Eric, I suggest that the potential for thunderstorms is fully apparent on days
where a thunderstorm might develop. In fact, the the weather bureau forecasts
such, often starting the day before. In addition, thunderstorms develop of a
period of time, meaning they are no surprise when they hit. The problem some
sailors have is that the winds and such are so nice right up until the storm
breaks, so they ignore that it is likely to break in about 30 minutes or
whatever. If a boat and/or sailor are not up to the effort, then the sailor
should makes plans as how to handle the situation. Thunderstorms can produce
winds of 90+ knots for a short period of time. You need to get your sails down
and get yourself in a protected from the north cove and/or give yourself a mile
or more of searoom to the south.

Your trig may be correct as far as the altitude is concerned but
practically speaking, you can rarely see anything 300 nm away.

I would agree they don't tend to come up on you in 10 minutes but it
may take a lot longer than 10 minutes to get to a safe
harbor/dock/anchorage.

Eric

(JAXAshby) wrote in message
...
There are lots of places where people sail and it's difficult to see a
thunderstorm coming

bull****. Thunderstorm clouds go as high as 60,000 feet sometimes, which
means
they can be seen up to 300 nm away. Even 10,000 foot high clouds can be
seen
up to 122 nm away. Can't see that coming?

And there are many places where the potential
exists every day in the summer

thunderstorms don't form inside of 30 seconds. You *KNOW* they are coming,
if
one just pays attention.