Earlier this month, Environment and Climate Change Canada (ECCC) launched a new severe weather alert system that relies on polygons to distribute weather warnings more accurately. Thanks to new autonomous tech, the alerts will also be issued faster than ever before.
Prior to the polygon-based warning system, severe weather alerts for thunderstorms and tornadoes would be issued to anyone within the predetermined alert zone where the storm was passing through. But because these zones are large and geographically spread out, residents who weren’t at risk would still be alerted. “This can lead to alert fatigue and people ignoring critical information that can keep them safe,” says Samantha Bayard, ECCC spokesperson.
So how exactly do polygons improve weather warnings? According to Bayard, the key is precision.
“By using free-form polygons, forecasters can more accurately define the area under threat, helping ensure that alerts are targeted to those most likely to be impacted,” she says. “The move to more precise warning areas also introduced new warning capabilities, including the ability for warnings to overlap and for multiple warning areas to be merged or split as conditions change.”
One example from ECCC’s news release demonstrates what layered alerts could look like. Over Calgary, a red tornado warning polygon is layered over an orange severe thunderstorm warning polygon, and a separate yellow warning polygon is also visible. In the background is a blanket yellow severe thunderstorm watch that was issued using the pre-determined alert zone.
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According to ECCC, severe thunderstorm and tornado watches will continue to be issued in line with larger alert zones, as will other types of weather alerts such as rain or heat warnings. For now, polygons will only be used for severe thunderstorm and tornado warnings (not watches), but Bayard says ECCC is still evaluating if other warning types could benefit from being more targeted.
The implementation of semi-automated text generation for weather alerts will also improve warning delivery time. “Under the previous system, forecasters’ only avenue to get information specific to the storm was through writing that information on the fly, which required time to manually curate and type out,” says Bayard.
Now, storm information can be generated simultaneously in both English and French and sent directly to users. “Ultimately, the goal is for people in Canada to always take severe weather alerts seriously and act swiftly to keep themselves, their loved ones, and their property safe,” says Bayard.
ECCC’s polygon-based warning system is the most recent development in a larger effort to modernize the public weather program. “Last year ECCC introduced colour-coding to our weather alerts, and we will continue to roll out improvements to weather forecasting and alerting over the next few years,” says Bayard. The three-tier system, which ranks weather alerts as yellow, orange, or red based on severity, was launched in November.
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