822 FXUS01 KWBC 141856 PMDSPD Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 254 PM EDT Fri Aug 14 2026 Valid 00Z Sat Aug 15 2026 - 00Z Mon Aug 17 2026 ...Severe thunderstorms and Heavy rainfall/flash flooding threat continues along a corridor from the Midwest to the central Appalachians and across the central High Plains... ...Dangerous heat continues from the Central/Southern Plains to the Southeast through the weekend... A highly active pattern will continue across U.S. through the weekend as a broad western trough interacts with a strengthening ridge over south-eastern U.S. A pronounced mid/upper-level trough over western U.S. will slowly progress eastward, as embedded shortwave energy ejects from the Great Basin and Rockies into the central Plains and Midwest. Meanwhile, the ridge will support the northward transport of warm moisture ahead of the advancing disturbances. At the surface, a slow moving frontal boundary extending from the northern/central Plains through the Midwest/Great Lakes and Ohio Valley will provide a focus for repeated showers and thunderstorm development through the weekend. The boundary will interact with moist and unstable air mass, supporting training and back-building of thunderstorms that can lead to excessive rainfall and flash flooding. With saturated soil from previous rainfall and ongoing flash flooding, a Moderate Risk (level 3/4) of Excessive Rainfall have been issued for parts of the Midwest, while a Slight Risk (level 2/4) highlights portions of the Appalachians, Ohio Valley, and Midwest through the evening into Saturday morning, while a broad Marginal Risk (level 1/4) highlights the Southeast. Much of the frontal zone will remain stationary on Saturday, but a portion of the frontal boundary will move slightly southward into parts of the Southeast. This will shift the chances for excessive rainfall and severe threat southeastward through Saturday, while another round of flash flooding threat continues across central Plains into Midwest/Great Lakes, Ohio Valley, Mid-Atlantic. WPC has placed a Moderate Risk (level 3/4) of Excessive Rainfall for portions of the Great Lakes and Ohio Valley. SPC has also highlighted a severe thunderstorm threat capable of producing severe wind gust and large hail across portions central Plains into the Midwest, Ohio Valley, and Mid-Atlantic through the weekend. On Sunday, the frontal zone will move slightly northeastward but will remain relatively stationary, bringing another risk for excessive rainfall across portions of central/southern Plains, Midwest, Ohio Valley, and Northeast while a severe thunderstorm threat continues over portions of Ohio Valley and Mid-Atlantic. Across the west, the southwesterly flow will bring monsoonal moisture into portion of the Interior West, the Four Corners, and central High Plains. With the combination of instability and sufficient moisture, showers and thunderstorms will develop across the area through the weekend. Some storms may produce periods of heavy rainfall, which can lead to flash flooding in vulnerable terrain, especially burn scars, slot canyons, and urbanized areas. The upper ridge will continue to bring dangerous heat across southeastern U.S. through the weekend. Afternoon highs are expected to reach upper 90s to low 100s, while overnight lows will remain relatively warm, providing only minor relief. With the combination of high humidity, heat indices may reach up to 115 degrees, resulting in widespread Major to Extreme HeatRisk levels. Several consecutive days of high heat stress can lead to heat-related illness. Oudit Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php $$