Asheville got 30 inches of rain in 24 hours. This is entirely due to the uplift of the storm caused by the mountainous terrain.
The air can contain only a finite amount of moisture which is temperature dependent. The Dry Adiabatic Lapse Rate is 5.4°F per 1,000 ft. That is, for every thousand feet the air rises, it cools 5.4°F. It doesn't take long for the air to become saturated. When saturated air continues to cool, precipitation occurs. Hurricanes are rapidly rotating, rising, masses of moisture saturated air.
The ground in the mountains is incapable of absorbing very much of that rain. The water must go somewhere so it runs off producing catastrophic flooding.
SpyNavy
Garde la Foi, mes amis! Nous nous sommes les sauveurs de la République! Maintenant et Toujours!
(Keep the Faith, my friends! We are the saviors of the Republic! Now and Forever!)
LonePalm, le Républicain du verre cassé (The Broken Glass Republican)
Don’t forget, this isn’t an “unprecedented event”, it rained worse in Nelson Co. Virginia when Camille stalled over the area for a day or so. It rained 25-30 inches in less than 5 hours there.
Climate weenies are milking this event like a late to the machine cow.