Uk Convective General Discussion & Forecasts, 28th June 2012>

[Paul Sherman]

another link that most of you may find very useful

http://forum.netweat...rstorms-setups/

a first class guide to the various types written by Nick F Senior Forecaster for Net Weather.

well worth reading

Hoping John as an ex Met man can give me a possible reply on this if he could.

The Storm that hit Newcastle yesterday evening had a classic Bow echo feature (Eg pushing out and bowing near Newcastle)

Question is, how on earth can the Met Office be so certain that an embedded Supercell was to blame for that Storm which was essentially along the Cold Front and looking like a severe Squall Line ? Do they have enough dopplar or good enough grade radars to pick up that this was definately a Supercell.

I watched all the Storms closely yesterday and the only ones that stuck out to me were the 3 HP or Classic Supercell Signatures around the Leicester, Notts and Lincs Areas.

Regards

Paul S

[johnholmes]

Hoping John as an ex Met man can give me a possible reply on this if he could.

The Storm that hit Newcastle yesterday evening had a classic Bow echo feature (Eg pushing out and bowing near Newcastle)

Question is, how on earth can the Met Office be so certain that an embedded Supercell was to blame for that Storm which was essentially along the Cold Front and looking like a severe Squall Line ? Do they have enough dopplar or good enough grade radars to pick up that this was definately a Supercell.

I watched all the Storms closely yesterday and the only ones that stuck out to me were the 3 HP or Classic Supercell Signatures around the Leicester, Notts and Lincs Areas.

Regards

Paul S

hi Paul

As far as I know they do not have doppler radar, nor indeed why they referred to it as a super cell. I personally found it a little difficult to position the cold front most of yesterday. Using Td values then I would have positioned it some distance behind the reports of severe storms in NE England which is perhaps why UK Met quote as they do?

All I can suggest Paul is that you pm them, explain your view and why you feel they may be mistaken. Undoubtedly you have personal experience of severe storm cells and tornadoes, explain this. I am sure they will forward it on to the forecast room for someone to send a response. Let me know what they say please.

John

[Bobby]

Here's an interesting radar shot I saved from yesterday, if any experts want to analyse

There were tornado reports from that cell

[NL]

Hoping John as an ex Met man can give me a possible reply on this if he could.

The Storm that hit Newcastle yesterday evening had a classic Bow echo feature (Eg pushing out and bowing near Newcastle)

Question is, how on earth can the Met Office be so certain that an embedded Supercell was to blame for that Storm which was essentially along the Cold Front and looking like a severe Squall Line ? Do they have enough dopplar or good enough grade radars to pick up that this was definately a Supercell.

Regards

Paul S

Owdo Paul, from what I gather it looked like a classic (American style) bow echo as you specified and not a supercell, but as far as I'm aware the relatively 'new' radar in High Medomsley just outside Sunderland has doppler capability but I'm not sure if it was implemented or whether the software is 'switched-on'.

[Paul Sherman]

Yes Barb that was the First Supercell of the Day and it did produce a Tornado near Newbold Verdon

Please See Pics Below

http://www.ukweatherworld.co.uk/forum/index.php?/topic/92017-rfmi-leicestershire-hail-35-plus-reported-poss-tn-damage-280612/page__view__findpost__p__809270

There were 2 More HP Or Classic Supercells, Not sure on wether the 2nd produced a Tornado but the 3rd and Tail End Charlie did produce the Significant Tornado between Sleaford and Ewersby (This was the Cone Tornado so many have seen)

Thanks John, will Email them as if anything it looked like a Severe Squall Line which had a Bow Echo Feature as it bowed out near Newcastle. Have experienced these in the states and they can have EF1 To EF2 Strength Winds within them and I can see why people might have thought it was a Supercell, nothing on the radar in the NE Suggested Supercell to me and I watched it closely all day long.

