What are the Shipping Forecast areas, when is it broadcast and what music is used on BBC Radio 4?
The life-saving forecast vital to sailors and fishermen is also a source of comfort for millions of radio listeners
THE Shipping Forecast, broadcast four times a day on Radio 4, is a national institution - although to many it is little more than incomprehensible words and numbers.
But it is, in fact, a vital tool for Britain's sailors and fishermen navigating our rugged coast. Here's how it works...
What is the Shipping Forecast?
The Shipping Forecast is broadcast on longwave Radio 4 at four precise times a day: 0048, 0520, 1201 and 1754.
Using a unique and detailed scale system, it tells sailors and fishermen on Britain and Ireland's coastal waters what weather to expect in the coming hours.
The forecast was first developed by the world's first weatherman, Vice-Admiral Robert FitzRoy in February 1861.
He created it in response to a passenger ship being wrecked off Anglesey two years earlier, killing 450 people.
It was first published in newspapers in 1867, making 24 August 2017 its 150th birthday.
The forecast was broadcast in its familiar radio format for the first time in 1911, with pauses introduced for the First and Second World Wars.
Using a strict 350-380 word limit, the forecast follows a set pattern as the announcer moves clockwise around the various areas (see below) of sea around the British Isles.
A general synopsis names the area and gives the air pressure and its prediction before each forecast is then read out.
Wind direction comes first before the Beaufort scale is used to measure the force, with the number 1-7 signifying light to medium winds, while winds of force 8 or more are given names (Gale 8, Severe Gale 9, Storm 10, Violent Storm 11 and Hurricane force 12).
Changes in wind direction are given as "veering" meaning a clockwise change and "backing" meaning an anti-clockwise change.
Precipitation (rain), if any, is then explained, before visibility. "Icing" warnings may also be forecast if temperatures are very low and winds are high.
It all combines to result in a typical forecast reading like :"Hebrides. Southwest gale 8 to storm 10, veering west, severe gale 9 to violent storm 11. Rain, then squally showers. Poor, becoming moderate".
On Friday, May 30, 2014, for the first time ever the BBC failed to transmit the Shipping Forecast at 0520.
While the announcer read the forecast, producers failed to switch from the BBC World Service back to Radio 4, meaning listeners could not hear it.
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What are the areas the Shipping Forecast covers?
The divisions of the sea around the British Isles are named after sandbanks, channels, estuaries, islands, coastal shapes, towns, islets, peninsulas, bays and capes, while FitzRoy is named after the forecast's inventor.
The list of sea areas is as follows, going from clockwise from the North East: Viking, North Utsire, South Utsire, Forties, Cromarty, Forth, Tyne, Dogger, Fisher, German Bight, Humber, Thames, Dover, Wight, Portland, Plymouth, Biscay, Trafalgar, FitzRoy, Sole, Lundy, Fastnet, Irish Sea, Shannon, Rockall, Malin, Hebrides, Bailey, Fair Isle, Faeroes and Southeast Iceland.
The last broadcast of the Shipping Forecast at 0048 traditionally comes after the playing of "Sailing By", an orchestral piece by Ronald Binge.
It was first used to fill the gap between the previous programme ending and the Shipping Forecast's broadcast time, but now every effort is made to play a part of the piece before the forecast begins.
The forecast is then followed by the National Anthem before the BBC World Service takes over at the 1am pips.
How long has the Shipping Forecast been broadcast?
November 30 marked 150 interrupted years of the Shipping Broadcast.
It is believed to be the longest running continuous weather forecast in the world.
The shipping forecast is now 93 per cent accurate overall, and the forecast for inshore waters is about 97 per cent accurate.