Thursday flakes; arctic cold this weekend

Twin Cities residents will have a rare opportunity to use their shovels Thursday.

We were overdue for snow.

Through Wednesday, our season snowfall total at  Minneapolis-St. Paul International Airport was only 5.2 inches:

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That's 15.2 inches below our average season snowfall total through Dec. 27.

Thursday snow

Our Thursday morning commute is likely to be slowed by snow:

The snow should taper off in most areas by early Thursday afternoon, with totals in much of Minnesota in the 1- to 2-inch range.

The National Oceanic and Atmospheric Administration's North American Mesoscale forecast model shows the potential snow pattern Thursday into Thursday evening:

The color chart to the right of the loop refers to the strength of the signal that returns to the radar, not to the amount of snow.

Temperature trends

Our Thursday highs are expected to be in the single digits in northern Minnesota, with some lower teens possible in the south.

That's still well below average for late December, but milder than we've seen in recent days.

Thursday night, Friday morning lows dip well below zero in the north:

Friday highs are very cold, with only single digits in the south, and below zero highs north:

Arctic chill will be with us through this weekend.

Even in the Twin Cities metro area, the temp is expected to stay below zero this entire weekend.

Winds will give us very cold weekend wind chill temps:

New Year's Day looks mostly sunny, but cold.

It will warm up ... eventually.

NOAA's Global Forecast System model shows a Twin Cities high temp in the 20s one week from Friday.

Wouldn't that feel mild after this cold stretch!

Ice safety

Although recent cold weather has helped thicken up our lake ice around Minnesota, this is a good time for a reminder that lake ice is never 100% safe.

According to the Minnesota Department of Natural Resources, you need at least 4 inches of new, clear ice to walk on, and 8 to 12 inches of ice to support a car:

More than a foot of new, clear ice is needed to support a truck.

Ice thickness can vary greatly over short distances, so it's best to know the lake if you plan to venture out onto the ice.

According to the Minnesota DNR:

THE COLD FACTS ABOUT ICE

You can’t judge ice conditions just by appearance or thickness. Many other factors, including water depth, size of water body, water chemistry, currents, snow cover, age of ice, and local weather combine to determine its strength.

New ice is usually stronger than old ice. Four inches of clear, newly formed ice may support one person on foot, while a foot or more of old, partially thawed ice may not.

Ice seldom freezes uniformly. It may be a foot thick in one location and only an inch or two just a few feet away. Ice near shore can be weaker than ice farther out. Check ice thickness every 150 feet at a minimum.

Ice formed over flowing water and currents is often dangerous. This is especially true near streams, springs, channels between lakes, bridges, culverts and aeration systems. Also, the ice on outside river bends is usually weaker due to the faster current.

The insulating effect of snow slows down the freezing process. The extra weight of snow cover also reduces how much weight the ice sheet can support. Shovel any snow before testing the ice for thickness and color.

Watch for large cracks, depressions or pressure ridges in the ice and avoid those areas.

Moving fish populations can bring warm water up from the bottom of the lake, and waterfowl can warm the surface of the ice causing holes to open up, posing a threat to anyone traveling on the ice.

Programming note

You can hear my live weather updates on Minnesota Public Radio at 7:49 a.m. Thursdays and Fridays, and at 7:35 a.m., 9:35 a.m. and 4:35 p.m. each Saturday and Sunday.