What to know
- Environment Canada lifted Toronto’s orange snowfall alert Thursday afternoon, signalling the worst of the storm has passed, though hazardous conditions may still linger.
- Residents questioned why the alert remained yellow for so long, despite severe conditions, prompting clarification about how the new colour-coded system works.
- Meteorologists say forecasts evolve as data improves, with snowfall amounts, impacts, and storm behaviour only becoming clear once systems fully develop.
A local meteorologist is sharing insights about Environment Canada’s colour-coded system after residents questioned the time it took to update snowfall alerts amid a major storm.
After up to 35 cm of snowfall piled up Toronto’s streets on Thursday, Environment Canada lifted its orange snowfall alert for the city as of 3:28 p.m.
Read More
Environment Canada’s Program Meteorologist Monica Vaswani tells Now Toronto that although the end of the alert signals that the bulk of the snowstorm is now over, it doesn’t mean that its impacts will suddenly be gone.
“At this point, you’re just looking at maybe some remnant flurries. But basically, the worst of the storm has moved through and passed,” she said on Thursday.
“The reason that we had the orange-level [alert] is because we expect impacts to persist throughout this day and into the next day as well. So, even though the snow has ended, roads could still be in very bad conditions. There’s still going to be lots of, possibly, ice underneath the snow…So, it’s still not safe, essentially, to go outside.”
ALERT RAISES QUESTIONS AMONG LOCALS
Launched two months ago, the new system assigns yellow, orange or red alerts based on the expected severity and impact of weather events.
According to Vaswani, Environment Canada first issued a yellow alert around 1:44 p.m. on Wednesday, predicting 10–20 cm of snow would be hitting the city.
The alert was then updated to orange at 7:53 a.m. on Thursday, as the weather agency changed the estimate to 20–35 cm by this afternoon. This means it took the agency 18 hours to upgrade the alert.
Read More
After the storm caused multiple disruptions, including school closures, transit delays, and service disruptions, some residents raised questions about the time it took to upgrade the alert, wondering why the agency took so long to update the alert.
“I’ve got questions about the new Environment Canada colour-coded warning system when a yellow snow warning is in place for a 30cm storm that cancels all schools in Canada’s largest city. It’s brutal outside, 50km/h winds, -25 C wind chills. If [there is] no orange warning now, then when?” one user wrote on X, before the alert was updated.
Other users in the comments agreed, also raising concerns about the system.
“Also having 10-20cm as the main warning up until at least 11pm when I went to bed. People see that and think, ‘meh,’” another person said.
“The warning has been utterly confusing,” a different user added.
ENVIRONMENT CANADA CLARIFIES NEW SYSTEM
Vaswani explained that snow-related Environment Canada’s colour-coded alerts depend on a range of factors, including the amount of snow expected and its impact on the local community.
While yellow alerts apply to snow events where 15–30 cm of snow is expected within 24 hours, orange alerts indicate between 30–60 cm of snow within that period. Additionally, while the impacts of a yellow-coded snowstorm are expected to lift off in a day, those of an orange-coded storm could last longer.
“If we expect widespread travel impacts, widespread highway closures, stranded vehicles for long periods of time, ability outages for long periods of time, that can cause us to go into that orange level,” she added.
In this case, the meteorologist said the alert was originally yellow because initial forecasts indicated only up to 20 cm of snow, with lesser impacts or closures. But come this morning, the forecast was updated, and with it, the colour of the alert.
WHY DO FORECASTS CHANGE?
According to Vaswani, Environment Canada determines forecasts based on:
- Human meteorologists intakes, who use their expertise in the atmosphere and the environment to predict weather conditions;
- Computer models that help them determine where low pressure systems will be installed.
For this particular forecast, the meteorologist said machines had certain difficulty determining the impact of the storm.
“It wasn’t really until yesterday that they all started to sort of come together and give the same message, which was an increasingly intense snowstorm for much of southern Ontario, including the GTA,” she said.
“The second thing is, there’s also these, basically little areas or little bands of particularly heavy snow that the models cannot pick up on in advance, and we sort of have to wait until the event starts to see where those set up.”
Due to these challenges, the agency was only able to determine the real impact of the storm by this morning, when the alert was then updated, she said.