Owdo Paul, from what I gather it looked like a classic (American style) bow echo as you specified and not a supercell, but as far as I'm aware the relatively 'new' radar in High Medomsley just outside Sunderland has doppler capability but I'm not sure if it was implemented or whether the software is 'switched-on'.

Thanks Paul, Thats what it looked like too me as well, and they can be more ferocious than a Supercell at times with winds easily over 100mph and Large Hail contained

[Alex95]

Yes Barb that was the First Supercell of the Day and it did produce a Tornado near Newbold Verdon

Please See Pics Below

http://www.ukweather...post__p__809270

There were 2 More HP Or Classic Supercells, Not sure on wether the 2nd produced a Tornado but the 3rd and Tail End Charlie did produce the Significant Tornado between Sleaford and Ewersby (This was the Cone Tornado so many have seen)

Thanks John, will Email them as if anything it looked like a Severe Squall Line which had a Bow Echo Feature as it bowed out near Newcastle. Have experienced these in the states and they can have EF1 To EF2 Strength Winds within them and I can see why people might have thought it was a Supercell, nothing on the radar in the NE Suggested Supercell to me and I watched it closely all day long.

Thanks Paul, Thats what it looked like too me as well, and they can be more ferocious than a Supercell at times with winds easily over 100mph and Large Hail contained

Are these high winds usually very localised? That would explain why half of my street has lost ridge tiles whilst some other suburbs had little wind at all! For a 10 minute spell yesterday the winds were easily gusting to 70mph at a guess. I've experienced a Florida tropical storm with sustained winds of over 50mph, and yesterday was briefly comparable. I'm sure there is a Youtube video of a churchyard experiencing a similar scene to Newcastle, only somewhere else in England yesterday, and people suggested that was a microburst.

I'm gonna go read up on bow echos now!

EDIT:

http://en.wikipedia.org/wiki/Bow_echo

This may explain many conditions which were experienced in Newcastle, from the storm rotation to the damaging winds. I wonder if we had a 'wet downburst'?

Edited June 29, 2012 by Alza

[Paul Sherman]

8 Mins onwards gives you a good impression of what these are like.

Edit: And from your Wiki Link, that was the exact Radar representation that I saw over Newcastle last evening, if anyone from the local area has radar grabs would be great to put them up and correlate.

[Cheshire Freeze]

I wonder if we had a 'wet downburst'?

Is that a posh term for diarrohea?

[Kain]

Kudos to the Shropshire Star (my local paper) actually attributed the storms yesterday to a Spanish Plume event!

[Cloud 10]

Edit: And from your Wiki Link, that was the exact Radar representation that I saw over Newcastle last evening, if anyone from the local area has radar grabs would be great to put them up and correlate.

Saved these from yesterday for 4pm.

[Alex95]

8 Mins onwards gives you a good impression of what these are like.

Edit: And from your Wiki Link, that was the exact Radar representation that I saw over Newcastle last evening, if anyone from the local area has radar grabs would be great to put them up and correlate.

Looking at that, we may well have had a downburst here in Newcastle. I actually experienced a severe-warned thunderstorm in Tampa, Florida last August, and the news said there had been a downburst, and yesterday's storm was very reminiscent of that one. You have to wonder how accurate these reports are though, as they said the downburst 'caused a waterspout in Tampa Bay', which doesn't really ring true. They may have been associated, but it certainly didn't cause a waterspout.

[Supacell]

I am surprised nobody has noticed the risk for further thunderstorms tomorrow (later on today) with some decent CAPE (okay nothing like Thursday but still 500-700j/kg which is enough) and a LI of around -3.

[multi cellular thunderstorm]

I am surprised nobody has noticed the risk for further thunderstorms tomorrow (later on today) with some decent CAPE (okay nothing like Thursday but still 500-700j/kg which is enough) and a LI of around -3.

I'm finding it hard to get excited about todays (Saturdays) potential, after what happened on Thursday.

The one thing about Thursday though, is that I struggled to get good photos and only really got video. Didn't manage to capture any CG's on video or photo so I'll be hoping for a chance to make up for that sometime soon.

