Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 455 PM EDT Sat Sep 28 2024 Valid 00Z Sun Sep 29 2024 - 00Z Tue Oct 01 2024 ...Post-Tropical Cyclone Helene continues to weaken and should dissipate by Monday... ...Excessive rainfall/flash flooding possible for portions of the Appalachians Sunday into Monday... ...There are Excessive Heat Warnings over parts of Southeastern California and the Southwest... Post-Tropical Cyclone Helene continues to weaken and its surface circulation should elongate/possibly dissipate by Monday. The system will produce moderate to heavy rain over parts of the Ohio/Tennessee Valleys, portions of the Appalachians and Mid-Atlantic States, and along its southeast periphery in Florida into Monday. A Slight Risk of excessive rainfall exists for portions of the Appalachians. The associated heavy rainfall could create scattered occurrences of flash flooding on Sunday and Monday. Meanwhile, a wave of low pressure over the Pacific Northwest will move northeastward through West-Central Canada and into Central Canada as it deepens and occludes, dragging a dry cold front east through portions of the Intermountain West and Great Basin. Ahead of the front, a warm core high will remain over the Four Corners Region through Monday, keeping conditions record hot across portions of the Southwest into early next week, where excessive heat warnings are in effect. High temperatures over Southeastern California and the Southwest will range from the upper 90s into the 110s, and low temperatures will be in the upper 80s to low 90s, providing little relief from the heat overnight. Roth/Ziegenfelder Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php