North France – Benelux tornado outbreak of October 20, 2013

A tornado outbreak swept across northern France, Benelux and the extreme south of UK on October 20, 2013. As of now, 9 tornadoes have been confirmed with five already being assigned intensities: 6 tornadoes in France, 1 tornado in Belgium, 1 tornado in the Netherlands and 1 in the UK.


EF0 Bray-sur-Somme tornado. Source: Florian Delpanque / Keraunos.org.

Tornadoes on October 20 in outbreak area:

France (investigated by Keraunos.org)

Belgium

Netherlands

United Kingdom (investigated by TORRO)

The most damaging was the EF2 Bailleul tornado. Keraunos is making a detailed damage survey, the preliminary results show a 9 km long damage track. The tornado skimmed the commercial center, just south of Bailleul. Over 1600 houses were left without electricity. Jean-François Wierez of Pluymstraete was right in the tornado path: “Around 7:15 p.m., I was in my garage when I saw the door of it blown inward. The electricity was cut off, I heard a noise in the house. Everything was devastated. I have two fireplaces that threaten to collapse … “

EF2 Bailleul tornado damage track by Keraunos field survey. Source: Keraunos.org.

EF2 Bailleul tornado damage by Keraunos field survey. Source: P. Mahieum / E. Wesolek / Keraunos.org.

More on the Baileull EF2 tornado and the Keraunos field survey and event analysis on Keraunos.org report.

The EF1 Neuilly-sur-Eure, EF0 Quittebeuf and EF0 Bray-sur-Somme tornadoes did less damage. The EF1 Nieully-sur-Eure tornado produced a damage track at least 4 km long, reaching a maximum width of 250 m. Other north France tornadoes are also under investigation.

EF0 Quittebeuf tornado damage by Keraunos field survey. Source: Keraunos.org.

The morning Hayling Island was investigated by TORRO and assigned T2 rating.

The tornado outbreak formed on the cold front ahead of the low over the British isles. The environment was characterized by low instability (MUCAPE in the 500 – 800 J/kg range), but very high shear, exceeding 30 m/s and high helicity. In addition, very low LCLs in the 100 – 300 m range made conditions very favourable for tornadogenesis. A number of low topped tornadic supercells developed, among them at least one has been identified as a cyclic tornadic supercell, dropping possibly no less than 3 tornadoes (Keraunos.org). A more detailed environment analysis has been done by Keraunos.

Eumetsat VIS satellite image of the low-topped supercells over northern France and surrounding areas. Source: Eumetsat / Keraunos.org.

Spectacular supercell over the Netherlands on October 20. Note the tilted ‘barber pole’ updraft. Source: www.onweer-online.nl/.

More on the north France – Benelux tornado outbreak of October 20 when more details are available.