What is a blimp doing out in the middle of nowhere?
A little research supplied the answer. This is a Tethered Aerostat Radar System. They let the blimp out on several thousand feet of line and its down-looking radar keeps an eye on things. Like illegal activity from across the border.
But this particular TAR is about 20 miles from the border. Either it can see a long way, or officials only care if Mexicans get so close.
At any rate, this one wasn't flying—because of the rain, I suppose. Does that mean smugglers know it's safer to cross in bad weather?