Which forecast?

[Guest]

Monday's 0535 forecasts as broadcast by BBC Radio 4 -
Shipping: Wight, Portland, Plymouth W or SW 6 decreasing 4 or 5
Inshore Waters (in same BBC broadcast): St Catherine's Point to Land's End SW 6 to gale 8 decreasing 4 or 5

If sailing off, say, Dartmouth which one is right - a strong wind or a gale?

 

[billmacfarlane]

They look much the same forecast. The part of the Inshore forecast that refers to the F8 might be due to the wind gusting round headlands. If the wind is an F6 , then you can easily get gusts of F8 round headlands. Personally I always take the worst forecast as the one to believe.

 

[jimi]

Absolutely .. that way you're rarely disappointed. I speak from experience here having in the past hunted around all the forecasts until I find one I like!

 

[bedouin]

On the contrary - I have often been disappointed that way.

I find that the Met forecast often forecasts winds signficantly stronger than are actually experienced - as a result I've missed several nice F4/5 sailing days, waiting for the forecast F7/8 that never materialised.

For me the Met Office are guilty of "crying wolf" - they forecast too many gales that just don't happen, as well as missing the odd hurricane.

 

[Chris_Stannard]

It all goes back to a forecast is just that, a forecast is someones view of what could happen based on the evidence he has, which is likely to be up to six hours old. I was trained in met many years ago and was told that if you are good you will roughly corerect 60% of the time. The bigger the area you forecast for the less likely you are to be right for a particular place.

The statement I believe least is the decreasing later bit. Last Friday I came back from France with a forecast of 4 to 5 possibly 6 at first decreasing to 3 to 4 later.
I set off at 7.30 BST and got the 6 the whole way over.

Incidentally Bill is right, both forecasts mean the same thing, and the coastguards forecast, which is usually much more local, will say 5 to 6 possibly 7 round exposed headlands.

Chris Stannard

 

[Langouste]

If sailing off Dartmouth stick to the inshore forecast. Just take a look at the size of the seaareas to see the vast areas of green that the shipping forecast has to cover.

 

[Guest]

I find all the replies interesting, but none has answered the question I was asking.
If the inshore waters forecast is for F8 anywhere within its 12 miles offhsore area why not in the shipping forecast too.? After all, the headlands you speak of are in both areas, the forecasts come from the same office and so should be the same for both areas, shouldn't they? I could have understood it if the sea area forecast was for winds stronger than in the inshore waters, but not the other way around.

 

[Guest]

Cornishman 983 writes

>I find all the replies interesting, but none has answered the question I was asking.
If the inshore waters forecast is for F8 anywhere within its 12 miles offhsore area why not in the shipping forecast too.?

The basic problem is the size of the sea area. When they talk about force 4/5 in a sea area that is the general condition for the entire area. Sometimes you hear something like Rockall 5 or 6, possibly gale 8 in North later. They are trying to be helpful. In a smaller area you can give a better prediction based on your model for that small area.

What do you believe? Ah, now that is a different question. Sailing from Calais to Dover the BBC Weather Forecast was for a NorthEasterly 4/5. Perfect. We actually got a westerly 8. I think you take all forecasts with a huge pinch of salt. It would be foolish to ignore a gale warning but in sheltered waters we often have enough warning to scurry for shelter once things start to build.

Regards


Fred

 

[vyv_cox]

The accuracy of the forecast also depends very much on the synopsis. If you are going to be close to the centre of a low it is too much to expect that the wind will behave according to forecast, either in speed or direction. If there is a low off SE Iceland and you are in Thames, the forecast will probably be more accurate. Except that the forecast doesn't normally include fronts, which cause variations in speed of several forces and direction more than 90 degrees.

(I realise that this still does not answer the original question. Perhaps the inshore and offshore forecasts are generated by two different people. One an optimist, the other a pessimist? Maybe quite different sources of information, for contractual reasons?)

 

[Chris_Stannard]

A Sea Area forecast is just that, out in the middle where land effects can be excluded form the picture. An inshore forecast has to take into account land effects.

In the Solent in the summer you can have a Sea Area forecast of N/NE 3 to 4 and an inshore forecast of Sea Breezes from the South veering to South West 5 possibly 6 in the late morning to afternoon. both are right but the latter is a local affect caused by the land heating up. This usually only extends about 10 miles offshore so would not be of interest to some one up mid channel

Chris Stannard