Thousands of Northland residents spent Sunday with power after a spring snow storm brought strong winds and heavy snow overnight.

Lake Country Power reported more than 4,700 customers were without power as of 9:30 p.m. Sunday, down from 9,400 from earlier in the day.

"Lake Country Power anticipates that an undetermined number of outages will last through Monday," Lake Country said in a news release Sunday afternoon. All 17 of its line crews were fixing outages, and while some were anticipated to work through the night, the company reported it would send most home at 10 p.m. for safety. They will resume work Monday morning.

Minnesota Power's outage map reported 75 outages throughout the Northland, adding up to more than 1,000 customers without power as of 9:30 p.m. That's down from about 5,900 customers without power at 11:30 a.m.

The company said additional crews were being brought it to fix the lines downed by "wet, heavy snow."

Line crews were being called in from International Falls and Little Falls to help near Cloquet, Gnesen, Midway and Meadowlands, while many crews had to restring wire in affected areas.

"We have called in 5 additional contractor crews from Xcel Energy to assist," Minnesota Power spokeswoman Amy Rutledge said in a statement Sunday night. "Our crews will be working throughout the night with the majority of all outages expected to repair, some repairs to a smaller number of customers may extend into Monday morning."

A downed line even temporarily closed Interstate 35 from Exit 245 to Exit 246 on Sunday morning, the Proctor Fire Department said on Facebook. I-35 was closed from about 7:30-9 a.m., according to the Minnesota Department of Transportation website.

"When the snow turned to rain, it caused some lines to 'gallop,' meaning the lines were slapping each other when the weight of the snow released only to blow the fuse again," Lake Country said.

Many other lines were hit by breaking branches.

Justin Schultz, a meteorologist for the National Weather Service in Duluth, said this weekend's storm, which began Saturday afternoon and let up by midday Sunday, was perfect for taking down power lines.

"That combination certainly contributes to it when you have the snow as wet and as heavy as it is, it weighs down a lot of the branches," Schultz said. "All you need is some kind of some jostling from the strong winds that we had. And if you have branches that are over power lines or things like that, that's certainly a recipe for a lot of power outages across the area, which is exactly what we saw."

Schultz said strong northeast winds off Lake Superior reached 60 miles per hour, resulting in large waves on the lake.

The largest snowfall totals were recorded south of the Twin Ports.

Reports near Wrenshall and Holyoke in Carlton County showed 7.5 inches of snow while Patzau in Douglas County received 7.8 inches of snow.

The snow dropped 6.2 inches of snow at the Weather Service office near the Duluth International Airport, Schultz said, adding that the liquid water equivalent — a measure of the rain and melted-down snow — was 1.37 inches.

"So a good amount of moisture associated with this system," Schultz said.

Other places saw all rain. Butternut, Wisconsin, in southern Ashland County, received about 2.5 inches of rain during the storm.

With all the wet snow and rain falling on soil already saturated by melting snow, the Weather Service is keeping its eyes on the potential for flooding, most notably along the Mississippi River but also the Nemadji River in Douglas County.

"River flooding is another concern that we've had and over the next week or so we will be watching for the responses in the rivers," Schultz said.

Thunder snow

Late Saturday night, just as the rain turned to big, fluffy flakes of snow in the Twin Ports, it was joined by weather you might expect in the warm summer months: a flash of lighting followed seconds later by the rumble of thunder.

Schultz said the ice crystals moving around in clouds can charge.

"If you have enough charge build up, then you know you can have that kind of electrical energy that's required to generate lighting and thunder," Schultz said.

He said that the strength of the storm added to the lighting.

The "very strong, potent area of low pressure" was full of moisture and lift, Schultz said.

"So far this winter, that's probably one of the stronger areas of low pressure that I've seen," he said. "But in doing so, what it also did was it helped to bring in a good bit of instability. So we actually had an environment that was a bit more unstable than what you typically would see with other winter storms."

This story was updated several times with updates from power companies. The final version was published at 9:30 p.m. (March 29) The initial version was posted at 11:33 a.m. (March 29).