, the Southern Appalachians, the Ohio Valley, and the Tennessee Valley, Sat, Mar 27. - Heavy rain across portions of the Middle/Lower Mississippi Valley, the Ohio Valley, and the Tennessee Valley, Wed, Mar 31. - Heavy snow across portions of the Pacific Northwest and the Northern Great Basin, Sun, Mar 28. - Flooding possible across portions of the Central Plains, the Southeast, the Lower Mississippi Valley, and the Tennessee Valley. - Flooding occurring or imminent across portions of the Middle Mississippi Valley and the Ohio Valley. - Flooding likely across portions of the Central Plains and the Lower Mississippi Valley. - High winds across portions of the Northern Plains, Mon-Tue, Mar 29-Mar 30. - High winds across portions of the Mid-Atlantic and the Northeast, Mon, Mar 29. - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Sat, Mar 27 and Tue-Wed, Mar 30-Mar 31. - Heavy snow across portions of mainland Alaska, Sun-Mon, Mar 28-Mar 29. - High winds across portions of mainland Alaska and the Aleutians, Sun-Mon, Mar 28-Mar 29. Detailed Summary: The medium-range forecast period (Saturday, March 27th to Wednesday, March 31st), a front extending from the Ohio Valley to the Central/Southern Plains, will move southeastward to the Lower Great Lakes and southwestward to the Lower Mississippi Valley/Western Gulf Coast by Sunday. Moisture from the Western Gulf of Mexico will flow northward, intersecting the boundary and will produce an area of heavy rain over parts of the Tennessee Valley and the Central/Southern Appalachians on Saturday. On Sunday, moisture will stream onshore over parts of the Pacific Northwest for a short time ahead of the next front to come onshore off the Pacific. The moisture will help produce an area of heavy snow over the Cascades on Sunday. Meanwhile, low pressure over the Central Plains on Saturday will move across the Northeast on Sunday into Monday. The low will help produce an area of heavy precipitation over parts of Northern New England. The area of precipitation will produce mountain snow and valley rain on Sunday. In the meantime, the low associated with the front moving onshore over the Pacific Northwest will deepen over Western Canada and continue to move eastward just north of the U. S./Canadian border continuing to deepen. The deep low will have a strong pressure gradient associated with producing an area of high wind over parts of the Northern High Plains and into the Northern Plains on Monday and Tuesday. Furthermore, the aforementioned low over the Northeast will likewise become very deep as the low moves off the Northeast Coast. The pressure gradient associated with the low will produce an area of high wind along the coast from parts of New England to parts of the northern Mid-Atlantic Coast on Monday. The Northwest front will move eastward to the Great Lakes, extending roughly southward to the Lower Mississippi Valley/Southern Plains by Wednesday. Moisture from the Western Gulf of Mexico will stream northward over the region, intersecting the boundary, producing an area of heavy rain over parts of the Lower Mississippi Valley, Southern Ohio Valley, and Tennessee Valley on Wednesday. For Alaska, low pressure over the Gulf of Alaska and associated front will move inland over the Alaska Panhandle on Saturday. The low-pressure areas will stream moisture into the Alaska Panhandle on Saturday, producing an area of heavy precipitation over the Alaska Panhandle and bring heavy coastal rain, along with interior and higher elevation snow. Another area of deep low-pressure over the Northwestern Pacific on Saturday will move into the Bearing Sea on Sunday and into the Western Mainland on Monday. The strong pressure gradient around the low will produce high wind over the Aleutians into the Alaska Peninsula and parts of the Southwest Mainland on Sunday and Monday. The same storm will produce an area of heavy snow over parts of the Southwest into parts of the South-Central Mainland on Sunday into Monday. In particular, the heavy snow will develop over the Nulato Hills, the Kuskokwim Mountains, and the western parts of the Alaska Range. As the system moves east across the Gulf of Alaska, moisture will stream inland over the Alaska Panhandle and into parts of the eastern section of the South-Central mainland on Tuesday into Wednesday. Ziegenfelder