Why smoke makes it more difficult to forecast the weather

A string of predicted 30 C days that pan out to be only 26 or 27 degrees and thunderstorms in the forecast that never come to fruition are some of the oddities you may have noticed in the Calgary weather forecast lately.

Calgary is on track for potentially the smokiest summer it's ever seen — with about 60 more hours needed to break the record set in 2018 — and that smoke makes it tricky for weather forecasters to do their job, accorrding to Kyle Brittain, the Alberta bureau chief for The Weather Network.

One of the tools forecasters use is weather models.

"These supercomputers basically absorb weather conditions," Brittain told The Homestretch on Thursday. "So, you know, temperature, wind speed, humidity, and you get all these different inputs into weather models that help you get a forecast. But one of those is not wildfire smoke."

So when a weather model predicts a high of 32 C, it doesn't account for, say, a thick layer of smoke rolling in that afternoon that could block some of the sun's energy.

"You really miss out on a lot of solar heating and your temperature can really bust," said Brittain. "So meteorologists are also looking at real time observation [and] satellite imagery. If they can anticipate that a smoke plume may roll in, they might have to dial back those daytime highs a little bit."

And when daytime temperatures aren't so high, that complicates thunderstorm forecasts, too.

"Often you need certain temperatures to be reached for thunderstorms to initiate and get going," said Brittain. "There have been many cases this summer where we've been waiting for thunderstorms that didn't occur, and we're really blaming that on the wildfire smoke."

Factoring in the smoke

Including smoke as a predictable measure of the weather forecast is easier said than done. There are some smoke models, like firesmoke.ca and FireWork, Environment Canada's product. But for the most part, these programs are experimental, said Brittain, and usually "hit or miss" for accuracy.

"[It's] very, very tricky to kind of model just how high that smoke is going to go in the atmosphere, because that's going to determine what the winds are going to do to it and what any precipitation might do to it," he said. "I suspect it will always remain quite tricky."

He said that smoke will probably be inputted more into forecasts, moving forward. But in the meantime, meteorologists rely on their human skill.

"You're not just looking at a computer model and saying, 'OK, here's what the models are showing,'" said Brittain. "You're also using pattern recognition in your experience as a forecaster, saying, 'OK, well, we've seen this before.'"

It's something they'll have to keep doing, as Brittain said Calgary shouldn't expect clear blue skies until September.

With files from The Homestretch.