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SOMBA K'E/YELLOWKNIFE
An unusual weather pattern over Great Slave Lake is the source behind the near record snowfall that hit Yellowknife over the weekend, according to Environment Canada.

Dylan Applejohn, 2, left, builds a snowman at the Applejohn residence on Banke Crescent on Sunday with his brother Evan, 8. - Simon Whitehouse/NNSL photo

The capital city became a winter wonderland briefly for the first time since the spring melt.

Approximately 18 centimetres of snow had accumulated on the ground by noon on Sunday. Most of the snow had melted by Monday, when the national weather agency recorded just four centimetres of the white stuff remaining on the ground in Yellowknife by 6 a.m.

Trace amounts of snow were seen in the capital city on Tuesday and Wednesday, but most of the snow came late Friday night and early Saturday morning. By 6 a.m. on Saturday, about 14 cm had accumulated on the ground.

The snowfall was the result of what is called a "lake effect snow squall," caused by cold air travelling over the open water of Great Slave Lake, meteorologist Yvonne Bilan-Wallace told Yellowknifer on Monday.

Lake effect snow occurs when cold air from over land combines with warmer air over open water and can make "snow streamers" capable of dumping large amounts of snow in a relatively small area over a short period of time, she said.

This type of snowfall is more commonly seen south of the lake, said Bilan-Wallace.

"To see it coming up the other way ... it took me a little bit by surprise," she said. "Until that lake freezes over, any time you have a good fetch - a good wind that blows over that open water - you can get heavy snow."

After a warmer-than-average fall, last weekend's dump came just short of setting records, with the second-most snow on the ground on record on both Oct. 13 and 14, said Bilan-Wallace. The record for most accumulation for Oct. 13 was set in 1959 with 15 cm of snow. That same year also holds the record for most snow accumulation on Oct. 14, when Environment Canada recorded 20 cm.

While the weekend's snow came later in the year than average, there have been years in Yellowknife such as 1955 and 1995 when only trace amounts of snow had been seen by the end of October, she said.

The sudden dump of snow was also surprising to airport workers who worked all-out over the weekend to keep the runways open, said Lee Stroman, manager at the Yellowknife Airport.

While the airport's three snow-clearing trucks have been ready for winter for some time, it took all of the airport's resources to keep up with the snow squall, he said.

"At the rate it was falling on Friday all we could do was keep up," said Stroman.

While the airstrip remained open all weekend, the weather did cause delays and at least one flight was turned around, he said. However, Stroman was unable to give exact numbers on how many flights were affected by the storm, because each individual airline makes decisions on whether or not to land their planes based on the type of aircraft and the conditions on the ground during arrival, said Stroman.

Department of Transportation snowplows were also working over the weekend to clear the highways, said department spokesperson Earl Blacklock.

"It did catch us a little by surprise, but obviously we were out clearing," he said. "I haven't heard of any accidents over the weekend related to road conditions."

While recent weird weather may be the bi-product of climate change, which is arguably being felt more in the North than in the rest of the country, not all strange weather events are due to the long-term warming trend, said Bilan-Wallace.

"Certainly we have seen a lot of changes in the trends - particularly in the winter. We know the climate up there has been changing," she said. "However, we also have to recognize that one event is not a definitive answer. One storm, one weather season does not make a climate trend."

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