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uk.sci.weather (UK Weather) (uk.sci.weather) For the discussion of daily weather events, chiefly affecting the UK and adjacent parts of Europe, both past and predicted. The discussion is open to all, but contributions on a practical scientific level are encouraged. |
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#1
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As of 11.30 am on the 15th Dec the current News 24 forecast can be
summarised as follows for England and Wales. (Apologies to Scottish and N.I members but this one seems to be missing you, largely). Basically the snow is forecast for Wales in the early hours tomorrow and then spreads to the Midlands in the morning and then Central Southern England. The SW, London, East Anglia and the S.E should miss the snow with rain being generally forecast for these areas though no doubt higher ground in these regions may see a short spell of wet snow. The striking thing was there was no mention of strong winds or gales at all other than "over the Channel in Northern France." Dave |
#2
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On Dec 15, 11:56*am, Dave Cornwell wrote:
As of 11.30 am on the 15th Dec the current News 24 forecast can be summarised as follows for England and Wales. (Apologies to Scottish and N.I members but this one seems to be missing you, largely). Basically the snow is forecast for Wales in the early hours tomorrow and then spreads to the Midlands in the morning and then Central Southern England. The SW, London, East Anglia and the S.E should miss the snow with rain being generally forecast for these areas though no doubt higher ground in these regions may see a short spell of wet snow. The striking thing was there was no mention of strong winds or gales at all other than "over the Channel in Northern France." Dave Usually the strongest winds will be to the right hand side of the storm's direction - and if the storm is moving at a fair lick it means the "left-hand-side" winds - i.e. those on the south coast will tend to be ameliorated. Not always the case when the storm is moving slowly - so if the storm track has moved further south, then the south coast may well be out of the firing line. Richard |
#3
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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. Stephen. |
#4
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On Dec 15, 2:11*pm, Stephen Davenport wrote:
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. Stephen. Sig Wave height reached 27' at Sevenstones early afternoon, though it's decreased significantly now. Waves up to 9 metres along the north Cornish coast recently http://www.channelcoast.org/data_man...arts/?chart=76 Probably cleaning up a bit now. This pic is worth a look, taken from the top of the lifeboat slip http://www.sennen-cove.com/lbtdy.htm . Let's hope they don't have to launch. Graham Penzance |
#5
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"Stephen Davenport" 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. |
#6
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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 |
#7
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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. |
#8
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On 15/12/11 19:48, Stephen Davenport wrote:
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. Thanks Stephen. Hugh |
#9
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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 |
#10
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Graham Easterling wrote:
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. Yes, it's the average height of the one-third highes waves in the sea state. For example, if you have a wave measuring device at a point and you measure the crest to trough height of 300 successive waves passing that point the significant height is the average height of the 100 highest waves. The significant wave height is the standard way of describing a sea state. The multiplier to get the most probable height of the highest individual wave is dependent on the period of time considered. The multiplier of 1.63 is applicable to about a 20-minute period whereas a multiplier of 1.86 is applicable to a 3-hour period. In other words, for any constant level of significant wave height the most probable corresponding maximum individual wave height increases with increasing time. That is, of course, only the most probable value. In the real world there's a great deal of variability and it is not at all uncommon to find cases in measured data where the maximum individual wave height is double the significant wave height, or even higher. -- Norman Lynagh Tideswell, Derbyshire 303m a.s.l. |
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