Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 415 PM EDT Thu Jul 28 2022 Valid 00Z Fri Jul 29 2022 - 00Z Sun Jul 31 2022 ...Additional rounds of excessive rainfall across parts of the Ohio/Tennessee Valleys are expected to trigger areas of flash flooding through Friday... ...Daily rounds of heavy downpours could cause flash flooding across portions of Arizona to the Four-corners region for the next few days... ...Excessive heat continues in the Pacific Northwest; hot and humid across the southern tier to the East Coast but cool air over the central Plains expected to expand eastward... Rounds of heavy rain triggered between a pair of frontal boundaries are expected to prolong the threat of flash flooding from the central U.S. eastward across the Tennessee/Ohio Valleys and into the central/southern Appalachians for the next couple of days. As the core of a cool air mass dipping into the Great Lakes and forces a cold front through the Midwest and the Ohio Valley into tonight, additional rounds of heavy rain are forecast to move across the flood-stricken eastern Kentucky later tonight into Friday with additional flash flooding episodes possible. The highest threat of flash flooding is forecast to shift farther east into West Virginia on Friday. Meanwhile, the threat of flash flooding will also extend west across the Tennessee Valley, mid-Mississippi Valley and into the central Plains, as well as east into the central/southern Appalachians. By Saturday, the cold front is forecast to push across the East Coast with some heavy rain and thunderstorms possible across the Mid-Atlantic early in the day as cooler and drier air filters in from the north during the day behind the front. Meanwhile, monsoonal moisture is forecast to persist across Arizona to the Four-corners region through the next few days. Day-time heating will continue to trigger scattered thunderstorms across the region each day. Some of the thunderstorms will likely contain heavy downpours that could lead to flash flooding concerns especially over burn scars. Some of the monsoonal moisture is forecast to spill northeastward and interact with the western extension of the aforementioned front to trigger an area of heavy rain over portions of the central High Plans tonight before edging east toward the central Plains on Friday. Flash flooding will be a concern should the heavy rain becomes slow-moving under this weather pattern. By Saturday, a low pressure wave could form along the front with a round of heavy rain possible from the central Plains east toward the mid-Mississippi Valley, where flash flooding is possible. For the rest of the country, the heat will continue to be the story especially over the Pacific Northwest where afternoon temperatures could exceed 110 degrees at the hottest locations in the interior section. Seattle is forecast to witness the longest stretch of 90+ temperatures on record for the next few days. Nights will be abnormally warm as well with record high minimum temperatures possible. Over the southern Plains, the heat should be slightly less intense for the next couple of days as the cool air mass from the north edges ever so slightly toward the region. Farther east, heat and humidity is forecast to increase some along the East Coast on Friday as a weak warm front lifts northward into New England. Hottest temperatures are forecast to be in the Carolinas where upper 90s are expected for afternoon highs. By Saturday, cooler and drier air is forecast to filter into the Mid-Atlantic behind a cold front. Meanwhile, cool air over the central Plains associated with the heavy rain behind the front is forecast to expand eastward. Kong Graphics are available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php