US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 445 PM EDT Tue Mar 24 2020 Valid Friday March 27 2020 - Tuesday March 31 2020 Hazards: - Heavy precipitation across portions of the Pacific Northwest and the Northern Great Basin, Fri-Mon, Mar 27-Mar 30. - Heavy rain across portions of the Lower Mississippi Valley, the Tennessee Valley, the Mid-Atlantic, the Southern Appalachians, the Southeast, and the Southern Plains, Mon-Tue, Mar 30-Mar 31. - Heavy rain across portions of the Northeast, the Central Appalachians, the Middle Mississippi Valley, the Mid-Atlantic, the Great Lakes, and the Ohio Valley, Fri-Sat, Mar 27-Mar 28. - Severe weather across portions of the Central Plains, the Middle/Lower Mississippi Valley, and the Southern Plains, Fri, Mar 27. - Severe weather across portions of the Lower Mississippi Valley, the Ohio Valley, and the Tennessee Valley, Sat, Mar 28. - Flooding possible across portions of the Middle Mississippi Valley, the Southern Appalachians, the Ohio Valley, and the Tennessee Valley. - Flooding occurring or imminent across portions of the Middle/Lower Mississippi Valley, the Northern Plains, the Southeast, the Southern Plains, and the Ohio Valley. - Flooding likely across portions of the Mississippi Valley and the Northern Plains. - Much above normal temperatures across portions of the Lower Mississippi Valley, the Tennessee Valley, the Mid-Atlantic, the Southern Appalachians, the Southeast, and the Southern Plains, Fri-Sun, Mar 27-Mar 29. - Much above normal temperatures across portions of the Great Lakes, the Upper Mississippi Valley, and the Northern Plains, Mon-Tue, Mar 30-Mar 31. - Enhanced wildfire risk across portions of the the Southern Rockies, the Central Rockies, the Southern Plains, the Central Plains, and the Southwest, Fri, Mar 27. - Heavy precipitation across portions of the Alaska Panhandle, Fri-Sat, Mar 27-Mar 28. - High winds across portions of mainland Alaska and the Aleutians, Fri-Sun, Mar 27-Mar 29. - Much below normal temperatures across portions of the Alaska Panhandle and mainland Alaska, Fri-Tue, Mar 27-Mar 31. - Much below normal temperatures across portions of mainland Alaska, Sat-Tue, Mar 28-Mar 31. - High significant wave heights for coastal portions of mainland Alaska and the Aleutians, Fri-Sat, Mar 27-Mar 28. Detailed Summary: During the medium-range period (Friday 3/27 to Tuesday 3/31), a surface low pressure system is forecast to intensify over the Central Plains Friday and move northeastward toward the Great Lakes through the weekend. Heavy rain is expected across the Ohio Valley for the end of the week as ample moisture interacts with the associated stationary/warm front east of the low. There is also the possibility of some wintry weather northwest of the low track, but low confidence remains regarding precipitation type and higher amounts. Ahead of the cold front associated with the low, warmer than average temperatures will be widespread across the central and eastern U.S. A hazard area was drawn where these temperatures or heat indices could reach 90 degrees or more (southern Texas and Florida), and where record highs could be set (from the Lower Mississippi Valley to Southeast and Southern Appalachians), but the anomalous warmth should extend as far north as the Ohio Valley and Mid-Atlantic through the weekend. On the other hand, behind the cold front cooler temperatures are expected, but the bigger hazard is the potential for gusty winds and dry conditions for the Southern/Central High Plains, where favorable fire weather is forecast. The north-central tier is also expected to warm up by early next week, and a hazard area was drawn where these relatively warm temperatures could lead to snowmelt. Confidence is lower for the next upper-level trough swinging through the Southwest for the beginning of next week, as model guidance differs on speed and depth of the trough. But it appears that the trough could bring both Pacific and Gulf of Mexico moisture into the Southern Plains to Lower Mississippi Valley beginning Monday, leading to a possible heavy rain threat there and spreading into the Southeast by Tuesday. This will continue to be refined as models hopefully converge over the next few days. Over the Pacific Northwest, onshore flow of moist Pacific air will cause the potential for precipitation through the period. Heaviest precipitation amounts currently look like they will occur Sunday, but with some precipitation before and after. In general, snow is expected in higher elevations with rain in lower elevations. Some precipitation, with snow in higher elevations, is forecast for the Northern Rockies and Great Basin as well. In Alaska, a return to much colder than normal conditions is forecast to overspread Alaska from north to south due to an upper-level trough taking hold over the state. At the surface, a low pressure system is expected to move across the southwestern mainland Friday and across the Gulf of Alaska over the weekend. With this feature, significant waves are possible along the Alaska Peninsula. High winds will also be possible spreading along the coast of the Bering Sea into the southwestern part of the state. Behind the low, gap winds are likely in favored areas in the Alaska Peninsula over the weekend. The potential for localized gap winds may move into the Panhandle on Monday. Additionally, this low could cause heavy precipitation in the Panhandle over the weekend with increasing moisture inflow ahead of it. Tate