Depression 'Z'

A tragic combination of weather circumstances, all centring on what at first seemed a negligible de­pression crossing the Atlantic from the Azores, was respon­sible for the chaos and death of the week-end. First reports of the depres­sion—an area of low-pressure air—indicated that it was of no major importance. That was last Thursday, when a merchant ship reported by radio from a position well to the south-west of Iceland.

In the eighth-floor offices of the Air Ministry’s Meteorologi­cal Office in London the forecasters marked it on their charts and christened it Depression “Z.” The original messages had come from the Consuto, one of the “volunteer” weather reporting ships which help to build up an accurate weather picture every day.

The experts had then no indication that Depression “Z” would become important, or even that it was likely to reach Britain. They classified it as a secondary depression which had broken away from a major depression over the Azores.

Serious build-up

It was not until some hours later, when the forecasters received messages from their official weather-report­ing ship in the area, the Weather Explorer, which sends reports every three hours, that they realised that something serious was build­ing up. The depression had moved fast—350 mile’s in six hours— and was intensifying. The position was still not vitally serious and the expectations were, at the worst, of high winds affecting Northern Scot­land and the Shetlands.

By noon on Friday the pic­ture had worsened. The weather ships were reporting winds of gale force and the edge of the gale had already reached the Shetlands and Faroes.  By then gale warnings had been issued for practically the whole of Western Britain, and it was obvious that although the centre of the bad weather would be in the north, the whole of the country would suffer in time.

The depression moved steadily on. What was hap­pening was that the area of low-pressure air was being steadily followed by a vast area of high-pressure atmo­sphere stretching from Green­land down the Eastern Atlantic to the North African coast.

Down North Sea

Depression “Z” now the centre of roaring gales —wind gusts of 113 miles an hour, unprecedented in Britain, were recorded at Kinloss, in Scotland — was being fed by vast quantities of air from the high-pressure system pressing on its heels. Then, on Saturday, Depres­sion “Z” moved on in a great arc into the North Sea and to­wards the south. Tremendous northerly winds were sweeping down the North Sea now, carrying with them great masses of water into an area which was already suffering from the abnormally high tides associated with the period of a full moon.

The weather people were alert to the position. Well in advance they had plotted the areas where the gales would strike and had assessed the obvious danger of serious flooding. All the warnings had been issued, for, though De­pression “Z” was beginning to lose some of its intensity, it was still a major danger.

And, while reports of disaster were coming in. with practically every weather station in the country reporting gales, some even hurri­canes of more than 100 miles an hour, weather reports com­ing from the Atlantic showed a very different picture.

The high-pressure belt was still moving eastwards, still providing the air that was be­ing sucked into the devastating centre of Depression “Z” but there was nothing in the Atlantic reports to indicate that the high-pressure system was partly responsible for the tragedy that was preceding it.

Tragic ‘ifs’

Reports of sunshine, In­creasing temperature, and gentle breezes were being plotted in the path along which the depression had followed only a few hours earlier. The weather men pointed out a series of tragic “ifs” in the week-end story of the elements. If the depression had not coincided with the full-moon tides. … If it had not been followed by the per­sistent high-pressure area which fed it. . . . If, one day in the middle of last week, the negligible little Depression “Z” had not broken away from its parent low – pressure system over the Azores. . . .