I sail in Lake Ontario on a Hunter 36, based in the Outer Harbour Marina in Toronto. This is my first full season of sailing. This past weekend my wife and I made the 25 NM trip south across the lake to Niagara-on-the-Lake for an overnight stay. We had beautiful weather both ways (although a little more wind would have been nice).
We almost didn't make the trip because the forecast was calling for "Chance of thunder showers" for most of the time we would be sailing. I checked the Environment Canada radar before each crossing and everything looked clear, and as it turned out everything was fine. But those forecasts made me very nervous and had me constantly scanning the skies for approaching thunderheads (which never materialized).
How dangerous is it to be caught out on Lake Ontario if a thunder storm does develop? I'm fairly confident in my ability to handle the boat in the rain/wind/waves that might be encountered (assuming I have enough advance notice to get the sails properly reefed or even dropped completely). How worried should I be about lightning?
How seriously should I take warnings of 'chance of' thunder showers/thunder storms? Did I just get lucky over the weekend? What sources of weather forecasts are reliable in my area? I check the Marine Forecasts for Lake Ontario, and use the Environment Canada weather radar. Most of the 'possible thunder shower' warnings were coming from The Weather Network, it occurred to me that maybe they are very 'conservative' with their predictions, preferring to predict possible rain and have the weather turn out to be nice than the other way around? That seems generally sensible, but it almost cost me a very nice weekend of sailing.
As I understand it; A 30% chance of thunder showers means that there is a 30% chance that any one place in the forecast area will be hit by a thunderstorm. In other words, the thunder showers will most probably be out there, but, there is only 1/3 of a chance they will come over you.
I also look for the marine forecast that says high wind, dangerous lightning, hail, or waves that will be X% higher than predicted. That stuff often comes with small craft advisories.
A smart phone is a big help. I use Wunderground.com
As for getting struck by lightening, I'm in Fisher's Island Sound, CT. so I don't know if being in fresh water is a factor. I have a keel stepped mast and getting anywhere near it in lightening makes me nervous, to say the least.
Then again, sailors drown, get run down by power boats, get hit in the skull by a boom, and do untold damage to their livers every year. I have yet to read about one getting hit by lightening. Sailboats yes, sailors?.... so, of course, I get the bright idea to google it...
Laser sailor gets struck by lightning | The Daily Sail