Life-threatening cold to hit B.C. North and Central Coast, Environment Canada warns
Arctic outflow brings extreme cold and strong winds, posing urgent frostbite and hypothermia dangers to Terrace and Kitimat
Environment Canada is warning of life-threatening cold weather in B.C. North and Central Coast from Wednesday until at least the end of the week.
In an Arctic Outflow Warning issued on Tuesday afternoon just before 4:30 p.m., the meteorological agency warns of the "first arctic intrusion of the year," adding that the strong outflow winds and cold wind chill values are expected to bring with it a risk of frostbite and hypothermia for residents venturing outdoors.
Wind chills, according to Environment Canada, are expected to be between -20ºC and -30ºC in Terrace and Kitimat, as arctic air combined with strong outflow winds generate temperatures that put residents at risk of frostbite and hypothermia within minutes if precautions are not taken when outdoors.
The arctic blast is expected over central and inland sections of the north and central coast starting Wednesday night, but areas like Bella Bella will see a slightly delayed onset to the cold air, with an expected start time of Thursday morning.
"Wind chill values may moderate on Sunday but uncertainty remains on the timing of the warm-up," said Environment Canada in the weather warning.
In an interview with The Skeena Reporter, Environment Canada meteorologist Armel Castellan said that the arctic outflow and its corresponding weather warning is nothing new, since Terrace and Kitimat will typically one at least a few times a year.
"What is bizarre is that we haven't had an arctic outflow yet this year and we're coming up on mid-January," Castellan said. "By the first week of January, 45 per cent of the snowpack has usually fallen, so there's typically a good few weeks if not couple months, just like we saw last year, where in November the switch was flipped, where we start seeing arctic outflows down the coast, both north and south.
In previous years, Terrace and area would see one or two arctic outflows, Castellan said. "This one just happens to bring us temperatures significantly below seasonal."
The temperatures Environment Canada is forecasting for Wednesday are approximately 10 degrees Celsius cooler than normal, Castellan said, but by the time Thursday rolls around, it'll be more than 15 degrees Celsius below normal. "The story here isn't so much about the temperatures than it is the winds and the wind chill."
"The frostbite and the potential for hypothermia, coupled with the fact that December was extraordinary for much of the province, in terms of temperature, is concerning," Castellan said. He added that Terrace saw its 12th warmest December on record and that's the least-warmest ranking they saw in all locations, with the exception of Old Crow, Yukon.
"The main thing with our arctic outflow warnings is that we're talking about strong winds to bring those temperatures down," Castellan said. "In this case, we're talking about the winds bringing those temperatures down below minus 20 degrees Celsius and even closer to minus 30 degrees Celsius."
When asked about when the extreme cold weather will end in Terrace and area, Castellan said that it will be with us until at least the end of the week but even then there's a lot of uncertainty. "Quite a few models agree on one thing: We cool off very quickly and peak, at least for the northwest, on the weekend, but it's a relatively slow warm up. It's going to take us a while before we get back up to seasonal averages, which are about zero degrees Celsius during the day and minus five degrees Celsius in the evening, for this time of the year."
Castellan said that it's likely going to be well into the fourth week of January before we see temperatures in the above-freezing figure, or just barely cresting over that.
Castellan also mentioned that there's also some uncertainty over a snowfall event that occur as early as Saturday or as late as Monday.
"There's a couple of models that bring some moisture down the panhandle. It could stall there and deliver almost nothing for Haida Gwaii, Prince Rupert, Terrace and Smithers, or it could dump snow on the area," Castellan said. "It could also create a situation in Vancouver and Seattle where you have widespread snow down to sea level that will warm up quickly because it's coming from the southwest and turn into a big slush fest," Castellan said.
Ultimately, Castellan said, a snow event is certainty part of an event like this, but that's by no means guaranteed.
The wind speeds Terrace is expecting are fairly significant because they're part of the reason we'll be seeing such cold air, Castellan said. "That cold, dense pool of arctic or modified arctic air is unable to go up and over mountains the same way; it's very terrain-specific."
"For the Skeena, the valleys are wide enough to allow a lot of movement of air, but it's still confined between the peaks and so that's why you end up getting relatively strong gusts and sustained winds," Castellan said.
In its 4 p.m. forecast, Environment Canada was forecasting winds of 20 kilometres per hour on Wednesday for Terrace, eventually leading to wind gusts of 40 to 60 kilometres per hour.