I remember that day vividly too. Was just south of the arboretum on 360. I've never seen the sky that color before or since. Young, naive and new to Austin my initial thought was "just another thunderstorm... but, is that color sky normal here?" Our receptionist was so scared she was crying, making it quickly obvious that it was not, in fact, normal.
I was at UT then, and had some time that day to go get some ballcap that I'd been searching for. I think it was a fitted .45s lid, but I can't remember for sure – I just remember that I finally found one in Pflugerville, and I saw no problem with heading up that way to get it. After all, what's a little rain? By the time I finally made it up there, the weather was absolutely fucking hellacious, and the shop owner I had talked to on the phone was long gone.
So naturally, I decided to head over to Lakeline mall instead, because I'd heard there was a good store there, and because I am a fucking idiot. Fortunately, one of my roommates (now my wife) was kind enough to tag along and point out that I'm a fucking idiot, and managed to get me pointed back towards campus.
That sky was absolutely ridiculous, and I still can't figure out what the hell I was doing driving around through sideways rain and wildly swinging traffic lights... desperately searching for a hat, of all things.