Hopefully some people who missed out on Thursday will get something later today. I can understand how frustrating it must have been to miss out.

Edited June 29, 2012 by multi cellular thunderstorm

[ZONE 51]

There is some unstable air around today and some rain then showers so maybe some thunder! not that it's as simple as that mind!

I think as we keep these battles with warm/cold air we could well see some more thunderstorms next week.

[Supacell]

Next week is looking good for thunderstorms with some instability being shown for somewhere every day of the week

MCT, i too was unable to get any decent CG bolts on Thursday. I did see a few but none on camera. I think two things made it difficult; one was the amount of rainfall and its intensity and the other was the enormity of the storm as the bolts were hitting in a different direction each time. Plus 95% of the lightning was in the clouds. Just a couple of weeks ago i filmed a little storm near Scunny and got some decent CG's on camera, but they were all striking in a similar area as the storm cell was small.

I think todays cells will, if they form, be much smaller. There is cold air aloft and some decent instability so should be fairly decent lightning. And the amount of water in the atmosphere is much lower so less likely that cells will be wrapped in rain. Chance of hail too with that cold upper air in place. There won't be any of that severe weather though, although i need to check this mornings charts as last night there was an overlap of shear and CAPE around the Humber so a chance of longer lived multicells developing around there.

[Coast]

Next week is looking good for thunderstorms with some instability being shown for somewhere every day of the week

GFS take on things currently:

Happy 4th July folks!!!

[Liam J]

NMM cape & li for this afternoon, nothing spectacular - Central, E/NE England being most at risk during the course of Saturday.

[knocker]

Lol Indeed, I think many have taken their eye off the ball because they're still digesting Thursday's convective event.

I want to add, though, that Thursday's severe convective weather episode wasn't just merely down to there being high CAPE, but its combination with high low level moisture and, most importantly, a very favourable vertical wind shear environment, which allowed for the sort of severe weather we witnessed during the day. Indeed, a completely shearless profile with lower moisture would not have seen the development of multicellular and supercellular storm modes, even if CAPE was larger than what was generated during that day.

Anyway, back to today... I've actually posted my thoughts elsewhere. Not sure whether to "import" them into here lol.

The CAPE that I saw wasn't that high. The SB, ML and MU cape for Nottingham ar 12z were 441, 179 and 368 J/Kg. Li 0. The cold air aloft was the trigger.

[johnholmes]

The interesting thing if you log on to the link below is how similar the Watnall ascent was at 00z and 12z on Thursday

http://weather.uwyo....2812&STNM=03354

I have not looked at other ascents but would imagine that the Camborne was similar at 00z but probably markedly different by 12Z-I may be wrong though.

To me as an ex forecaster, but with little recent experience of checking for severe storms, Thursday was a day somewhere over central/northern England was likely to have a fairly unusual storm.

below is the 00z Watnall with my suggested max values for Td and T in this area. the most severe storms occurred SE of here and again well NE of here (those in the NE were possibly just ahead of the cold front, those SE of here were associated with a marked trough shown on Met Fax charts.

hope this may help but Paul S is the man to chat to along with Nick F

[Cloud 10]

Showers seem to be kicking off quite early today,also a band of intensifying showers in the east

which may produce a few strikes before exiting to the north sea.

UKASF forecast holds some interest for today. UKASF » Storm >> View Forecast

Edited June 30, 2012 by Cloud 10

[Bobby]

Some frequent heavy downpours here, 15mm rain overnight and this morning.

[ItIsGee]

http://www.estofex.org/

european chase anyone?!

[Deluxe]

Showers starting to get going to the west and south-west of here. Hopefully by the time they reach the NE they'll have a bit of electrical bite to them!

[Staffordshire]

Could be some nice showers/storms todat, a rash of showers in wales atm!

[Supacell]

http://www.estofex.org/

european chase anyone?!

Lol, if only it was possible to get to Germany for this evening without having to spend over the odds for last minute flights i would be there