Boaters urged to seek shelter as 'waterspout watch' issued for coastal B.C.

A waterspout estimated to be 200 metres wide at its base off the coast of Lasqueti Island, B.C., in 2017.

Environment Canada has issued a waterspout watch for British Columbia's South Coast, urging mariners to prepare for the potentially dangerous weather phenomena.

Marine weather forecasters say conditions are favourable for the formation of waterspouts in the Strait of Georgia and on the west coast of Vancouver Island as a low-pressure system moves through the region.

"Wind speeds inside the spray ring of a waterspout are 45 knots or higher," the weather office warned Wednesday. "Vulnerable vessels are at risk of damage or capsizing."

Boaters are advised to postpone voyages along the B.C. coast or seek safe harbour until the warning is lifted, if possible.

Armel Castellan, a warning preparedness meteorologist with Environment Canada, says waterspouts are most common in the spring and fall. 

Recent plummeting temperatures in southwestern B.C. suggest the waterspout watch is not out of season, Castellan said.

Similar to tornadoes, waterspouts are whirling columns of air and moisture that can be extremely destructive, according to the U.S. National Oceanic and Atmospheric Administration.

The agency says there are two types of waterspouts – fair weather waterspouts and tornadic waterspouts.

Fair weather spouts typically form in relatively calm conditions and travel little distance, while tornadic waterspouts are associated with severe thunderstorms, hail and high seas, and have the same characteristics as land-based tornadoes, according to authorities.

Fair weather waterspouts typically dissipate quickly if they move onto land, while tornadic spouts that move onshore trigger tornado warnings, according to NOAA.

Authorities in Italy believe a waterspout may have been responsible for the sinking this week of a superyacht in the Mediterranean Sea with 22 people on board.

The bodies of five people, including one Canadian, have since been recovered from the wreckage while 15 others were rescued.

With files from The Associated Press