According to data from the U.S. Geological Survey, the amount of water in the earth's atmosphere could not possibly cover the earth.[11] In fact:
One estimate of the volume of water in the atmosphere at any one time is about 3,100 cubic miles (mi3) or 12,900 cubic kilometers (km3). That may sound like a lot, but it is only about 0.001 percent of the total Earth's water volume of about 332,500,000 mi3 (1,385,000,000 km3)
If all of the water in the atmosphere rained down at once, it would only cover the ground to a depth of 2.5 centimeters, about 1 inch.
Additionally, because only 1.7% of the earth's water is stored underground,[12] there is not nearly enough water in groundwater storage beneath the earth's surface to account for the amount of water necessary to flood the entire earth to the extent described in the Bible.
Simply put: there is not enough water in Earth's atmosphere to raise the ocean's levels over an inch, much less to cover Mt. Ararat with water from 40 days of rain. There is simply not that much water in the system.
https://bibleinterp.arizona.edu/articles/flood357903
https://www.youtube.com/watch?v=wL9eo9QaJb4
The Genesis flood story doesn't hold water.