What's with northern B.C.'s thunderstorms and lightning, and is it very, very frightening?
Hot weather fuelling B.C. wildfires is also causing an unusually high number of lightning strikes, experts say
It's become a near-daily occurrence in parts of B.C.: Your phone buzzes with a warning that a severe thunderstorm could develop at some point throughout the day.
"Every afternoon like clockwork," is how one resident of Prince George described the notifications, issued by Environment Canada.
In north-central B.C., where much of the activity has been focused, Prince George had either a watch or warning issued 24 times, far more than usual. Warnings, which means a storm is imminent or occurring, can be issued multiple times in a day.
Across B.C. and the Yukon, July saw 21 days with thunderstorm warnings and just 10 without, while a warning has been issued every day in August so far, with hundreds and sometimes thousands of lightning strikes in a single day.
"It has been a particularly lightning and thunderstormy patch," Environment Canada meteorologist Armel Castellan told listeners of CBC Daybreak North, which airs in northern B.C.
But, he said, "it really depends on how dry things are whether or not the lightning strikes matter" when it comes to sparking new wildfires, because it's unlikely for a new burn to spark in wetter conditions.
Unfortunately, this year, conditions in B.C. have been extremely dry, fuelling both the storms and the province's worst wildfire season on record in terms of land burned.
Leading cause of forest fires
Of the 359 wildfires currently burning in the province, 304 — about 85 per cent — have been determined to be caused by lightning. That includes the Downton Lake wildfire, which sparked evacuation orders north of Whistler this week, and the Donnie Creek blaze in northeast B.C., which is now the largest wildfire ever recorded in the province.
And the same heat that helps those fires burn is also conducive to the unusually high number of thunderstorms being seen this summer, Castellan explained.
A key ingredient for any thunderstorm, he said, is warm air rising from lower levels into cooler air at higher levels. With July recording some of the warmest temperatures ever seen in B.C., combined with an unstable atmosphere due to El Niño conditions coming in from the ocean, conditions have been ripe for lots of lightning.
On top of that, the heat from wildfires can sometimes generate its own storms, causing a "perpetual cycle" of new lightning and fires, Castellan said, adding that the study of this phenomenon is still in its early stages.
Watches versus warnings
Understanding the conditions that can cause a storm is also key to understanding the difference between a watch and a warning issued by Environment Canada.
Watches are issued to make the public aware that there is the potential for a severe storm due to the atmospheric conditions forecast for the day.
A warning is the next step in the process, issued when the storm is actually happening or seems imminent.
For instance, a severe thunderstorm watch will be issued if there is the potential for the development of a thunderstorm with either wind gusts of 90 km/h or greater, hail with a diameter of two centimetres or greater, or heavy rainfall, with 50 millimetres or more within one hour.
A warning would be issued if one or more of those conditions are spotted on radar.
In those cases, Environment Canada urges people to seek shelter with the slogan, "When thunder roars, go indoors!"
More seriously, the agency's own research has recorded an average of two to three deaths and 180 injuries related to lightning annually.
Months of storms to come
Looking ahead, Castellan said the three-month forecast for B.C. is for continued elevated temperatures, which means the risks for both more storms and more fires remain high.
"Probabilities are quite elevated — 80-, 90-per-cent probabilities — that we continue with this warm trend," he said.
"That's the concern, that this is going to continue for several months."
ABOUT THE AUTHOR
