Thankfully, the problem went away and didnt reoccur, but it was weird:

Got caught in some serious hail, "bigger than quarter" sized, which is very rare for NJ. Last month there were hundreds of cars wrecked by hail on the Queens/Long Island border (a few miles away), which never happens here, so thanks to climate change, I guess north NJ is now going to get hail now and then. The hail is PINGING off the roof, so I book it down a sidestreet in an industrial area and find a big awning over a loading dock to park under. After 10 min or so, the hail turns back into torrential rain and I head back to the main road. In those 10 min, I guess the street was completely diluged with rain because even tho it wasnt at a low point for the area, it was flooded and I couldnt see it in the heavy rain. Drove right smack into the middle of it. Kept a steady foot on the gas and made it to the other side, couldnt even tell you how deep it was but I know the bumper was pushing water.

Next is a 30min highway ride. I get on a small 3 lane highway and after I get on I'm in the right lane. Hit a puddle at 40mph that seemed flat but the pavement was depressed and sent a huge wave off the side of the highway. Luckily a fat pig car like a G8 with new tires didnt hyroplane enough to scare me and I carried on.

Later I'm in the left lane, and I keep seeing flashing lights. I keep checking my mirrors for po-po or an ambulance or something, but nothing. Then I start wondering if the guy behind me is flashing his hibeams at me, and I keep missing it in my mirrors but seeing it on the car in front of me. Its two lanes of heavy traffic in heavy rain about 40-45mph and limited exits (every 10 miles) and it would be pretty stupid to be flashing hibeams as nobody is getting out of your way and it would get you nowhere. But it keeps happening. After a min of driving I've got new cars ahead and behind, and I realize its STILL happening. Its ME. The dashboard is normal, stereo is normal, everything electrical normal but my headlights or fogs or both are surging quickly like almost flashing. Then as the rain lets up and traffic thins further up the road, I notice everybody getting out of my way in the left lane.... which was nice, unless a cop sees me and think I'd being an asshole in the left lane.

Either way, it does it on my whole 30 min ride. I get off the highway and am at a light behind a car, and no flashing. Now I'm wondering if I'm going insane. I make a few turns and wind up on a windy mountain road with no street lights. It starts happening again, and the woods look like a disco. Its bordering dangerous. My destination was at the end of the block, and I park behind a car..... headlights are normal. So it seems like it only happened at speed. I put the car in park and rev the car. At about 2.5k rpm, the headlights start strobing/pulsing again. Under that, it stops. Kooky.

Anyway, 4 hours of losing poker later, I go out to the car wondering if whatever weird short in the alternator is causing this drained the battery, it starts up normal and no more flashing lights since. Thats the story (its rare I have an interesting car story with a happy ending).

I'm gona guess water got inside the alternator? But at low spin its not noticeable? Dunno. Stock fogs and headlights other than Sylvania bulbs.