Environment Canada has issued a tornado watch for portions of northwestern Ontario – with several of the communities still reeling from recent heavy rainfall.

On Monday, the agency initially issued the watch for the communities of Fort Frances, Emo, Rainy River, Atikokan, Ignace, English River, Seine River Village, and Mine Centre. An update has since lifted the watch on some areas, but Ignace-English River, Atikokan-Shebandowan-Quetico Park, Upsala-Raith, and Seine River Village-Mine Centre are still on tornado watch.

It was noted that conditions in the listed areas are favourable for the development of severe thunderstorms – which in turn could produce tornadoes, as well as strong winds, hail, and more heavy rain.

The Weather Network has advised residents living in the potentially affected regions to monitor the forecasts closely and prepare to take shelter should the worst come to pass. Residents in northwestern Ontario have also been warned that the thunderstorms capable of creating brief, fast-moving tornadoes can also conceal the tornadoes in rain, making them difficult to discern from afar.

The weather news outlet offered a reminder that a tornado watch “does not mean a tornado has been spotted;” it instead refers to when Environment Canada observes that atmospheric conditions could possibly lead to a tornado’s formation.

Read more: Saturday derecho damages two provinces, leaves 10 dead

The tornado watch declaration comes about a week after a derecho storm event slammed through Ontario and into Quebec. Generating winds of up to 132 km/h, the storm damaged multiple homes and cars, as well as knocked out the power of as many as 900,000 homes in both provinces.