Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 341 AM EDT Sat Sep 28 2024 Valid 12Z Sat Sep 28 2024 - 12Z Mon Sep 30 2024 ...HELENE is forecast to continue to weaken and dissipate by Monday... ...There is a Marginal Risk of excessive rainfall over parts of the Ohio/Tennessee Valleys on Saturday and over the Central Appalachians/Mid-Atlantic Sunday... ...There are Excessive Heat Warnings over parts of Southeastern California and the Southwest... HELENE is forecast to continue to weaken and dissipate by Monday. The system will produce moderate to heavy rain over parts of the Ohio/Tennessee Valleys. Therefore, the WPC has issued a Marginal Risk (level 1/4) of excessive rainfall over parts of the Ohio/Tennessee Valleys through Sunday morning. The associated heavy rain will create localized areas of flash flooding, affecting areas that experience rapid runoff with heavy rain. On Sunday, the area of moderate to heavy rain will move eastward to the Central Appalachians/Mid-Atlantic. Therefore, the WPC has issued a Marginal Risk (level 1/4) of excessive rainfall over parts of the Central Appalachians/Mid-Atlantic from Sunday through Monday morning. The associated heavy rain will create localized areas of flash flooding, affecting areas that experience rapid runoff with heavy rain. In addition, there will be a Marginal Risk of excessive rainfall over parts of the Florida Peninsula on Saturday and Sunday. Meanwhile, a wave of low pressure over the Pacific Northwest will move northeastward into West-Central Canada by Sunday while the trailing front moves into the Northern Plains. The system is expected to produce little precipitation along the boundary. Moreover, an upper-level high will remain over the Four Corners Region through Monday. High temperatures over Southeastern California and the Southwest will range from the upper 90s to 110s, and low temperatures will be in the upper 80s to low 90s, providing little relief from the heat overnight. The temperatures have prompted Excessive Heat Warnings over parts of Southeastern California and the Southwest. Ziegenfelder Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php