The Great Storm of 1987

Falling trees and masonry damaged or destroyed buildings and cars. Numerous small boats were wrecked or blown away. A ship capsized at Dover, and a Channel ferry was driven ashore near Folkestone.

The storm killed 18 people in England and at least four more in France. The death toll might have been far greater had the storm struck in the daytime.

Four or five days before the storm struck, forecasters predicted severe weather on the following Thursday or Friday. By mid-week, however, guidance from weather prediction models was somewhat equivocal. Instead of stormy weather over a considerable part of the UK, the models suggested that severe weather would reach no farther north than the English Channel and coastal parts of southern England.

During the afternoon of 15 October, winds were very light over most parts of the UK. The pressure gradient was slack. A depression was drifting slowly northwards over the North Sea off eastern Scotland. A col lay over England, Wales and Ireland. Over the Bay of Biscay, a depression was developing.

The first gale warnings for sea areas in the English Channel were issued at 0630 UTC on 15 October and were followed, four hours later, by warnings of severe gales.

At 1200 UTC on 15 October, the depression that originated in the Bay of Biscay was centred near 46° N, 9° W and its depth was 970 mb. By 1800 UTC, it had moved north-east to about 47° N, 6° W, and deepened to 964 mb.

At 2235 UTC, winds of Force 10 were forecast. By midnight, the depression was over the western English Channel, and its central pressure was 953 mb. At 0135 on 16 October, warnings of Force 11 were issued. The depression now moved rapidly north-east, filling a little as it did, reaching the Humber estuary at about 0530 UTC, by which time its central pressure was 959 mb. Dramatic increases in temperature were associated with the passage of the storm's warm front.

It's clear that for sea areas, warnings of severe weather were both timely and adequate. Forecasts for land areas, however, left much to be desired.

During the evening of 15 October, radio and TV forecasts mentioned strong winds but indicated that heavy rain would be the main feature, rather than strong wind. By the time most people went to bed, exceptionally strong winds hadn't been mentioned in national radio and TV weather broadcasts.

Warnings of severe weather had been issued, however, to various agencies and emergency authorities, including the London Fire Brigade. Perhaps the most important warning was issued by the Met Office to the Ministry of Defence at 0135 UTC, 16 October. It warned that the anticipated consequences of the storm were such that civil authorities might need to call on assistance from the military.

In south-east England, where the greatest damage occurred, gusts of 70 knots or more were recorded continually for three or four consecutive hours.

During this time, the wind veered from southerly to south-westerly. To the north-west of this region, there were two maxima in gust speeds, separated by a period of lower wind speeds. During the first period, the wind direction was southerly. During the latter, it was south-westerly. Damage patterns in south-east England suggested that whirlwinds accompanied the storm. Local variations in the nature and extent of destruction were considerable.

Comparisons of the October 1987 storm with previous severe storms were inevitable. Even the oldest residents of the worst affected areas couldn't recall winds so strong, or destruction on so great a scale.

• The highest wind speed reported was an estimated 119 knots (61 m/s) in a gust soon after midnight at Quimper coastguard station on the coast of Brittany (48° 02' N 4° 44' W)
• The highest measured wind speed was a gust of 117 knots (60 m/s) at 0030 UTC at Pointe du Roc (48° 51' N, 1° 37' W) near Granville, Normandy
• The strongest gust over the UK was 100 knots at Shoreham on the Sussex coast at 0310 UTC, and gusts of more than 90 knots were recorded at several other coastal locations
• Even well inland, gusts exceeded 80 knots: 82 knots was recorded at London Weather Centre at 0250 UTC, and 86 knots at Gatwick Airport at 0430 UTC (the authorities closed the airport)

TV weather presenter Michael Fish will long be remembered for telling viewers, the evening before the storm struck, that there would be no hurricane. But he was unfortunate. Fish was referring to a tropical cyclone over the western part of the North Atlantic Ocean that day. This storm, he said, would not reach the British Isles - and it didn't.

