The first Supercell was descovered in the UK Simon and not in the USA as many
think.I think this was the Wokingham storm mentioned earlyer.
Simon Spiers

The Wokingham storm of July 1959 was certainly a supercell, as Les says,
as was probably the even more dramatic Horsham hailstorm of 5 Sept 1958
(unusually late in the year), with cricket-ball sized hail. It is difficult to
see how the Hampstead storm could have been a supercell as it was stationary
and the wind speed at all levels was quite low, as far as I know. One of the
requirements for a supercell is considerable wind shear to maintain the
structure and this was certainly present in the Wokingham storm, as it moved
NE'wards against the surface flow. The Horsham storm is a less obvious case.
As one who witnessed it (though the large hail had ceased) I still reckon it
was the best storm I have seen. Cloud tops reached 48,000 to 52,000 feet and
the lightning was unbelievable. Spoilt for life at the age of 15!

Tudor Hughes, Warlingham, Surrey

I always thought that the Hampstead storm was what the Americans (&
Australians) defined as a "severe pulse" storm - that is, a severe single
cell without rotation.

The Wokingham Storm -was- the one that started the current thinking on
steady state storms. It was Browning & Ludlum that got this one (ukmo, not
nssl). One for the pub trivia games this. The couple of papers produced are
still required reading and are still referred to, they got it spot on with
the crude equipment of the time right down to the bwer (echo- free vault)
analysis. Perhaps we should all meet in Wokingham sometime preferably when
there is another "severe right" coming our way after we've all been at the
pub (:

There was another (severe AND tornadic) storm in London in the 1950's but
I've got no further info on this one just some faded memories of some pathe
newsreel footage of the time.

I've got quite a lot of photographs and webcam captures of what I've
regarded as suspicious looking single cells - normally in north or north
west wind regimes when the brn has been within range (supercells possible)
but low cloud height / CAPE. I've reported quite a few on this ng over the
years - some with quite dramatic rotation! My older - style website had
quite a few pix, unfortunately now archived. I'll trawl some of them out and
post the links to the pictures up as well as pdf'ing the papers and posting
them up too, they're surprisingly quite readable even by folk with a basic
interest in meteorology.

It all seems a lot easier going after severe storms now than a few years ago
with Bernhard Oker's website, Estofex, Topkarten and the rest! Pity about
the road network..

However summer approaches and the time for the severe thunderstorm season
and reports of H7 hail rather than a few flakes of snow, time for some brn
in range and high CAPE perhaps this year i'll get the real I am (:

Les

"TudorHgh"


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.659 / Virus Database: 423 - Release Date: 15/04/2004

I always thought that the Hampstead storm was what the Americans (&
Australians) defined as a "severe pulse" storm - that is, a severe single
cell without rotation.


That fits the bill rather well. The storm broke out at the southern end of
a line of convergence of surface winds, the synoptic situation being a very
weak southerly. Definitely not a supercell.

There was another (severe AND tornadic) storm in London in the 1950's but
I've got no further info on this one just some faded memories of some pathe
newsreel footage of the time.

Very likely 7 Dec 1954. There was an unstable cyclonic south-westerly
and the storm did a fair amount of damage but it seems to be to have been a
long way from being a supercell. Maybe more like the series of severe storms
that flooded parts of Sussex on 11/12 October 2000. A warm moist surface (the
Channel), an unstable atmosphere and a good deal of local cyclonic and coastal
convergence. Tremendous rainfall but again, not supercells.

Tudor Hughes, Warlingham, Surrey.

Simon Wyndham wrote in message ...
Hi,

Layperson question. Has a supercell TS ever been recorded in the UK
before? Much has been made of the discovery of the supercell in the UK,
but was this discovery made from observing other countries, or from an
actual occurrence in the UK?

Simon

Simon and all,

As others have mentioned, without Doppler radar it is difficult to
answer this. However, my opinion is that low-topped or "mini"
supercells are rather common in the UK, as high wind shear coupled
with instability is common, especially in autumn/early winter. This
type of storm has been studied with Doppler radar in the US,
especially in California. They tend to produce weaker tornadoes than
their "Great Plains" cousins, though. However, the mesocyclones they
produce are thought to have similar strengths to the Great Plains
events, as the CAPE is concentrated in the highly-sheared lower
atmosphere.

