Mother Nature may throw a wet blanket on Christmas and on much of the fun for many winter-loving Minnesotans.

An inch of rain predicted for Sunday will not only make Christmas dreary in the Twin Cities, it could make a mess for skaters, skiers and snowmobilers who've been reveling in winter's glory since last week's storm dumped a half a foot of snow. The winter rainstorm could also cause rivers jammed with ice to overflow and streets to pool with water if storm sewer drains are clogged with snow and fall debris.

And for those who want to spend time on a frozen lake? The ice in many areas isn't thick enough, and higher-than-normal temperatures combined with the rain will make conditions even more unsafe.

"Find me someone in the state of Minnesota who's an outdoor enthusiast who's going to be happy when it's raining on Christmas morning, including Santa," said Pam Hoye, spokeswoman for Afton Alps, a ski area near Hastings. Although many downhill ski and a few cross-country ski areas that make snow will survive the warmth and rain, the natural stuff won't fare as well.

"We have a 20- to 46-inch base on most of our slopes," Hoye said. "And we can make more."

The man-made snow along a 5-kilometer loop at Hyland Lake Park Reserve and a 2.5-kilometer trail at Elm Creek Park Reserve also should hold up, said David Thomas, outside supervisor at Hyland Hills Ski Area.

"We have 2 or 3 feet in most areas, so it will take a lot of rain for many days to have any effect on us," he said. "And we have a lot of equipment to recuperate if we do get rain."

But even those who can make snow are crossing their fingers for the real thing. "I'm hopeful our Christmas gift will be that it doesn't rain on Christmas Day," Hoye said.

Snow teaser

One to 2 inches of snow is expected on Friday, brightening up the landscape, said Lisa Schmit, meteorologist at the National Weather Service in Chanhassen. Saturday should be dry and mild with a high temperature of about 30 degrees, she said.

But a pleasant winter day likely will give way to ugliness overnight with the dreaded wintry mix — some rain, a bit of sleet and a little snow — nothing resembling a holiday snow globe.

"There could be some freezing precipitation with that," Schmit said. "It could put a light glaze on some roads by Sunday morning."

When the temperature warms into the upper 30s, what falls will be rain, she said. If it was snow, it might amount to about 10 inches depending on the temperature, Schmit said. Instead, an inch of rain will turn some ice rinks into puddles and shrink the natural snowpack, to the dismay of skiers and snowmobilers.

Most of those waiting to go out on Minnesota's frozen lakes already are frustrated with winter.

Ice depths on lakes across Minnesota have varied, causing concern with the "security of the ice," said Lisa Dugan, boat and water safety outreach coordinator for the Department of Natural Resources.

Temperatures that plunged below zero last week gave some people the false impression that the lakes would be frozen solid. But higher-than-normal temperatures before and after the arctic blast have caused havoc with Mother Nature's icemaking. Even on the same lake, ice depths can vary from 1 inch to 9 inches, Dugan said.

"The warming and cooling doesn't create good solid ice," she said. And that means a few vehicles are crashing through the ice on lakes around the state, she said.

To make matters worse, last week's snowfall insulated some lakes, complicating ice-making, Dugan said. And the coming rain and warmth could melt what's there.

"We like to advise people to check the thermometer, not the calendar," Dugan said. Just because January is near, it doesn't mean the ice is safe. "We need a lot more days of below-freezing temperatures," she added.

At least 4 inches of new, clear ice is needed for those who want to walk out to their fishing hole; at least 5 inches is needed to support a snowmobile, and 12 to 15 inches is needed to support a truck, according to the DNR's website, which offers ice safety tips.

A bit of good news for those counting on a white Christmas: The day will begin with snow on the ground. The last two years, there was either no snow or barely a trace, putting them in the brown Christmas category, according to the Weather Service. "There has to be at least an inch of snow on the ground for it to be technically a white Christmas," Schmit said.

Mary Lynn Smith • 612-673-4788