In Northern Ontario, some tornadoes go undetected by ground spotters because of the sparse population and remote landscape; they are often discovered after the fact by aircraft pilots, where aerial observations of damaged forest confirm occurrences. All of Northern Ontario north of a line from Lake Nipigon to Timmins has no weather radar coverage by Environment Canada making it difficult to detect tornadoes in far northern Ontario when they occur.
In Northern Ontario, some tornadoes go unnoticed because of the sparse population and remote landscape, leading to their discovery only after the fact by aircraft pilots who observe damage to forests.  The lack of weather radar coverage in the region north of a line from Lake Nipigon to Timmins makes it difficult to detect tornadoes in far northern Ontario when they occur.