Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 401 AM EDT Sun Aug 07 2022 Valid 12Z Sun Aug 07 2022 - 12Z Tue Aug 09 2022 ...Dangerous heat across parts of the Pacific Northwest, Middle Mississippi Valley, Central Plains, and Northeast Coast... ...There is a Slight Risk of excessive rainfall over parts of the Upper Great Lakes to the Northern Plains and from the Mid-Atlantic, Central/Southern Appalachians, and Ohio Valley into Sunday morning... ...There is a Moderate Risk of excessive rainfall over parts of the Upper Great Lakes and Upper Midwest today and into Monday morning... ...There is a Marginal Risk of severe thunderstorms over parts of the Upper Mississippi Valley through Sunday morning... Monsoonal moisture will continue to draw northward from the Southwest and pool with moisture from the Gulf of Mexico over the central U.S. along a sprawling, slow-moving frontal boundary; providing extra juice for scattered to widespread showers and thunderstorms through midweek. This moisture will trigger diurnal thunderstorms across the Southwest, Southern Rockies and into the adjacent High Plains. SPC has Marginal Risks from the Desert Southwest to the Upper Mississippi Valley for severe thunderstorms today. WPC has portions of these Southwest/Southern Rockies/Plains identified as having a Slight (or Marginal) Risk for excessive rainfall and localized flash flooding through Wednesday morning. The associated heavy rain will create mainly localized areas of flash flooding, with urban areas, roads, and small streams the most vulnerable. The segment of the frontal boundary across the north-central tier of the country will slowly track toward the Great Lakes and Northeast regions over the next few days. Moderate to heavy rainfall is expected to repeatedly track across the Plains/Upper Mississippi Valley over areas near saturation from recent rains. The rain expected today will likely reach or exceed local FFG quickly, thus increasing the risk for scattered to widespread areas that may experience flash flooding. WPC has a Moderate Risk over parts of southern Minnesota/Wisconsin and northern Illinois/eastern Iowa. As the front progresses east so will the areas that may see moderate to heavy rainfall and flooding concerns. Furthermore, on Saturday into Sunday, showers and thunderstorms over parts of the Northeast to the Central Gulf Coast; some of these storms may produce heavy rain. Therefore, the WPC has issued a Marginal Risk of excessive rainfall over parts of the Mid-Atlantic, Central/Southern Appalachians, and Ohio Valley into Sunday morning. The associated heavy rain will create mainly localized areas of flash flooding, with urban areas, roads, and small streams the most vulnerable. The threat of excessive rainfall decreases slightly on Sunday to a Marginal Risk over this area. Meanwhile, an upper-level high over the Central Plains and Middle Mississippi Valley will aid in allowing temperatures to rise into the triple digits. These hot temperature when combined with the high humidity, will result in the air feeling even hotter. Numerous Excessive Heat Warning and Heat Advisories are in effect across of the Middle Mississippi Valley and Central Plains through Saturday evening. Furthermore, weak ridging will allow temperatures to rise into the 90s across the Pacific Northwest, also prompting Heat Advisories. Campbell Graphics are available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php