Greetings! Today’s forecast calls for a cold front to sweep into the region later this afternoon, accompanied by heavy rain showers and thunderstorms in the mountains and foothills. Unfortunately, the slow storm motion caused by the absence of a steering current in the atmosphere increases the risk of flash floods this evening.
Low pressure should develop over NE Georgia tomorrow, causing a surge in southerly flow into the foothills. The southerly flow will transport deep tropical moisture into the region, which leads to more rainfall and thunderstorms forecast across the mountains and foothills. The risk for localized flash flooding will remain with the possibility of a stalled frontal boundary causing rain and thunderstorms to train over the same areas repeatedly.
Monday night into Tuesday, the eastern slopes of The Blue Ridge might experience anchoring showers and thunderstorms due to the strong south/southeasterly flow. One mitigating factor, though, will be the lack of northwesterly flow aloft. Since the antecedent soil moisture conditions are already very wet at this point in the forecast cycle, the chance for flash flooding will continue.
Moving Tropical Storm Idalia, she is expected to reach the eastern Gulf of Mexico by Tuesday morning. Deep tropical moisture transport into the area will interact with a frontal boundary that will be moving into The Western Carolinas. As a result, we can anticipate widespread heavy rain and thunderstorm activity throughout Tuesday. With the soil moisture conditions already being very wet at this juncture of the forecast period we need to continue to monitor the entire area for flash flooding. The NWS indicates a Flash Flood or Flood Watch may be required.
As Idalia continues through the Eastern Gulf of Mexico on Tuesday night, it is expected to gain strength. At the same time, the frontal boundary is projected to stall briefly across the region, allowing heavy rain and thunderstorms to persist. Consequently, the flash flood risk is expected to peak Tuesday Afternoon through Wednesday morning.
To summarize, heavy rainfall is likely across the Western Carolinas this week, regardless of Idalia’s track and her direct impacts.
Cooler temperatures are expected by late week, and Friday into the first half of the weekend should be delightful. The mercury will rise again over the late weekend, with temperatures possibly reaching close to 90° or even into the 90s.
-Chris White, Chief Meteorologist