Twin Cities drivers got a slow-motion and ugly reminder Monday of what winter driving can bring.

A dusting of snow as the morning rush hour began led to a sudden coat of ice on metro-area streets and highways, turning what might have been an easy Veterans Day commute into a calamity of collisions and miles-long traffic tie-ups.

Roads should be clear and dry on Tuesday and remain so through the week amid steadily rising temperatures. Even Monday afternoon's rush hour went smoothly.

But that was after more than 50 crashes were reported during the morning commute, said State Patrol Lt. Eric Roeske. Most occurred at the tops and bottoms of ramps where motorists could not stop, he said, but mainline highways, freeways and local thoroughfares had their share, too. No injuries were reported among the 50 accidents, the Patrol said.

On the steep Ramsey Street hill west of downtown St. Paul, a demolition derby of sorts took place, with at least a half-dozen crashes. In Minneapolis, a Metro Transit bus went sideways and blocked several lanes of southbound Interstate 35W south of downtown for about an hour. Twitter was awash with reports of spinouts and crawling lines of vehicles, and motorists lashing out at the Minnesota Department of Transportation for not reacting sufficiently to the icy conditions.

Most observers across the metro area measured less than a quarter-inch of snow, said state climatologist Greg Spoden. But as cars drove over the snow, it compacted and melted slightly, then refroze because the pavement surface and air temperatures were below freezing.

On Ramsey Hill, Kristin Rasmussen woke up to see six or seven crashes. She said it was one of the worst scenes she has seen there. City street crews didn't respond, and Rasmussen said a police officer handing out forms to accident victims told one "you are on your own."

That left the task of making the road passable to neighbors, who bought ice melter at a hardware store to spread on the street, and cleared a driving lane with shovels.

Snow 'flash froze'

City spokesman David Hunt said a "snow squall" hit the southern half of St. Paul, which includes Ramsey Street, and it "came down fast, compacted quickly and flash froze."

"We had our street supervisor out about 6:30 a.m. driving the streets and didn't see any issues," Hunt said. "You go eight months without having your winter driving hat on and these things happen."

In Minneapolis, nine trucks were out putting salt down on the streets. Had the snow fallen after Dec. 1, there would have been 40 trucks ready to roll, but most are still involved in leaf-clearing, said Mike Kennedy, city street maintenance supervisor.

Kennedy said he heard criticism that his department appeared unaware of the forecast, but the forecast called only for flurries.

"It's a timing issue," said Mike Chapman, of the University Center for Atmospheric Research in Boulder, Colo., who examined readings from Minnesota roadside weather monitors on Monday. The time of day and the fact that it was early in the season were a bad combination, Chapman said.

'It doesn't take much'

The light, fluffy snow began falling around 7 a.m. and quickly intensified as it moved over the metro area. It was the first measurable amount of the season, and the subfreezing temperatures allowed it to accumulate on the roads. Drivers packing it down only made things worse.

"Any kind of snow that is more than flurries can cause problems," said National Weather Service meteorologist Chris Franks. "It doesn't take much."

The long-term average first date of the Twin Cities' first 1-inch snowfall is Nov. 18. Last year it came on Nov. 19, as part of a 3-inch snowfall, which turned out to be the second-heaviest of the winter.

Although scores of drivers criticized MnDOT on Twitter, saying they didn't see any trucks treating the roads, the agency dispatched crews as needed, said department spokesman Kent Barnard.

"Weather is hard to predict; this was not a surprise," Barnard said. "If we have a threat of snow, we start calling in crews. We take no chances with public safety."

Trucks were on the roads by 7 a.m., but they could only move as fast as traffic, which was at a snail's pace, Barnard said.

He said the conditions would not have deteriorated so quickly if chemicals had been applied to the roads earlier this season and had a chance to build up on the pavement.

Two days after two tornadoes

The snow fell less than two days after the Twin Cities saw a record high temperature of 69, followed by two small tornadoes in Dakota County.

Some folks there were puzzled as to why they heard no sirens warning of tornadoes over the weekend. While Dakota County officials couldn't be reached during the government holiday Monday, a National Weather Service meteorologist said that his colleagues in Chanhassen never issued a warning that would trigger such sirens.

"It was one of those cases where a line of storms moves through, a little tornado spins up quickly and is gone as quickly," Jacob Beitlich said. "The cycling time for our scans is four to five minutes, but these things can come and go in 90 seconds to two minutes. And the storm itself didn't have a history of severe weather."

Even so, he said, "No storm without a warning is our end goal, so plenty of people will look at this case by way of further research."

Staff writers Bill McAuliffe and David Peterson contributed to this report. • 612-673-4482 • 612-673-7768