Tree-cracking cold: 39 below up north, 13 below in Twin Cities by Friday morning

Wind chill advisories continue until 9 a.m. Friday

Frost cracks in a tree
Frost cracks in a tree.
Bob Bricault, Michigan State University Extension

The roof beams sent a loud boom through the Huttner Weather Lab Wednesday night.

Trees and wood expand and contract as temperatures change. Extreme cold can cause trees to crack, and the studs in your walls and roof to pop on cold arctic nights.

Frost cracks in a tree
Frost cracks in a tree.
Bob Bricault | Michigan State University Extension

Paul Hetzler is an ISA-certified forester and a horticulture and natural resources educator for Cornell Cooperative Extension of St. Lawrence County in New York. He wrote this piece about the popping noises trees can make in subzero cold.

So what does happen when trees go ‘pop’ in the night (or day)?

As we all know, when water freezes, it expands. Luckily, sap is not pure water. It’s endowed with antifreeze in the form of sugars, and to a small extent, dissolved minerals.

There comes a point, however, when even sugar-fortified sap will freeze and expand. This may rupture the bark of a tree, resulting in an audible crack as well as a visible one. In many cases frost cracks close with no long-term ill effects, but sometimes they do become perennial.

Rapid temperature change: 50 degrees colder

Temperatures plunged 50 degrees in parts of Minnesota between Wednesday and Thursday morning.

Here are some selected minimum air temperatures from around Minnesota Thursday morning.

  • Minneapolis-St.Paul International Airport: 11 below zero

  • Mankato, Minn.: 19 below zero

  • Redwood Falls, Minn: 21 below zero

  • Crane Lake, Minn.: 35 below zero

  • Ely, Minn.: 37 below zero

  • Lake Kabetogema, Minn.: 39 below zero

Coldest so far

Many Minnesota locations recorded the coldest temperature so far this winter season Thursday morning. The Twin Cities reading of minus 11 beat the minus-9-degree temperature recorded on Jan. 19.

Friday morning looks equally cold in some locations. I’m predicting temperatures will bottom out between minus 10 and minus 13 in the Twin Cities early Friday morning.

Low Temperature forecast Friday morning
Low Temperature forecast Friday morning

Temperature roller coaster ahead

The upper air pattern favors alternating Pacific and Arctic air mass swipes over the next week. That means highs in the 30s look likely Saturday, Monday and again next Thursday. In between temperatures chill into the 20s.

Temperature forecast for Twin Cities area
Temperature forecast for Twin Cities
NOAA via Weather Bell

There is a chance for some snow Monday.

Stay tuned.

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