On Dec 15, 7:48*pm, Stephen Davenport wrote:
On Dec 15, 7:07*pm, Hugh Newbury wrote:





On 15/12/11 18:33, Gavino wrote:

"Stephen *wrote in message
....
It'll be nasty over the northern half of France. Gusts 60-70mph
possible, and 70+ in places, e.g. Brest Peninsula.

8 to 10 metre total sig wave in the Bay of Biscay.

A red alert has been issued in Spain for the Biscay coast of the Basque
region tomorrow. Waves up to 10m are expected.

Please, what is a "sig wave"?

Hugh

--

Hugh Newbury

www.evershot-weather.org

=====================================

Sorry... sig = significant. Total significant wave height -- combined
wind wave and swell. Multiply by about 1.63 for maximum wave.

Stephen.- Hide quoted text -

- Show quoted text -

I always understood it to be mean wave height (trough to crest) of the
highest third of the waves. Certainly, this is how my various books on
sea & surf define it, as do most of the sites showing swell
forecasts.

The wind wave /swell combinations is pretty hard to predict, unlike
the pure swell. Magic Seaweed has a good go, and correctly predicted
the 30' swell of west Cornwall this morning.
http://magicseaweed.com/UK-Ireland-MSW-Surf-Charts/1/

The height of swell generated breaking waves decreases with an onshore
wind (to a point - a severe gale is something else!) A light to
moderate offshore gives the biggest break for a given swell.

Graham
Penzance