Will Rafael bring another flash flood disaster to the southeastern US?
Rain, while not directly associated with the hurricane, can be heavy enough to trigger incidents of flash flooding into Thursday night. However, there are striking differences comparing this setup to Helene.
Heavy rain will spread across portions of the Southeastern states into Thursday night as Rafael churns hundreds of miles to the south over the Gulf of Mexico, AccuWeather meteorologists warn.
The rain, while not directly associated with the hurricane, can be heavy enough to trigger incidents of flash flooding in the short term.
In late September, heavy rain fell on the southern Appalachians before Helene's arrival. However, a striking difference this time will be that the heaviest rain is likely to fall on the coastal areas of the Southeast rather than the southern Appalachians. Another big difference will be Rafael's path, which may continue westward across the Gulf of Mexico as opposed to making landfall in the United States.
In the recent flash flood disaster in the southern Appalachians, intense rain fell just before Helene's arrival and produced flash flooding on its own. Hours later, Helene arrived and unloaded copious amounts of rain in roughly the same area.
Rainfall just prior to and during Hurricane Helene from late Sept. 2024.
In the current situation, the widespread dry ground may absorb a significant amount of rain that falls through Thursday. Parts of the Southeast have not had more than spotty showers since Helene in late September.
The rain through Thursday night can be heavy but spread out over many more hours. A broad zone of 2-4 inches of rain is forecast along the southern Atlantic coastal plain, with local amounts of 8-12 inches. However, the downpours will occur in a zone with a five-week deficit of 2-4 inches.
If Rafael attempts to make a run at the U.S. despite the latest predictions, rain associated with the storm will fall farther to the west, more over Louisiana and Mississippi, than the heaviest downpours through Thursday. This instance or more likely from a non-tropical storm pushing slowly eastward from the Great Plains, would result in a more even distribution of rainfall in the southern United States that should prevent widespread flooding problems in the Southeast, especially in the southern Appalachians.
Despite the big differences between Rafael and Helene, enough rain could fall on central and southeastern Georgia and the South Carolina Low Country to cause urban-style flooding, small stream flooding and flooding in low-lying areas.
Any tropical storm or hurricane that transitions to a tropical rainstorm has the potential for excessive rainfall and flooding should it track over the region.
Even though the ground has become dry in the weeks since Helene, it may not take as much rain to trigger issues in the southern Appalachians, especially where drainage infrastructure and roads have not been fully repaired since Hurricane Helene.
A damaged tree canopy post-Helene from the southern Appalachians to some coastal areas of the Southeast may also lead to greater and faster runoff in some instances than if most trees were still intact.
Aside from the risk of flash flooding, which may be focused on a small area, the storm may bring much-needed rain and wildfire relief over a broad area later this weekend to next week. In some cases, the storm duo may bring the first soaking rain in months to parts of the Central and Eastern states.
Storm chaser Aaron Rigsby reported live from South Carolina on Nov. 7 as flash flooding not associated with Rafael destroyed roadways and led to dramatic water rescues.
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