Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 358 AM EDT Sat Aug 17 2024 Valid 12Z Sat Aug 17 2024 - 12Z Mon Aug 19 2024 ...There is a Slight Risk of excessive rainfall over parts of the Mid-Atlantic on Saturday/Sunday and Southwest/Eastern Great Basin on Saturday... ...There is a Slight Risk of severe thunderstorms over parts of the Pacific Northwest, Great Basin, and Ohio Valley on Saturday and southern Mid-Atlantic to Southeast/Lower Mississippi Valley on Sunday... ...There are Excessive Heat Warnings and Heat Advisories over parts of the Southern Plains and Lower Mississippi Valley... A front extending from the Great Lakes/Ohio Valley across the Middle Mississippi Valley and then to the Central High Plains will move eastward to the Mid-Atlantic/Southeast Coast and southward to the Southern Plains by Monday. On Saturday, showers and thunderstorms will develop along and ahead of the boundary from the Great Lakes/Ohio Valley to the Tennessee/Lower Mississippi Valleys. Additionally, upper-level energy will intersect a pool of tropical moisture over the northern Mid-Atlantic, producing heavy rain. Therefore, the WPC has issued a Slight Risk (level 2/4) of excessive rainfall over parts of the northern Mid-Atlantic through Sunday morning. The associated heavy rain will create mainly localized areas of flash flooding, with urban areas, roads, small streams, and low-lying areas the most vulnerable. Furthermore, the boundary will trigger showers and severe thunderstorms over parts of southwestern Ohio, eastern Kentucky, and extreme north-central Tennessee. Therefore, the SPC has issued a Slight Risk (level 2/5) of severe thunderstorms over parts of the Ohio/Tennessee Valleys through Sunday morning. The hazards associated with these thunderstorms are frequent lightning, severe thunderstorm wind gusts, hail, and a few tornadoes. Moreover, upper-level energy and a plume of monsoonal moisture will aid in creating showers and thunderstorms with heavy rain over parts of southern Utah and northwestern Arizona. Therefore, the WPC has issued a Slight Risk (level 2/4) of excessive rainfall over parts of the Great Basin/Southwest through Sunday morning. The associated heavy rain will create mainly localized areas of flash flooding, with urban areas, roads, small streams, and low-lying areas the most vulnerable. In addition, the energy will produce showers and severe thunderstorms over parts of the Great Basin. Therefore, the SPC has issued a Slight Risk (level 2/5) of severe thunderstorms over parts of the Great Basin through Sunday morning. The hazards associated with these thunderstorms are frequent lightning, severe thunderstorm wind gusts, and a minimal threat of hail and tornadoes. Also, an upper-level low over the Pacific Northwest Coast and associated energy will develop showers and severe thunderstorms over parts of Oregon and Washington State on Saturday. Therefore, the SPC has issued a Slight Risk (level 2/5) of severe thunderstorms over parts of the Pacific Northwest through Sunday morning. The hazards associated with these thunderstorms are frequent lightning, severe thunderstorm wind gusts, hail, and a minimal threat of tornadoes. On Sunday, as the front moves into the Mid-Atlantic, Southeast, and Lower Mississippi Valley, showers and severe thunderstorms will develop along and ahead of the boundary. Therefore, the SPC has issued a Slight Risk (level 2/5) of severe thunderstorms over parts of the southern Mid-Atlantic to Southeast/Lower Mississippi Valley from Sunday through Monday morning. The hazards associated with these thunderstorms are frequent lightning, severe thunderstorm wind gusts, hail, and a minimal threat of tornadoes. Further, a strong pool of moisture will be over the Mid-Atlantic on Sunday, aiding in producing showers and thunderstorms with heavy rain over parts of the northern Mid-Atlantic. Therefore, the WPC has issued a Slight Risk (level 2/4) of excessive rainfall over parts of the northern Mid-Atlantic from Sunday through Monday morning. The associated heavy rain will create mainly localized areas of flash flooding, with urban areas, roads, small streams, and low-lying areas the most vulnerable. Moreover, monsoonal moisture and daytime heating will create showers and thunderstorms over parts of the Southwest, Eastern Great Basin, and Central Rockies from late afternoon into late evening on Sunday. Additionally, the upper-level low over the Northwest will produce rain, with maybe an embedded thunderstorm over the region on Sunday. Meanwhile, upper-level ridging over parts of the Southern Plains and Lower Mississippi Valley will produce high temperatures in the upper-90s to low-100s with dew points in the low to mid-70s have prompted Excessive Heat Warnings and Heat Advisories over parts of the Southern Plains and Lower Mississippi Valley. The sweltering summer heat will continue over the south. A prolonged stretch of high temperatures in the upper 90s and triple digits will be focused over portions of the Southern Plains and Gulf Coast through Monday. Low temperatures in the low-80s/upper-70s are also forecast along the Gulf Coast, providing little relief from the heat overnight. Moreover, the combination of summer heat and high humidity will support daily maximum heat indices near 110F. People spending more time or effort outdoors or in a building without cooling are at an increased risk of heat-related illness. Ziegenfelder Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php