Yikes- that's scary stuff!! I've only been caught in a severe thunderstorm once. And I set a speed record on my commuter. Seriously, I was out and there was nothing to do but pedal as fast as I could. Luckily, I was only about 1.5 miles from home so it wasn't too scary (but the lightning and hail was a little scary).

If it looks really bad before I leave for home, I've been known to just wait at work until my hubs gets off and can come get me (usually means hanging out at work for an extra hour or more). Usually when severe weather has hit in the middle of the day, I've had co-workers who have offered to drive me home sans bike (and I'll drive the bike home the next day).