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Record number of thunder days

PostPosted: 2014 Nov 10, 16:16
by John Oliver
Five loud rumbles of thunder (distance <2 miles) between 2335 and 2355hrs last night (9th) brought the tally of thunder days this year at Dorchester to 19.
This beats the previous highest annual total (since recording began in 1962) of 18 days set in 1976.

2010 is the only year in the records to be completely thunder-free.

John
Dorchester
south Dorset

Re: Record number of thunder days

PostPosted: 2014 Nov 11, 13:27
by Martin Rowley
... The number of 'thunder heard' days here at West Moors (east Dorset, not far to the north of Hurn) has just reached 25, with a developing cluster of CB/TS grazing the Poole basin coastline early hours 10th.

Because the figure seemed to be getting 'interesting', I tried to work up some sort of statistical background using Hurn published data with which to place this figure in context: the results are (updated to yesterday) here . . .
http://booty.org.uk/images/Hurn_thunderheardanalysis_1973_2003.jpg

Note that there is one year missing from this 1973-2003 dataset and crucially, I'm not sure that Hurn was fully 24/7 towards the end of this period; however, checking against the Met Office gridded dataset and Dorchester figures for the same period, the essential data (means, standard deviations etc.) all look 'sensible'.

25 days is significantly outside the 'normal' envelope of expectations. Looking at other data (not shown), I suggest that we've had the most thundery year for at least four decades.

The breakdown of this year's events into three crude categories is as follows:-

[A] 'Flash-bang-gone' - that is the odd crack and rumble from a quickly passing storm = 10
[B] Extended 'classic' CB activity - several discharges, mix of CC/IC and CG, though latter isolated = 12
[C] Distant (edge of hearing) activity from adjacent clusters = 3

Martin.

Re: Record number of thunder days

PostPosted: 2014 Nov 12, 13:56
by Martin Rowley
Martin Rowley wrote:... The number of 'thunder heard' days here at West Moors (east Dorset, not far to the north of Hurn) has just reached 25 ....


... have now updated for a single 'flash-bang-gone' event this morning (12th November): now 26 days with thunder heard this year and the breakdown now becomes ...

[A] 'Flash-bang-gone' - that is the odd crack and rumble from a quickly passing storm = 11
[B] Extended 'classic' CB activity - several discharges, mix of CC/IC and CG, though latter isolated = 12
[C] Distant (edge of hearing) activity from adjacent clusters = 3

Martin.

Re: Record number of thunder days

PostPosted: 2014 Nov 12, 14:19
by Graham Easterling
[A] 'Flash-bang-gone' - that is the odd crack and rumble from a quickly passing storm = 10
[B] Extended 'classic' CB activity - several discharges, mix of CC/IC and CG, though latter isolated = 12
[C] Distant (edge of hearing) activity from adjacent clusters = 3


I rather like those categories. I've always thought that reporting days with thunder was a bit too basic, after all hail is divided into 'large' and 'small'. I know that in the COL returns there is space for a description of thunder events, but perhaps a sub-division of thunder days into categories like these would aid subsequent research. I'm seriously considering putting an indicator against each thunder event in my records.

It hasn't been an especially thundery year here, 9 days with thunder so far, the highest I've recorded was 13 in 2006. (A different matter as far as hail is concerned, 20 days in both January & February, my record was 26 for an entire year in 2008).

For Penzance
[A] 'Flash-bang-gone' - that is the odd crack and rumble from a quickly passing storm = 3
[B] Extended 'classic' CB activity - several discharges, mix of CC/IC and CG, though latter isolated = 4
[C] Distant (edge of hearing) activity from adjacent clusters = 4

We did have a particularly spectacular storm in July, photos attached, taken looking across Newlyn harbour towards Penzance.

Re: Record number of thunder days

PostPosted: 2014 Nov 12, 19:41
by Nick Gardner
Thunder days here are now up to 21.

This is highest I've recorded with the previous high being 19 days in 2006.

I have no idea what my ABCs would be; that information has long gone/wasn't recorded!