The Wiltshire Tornado of 1859: Thirteen Miles of Ruin

At about half-past one on Friday 30 December 1859 a tornado crossed north Wiltshire from Bowood Park, near Calne, to Ogbourne St George. This page is the companion to the short film Thirteen miles of ruin, with the sources behind each card.

The survey

Alfred Charles Smith, rector of Yatesbury, walked the whole track and published his account in the Wiltshire Archaeological and Natural History Magazine the following year. His figures: the storm "shaped its course for E.N.E., and took nearly a straight line in that direction for about thirteen miles, its breadth varying from 250 to about 400 yards". It took two or three minutes to pass any one place. He declined to estimate its forward speed, and no one was killed.

Smith also gave the geometry of the track: "a line drawn from the point of its commencement, one mile south of Calne, to that of its final disappearance at Ogbourn St. George, will very nearly pass through every farm estate and village enumerated above". That line is 12.8 miles long at a true bearing of 76°. The film draws exactly that line, with the places he names plotted beside it at their modern village centres. The red band is a diagram of a 300-yard breadth, not a surveyed boundary.

Smith's line from Bowood to Ogbourne; the red band is a 300-yard diagram, not a surveyed track. Map data © OpenStreetMap contributors.

Along the track

• Bowood Park: "where it broke off the large branch of an oak tree within the precincts of Bowood Park" — the first damage, about a mile south of Calne.
• Quemerford: "astonishing the inmates by bursting in the door and windows".
• Blackland: "swept down no less than one hundred and forty eight trees, some of great size and beauty".
• Hail Farm (now Hayle Farm): "a vast number of trees (amounting in all to about one hundred) were prostrated in every direction".
• Cherhill: "scarcely a tree stands unscathed … and scarcely a cottage retains its roof".
• Yatesbury, Smith's own parish: "taking up a heavy broad-wheeled waggon weighing 22 cwt., and lifting it over a high hedge". 22 cwt is about 1.1 tons.
• Winterbourne Monkton: "the old Rectory House, which had stood for many generations was altogether dismantled and became a ruin".
• Hackpen Hill: "even to the summit of old Hackpen … merely giving a passing salute by scattering a little thatch here and there".
• Temple Farm: "where it overturned several trees, and tore off the thatch of barns and other buildings".
• Ogbourne St George: "where it left its last parting token, by blowing down a small barn and two trees".

Why a tornado

Most trees fell eastward, along the track. The telling exceptions are the trees that fell towards each other: in a triangular meadow west of Cherhill, the trees on both long sides fell inward, and west of Yatesbury churchyard two parallel rows fell across the track towards each other. A few trees fell with their heads to the west, against the gale: two at Quemerford, one at Cherhill, one at Yatesbury. Eastern roof slopes were stripped while the western faces, which took the wind, stayed on. Convergent falls, backward falls and lee-side unroofing are what a rotating vortex explains. George Rowell, who spent three days on the track, could not see a whirl and preferred a downrush of air behind falling rain; four backward trees are a thin sample.

Rowell's sketch map of Cherhill; the arrows show "the direction of the wind, as indicated by the fallen trees".

Hail

At Bowood, Mr Spenser saw hailstones "nearly half an inch in thickness, and from two to three inches in diameter, star-shaped, with rays ranging from four to seven in number". Others were wedge-shaped, about three inches long, and fell clear of the rain.

Rowell's plate of the hailstones.

The weather that day

The NOAA/CIRES/DOE 20th Century Reanalysis (version 3) rebuilds weather maps for 1859 from surface pressure observations. At noon on the 30th the low had moved away to the north and southern England lay in a strong south-westerly. The tornado cannot appear in it: the nearest grid point to Yatesbury is 49 km (30 miles) away, and the track was a few hundred yards wide.

At the Radcliffe Observatory, Oxford, the register for the 30th reads "Stormy", wind south-west, rain 0.37 inch, anemometer 569 miles in the day, about 24 mph. The barometer was rising: 29.133 inches on the 29th, 29.422 on the 30th. The register does not mention the tornado. (Rowell's lecture gives 25½ mph from the west-south-west.)

How strong?

TORRO's list rates the event T6, Calne to Ogbourne St George, ST9769 to SU2074 (Brown, Meaden & Rowe 2013). Read against the TORRO scale, Smith's descriptions — mature elms uprooted, roofs removed in one piece, a garden wall laid flat, a loaded waggon lifted — fall in the T4 range, perhaps T5 if the Winterbourne Monkton rectory walls failed rather than only its roof. That is a reading of the descriptions, not a damage survey.

Notes on the film

• The track is Smith's stated line, not a route joined through village centres. Village points are modern centroids.
• No forward speed is given, because Smith gave none.
• Weather map: 20CRv3 ensemble mean, sea-level pressure every 4 mb, 10 m wind.
• Music: original.

Sources

• Smith, A. C. 1860. The Great Wiltshire Storm of December 30th, 1859. Wiltshire Archaeological and Natural History Magazine 6: 365–388.
• Rowell, G. A. 1860. A Lecture on the Storm in Wiltshire. Oxford.
• Burt, S. (ed.). Radcliffe Observatory, Oxford: meteorological observations 1853–1860. figshare, doi:10.6084/m9.figshare.13333925.
• Slivinski, L. C. et al. 2019. Towards a more reliable historical reanalysis: improvements for version 3 of the Twentieth Century Reanalysis system. Quarterly Journal of the Royal Meteorological Society 145: 2876–2908.
• Brown, P. R., Meaden, G. T. & Rowe, M. W. 2013. Tornadoes in Great Britain and Ireland to 1960: Part 3: years AD 1851–1875. International Journal of Meteorology 38 (378): 68–73.
• Map data © OpenStreetMap contributors.