Particle.news
Get it on Google Play
Download on the App Store
6 ARTICLES
·
last mo.

Canada Moves to Polygon-Based Tornado and Severe Thunderstorm Warnings

Officials say the change should cut mobile over-notifications by sending faster, more precise bilingual warnings to people actually in a storm’s path.

Environment Canada said the new alert system will allow for more precision.
A new storm warning system will target alerts specifically to the area forecasters think will be hit rather than issue alerts to a broad area.
A lightning bolt strikes the CN Tower during an electrical storm in Toronto, early Thursday July 14, 2016. Heavy winds and rain brought down trees and power lines overnight in Toronto. THE CANADIAN PRESS/Mark Blinch
A tornado on July 18 caused damage in parts of west-central Alberta. Environment and Climate Change Canada has an updated alert system for tornadoes and severe thunderstorms.

Overview

  • Environment and Climate Change Canada rolled out polygon-based warnings for severe thunderstorms and tornadoes on Tuesday, Aug. 11, 2026, enabling forecasters to draw precise perimeters around the area expected to be hit.
  • Forecasters can create and update multiple or overlapping polygons in real time and the system will generate semi-automated bilingual text that can list up to 10 nearby locations ordered by time of arrival.
  • Targeted push alerts will be sent through mobile networks and the WeatherCAN app while radio and television will continue to use legacy zone-based broadcasts during a transition period for third-party platforms.
  • The change applies only to severe thunderstorm and tornado warnings so watches and other alerts such as heat warnings will remain tied to pre-determined zone areas.
  • Officials and experts expect fewer unnecessary Alert Ready notifications and less alert fatigue if platforms and the public adopt the new format, noting the United States has used polygon warnings since 2007 with lower false-alarm rates.