Dan Pryor initially called a friend to bring over a shop vac Monday morning when floodwaters started creeping into his San Diego home. But in a matter of minutes, the volume was no match for even the most heavy-duty vacuum. “It’s like half an inch, but in a few minutes, the seeping water turned into 3 inches,” said Pryor, 49. “Next thing I know, it was 12 inches, then it got to about 18 inches,…