solenthandbook.com 24 WEATHER WEATHER good quality. If all 3 say something different then my confidence in the forecast goes down – and this is a really useful bit of information, as it’ll affect how ambitious your plan for that day is. Also, a low confidence forecast makes the use of your barometer, wind instruments & physical observations (looking for clouds, feeling a change in air temperature and is my tea getting diluted when I’m on deck) even more important. One thing to remember with “high resolution” forecasts is that they are only as good as the models that underpin them. In the Rio Olympics the single most important feature was Sugar Loaf, at what was usually the windward end of the Medal Race course. This is a 396m high huge dome-shaped rock – but it’s much less than 1km wide and doesn’t show up at all on any of the land models used for weather forecasting! This is not a criticism, it’s a function of a computer model. In general the smallest thing that can be simulated by a model is 3-4 times the size of the grid used. This means that a 1km resolution forecast won’t see anything that is less than about 3-4 km across – which means that effectively the Western Solent doesn’t exist as far as weather models go. Back to my 15 minute forecast – by now I’ve got a good idea of what’s forecast to happen through the day weather-wise, which I’ll write down in my logbook if I’m off sailing. I tend to go to the Inshore Waters forecast and the Shipping Forecast, both available on the Met Office site if I’ve missed the broadcast, to look specifically for sea state and as a confirmation of the weather. I’m up to 10 minutes now. The thing with sailing around the Solent though is that a lot of the weather features are what I like to call “sub-grid”, i.e. they’re caused by land features which, as we’ve seen, don’t show up on the weather models. The most civilised way to sort through these is to stop the forecast clock long enough to brew another mug of tea (other beverages are available) and then sit at the nav desk with your forecast, a chart and a pencil, and sketch out the incoming wind going through any gaps and around or over any obstacles. This should allow you to predict, for example, funnelling through Hurst Narrows with a SW; the way a W tends to turn in to a WNW going down Southampton water; and that in a strong E it’s best not to leave Cowes with too much sail up even if there’s only 10 kts in the marina. We’re now at the end of our 15 minutes – and not only do you have a good forecast firmly in your mind you also understand what the weather is that’s coming through. This means that as the day goes on and, say, the front slows down and you don’t get the lowering clouds coming through as you initially expected, then you can confidently say that the veering wind will come along later, or you’ve got a bit more time before the showers hit. This way the knowledge you gave yourself at the beginning of the day will translate into better understanding of what’s going on and therefore what is still to come. And you’ve had a mug of tea in peace. Make the Solent your destination for full- service boat repairs and maintenance. Find specialist support and equipment sales, so you can spend more of your time on the water. boatcare.co.uk SBS TRAILERS Onsite hardstanding Engine servicing for inboard and outboard Yacht finishing and paint repairs Antifouling and coppercoat Hull polishing and GRP repairs Teak decks and bespoke carpentry Seacocks, winches and bow thrusters Supply of specific and general chandlery parts Major suppliers of: 02380 178691 [email protected] 02392 584374 [email protected] boatcare | Deacons Marina boatcare | Haslar Marina Paul Wyeth