Valley warm and dry this winter
Wednesday, Feb 17, 2016 02:58 pm
The Bow Valley has been unseasonably warm and dry so far this winter.
Environment Canada officials say this year ranks up there as one of the top three substantial El Niño events in the past 40 years, leading to much warmer and drier conditions than historically seen in the mountains and across Alberta.
“In November conditions really started to warm up to 1 to 2 C above normal, and since Christmas they’ve been 2 to 3 C above normal,” said Kirk Torneby, a meteorologist with Environment Canada.
“Over the same time period, we’re at about 25 per cent less overall in precipitation. There was a big event for snow back in November, but since then it’s been relatively dry across all of the province.”
El Niño is a climate cycle in the Pacific Ocean with global effects on weather patterns.
Every three to seven years, an El Niño event may last for many months. During the past 40 years, 10 of these major El Niño events have been recorded, the worst of which occurred in 1997-98.
Torneby said Banff and Canmore have not seen any record high temperatures so far this winter, but they’ve come very close. He noted the Bow Valley usually sees highs of about -3 C at this time of year.
“We’re talking about records going back to the late 1800s, and there’s temperature records of about 8 degrees C and 10 degrees C for this time of year,” he said.
“There’s been a few days this year that we’ve reached close to that. Feb. 18-19 came close, and Feb. 6, 7 and 8 came close to the record highs.”
John Pomeroy, a Canmore resident who is director of the Centre for Hydrology at the University of Saskatchewan, said it’s an exceptionally warm winter.
He said air temperatures recorded at Bow Valley Provincial Park station are well above normal, with the long-term average at this time of year sitting at -5 C.
Pomeroy said temperatures for much of this week and last were about 8 C above average.
“That’s pretty shocking,” said Pomeroy, who is also the Canada Research Chair in Water Resources and Climate Change.
“I’m a scientist, but I look at the plants and the poppies are coming out of the ground in front of where I live. Poppies in February. Wow.”
Bow Valley Provincial Park station recorded 67 mm of precipitation from Nov. 1 until now.
“We’d normally expect 95 mm of precipitation,” he said. “More than half of the 67 mm we got was one storm in November.”
Pomeroy also pointed to another station in the Ghost River headwaters, but at a much higher elevation than the one at Bow Valley Provincial Park.
He said precipitation has been close to normal since the beginning of November, with 82 mm recorded compared to the normal 90mm.
But Pomeroy said air temperatures there are much higher.
“Even up there it has been up to 8 C, and the average temperature for this time of year is -7 C,” he said. “It’s been fluctuating between zero and 8 C so that’s wildly above normal,” he added.
Pomeroy said precipitation is normal in lower areas, close to normal at lower elevations, but overall above normal temperatures this winter.
“The result is the snowpack is below normal,” he said.
It’s too soon to say what this means in terms of stream flow for summer.
“We get a lot of snowfall in April and May and we just don’t know what’s that’s going to do, but there’s a likelihood El Niño could persist,” said Pomeroy.
Pomeroy said the area can expect warmer temperatures and less snow into the future.
“We’ve had a lot of warming since the early 1960s already,” he said.
“The winter minimums have gone up 4 or 5 degrees C since the early 1960s and there’s been overall a warming of 1.5 to 2 degrees C,” he said. “A lot of that is in winter, not much is evident in summer.”
Based on projections from a variety of climate models, Pomeroy said it’s suggested there will be ongoing winter warming and a shift from a snowfall-dominated climate to one with more rain by 2050.
“We might get there much earlier than that,” he said.