There is only one problem: It doesn't tie to global temperatures. Below is the plot of global temperatures from 1950 to 2014. Climate Central shows a huge rise in heavy rain from 1950 to 1977. But, temperatures during that period were flat (compare graphs).
Temperatures rise rapidly from 1978 to 1998 but the rate of rise in Texas heavy rains is the same. In fact, the 'rise' in heavy rains is actually flat from about 1990 to 2014 (upper graph).
But, it isn't just Climate Central that incorrectly tries to tie temperatures to heavy rain. The U.S. government has made the same mistake. Their study is for the entire nation.
Note the decrease in heavy rain from 1910 to 1940 (brown bars). Now, compare world temperatures from 1910 to 1940 (graph below with brown vertical lines from 1910 to 1940). Temperatures are rising rapidly, at least as rapidly as the 'man made' global warming from 1978 to 1998! That would show an opposite correlation to the one claimed.
And, the study shows heavy rain increasing in the 2000's even though temperatures were flat to even slightly down.
What these two studies inadvertently prove is that U.S. heavy rain is not tied to world temperatures.