US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 440 PM EDT Tue Jul 21 2020 Valid Friday July 24 2020 - Tuesday July 28 2020 Hazards: - Heavy rain across the central to western portions of the Gulf Coast into south-central Texas, near the North Carolina coast, over the Upper Mississippi Valley, as well as parts of the southern Rockies, Fri-Sat, Jul 24-Jul 25. - Heavy rain across portions of the northern Plains, as well as the eastern slopes of the central to southern Rockies and nearby High Plains, Sun-Mon, Jul 26-Jul 27. - Heavy rain across portions of the eastern slopes of the southern Rockies and nearby High Plains, Mon-Tue, Jul 27-Jul 28. - Heavy rain across northern Missouri, Tue, Jul 28. - Flooding possible across portions of the central Plains. - Flooding occurring or imminent across portions of the northern Plains. - Flooding likely across portions of the mid-Mississippi Valley. - Excessive heat across portions of the central Plains, the mid and upper Mississippi Valley, and the northern Plains, Sun, Jul 26. - Excessive heat across portions of the central and northern Plains, and the upper Mississippi Valley, Fri-Sat, Jul 24-Jul 25. - Excessive heat across portions of the mid-Mississippi Valley, Mon, Jul 27. - Excessive heat across portions of the lower Mississippi Valley, and the Mid-Atlantic, Mon-Tue, Jul 27-Jul 28. - Much above normal temperatures across portions of the northern Plains, the upper Mississippi Valley, and into the Great Lakes, Fri-Sun, Jul 24-Jul 26. - Much above normal temperatures across portions of the interior Mid-Atlantic into the central Appalachians, Mon-Tue, Jul 27-Jul 28. - Much above normal temperatures across portions of the central Great Lakes, Fri-Mon, Jul 24-Jul 27. - Heavy rain across much of the Alaska Panhandle into southern Alaska, Sun-Mon, Jul 26-Jul 27. Detailed Summary: An expansive upper-level high will dominate much of the mainland U.S. through the medium range period (Friday, July 24 - Tuesday, July 28) as upper-level troughing works its way across the Pacific Northwest into the northern Plains. This upper-level pattern is expected to result in a so-called "ring of fire" where summer heat and a lack of rain are expected continue for a while over the central U.S. as the highest chance of rain rotates around the upper-level high. In the mean time, the National Hurricane Center continues to monitor the potential of a tropical cyclone forming in the Gulf to the south of the upper-level high, as the cyclone generally tracks west or west-northwest across the western Gulf Coast into southern Texas late this week into the weekend. This would mean the threat of heavy rain will be most likely tracking westward across portions of southern Texas late this week into the weekend. Meanwhile, some monsoonal moisture will likely trigger showers and thunderstorms each day across the central and southern Rockies. It appears that the most likely places to see heavy rain will be in parts of the far southern Rockies on Friday and Saturday, shifting farther northward to along the eastern slopes of the central and southern Rockies, and nearby High Plains by early next week. Over the northern U.S., a cold front moving steadily across the area could trigger thunderstorm clusters that could lead to heavy rainfall working its way south across the upper Midwest on Friday, possibly reaching northern Missouri by next Tuesday. Meanwhile, showers and thunderstorms ahead of an exiting cold front should result in heavy rainfall on Friday across eastern North Carolina. Although the upper-level high will expand across the eastern two-thirds of the country, the associated heat underneath the high is not expected to be too extreme, with forecast high temperatures staying below the century mark through the medium-range period. Nevertheless, we do expect much above normal temperatures to span from the northern Plains to the Great Lakes Friday into the weekend ahead of the cold front. Increasing humidity ahead of the front will result in high heat indices during the afternoon over the northern Plains on Friday, gradually working its way southward into the lower Mississippi Valley by next Tuesday. Excessive heat have been highlighted on the Hazards map for these areas. Meanwhile, westerly winds descending from the Appalachians combining with increasing humidity will raise the likelihood of much above normal temperatures for parts of the Mid-Atlantic early next week. In Alaska, a heavy rain area has been introduced for much of southeastern Alaska for Sunday and Monday as models show a trend toward a wetter and stronger low pressure system edging closer to the area by that time frame. Some of the heavy rain could briefly spill into the southern coastal area of Alaska and then further inland across southern Alaska. Kong