tornadoes in December were almost unheard of.
I am quite the amateur meteorologist (40 years experience), with a major in tornado phenomenon.
And no, tornadoes in December happen very commonly, and have as far back as records exist.
And no, tornadoes today are NOT increasing in frequency or intensity. On the contrary, things have been rather quiet for the last number of years. Tornadoes were probably MORE intense and frequent back in the 50's thru the 70's.
In Europe (especially England), the most intense, devastating tornadoes occurred HUNDREDS of years ago.
TORRO | Research ~ Tornadoes ~ Extremes
Most intense tornado
Three tornadoes in Britain are believed to have reached T8; their antiquated nature necessitated great caution in assigning intensities, so it is possible that they may have been even stronger.
On
23rd October 1666 the most intense tornado on record for the UK (and England) passed through
Welbourn, Wellingore, Navenby and Boothby Graffoe in Lincolnshire. The Welbourn tornado has been rated at T8-9 with a reported maximum track width of 200m and a track length of 5km.
Thomas Short writing in 1749 described it as
"it came with such Violence and Force, that at Welbourn it levelled most of the Houses to the Ground; broke down some, and tore up other Trees by the Roots, scattering abroad much Corn and Hay. One Boy only was killed. It went on to Willingmore [Wellingore], where it overthrew some Houses, and killed two Children in them. Thence it passed on and touched the Skirts of Nanby [Navenby], and ruined a few Houses. Keeping its Course to the next Town [Boothby Graffoe], where it dashed the Church Steeple in pieces, furiously rent the Church itself, both Stone and Timber Work, left little of either standing, only the Body of the Steeple."
Artist's impression of the St. Mary le Bow tornado
(Credit: Chris Chatfield)
Artist's impression of the Montville tornado
(Credit: Chris Chatfield)
The second, also the UK’s earliest known tornado, occurred on
23rd October 1091. The church at
St. Mary le Bow in central London was badly damaged, with four rafters - each 7.9 m long (converted from the reported 26 ft) - being driven into the ground (composed of heavy London Clay) with such force that only 1.2 m (converted from the reported 4 ft) protruded above the surface. Other churches in the area were demolished, as were over 600 (mostly wooden) houses. This has been rated T8? due to the difficulty in estimating an event so long ago and the damage reports having been written over 30 years after the event.
On
14th December 1810, a T7-8 tornado tracked from
Old Portsmouth to Southsea Common (Hampshire) also causing immense damage - although no deaths, it is believed. Some houses were completely levelled and many others were so badly damaged that they had to be demolished; chimneys were blown down and the lead on a bank roof was "rolled up like a piece of canvas and blown from its situation".
The most intense tornado on record for Wales was the
Dyffryn Dowlais to Bedlinog, Merthyr Tydfil tornado of
27th October 1913 which reached T7.
The most intense tornado on record for Scotland occurred in
September 1767 at
Blairgowrie, Perth & Kinross rated at T6?.
The most intense tornado on record for Northern Ireland was the
31st December 2006 Ardmore, Co Armagh to Loanends, Co Antrim tornado rated at T4-5.
The most recent T7 tornado was on
8th December 1954 which hit
Gunnersbury in London. The most recent T6 tornado was on
28th July 2005 (rated T5-6) which hit
Birmingham.
Note following a review in the 2010s the 23rd October 1091 tornado is no longer the most intense on record for the UK.
Across the continent, a number of tornadoes are believed to have reached T10 - although it is always difficult to rate violent tornadoes, especially those at the upper end of the category. Violent (T8-T11) tornadoes have occurred in many countries, although only a few nations have experienced a T10. However, two tornadoes are rated T10-11 with the upper category implying windspeeds close to the 500 km h-1 (311 mi h-1) mark. On
19th August 1845, a violent T10-11 tornado devastated
Montville (Seine-et-Maritime) in France. Sources give conflicting information as this lunch-time tornado travelled 15 or 30 km, was 100 or 300 m wide and killed 70 & injured 130 or (less probable) killed 200 people.
At a similar time of day on
24th July 1930, the
Treviso-Udine area (Veneto / Friuli-Venezia Giulia) of Italy was devastated by a 80 km long T10-11 tornado, which claimed 22 or 23 lives.