US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 416 PM EDT Fri Jul 03 2020 Valid Monday July 06 2020 - Friday July 10 2020 Hazards: - Heavy rain across portions of the Upper Mississippi Valley and the Northern Plains, Tue-Wed, Jul 7-Jul 8. - Heavy rain across portions of the Southeast, the Mid-Atlantic, the Southern Appalachians, and the Tennessee Valley, Mon-Tue, Jul 6-Jul 7. - Flooding occurring or imminent across portions of the Middle Mississippi Valley and the Northern Plains. - Excessive heat across portions of the Central Appalachians, the Northern Plains, the Tennessee Valley, the Middle Mississippi Valley, California, the Upper Mississippi Valley, the Southeast, the Great Lakes, the Ohio Valley, and the Southwest, Mon-Fri, Jul 6-Jul 10. - Excessive heat across portions of the Central Plains, the Lower Mississippi Valley, the Northern Plains, the Tennessee Valley, the Middle Mississippi Valley, the Upper Mississippi Valley, the Southeast, the Southern Plains, and the Ohio Valley, Wed-Fri, Jul 8-Jul 10. - Much above normal temperatures across portions of the Northeast, the Central Appalachians, the Mid-Atlantic, the Upper Mississippi Valley, the Great Lakes, and the Ohio Valley, Mon-Fri, Jul 6-Jul 10. - Much above normal temperatures across portions of the Mid-Atlantic and the Northeast, Wed-Fri, Jul 8-Jul 10. Detailed Summary: Stifling summer heat is the big story in the medium range (Mon 7/6 - Fri 7/10). South Florida will contend with steamy conditions both day and night much of the period. Sea surface temperatures surrounding the Florida peninsula remain much above normal and upper level ridging returns next week. As the ridge builds across Florida, the excessive heat will extend north into the Panhandle and along the central Gulf Coast late week. Farther north, the hottest temperatures versus normal are expected to take place from the Great Lakes to the Northeast. Max temperature departures will hover around 12 degrees above normal in these regions, which combined with dew points near 70 degrees could lead to heat indices reaching the century mark. Excessively hot conditions take hold of the Ohio Valley and across much of the Corn Belt next week. Meanwhile, a strengthening upper level ridge over the Southwest and central High Plains should make for excessively hot conditions from southern Arizona to the high desert of Southern California. The ridge is forecast to grow in size across the west-central U.S. and as it does, so will its footprint of sizzling summer heat. The central Plains, Missouri and Mississippi Valleys can anticipate daily high temps in the mid and upper 90s along with heat indices ranging between 105-110 degrees. Precipitation-wise, the two most active regions look to be the northern Plains and the Southeast. As a series of upper-level disturbances track through the Northwest, they emerge in the High Plains of Montana, the Dakotas, and Minnesota. Passing upper level disturbances and corresponding frontal boundaries will trigger episodes of showers and thunderstorms, some of which could be severe and/or contain heavy rainfall. A slow moving upper trough along the Gulf Coast and over the Southeast is also likely to produce unsettled weather. With both the Gulf of Mexico and Atlantic moisture sources available, there should be plenty of scattered showers and storms that form along a stationary front stretching from the Lower Mississippi Valley to the Southeast coast. The positioning and movement of the trough remains unclear, which means where the heaviest precipitation sets up could change. The heaviest precipitation is currently forecast to extend from the Florida Panhandle, up through Georgia and into the Carolinas. There is still the potential for heavier rainfall elsewhere in the Southeast depending on the positioning and speed of the upper trough. Alaska remains hazards-free as the state is wedged between a large upper level ridge over the Gulf of Alaska and northeast Pacific, an upper low over northeast Russia, and an upper low over the Yukon. Scattered showers should track across interior Alaska next week with locally heavy totals possible along the Alaska Range. By days 6-7, there may be a deepening trough that introduces heavy rainfall to the southern mainland but ensemble guidance indicates low confidence in amounts at this time. Temperature wise, western Alaska looks to start the period on a warm note, but as troughing develops over the state next week, expect cooler than normal temperatures to return across much of the mainland. The state continues to be monitored for any increased fire weather potential through the first full week of July. Mullinax