The only thing worse than driving around in 2 feet of snow is driving around in 2 feet of snow and subzero temperatures.

"We can sand and salt, and when it warms up and the snow melts and turns into water, the roads will be fine," said Kim Morris, director of community relations for the Utah Department of Transportation. "But when it gets to near-zero temperature, no matter how much salt is in there, at some point, that stuff is going to freeze and turn to ice again."Black ice and fog are being blamed for a massive pileup on I-215 Tuesday morning involving more than 50 vehicles. Officials were forced to close westbound I-215 near I-15 while 31 wreckers towed away the vehicles. Eastbound lanes at Redwood Road and I-215 were also closed.

Fifteen people were taken to local hospitals and treated for minor scratches and abrasions, said Salt Lake County fire dispatcher Connie Kelson. "Nothing serious, just lots of messed up cars," she said.

William J. Alder, meteorologist in charge of the National Weather Service's Salt Lake Office, explained the patchy fog in the area and said such fog develops easily in low parts of the valley, especially near the Jordan River.

"It's the lowest part of the valley, so the air wants to pool in there. The water and the added moisture (from the river) adds to the likelihood of getting fog," he said. "The fog may only be a quarter or half of a mile wide, but it can be extremely dense right along a body of water."

Temperatures in much of the state were well below zero Monday night. The temperature at the Salt Lake International Airport dropped to zero at 7:30 a.m. Tuesday, Alder said. "The temperature usually drops to the lowest point just before sunrise," he said.

That was the lowest temperature recorded at the airport since Christmas Day 1987, he said.

Temperatures will be nearly that low again Tuesday night, making driving extremely hazardous at night and in the early morning.

The chill is taking some of the glee out of the weekend's mighty storm. High temperatures Tuesday and Wednesday will hover in the teens and low 20s.

Children who want to play in the fresh snow and skiers anxious to do a more sophisticated version of the same thing should don plenty of warm clothing before venturing outside.

There is a little warm news for people living in the western part of the state. A storm system dropping into Nevada from Southern California will bring clouds into western Utah by Tuesday night, Alder said.

The light cloud cover may make temperatures 1 or 2 degrees warmer.

"It could be fairly cloudy statewide tomorrow (Wednesday)," Alder said. "Some areas in the western part of the state won't be quite as cold because of the clouds. There will be a little scattered snow in the western part of the state Wednesday. Nothing much. Maybe skiffs in the valley and an inch or two at the resorts."

The storm will be dropping into Southern California and Arizona later in the week, possibly pausing long enough to drop some snow on southern Utah Thursday, he said.

Exhausted road crews have been working 20 hours a day since Christmas Eve, Morris said. "There may be some icy spots, but it's not because of lack of effort on the part of the UDOT or the city and county crews.

"As long as we have cold temperatures and this much snow, there will be icy conditions. Drivers have to remember that just because the freeway has a speed limit of 55 miles an hour, that's not the speed they can drive. You have to look at the roads and drive according to conditions."

People planning to travel on New Year's Eve should be on the watch for a second storm expected to move into the state that night.

"It could continue to the early part of New Year's Day," Alder said. "It doesn't look like a major storm. It could drop maybe 2 or 3 inches in the valley and about a foot in the mountains. We will have to get closer to it to be fancier with the numbers."

Alder's rough estimate will delight skiers hoping to get another day or two of skiing in over the long weekend.

The Great Salt Lake had little to do with the heavy snowfall over the weekend, Alder said. "We could have had a mini-lake effect Monday, causing it to snow an inch or two in Davis and Salt Lake counties," he said. But for the most part, the lake shouldn't get any blame for nature's bounteous gift this weekend.