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THUNDERSTORM 0014
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Date: 15-06-1998
Time: 15:25 BST This is the first Supercell-like thunderstorm I have seen (and filmed). Much to my surprise I was not expecting to see my first one in the UK, let alone outside my house! With this year being fairly violent so far in terms of storms, this was the icing on the cake and we weren't even half-way through storm season yet. Originally I wasn't on the lookout for storms on this day as there were none forecast for the north (mainly for southeast), but the calm weather was soon to be broken. The mini-Supercell came after a previously developing storm cell that I observed passing through around 13:30. The first cell had ominous characteristics that deferred it away from a traditional British thunderstorm, such as a really dark rolling base and a tremendous downpour, but no electrical activity. It cleared at 14:15, leading the way for the Supercell at around 3pm. I hadn't caught the lightning on camera from this storm as I was still running home as fast as possible in the torrential rain. By the time I got the camera set up the lightning activity had dissipated and fell silent. My fellow storm enthusiast Matt Robinson reported he saw some C-C with branches which I missed whilst running and fumbling around for my door keys as it happened! However the lightning wasn't of any relevance after I found something else to film...
I had set the camera up facing northwest down the
Cheshire plain, not really taking any notice of it at first as I was still
trying to dry off from running in the torrential rain. Suddenly a piece of
cloud lowering from the base caught my eye and I zoomed in frantically to
get a better shot. It turned out to be a
silhouette of a rotating vortex about 3-4 miles away northwest with a
low-contrast funnel connecting it to the parent mesocyclone above it for
about a minute. Slow but defined rotation of the storm base and cumulonimbus
towers were clearly seen in time-lapsed portions of the footage. The rain
was torrential and persistent with large-diameter raindrops as the core passed
right over Macclesfield, however no hail was reported (even from myself
after I had ran quarter of a mile through it!). The electrical activity was
weak but present with a few C-Cs in the core.
I have shown this footage to the general public including those in the US, and there has been much debate whether or not this was a tornado or just a funnel cloud. After studying the footage for many hours, in my opinion it is a tornado touchdown for sure even if it was only for a brief few seconds. The condensation funnel can be clearly seen connecting to the ground for a brief second as the camera focuses in on the footage which qualifies is as a tornado. Admittedly the visibility was reduced by trees but as the view of the camera looks downward onto the Cheshire plain it is a pretty flat angle. Also, as the landscape is predominantly pasture where it would have touched down behind the houses, trees and pylons, there wouldn't be much in the way of debris to lift. The mesocyclone was very low-hanging too and judging by the centre of rotation on the base the funnel could not be more than 3-4 miles away. It is open to debate but I believe if you stood under it you would have felt a slight gust of wind at least. The funnel structure dissipated 20 seconds after it was spotted and I was left viewing the slowly rotating mesocyclone cloud-base and towers as they span towards the south. Every now and then little suction funnels would appear under the mesocyclone, but none of them developed into as fully as the first.
This clearance also gave away the back-edge of a very large arcus cloud to the northwest where the core cell updraughts were as shown below.
Below are a pair of MPEG videos to show the motion of the mesocyclone and tornado.
As the cloud broke up, amazing tower growth was spotted over the Pennines to the northeast from developing storms. The anvils were showing mushroomed characteristics with no fibrous features. The heavy rain during the day from the two cells at 13:30 and 15:00 caused minor flood damage in Macclesfield and neighbouring Presbury where a severe rain-burst was also reported on the BBC news. Tytherington High School just down the road had to get a fire-engine to pump the water out of the music and reprographics rooms, and the river Bollin that runs through Macclesfield had suddenly rose 80cm-100cm in places. The water levels were clearly marked by flattened grass on the riverbank the following day after the flooding had receded, and part of the footpath on the Beach Lane road bridge that runs over the Bollin had collapsed in a landslide (see images below which were taken the following day).
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