It's worthwhile to consider whether or not the storm was, in any sense, a hurricane - the description applied to it by so many people.

In the Beaufort scale of wind force, Hurricane Force (Force 12) is defined as a wind of 64 knots or more, sustained over a period of at least 10 minutes. Gusts, which are comparatively short-lived (but cause much of the destruction) are not taken into account. By this definition, Hurricane Force winds occurred locally but were not widespread.

The highest hourly-mean speed recorded in the UK was 75 knots, at the Royal Sovereign Lighthouse. Winds reached Force 11 (56-63 knots) in many coastal regions of south-east England. Inland, however, their strength was considerably less. At the London Weather Centre, for example, the mean wind speed did not exceed 44 knots (Force 9). At Gatwick Airport, it never exceeded 34 knots (Force 8).

The Great Storm of 1987 did not originate in the tropics and was not, by any definition, a hurricane - but it was certainly exceptional.

South-east of a line extending from Southampton through north London to Great Yarmouth, gust speeds and mean wind speeds were as great as those which can be expected to recur, on average, no more frequently than once in 200 years. So, comparison with the great storm of 1703 was justified. The storm of 1987 was remarkable for its ferocity, and affected much the same area of the UK as its 1703 counterpart.

Northern Scotland is considerably closer to the main storm tracks of the Atlantic than south-east England, so storms as severe as October 1987 can be expected far more frequently than once in 200 years. Over the Hebrides, Orkney and Shetland, winds as strong as those which blew across south-east England in October 1987 can be expected once every 30 to 40 years.

The 1987 storm was also remarkable for the temperature changes that accompanied it. In a five-hour period, increases of more than 6 °C per hour were recorded at many places south of a line from Dorset to Norfolk.

Especially rapid and large was the increase at South Farnborough in Hampshire, where the temperature rose from 8.5 °C to 17.6 °C in 20 minutes. The return frequency for a temperature increase this rapid is, like the return frequency for the wind strengths that occurred in the storm, about once in 200 years. Across southern England, rapid increases in temperature were followed by sharp decreases.

Ahead of the storm, barometric pressure had fallen rapidly, but neither the magnitude of the fall nor the rate of decrease was remarkable. The subsequent rise in pressure was, however, exceptional. Over much of southern England, increases of more than 8 mb per hour were recorded, with the most rapid at Hurn in Hampshire, where pressure rose 12.2 mb in one hour.

The greatest rise over three hours occurred at the Portland Royal Naval Air Station in Dorset, where, between 0300 and 0600 UTC, the rise was 25.5 mb. This was, by some margin, the greatest change in pressure - either upwards or downwards - ever recorded in three hours anywhere in the British Isles. At many places in southern England, the pressure rose more than 20 mb in three hours. The return period for such an occurrence is, again, roughly once in 200 years.

Journalists, looking for a sensational story, accused the Met Office of failing to forecast the storm correctly. Repeatedly, they returned to the statement by Michael Fish that there would be no hurricane - which there hadn't been. And it mattered not that Met Office forecasters had, for several days, been warning of severe weather. The Met Office had performed no worse than any of its European counterparts when faced with this exceptional weather event.

However, good was to come of this situation. Based on the findings of an internal Met Office enquiry, scrutinised by two independent assessors, various improvements were made. For example, observational coverage of the atmosphere over the ocean to the south and west of the UK was improved by increasing the quality and quantity of observations from ships, aircraft, buoys and satellites, while refinements were made to the computer models used in forecasting.

In an ideal world, storms like 1703 and 1987 will never take us by surprise. In the real world, however, we must remember that caprices of the atmosphere may occur at any time.

We must remember, too, that the mathematical models used in numerical weather forecasting, though remarkably successful, can never fully represent the complexity of the real atmosphere. And complete observational coverage of the atmosphere over the oceans west and south of the British Isles will probably never be achieved.

Extreme weather events, as the storm of 1987 showed, will always be very difficult to forecast.