I never understand why people think we can't have supercells in the
UK, as, if the conditions exist, they will occur. I admit that the
Great Plains-sized events are quite rare, but I suspect that many of
our severe hail storms, such as August 25th, 2001 in Lincs and the
massive June 7th, 1996 outbreak contained supercells, especially the
latter, where some of the hail swaths were over 100 miles long...far
too long and organised for multicell stuff.

cheers,

Paul K.

I took an interest in this after the last discussion here a while ago.I was pretty sceptical about
the attribution of true supercell characteristics to storms in the UK.
Apart from the Wokingham storm other candidates (mostly on circumstantial grounds ) for warm season
type supercells might be the Dover storm ,14 Oct 1964 (Pedgeley,Weather1965 p351 and following
correspondence),the Wiltshire Hailstorm July 1967 (Hardman ,Weather 1968,p404,and the South Coast
Hailstorms June 1983 (Wells specifically calls them 'supercells' based on satellite imagery,Weather
1983,p369)..
The West London tornado,December 1954 parent storm might be a candidate for a low topped
supercell.Radar imagery put the Cb tops around 22,00ft.
Except for the Wokingham storm the lack of diagnostic radar data gives good ground for Will's point
of view .The problem is that when 'Supercell' is mentioned US 'High Plains' storms are conjured up
and these just don't occur in the UK.Better candidates for supercells have been identified in radar
imagery in Switzerland,Italy and France.
On the otherhand,IMO, there is a better case for low topped ,cool season 'mini' supercells in the UK
in analogy to similar storms studied in eg Australia,California and Japan.The storm chase pages
posted for March this year are v interesting and provide good circumstantial evidence.More studies
like this are needed,but how you'd organise a full blown scientific study of them with doppler radar
I don't know.Perhaps the CSIP project will get lucky.In any case it's about time somebody wrote a
review of the case for UK mini supercells .I don't know whether this throws any light on the
problem-
Quarterly Journal of the Royal Meteorological Society - 2004 papers
Vol. 130 APRIL 2004 Part A No. 598
J. HOLDEN and A. WRIGHT - UK tornado climatology and the development of simple prediction tools
p.1009
doesn't appear to be available freely on line

--
regards,
david
(add 17 to waghorne to reply)

never understand why people think we can't have supercells in the
UK, as, if the conditions exist, they will occur. I admit that the
Great Plains-sized events are quite rare, but I suspect that many of
our severe hail storms, such as August 25th, 2001 in Lincs and the
massive June 7th, 1996 outbreak contained supercells, especially the
latter, where some of the hail swaths were over 100 miles long...far
too long and organised for multicell stuff.
cheers,Paul K.
I posted without reading yrs Paul.Am I right in thinking these are examples where MCSs eventually
formed and that the possible supercells occured in the early stages?What's yr assessment of the
radar imagery in these cases?

--
regards,
david
(add 17 to waghorne to reply)

"Waghorn" wrote in message ...
SNIP

I don't know.Perhaps the CSIP project will get lucky.In any case it's about time somebody wrote a
review of the case for UK mini supercells .

Maybe they soon will!

In any case it's about time somebody wrote a
review of the case for UK mini supercells .

Maybe they soon will!

Teaser!

--
regards,
david
(add 17 to waghorne to reply)

Apart from the Wokingham storm other candidates (mostly on circumstantial grounds ) for warm
season
type supercells might be the Dover storm ,14 Oct 1964 (Pedgeley,Weather1965 p351 and following
correspondence),the Wiltshire Hailstorm July 1967 (Hardman ,Weather 1968,p404,and the South Coast
Hailstorms June 1983
Add to that the Dunmow (Essex) Hailstorm ,May 1985 (Elsom & Webb,Weather 1987?)),

--
regards,
david
(add 17 to waghorne to reply)