Thunderstorm observation is an aspect of TORRO's work where every member should experience events which they can report. Such contributions are of great value to TORRO's ongoing research.

The main details required are the place, date and time of the occurrence of thunder in any part of the British Isles. The following information will be invaluable:

• Time of first observation of thunder (with or without lightning) with direction and estimated distance.
• Times of Heavy rain and/or hail if observed.
• Approximate nearest approach of the storm with direction and estimated distance.
• Approximate time of final observation of thunder (with or without lightning) with direction.
• A note on the intensity of the storm.
• Information on any damage caused by the storm, especially that attributable to lightning (both in the immediate vicinity of the observer and that reported by the regional press, tv, radio etc), hail (property, vegetation) or severe local winds.

The briefest note for any date will still be very helpful (it is not expected that a 24 hour watch will always be possible!)

Where possible, incidents of damage should be reported as soon as possible so that on-site investigations can be arranged

Copies of local press reports are a very important additional source of information; please submit any items relating to storm damage (NB it is important that the date of each incident is indicated as press reports can appear a while after an event).

Photographs of damage caused by lightning, hail, severe local winds or (thunderstorm related) flood are always welcome for our growing photographic collection.

Observers may use either Greenwich Mean time (GMT/UTC) or clock time (BST in summer) provided the standard of time is indicated.

The distance of a lightning discharge may be estimated by timing the interval between seeing the lightning and hearing the thunder. One mile is indicated by five seconds or one kilometre by three seconds. Thunder occurring at a distance of approximately three miles or less can be considered as "close".

Details of isolated storms and/or distant storms over mountainous and sparsely populated areas (and over the sea) are of special importance. As with all reports observers are urged to carefully note the dates and times.

Many members already contribute Thunderstorm reports, for which we are very grateful. If you are not currently doing so, we would very much encourage you to join our network of Thunderstorm Observers. Reports can be submitted in three alternative ways -

• On individual thunderstorm report forms, which can be downloaded from the TORRO web site (see below) -these can be submitted by post- either immediately after each event, or, if more convenient, in monthly batches.
• On a monthly thunderstorm report form, which like a batch of individual reports, should be posted to reach us within 15 days after the end of the month.
• By E-mail, either using the template available on the TORRO web site. (http://www.torro.org.uk/TORRO/appeal/quethtxt.php), or your own choice of template (e.g for a monthly report).
• As noted above, please also send in any press cuttings etc relating to damage caused by lightning, hail and (if thunderstorm related) flood or wind.

Regular, detailed monthly summaries are published in TORRO's International Journal of Meteorology. An annual report is also available. It is reproduced in the International Journal of Meteorology (together with the other annual reports - such as that on hailstorms), and is presented, as part of TORRO's annual Weather review, at the TORRO Spring meetings, usually held in March.
Sample Spring Meeting Agenda

Please also note that articles (or letters) on interesting/severe events are always welcomed as submissions to the International Journal of Meteorology. We have the capacity to provide full details of our storm records for particular days/periods of interest. Both detailed "case studies", and letters describing personal experiences of recent (or even not so recent!) thunderstorms, are very popular among readers, and contribute to the Journal providing an informative record for future generations.

Average number of days with "thunder heard", 1971- 2000

15-19 Days   10-14 Days   5-9 Days   Under 5 Days
©TORRO 2006

Principal sources of data include: TORRO and TCO Thunderstorm observers' reports, Climatological Observers Link station data (courtesy of Roger Brugge), and the Monthly Weather Report of the Met Office (published until 1993). Data has been checked for consistency between adjacent stations, however NB means for less populated areas will be based on fewer available observations, also, that as thunder observation requires a "24 hour watch" to be kept on the weather, a tendency for under-recording is likely.

If you require further details, or report forms*, please contact either -

Jonathan Webb, TORRO Thunderstorm division director, PO Box 84, Oxford OX1 4NP
e-mail using the Contact Form.

Prof Derek Elsom, Director of TORRO, Geography Unit, Oxford Brookes University, Oxford OX3 0BP
e-mail using the Contact Form.

* If you have easy access to photocopying facilities, please make copies