The ones around Houston are. They are about a foot wide and can seriously point your patio furniture in a different direction, or maybe even knock it into the pool.
They get more serious up toward Crawford but the serious Tornado Alley is west of there.
Having lived through 3 nice sized tornados in North and West Texas, I had to laugh at your description of Houston tornados...........
Now, you know as well as I do, that we have perfectly respectable tornadoes in Houston.
Ours are typically F3's about 275 miles in diameter.