US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 318 PM EST Mon Mar 02 2020 Valid Thursday March 05 2020 - Monday March 09 2020 Hazards: - Heavy rain across portions of the Lower Mississippi Valley and the Southern Plains, Sun-Mon, Mar 8-Mar 9. - Heavy rain across portions of the Southeast and the Mid-Atlantic, Thu, Mar 5. - Heavy snow across portions of the Central/Northern Rockies and the Central/Northern Great Basin, Sun-Mon, Mar 8-Mar 9. - Severe weather across portions of the Southeast, Thu, Mar 5. - Flooding possible across portions of the Southeast, the Lower Mississippi Valley, the Southern Appalachians, and the Tennessee Valley. - Flooding occurring or imminent across portions of the Southeast, the Middle/Lower Mississippi Valley, the Ohio Valley, and the Tennessee Valley. - High winds across portions of the Northeast, Fri-Sat, Mar 6-Mar 7. - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Sun-Mon, Mar 8-Mar 9. - Heavy snow across portions of mainland Alaska, Sun-Mon, Mar 8-Mar 9. - Much below normal temperatures across portions of mainland Alaska, Thu-Sat, Mar 5-Mar 7. - Much below normal temperatures across portions of mainland Alaska, Thu-Fri, Mar 5-Mar 6. Detailed Summary: The medium range period will begin on Thursday with an upper-level southern stream shortwave trough centered over the Lower Mississippi Valley, another trough over the north-central U.S., and ridging building into the West. Ahead of the first shortwave, the heavy rain and severe weather threats in the short range should persist for one more day on Thursday in the Southeast. Then, the northern and southern stream energy should interact over the east-central U.S. Friday, producing a surface low pressure system offshore in the Atlantic. There are model differences with the strength and position of this surface low. If the low tracks close to shore, it could spread snow to areas like southern New England, but many models show a more offshore track, so will continue to monitor. Regardless, the pressure gradient with this low should be strong enough to cause the potential for high winds for Cape Cod and the Islands, and maybe more of the Northeast if the low does track farther west. Underneath the aforementioned upper-level ridge, milder than normal temperatures are forecast that should shift east through the beginning of next week. The Northern and Central Plains to the Midwest could see high temperatures over 20 degrees above average! This is not considered particularly hazardous, but if areas that warm significantly overlap with snow covered areas, rapid snowmelt could be an issue. This looks most likely over southern Minnesota into northern Iowa and parts of Wisconsin. Temperatures a few degrees below normal are forecast over the eastern U.S. through the end of the week. Behind the ridge, another trough is expected to move across the West Coast over the weekend and farther east Monday. This could provide energy for heavy snow in the Wind River Range/Tetons. A frontal system ahead of this trough should have Gulf of Mexico moisture returning ahead of it, so there is potential for heavy rain in parts of the south-central U.S. once again early next week. The placement of the heaviest rain is yet to be determined, so the hazard area will continue to be refined, but delineated an area over the ArkLaTex and eastern Oklahoma for now. Over Alaska, below normal temperatures should diminish from west to east through the end of the week as troughing relaxes, with a flip to above normal temperatures possible early next week for the western part of the state. Then, precipitation is expected to spread first to the southwestern mainland, then across the south-central coast and then into the Panhandle for the beginning of next week, as moisture increases ahead of the triple point of a low pressure system centered over the Bering Sea. Precipitation could end up being heavy, though there remains model spread with amounts. Precipitation should stay snow in higher elevations while some rain or mix is possible along the coast. Tate