US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 320 PM EDT Fri Aug 13 2021 Valid Monday August 16 2021 - Friday August 20 2021 Hazards: - Heavy rain across portions of the Central Great Basin, the Tennessee Valley, the Mid-Atlantic, the Southern Appalachians, the Southeast, the Ohio Valley, and the Southwest, Mon-Wed, Aug 16-Aug 18. - Heavy rain across portions of the Upper Mississippi Valley and the Northern Plains, Wed-Thu, Aug 18-Aug 19. - Heavy rain across portions of the Central Plains, the Southeast, the Middle Mississippi Valley, the Upper Mississippi Valley, and the Northern Plains, Thu-Fri, Aug 19-Aug 20. - Heavy rain across portions of the Southeast, Mon, Aug 16. - Flooding possible across portions of the Southeast. - Flooding occurring or imminent across portions of the Southeast. - Excessive heat across portions of the Central Great Basin, California, the Northern Plains, and the Southwest, Mon, Aug 16. - Excessive heat across portions of the Central Plains and the Northern Plains, Mon-Tue, Aug 16-Aug 17. - Heavy rain across portions of mainland Alaska, Mon, Aug 16. - Heavy rain across portions of the Alaska Panhandle and mainland Alaska, Tue-Fri, Aug 17-Aug 20. Detailed Summary: The medium range forecast period (Monday, August 16 to Friday, August 20) features typical summertime weather hazards, with a few tropical systems to track as well. Starting in the southeastern United States, Tropical Depression Fred is currently forecast to slightly strengthen and regain tropical storm strength before making landfall over the Florida Panhandle on Monday. Fred is then expected to weaken and push inland near the Georgia and Alabama border through Tuesday. As a result, the most impactful hazard is likely to be associated with heavy rain near and to the east of the center due to the expected unorganized structure of Fred over the Florida Panhandle on Monday and portions of the Southeast through Wednesday as moisture lingers along a dissipating stationary boundary. Farther north, the aforementioned front may draw tropical moisture into the southern Appalachians, western Carolinas, and eastern Tennessee Valley early next week. Uncertainty regarding the highlighted heavy rainfall areas and exact rainfall amounts remains higher than average due to Fred's disorganization, but regardless of Fred's future, heavy rain near and ahead of the approaching frontal boundary could lead to isolated flooding concerns. Otherwise, a separate tropical disturbance (labeled Potential Tropical Cyclone Seven) and a feed of rich atmospheric moisture may impact southern/central Florida with heavy rain by the end of next week. As always, be sure to check with the National Hurricane Center for the latest tropical cyclone forecasts and outlooks. Elsewhere, heavy rain is also expected to impact drought-stricken regions of the Southwest and Northern Plains. Monsoonal showers are expected to continue producing scattered downpours over southern/central Arizona, New Mexico, and into southwestern Utah through at least Wednesday. That is when an associated retrograding upper-level low is forecast to exit into the western Pacific with the remaining atmospheric moisture escaping to the north and into the central Great Basin ahead of an approaching upper-level trough. For the Northern Plains and Upper Midwest, this section of the country is currently experiencing widespread extreme to exceptional drought, but some relief is on the way. An approaching cold front could spark numerous showers and thunderstorms beginning midweek between the Northern Rockies and Northern Plains. Scattered rainfall amounts great than 1 inch are possible across northeast North Dakota and northern Minnesota, where precipitable water anomalies appear highest within the latest forecast guidance. By late-week the cold front is forecast to reach the Central Plains, thus producing chances of heavy rain in places such as Kansas, Nebraska, and portions of the Midwest. Excessive heat will also remain a concern while gradually diminishing for parts of California, the central Great Basin, and the northern High Plains on Monday. Monday should be the tail-end of yet another heat wave for the western United States. Temperatures around 10 degrees above average with highs approaching the century mark are forecast across the Great Basin, with even higher temperatures found across the high deserts and San Joaquin Valley of California, before much cooler temperatures arrive on Tuesday. However, dangerous heat will linger one additional day throughout the northern High Plains before below average temperatures enter this area by Thursday. By the middle-to-end of next week the only area with potentially oppressive heat will be found across South Texas and the western Gulf Coast. High temperatures in the mid-to-upper 90s will be close to normal for this time of year, but heat indices around 110 degrees and low temperatures only dropping into the 80s can be dangerous if proper heat safety is not followed. For Alaska, a low pressure system and associated frontal boundaries will produce chances for heavy rain south of the Brooks Range on Monday throughout Interior Alaska. Heavy rain is also a possibility over the Alaska Panhandle and south-central portions of the state between Tuesday and Friday as two separate systems enter the Gulf of Alaska. Intense moisture transport overtop of an upper-level high located over the northeast Pacific could funnel multiple waves of heavy rain into coastal regions. Rainfall amounts of 2+ inches seem plausible throughout northern parts of the panhandle, with totals through the entire time period possibly greater than 5 inches. Snell