Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 323 AM EDT Thu Aug 26 2021 Valid 12Z Thu Aug 26 2021 - 12Z Sat Aug 28 2021 ...Severe thunderstorms and the potential for flash flooding are forecast across portions of the Northern Plains and Midwest through Friday... ...Uncomfortable and potentially dangerous heat continues throughout much of the central and eastern United States, as well as the Desert Southwest... Rain has been scarce this summer throughout much of the Northern Plains and Upper Midwest, but that will change over the next few days as widespread showers and thunderstorms are forecast develop and traverse the north-central United States through the end of the week. The features responsible for the active weather include a quasi-stationary boundary extending from the Lower Great Lakes across the Midwest and eventually into the Northern High Plains. Meanwhile, an upper-level trough over the Northwest, favorable jet stream dynamics, and a plentiful amount of atmospheric moisture could lead to thunderstorms turning severe and producing several inches of rain. For today, an Enhanced Risk (level 3/5) of severe weather has been issued across northern Iowa and southern Minnesota, where the threat of isolated tornadoes and damaging wind gusts are highest. Thunderstorms may also produce gusty winds and large hail across eastern Montana, as well as an area extending from northwest Illinois to South Dakota and northern Nebraska (surrounding the aforementioned Enhanced Risk). By Friday, additional rounds of severe thunderstorms are possible across the same regions, with greatest risk found once again across the Midwest. Even though much of this region is experiencing extreme drought, multiple inches of rain could fall and lead to flash flooding concerns for both rural and urban areas of the Upper Midwest to Upper Great Lakes today and Friday. Slight Risks (level 2/4) of excessive rainfall have been issued for eastern North Dakota to central Wisconsin today and for southeastern Minnesota into much of Wisconsin on Friday in order to highlight the potential hazard. South of the aforementioned frontal boundary, much of the central and eastern U.S. will deal with a few more days of sultry late August weather. An expansive upper-level ridge extending from the Southwest to the East Coast will fuel above average high temperatures and high heat indices, along with air quality issues in mainly urban areas. Widespread high temperatures into the 90s will be found throughout a large section of the country, with triple digits possible over the Central/Southern Plains and Middle Mississippi Valley today. While only a few daily record high temperatures are forecast to fall, dozens of daily record warm minimum temperatures could be broken through the end of this week across the eastern third of the country. These warm overnight temperatures in the 70s can make it extremely dangerous for those without access to proper air conditioning. Heat Advisories have been issued across numerous areas extending from eastern sections of the Southern Plains to New England. Meanwhile, dangerous heat is also forecast throughout the Desert Southwest today and Friday. High temperatures here could reach close to 115F, increasing the threat of heat-related illnesses. Excessive Heat Warnings are in effect between the Low Desert of California and southern Arizona. Elsewhere, scattered thunderstorms are possible along the Gulf Coast over the next few days and parts of the Northeast by Friday, a few of which could lead to isolated instances of flash flooding. Farther west, Air Quality Alerts due to wildfire smoke remain in effect across parts of the Great Basin and Northern/Central Rockies. Looking for cooler temperatures? Highs around 10-20 degrees below average are forecast across North Dakota and northern Minnesota through the beginning of the weekend and the Northern Rockies beginning on Friday. Snell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php