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Multi Vortex Funnel/Tornado Event!! - Maghera Area - April 29th

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Author Topic: Multi Vortex Funnel/Tornado Event!! - Maghera Area - April 29th  (Read 1105 times)
martinastro
Martin Mc Kenna
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« on: April 29, 2010, 09:09:33 pm »

Incredible evening from Maghera!. Conor McDonald and I have just seen an astounding convective event from our home town this evening. A menacing low level dark shower was approaching from the SW over the Sperrin Mountains, I drove out to the country with my Dog and parked on a quiet hill looking in that direction. That shower had a nasty gust front on the leading edge along with large black solid wedges of cloud which I mistook for outflow features. The shower passed over me and turned torrential with very large and heavy rain tops more typical of thunderstorm precip cores. Just as it passed I saw a incredible black low level cloud of enormous size appear through the window and cross into the east where I had a fantastic view of it. This massive black cloud was rotating at a speed so fast that I couldn't believe what I was seeing, the area of rotation was HUGE!, easily covering the size of several fields, the 'wall cloud' was spinning and exhibiting stupendous upwards vertical motion. I drove to a better place down the road and was blown away by the sight, looking E to NE I saw 3 massive areas of rotation from an obvious multi vortex funel/tornado event, the E sky had 3 separate areas of large scale spin and lift with ragged strings of scud lifting from all 3 areas from the ground and into the wall cloud at spectacular speed, the main vortex was the biggest showing the cloud wrapping up into a smooth funnel of large size. The scene was utterly amazing and looked exactly like a multi vortex event from a supercell in the US!!!. The horizon was obstructed by trees and small hills so can't comment on damage but I'm certain this touched the ground somewhere, it was rotating nuts for 15-20 mins easily and I had it in view at close range for a portion of this time. I rang Conor McDonald and he too seen the same thing and had chased it to Lavy then back to Maghera, we both got images, Conor got some video. Images don't do justice because the vortex was made from numerous lowerings of cloud and scud however you can see the shape of rotation in them. This was a truly remarkable event and the best severe weather experience we have ever had. I hope other witnesses come forward, the synoptic conditions for this need to be studied since it formed from a large shower in a low CAPE enviornment. Could the experts please look into this immediately - remarkable event!!!!. Don't expect good images because it was not 'photogenic', however visually it was violent and a sight we shall never forget for the rest of our lives!!!, will need to check time stamp on images, it was sometime between 19.00 and 19.45 BST.

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martinastro
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« Reply #1 on: April 29, 2010, 10:39:15 pm »

A few images of these phenomenal event on UKWW...

http://www.ukweatherworld.co.uk/forum/forums/thread-view.asp?tid=36545&posts=13#M538347
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scott86
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« Reply #2 on: April 30, 2010, 12:22:51 am »

Sounds like an immense experience! fantastic pictures aswell! congrats!!!
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martinastro
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« Reply #3 on: April 30, 2010, 12:29:33 pm »

Thanks Scott, I must have 40 or more images and when you flick through them you can see 3 areas of rotation with two tornadic/funnel tubes twisting side by side in the frames. I wonder if I can make a time lapse of these. Radar showed a hook echoe over Maghera area (thanks Paul Martin).  Pity the 'experts' on other forums think it was a bit scud - shame on them.
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martinastro
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« Reply #4 on: April 30, 2010, 01:04:16 pm »

Here's one image from approx 70 stills, you can see 3 crazy rotating areas when you go through the stills in sequence.

