Acknowledgements

We'd like to thank the following for their help and contributions in producing this report:

• The residents of Filkins and Broadwell, whose help and hospitality during our visit to the area was second to none. Without doubt it was their eye-witness accounts and willingness to discuss what they saw with us that made this report possible. We'd like to offer our utmost appreciation and thanks to the residents, and wish them a swift return to normality following their tornadic visitor.

• The contributing photographers who allowed us, during our research, to view the various stages of the storm's life and from various locations. Thanks to Sam Jowett and Andrew Davis.

• The PA Weather Centre, for providing the high resolution radar images of this thunderstorm, allowing us to have a bird's-eye view of the development of the cell.
  http://www.paweathercentre.com

• The Tornado and Storm Research Organisation (TORRO) for valuable information regarding tornado and severe thunderstorm formation and classification.
  http://www.torro.org.uk

• Multimap and Get-Mapping, two superb online resources for detailed mapping and aerial photography.
  http://www.multimap.com
  http://www.getmapping.com

• All of the named organisations and individuals whose online data helped in the research of the storm's structure and development.

 

Comments/Suggestions/Improvements

The following point offer suggestions and comments regarding this report, as sent to us by individuals via e-mail. We welcome all communication, and listed here are those suggestions which offer views on how this report and other areas of storm research can be improved.

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I am quite convinced that this storm indeed was a low-topped or mini-supercell indeed. The high wind shear indicates that mini-supercells were indeed possible and you visually observed that the storm had many characteristics of a supercell. I think the damage path is also
suggestive of a tornado.

Studies done in the U.S. have found -as you might know- that tornadoes become more likely as the 0 - 1 a.g.l. winds shear exceeds approximately 10 m/s (20 knots), which was the case in this situation as well

[Two suggestions offered]

- I'm not too sure that you can see a hook from the 5x5 km resolution data. I think it is time that the UK radar upgrades to a higher resolution which should be possible by interpolating the radar signals on a finer grid, eg. 1 x 1 km.

- I don't think the CAPE calculations, should be based on a parcel lifted from the surface. It seems a bit unlikely that the storm updraft would have had the properties of the lowest 10's of metres of the boundary layer. It's probably better to draw another curve based on a parcel consisting of air having the average properties of the boundary layer. It could be that in that case the soundings do not show much or any CAPE. But the environment in which the storm occurred at 17 UTC was probably quite a bit different than the environment that was sampled by the sounding 6 hours ealier at another location.

Pieter Groenemeijer
ESTOFEX
www.estofex.org

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In view of the level of detail you have both produced I am in no question that this was a supercell event. I have seen many supercell events in the US and there are many similar
signatures.

Mark Humpage
Torro
www.torro.org.uk

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