Recently on the Marilyn vos Savant discussion board:

From robert 46:

Margaret says: Winter is here, and an icy, snowy drive on the way home from work is very stressful.

Marilyn responds: When accidents happen, they’re worse, and bad road conditions make them more likely.

I agree with Marilyn.

The big problems on snow and ice are stopping distance and controllability. Traction goes down drastically. In my early twenties I would get up early after a light snowfall before the snowplows got to work and slide around the turns in town at 10-15 mph. It taught me how to drive on snow, ice, wet leaves, etc. There isn't much worse to driving than finding yourself in a situation where you have no control over a car using steering, brakes, or accelerator, and it is heading where momentum takes it. Many people forget how to drive in wet, snow, ice, and drive too fast for the conditions. It is bad enough around town, but on a main road it can be fatal, which could have happened to me:

I was on a four-lane divided highway (not controlled-access) in the left lane when a woman driving a black Ford Falcon came from the right across two lanes of oncoming traffic to make a left turn onto the road during a heavy rain. The driver ahead of me slammed on his brakes. I braked, but the four-wheel disk brakes were drenched with water and the car would hardly slow down, no matter how fast I pumped them [1]. The woman made the turn without being broadsided, but the driver ahead of me did not let off the brakes after she got by him and slid to a stop. I slid into him at about 10 mph. His rear bumper was high from braking and my front bumper low from braking, and it crunched the top of my left fender. Fortunately the driver behind me didn't sandwich my car. The front driver and I pulled off the road. There was no damage to his car, and we never bothered to exchange driver or insurance information. People may not think they are following too closely under bad road conditions, but finding out can be more unpleasant than what happened to me.

But what is more interesting about this story is that my father and I had headed off in opposite directions at the same time that morning. I was driving some 80 miles to the importer for routine service. My father was driving to work [2]. Unknown to me, he was so worried about my driving 80 miles in those bad conditions that he didn't notice the fuel gauge was low and ran out of gas on the way to work [3]. I continued on to the importer, but had to leave the car for body repair. The importer was having a car like mine delivered to a dealer in CT, so I rode down with the driver figuring I'd take the train to NY. The rain had ended hours before, and he was driving rather fast (like about 60 mph) when we came over a small rise. There was a car ahead of us moving at about 20 mph or less- the driver trying to decipher an intersection. I was about to yell at my driver, who seemed not to see it, when he reacted: he slammed on the brakes and turned right. He hit a roadside metal marker post, which tore the right steering linkage loose, and we came to a stop just before a gully with a thick stand of pine trees beyond it. So I had the dubious distinction of being in two auto accidents in two different sports cars of the same make and model on the same day- first when I was the driver, and then as the passenger. Another adventure in synchronicity.

[1] Disk brakes have net advantages over drums but a disadvantage. The rotor and pads are exposed and in rain subject to getting water on them (drum brakes aren't). This acts like a film of lubricant, lowering the friction between pads and rotor. My car was lightweight with low tire patch loading, was not good at squeegeeing water out from under the tread, and tended to aquaplane in heavy rain.

[2] There was a jog in the road that he took to the office. It shifted one lane to the right and then straightened. However, the roadway there was paving stones. My father regularly saw cars bounce off the guard rail in wet weather. Wet, worn paving stones offer almost no traction.

[3] Which happened around the same time as the accident.