US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 403 PM EDT Wed Mar 25 2020 Valid Saturday March 28 2020 - Wednesday April 01 2020 Hazards: - Heavy precipitation across portions of the Pacific Northwest and the Northern Great Basin, Sat-Mon, Mar 28-Mar 30. - Heavy precipitation across portions of the Northeast, Sun-Mon, Mar 29-Mar 30. - Heavy rain across portions of the Lower/Middle Mississippi Valley, the Tennessee Valley, the Mid-Atlantic, the Southern Appalachians, the Southeast, the Southern Plains, and the Ohio Valley, Mon-Wed, Mar 30-Apr 1. - Heavy rain across portions of the Great Lakes, the Northeast, the Central Appalachians, and the Ohio Valley, Sat, Mar 28. - Severe weather across portions of the Southeast, the Lower/Middle Mississippi Valley, the Ohio Valley, and the Tennessee Valley, Sat, Mar 28. - Flooding possible across portions of the Middle Mississippi Valley. - Flooding occurring or imminent across portions of the Lower/Middle Mississippi Valley, the Northern Plains, the Tennessee Valley, the Southeast, the Southern Plains, and the Ohio Valley. - Flooding likely across portions of the Mississippi Valley, the Northern Plains, the Tennessee Valley, the Southeast, and the Ohio Valley. - 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, Sat-Sun, Mar 28-Mar 29. - Much above normal temperatures across portions of the Upper Mississippi Valley and the Northern Plains, Mon, Mar 30. - Heavy precipitation across portions of the Alaska Panhandle, Sat, Mar 28 and Mon-Tue, Mar 30-Mar 31. - High winds across portions of the Alaska Panhandle, mainland Alaska, and the Aleutians, Sat-Mon, Mar 28-Mar 30. - Much below normal temperatures across portions of mainland Alaska, Sat-Tue, Mar 28-Mar 31. - Much below normal temperatures across portions of mainland Alaska, Sat, Mar 28. - High significant wave heights for coastal portions of mainland Alaska and the Aleutians, Sat, Mar 28. Detailed Summary: During the medium-range period (Saturday 3/28 to Wednesday 4/1), a surface low pressure system is forecast to track from the Central Plains toward the Upper Great Lakes over the weekend, with low pressure redeveloping offshore of the Northeast by Monday. Precipitation is likely over the northeastern quadrant of the U.S. with this low, while severe weather is possible just ahead of the associated cold front in the Lower Mississippi/Tennessee Valleys. Heavy rain could spread from the Ohio Valley in the short range into the Lower Great Lakes region on Saturday, as ample moisture interacts with the warm front associated with the low. There is also the possibility of some wintry weather in the Upper Midwest/Upper Great Lakes northwest of the low track, but snowfall amounts do not look to be very high there. Then by early next week, the interior Northeast can expect some snow at times with its precipitation, and potentially heavy snow amounts are possible particularly in western Maine. Ahead of the cold front associated with this low, warmer than average temperatures will be widespread across the central and eastern U.S. A hazard area was drawn 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. Slightly cooler than average temperatures are possible for the Rockies westward behind the front. The north-central tier is also expected to warm up by early next week, particularly Monday, and a hazard area was drawn where these relatively warm temperatures could lead to rapid 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 beginning Sunday. Rainfall amounts from Texas to the Lower Mississippi Valley should ramp up Monday and spread across the Southeast Tuesday into Wednesday, with the possibility of rainfall and flooding/flash flooding in those areas. This will be refined as models continue to 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. Northwestern Washington has the highest likelihood of precipitation continuing. 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, moderating closer to midweek. At the surface, a low pressure system is expected to move across the Gulf of Alaska over the weekend. With this feature, significant waves are possible along the Alaska Peninsula Saturday. Behind the low, gap winds are likely in favored areas in the Alaska Peninsula to Gulf Coast over the weekend, and the potential for localized gap winds may move into the Panhandle on Monday, which could impact transportation. Additionally, this low could cause marginally heavy precipitation in the Panhandle over the weekend with increasing moisture inflow ahead of it. There is also some precipitation potential for the Panhandle again early in the workweek, but uncertainty remains with the spatial extent of the precipitation and amounts. Tate