At 0048 on most weekday mornings, BBC Radio 4 broadcasts the Shipping Forecast, a four-minute recitation of conditions and predictions for the 31 sea areas around the British Isles. The forecast begins, when warranted, with the words And now the Shipping Forecast issued by the Met Office on behalf of the Maritime and Coastguard Agency. The voice is calm. The structure is unvarying since 1924.
Greer MacLennan, who keeps a 23-foot gaff-rigged sloop called Maggie May on a half-tide mooring at Kippford on the Solway Firth, listens to the late forecast most nights from a chair in her front room, ten miles inland from the boat. She has done so since she bought Maggie May in 2011. She does not own a printout of the sea areas. She knows them by ear.
The Solway Firth sits inside the sea area called Irish Sea, bounded by Lundy to the south, Malin to the north, and Rockall to the west across the open Atlantic. The forecast for Irish Sea, on a typical winter night, will describe wind direction, wind force, weather state, and visibility in that order, in compressed telegraphic style: Irish Sea. Southwest 6 to gale 8, occasionally severe gale 9 later. Squally showers. Moderate or good, occasionally poor.
The gale warning, when issued, comes first. MacLennan can tell from the opening line whether her plans for the next day are intact. A gale warning for Irish Sea means winds of force 8, 34 to 40 knots sustained, with seas she will not take Maggie May out into. A severe gale 9 means winds of 41 to 47 knots. A storm 10, 48 to 55 knots, occurs perhaps three or four times a year in her area.
The Beaufort scale, on which the forecast depends, is not arbitrary. Admiral Sir Francis Beaufort devised it in 1805 to standardize Royal Navy weather logs, and the scale's persistence in the marine forecast is a small monument to a system that worked. Each force corresponds to observable sea conditions as much as to wind speeds, and a competent skipper learns to read the sea as a calibration of the forecast.
MacLennan has a small notebook in which she has recorded, since 2014, the forecast prediction for the Irish Sea against what she actually observed on the days she sailed. The notebook contains 312 entries. The forecast has been substantially correct, by her loose criterion, in 281 of them, about 90 percent. The errors cluster around frontal passages where the timing was off by a few hours but the conditions were correctly predicted.
Her criterion for substantial correctness is that the actual conditions fell within plus or minus one Beaufort force of the prediction and the actual wind direction was within 30 degrees of the predicted. The Met Office's own internal accuracy targets for the Shipping Forecast are tighter than that, but the practical question for a skipper is whether the prediction was actionable, and within one force is actionable.
The visibility terms in the forecast are technical. Good means more than 5 nautical miles. Moderate means 2 to 5 nautical miles. Poor means 1,000 metres to 2 nautical miles. Very poor means less than 1,000 metres. The terms are unromantic. They were chosen to be unambiguous in a context where ambiguity costs lives.
The temporal modifiers carry weight. Imminent means within six hours of the forecast time. Soon means within 6 to 12 hours. Later means more than 12 hours. Backing means the wind direction is shifting counterclockwise. Veering means clockwise. A skipper who confuses backing and veering on the Solway can plan a passage in the wrong direction.
MacLennan teaches a Saturday morning seminar twice a year at the Solway Yacht Club on reading the forecast. She begins by playing a recording of the 0048 broadcast from a random night and asking the assembled students to write down what they would do the next day if they were planning to sail. The answers vary widely. The exercise teaches her, and them, that the forecast is heard differently by different ears.
She does not insist on a single right interpretation. She insists on a defensible interpretation. The forecast is data, the student is the analyst, and the analyst must be able to explain to anyone else why the chosen action followed from the data.
Gale warnings on the Solway are issued more often than at sea-area-average frequency. The Firth's geometry funnels Atlantic depressions through a relatively narrow opening between Galloway and Cumbria, and the resulting wind acceleration can push a force 7 prediction in Irish Sea up to a local force 9 inside the Firth itself. Local skippers learn to add a force when planning, particularly on a westerly.
The literary quality of the Shipping Forecast is real but secondary. Carol Ann Duffy wrote a poem called Prayer in 1993 that ends with the lines Darkness outside. Inside, the radio's prayer / Rockall. Malin. Dogger. Finisterre. The poem captured a national affection for the forecast as a kind of secular liturgy. MacLennan likes the poem. She does not let it interfere with her reading.
The Shipping Forecast was nearly cut from BBC Radio 4 in 1995 and again in 2010. Both times public protest reversed the decision. The forecast has economic value to a small number of working fishermen and small-boat skippers, and cultural value to a much larger number of people who listen for the sound of it, but the BBC's defenders argued both times that the cultural and the practical were difficult to separate.
MacLennan thinks they were right. She has watched friends who do not sail listen to the forecast for years and develop, through that listening, a kind of weather literacy they did not know they had. They cannot recite the sea areas in order. But they know what a force 8 means. They know what poor visibility means. They know what backing means.
The Maritime and Coastguard Agency, which authorizes the forecast, also issues separate inshore waters forecasts that cover the British coast in detail to about 12 nautical miles offshore. The inshore forecasts use less compressed language and add information on sea temperature and sea state. MacLennan reads the inshore forecast for the Mull of Galloway to St. David's Head every morning at 0500 before she decides whether to drive to the boat.
The 0048 forecast and the 0500 inshore forecast usually agree. When they disagree, MacLennan trusts the inshore for the next 24 hours and the Shipping Forecast for what comes after. The disagreement is informative. It usually means a front is moving faster or slower than the global model predicted.
She has been wrong about the forecast twice in fifteen years in ways that cost her something. Once she sailed in a force 7 that became a force 9 by mid-afternoon, and she lost a sheet block and tore a sail. Once she stayed in for a forecast force 8 that turned out to be a benign force 5, and she missed a Saturday she would have enjoyed.
Both errors are tolerable. Neither involved the Coast Guard. Neither involved injury. MacLennan considers two errors of that magnitude in fifteen years to be approximately the right error rate for an attentive skipper. A skipper who never makes the first mistake is staying in too often. A skipper who never makes the second is staying out too long.
The forecast does not protect her. It gives her information. She decides what to do with it. The decision is hers, and the responsibility is hers, and the next morning the radio at 0048 reads the next day's forecast in the same calm voice, and the loop begins again.
Filed under