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markt
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« Reply #5 on: April 30, 2010, 05:30:51 pm »

fanstastic stuff Martin!  I read what those durds were saying on the other forums, look forward to seeing a vid from it if possible! Smiley
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martinastro
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« Reply #6 on: April 30, 2010, 06:30:35 pm »

Thanks Mark - no video taken unfortnately (it didn't save on Conor's DSLR) but will try to put one together using still images, don't know if it will work though but will give it a try.
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JohnC
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« Reply #7 on: April 30, 2010, 10:59:36 pm »

Obviously a great experience, Martin,such a shame you didn't have the video,the sound would have been great too. You do seem to have a  lot of these extreme events over there, maybe because you're the first landfall east for the Atlantic storms.
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paulster78
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« Reply #8 on: April 30, 2010, 11:30:35 pm »

Heres that radar grab showing the menacing looking cell over Maghera at 7:20pm courtesy of Netweather.   Did you check the scene for any visible damage yet Martin.

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martinastro
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« Reply #9 on: April 30, 2010, 11:47:10 pm »

John, thanks, pity no video but now when I look back on it I don't I could take both stills and vid at the same time from the car, I tend to favour still images but the video would turned the sceptics in an instant. I got an email from another eye witness from NI who saw a massive black rapidly rotating cloud close to the ground at 19.16 - only thing is he's from Ballygalley (spelling?) in Co. Tyrone some distance from us so that shows more than one vortex event over NI that evening - interesting.

Paul, thanks a millon for posting that radar grab, that looks like some kind of hook/rotation area to me, look at the back building cell behind the first with echoes at the top of the scale, that matches the rainfall I experienced. Unfortunately this radar has been overlooked by the UKWW. Will be checking locaton on Sat, I'm not expecting to find anything since it was mostly fields in that direction, however any snapped trees would be nice to find!
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paulster78
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« Reply #10 on: May 01, 2010, 12:23:13 am »

No problem Martin, I have 6 or 7 radar images saved from before and after that one, just let me know if you want them.
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martinastro
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« Reply #11 on: May 01, 2010, 12:57:30 am »

Excellent stuff Paul  Smiley - good job you subscribed to the radar - just for events like these.
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« Reply #12 on: May 02, 2010, 12:46:32 pm »

Wish I had of been there to see that! What a start to the season. Some people on ukww think the world owes them a living. I have noticed somebody has started a new thread on ukww showing how the tornado formed over Maghera based on the mountains etc. However I have no idea what he means lol. Too in depth for me lol
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martinastro
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« Reply #13 on: May 02, 2010, 01:22:18 pm »

Thanks for the tip off Stuart, just had a look at it now  Smiley

David Smart emailed me last night with the model evidence.
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martinastro
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« Reply #14 on: May 02, 2010, 01:45:25 pm »

From expert David Smart...



I have run a WRF-ARW simulation initialised with the 12Z GFS run. Domains are nested down 9-3-1km. Spin-up time is rather short but, nevertheless, convection develops in about the right area around the right time. Attached is a snapshot at 1810 UTC showing model terrain-black contours every 50m , 10m Relative Vertical Vorticity-shaded (10^-6 s^-1) and 10m flow vectors every other grid point. Approx location of Maghera is indicated by the cross hairs. The output is best viewed in animation and I'll add a GIF movie when I can upload to the server.

As convection develops over the Sperrins outflow moves southwards channeled by the mountains to the west and high ground to the east. This collides with the environmental flow from the SW resulting in a gust front and band of enhanced low level vertical vorticity. to the NE there is a 'blob' of substantial enhanced vertical vorticity- this begins life as a vorticity feature over high ground to the NW and appears to be picked up' by the outflow front before growing and colliding with the high ground to the east. Nb the 1km grid will likely underestimate the absolute magnitude of these vorticity features.

Therefore the model suggests that the observations of rotating updraughts are likely explained by interaction of a gust front with the environmental flow. Also it appears that a more substantial terrain induced eddy can form in this situation. Given the moist environment this could be manifest as a rotating cloud close to the ground.

This example of a situation where, although the storm environment is 'benign', interaction of downdraughts with local terrain and the environmental flow can promote the formation of brief eddy or tornado-like circulations.

David
« Last Edit: May 02, 2010, 01:47:40 pm by martinastro » Report Spam   Logged



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