THE MINI AUTUMN OF 1969 IN BRIGHTON

By G. A. SOUTHERN Brighton, SzLssex

N rare occasions, a meteorological event will occur which, by its sheer drama, 0 beauty and intensity, will impress itself upon the memory and in time become a yardstick for measuring future similar events. It is with this in mind that I narrate the events surrounding 12 November 1969 in Brighton.

In common with the rest of south-east England, Brighton had enjoyed a warm and relatively dry summer in 1969. September and October had been very dry with a total of only 0.30 in. of rain for the two months. Indeed, October declared itself a summer month, being exceptionally sunny and warm, the daily maximum falling below 60°F on only four occasions. This dry, warm weather extended into November and the spell was not really broken until the 5th when cooler, wetter weather arrived. Autumn in 1969 was a very brief affair, being sandwiched between the late waning summer ending on the 5th and the arrival of the snows and frosts of winter which came early on the 17th. I t is this period, especially the period 11th to 16th which I have called ' The Mini Autumn ', that I propose to discuss.

On 8 November a large and deep depression was centred to the north of the British Isles and severe gales were forecast for Scotland. For the next week a large, slow-moving and complex trough lay from Scandinavia to Britain with minor disturbances crossing the country (Weather Log, November 1969). This resulted in a very wet, stormy week at Brighton. From the 11th to 16th, 3.76 in. of rain fell, the long-term monthly average for November being 4-2 in. Altogether, November 1969 yielded a total of 6.66 in.

On the 8th and 9th, gales blew across southern England, becoming severe in many places on the afternoon of the 9th. On the morning of Tuesday the IIth, the wind was blowing from the south-south-west; it was dull, overcast, and very mild, the maximum reaching 58°F and the minimum falling to only 51°F. The sea temperature following the warm October was high at 57°F. On the night of the IIth, the inhabitants of Brighton retired to the accompani- ment of strengthening winds, which by midnight had reached gale force 8, and there were occasional bursts of heavy, thundery-type rain.

Around 0500 hr on the 12th, we were wakened by a furious, noisy, squall of wind and hail; the hail was the size of peas and was accompanied by thunder and lightning, and the west-south-west wind gusted to 76 mph. About half an hour later, a further thunderstorm moved up the English Channel, but it appeared to be much less intense as its trailing edge only brushed the coast.

I concluded that the weather would now abate. At daybreak we woke to

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very dramatic skies: ragged scud contrasting vividly with the slower, majestic columns of cumulonimbus. At 1030 the sky rapidly darkened, so that office and vehicle lights had to be switched on, and many pairs of anxious eyes looked skywards wondering what was in store this time! Once again, the district was lashed with stinging squalls of rain and hail. At nearby Shoreham Coastguard Station, the wind in this squall gusted to 75 mph - and minor damage and some flooding occurred. As before, in the earlier pre-dawn storm, another less intense thunderstorm moved up the Channel some 30 niinutes later.

After the morning storms, the skies largely cleared, but the gale increased further with the cloud clearance, and from 1200 to 1400 the wind was blowing at severe gale force 9. Between 1730 and 1800, I noticed distant towers of cumulonimbus on the south-western horizon over the sea and as the skies darkened with drawing nightfall, there were distant flashes of lightning. The day had again been very mild despite the strong winds, the maximum being 58°F. Between 1800 and 2000 there were fitful bursts of rain and the wind moderated but still remained fresh and gusty.

Worse was yet to come! Around 2100 distant lightning to south-west indicated another thunderstorm and this was soon overhead; the worst storm of the day was upon us. This produced the most impressive hail, whitening the ground with stones, again the size of peas. The crash of hail on roofs and window- panes, plus the fierce squalls of wind, raised conversation to shouts. More damage was suffered in Brighton and the surrounding district in the form of battered roofs, fallen trees, houses struck by lightning and further flooding. This deluge was particularly impressive as in reality it was a series of storms, closely follow- ing one upon the other. Between 2100 and 2300 I recorded three. The total rainfall for the day measured 1.39 inches.

In the really severe thunderstorms it was paIticularly interesting to note their cellular structure and also that each burst of hail had its own characteristic size in stones.

After 2300 on the ~ z t l i , the wind quickly subsided and the clouds mostly cleared away. At o()oo on the following morning, the 13th, the wind was north- north-westerly and it was considerably cooler, the maximum only attaining 50°F.

The rest of the week was still unusually stormy. On the q t h , thunder and lightning again occurred and once again the wind gusted to 63 mph. On the 15th, the maximum gust attained 65 mph and again on the 16th there was another violent squall - thunder and lightning accompanied by more fierce hail, the wind gusting this time to 59 mph. I t really seemed as though all the adverse forces of autumn had culminated in this one week, for on 17 November the Downs to the north of Brighton received the first snow of the winter! In fact, November 1969 was a record breaker in Brighton. There were more gales, hail, thunder and snow reported than in an.y previous November for the past 10 years.

In conclusion, it would appear as though the thunderstortns that hit Brighton on 12 November developed to the east of the Isle of Wight, as friends living in Southampton, some 80 miles to the west of Brighton, were unaware of any thunder in that city.

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