Storm/convection Discussion

[A.J]

Lovely wispy top to what i think is a big anvil right above us!

Think i just heard a faint and distant rumble.

Nice to hear the west Midlands get some of the 'rumbley stuff'....its been a looooong time coming!

[Shiny_Bottom_1]

The ppn over here is very intense. Just had the 3rd shower in the last 20 minutes, all have been the heaviest here for a very long time.

[Costa Del Fal]

Getting darker now to my SW. The rain looks like it will just miss us but any Thunder or Lightning should be close enough for viewing.

[Costa Del Fal]

There are two showers to my SW and I'm not sure if the one you have now is the one I'm seeing, nicely defined spread out top. I'm in it's Wern edge so will miss this one, but is great to see against a blue sky backdrop.

I think i can see the one your on about but thats passed to my N/E Now. The stuff im focusing on is to my nearby SW.

[Costa Del Fal]

Just had a little rumble again i think.

Its quite slow moving.

[Costa Del Fal]

Just saw a plane flying quite low and appeared to be didging the big shower clouds-must be something going on up there.

[kanes_girl]

Just saw a plane flying quite low and appeared to be didging the big shower clouds-must be something going on up there.

just had a couple of rumbles here, but nothing special yet! fingers crossed

[Harry]

just had a couple of rumbles here, but nothing special yet! fingers crossed

I think for the August we've had, a couple of rumbles IS SPECIAL, lol

Had a moderate/heavy shower just pass through - the belly of it looked particularly nasty looking, with scuddy features to it.

[JamieUK]

Got a thunderstorm here now, constant thunder, quite large drops of rain and some lightning. This is the livliest year in terms of thunder heard. Woooo

EDIT: Absolutly tipping it down now, real gusty !

Right over head now, Thunder is loooud

http://www.mebeam.com/Storm

Edited August 25, 2009 by JamieUK

[Pale Blue Sky]

Am I hallucinating, or is it thundering on the south side of Northampton?

-PBS-

[NorthantsSnow]

Am I hallucinating, or is it thundering on the south side of Northampton?

-PBS-

Can confirm. A few loud rumbles of thunder here in the past few minutes following a heavy downpour in the last half hour.

[Harry]

Am I hallucinating, or is it thundering on the south side of Northampton?

-PBS-

I think many people are asking the same question - yesterday there were some strong indications (from other charts!!) of some thundery activity, including an Estofex Level 1 - there was nothing.

Today, there is nothing, and what do we have I wonder - thunderstorms/thundery showers.......'aint life a biaatch!'

Not especially sure why we are surprised to be honest - it has been well documented on here that the day after fronts have pushed through, are favourable for convective development, be it showers or thunderstorms - today is another which backs up that observation v well!!

Just to add to this, the shower which passed through a little while ago is showing signs of re-organising at moves in towards Kent and possibly Essex.

Edited August 25, 2009 by Harry

[Pale Blue Sky]

I think many people are asking the same question - yesterday there were some strong indications (from other charts!!) of some thundery activity, including an Estofex Level 1 - there was nothing.

Today, there is nothing, and what do we have I wonder - thunderstorms/thundery showers.......'aint life a biaatch!'

No kidding!

This little un-looked-for storm is producing more thunder than I've heard all year!

Shame I'm on the wrong side of the building to be able to see what the cloud looks like - from this window, I can see blue skies and towering cumulous - all the action is happening beyond my field of view.

[Costa Del Fal]

These wispy looking clouds look brilliant. Makes up for just missing the storm which died out after here.

[JamieUK]

Quite a few thunderstorms surrounding us here. Just deep constant rumbling. Pretty eery

[kanes_girl]

Quite a few thunderstorms surrounding us here. Just deep constant rumbling. Pretty eery

We must be getting the tail end here then, as i'm about 16 miles frm Ayls

[JamieUK]

Extremely heavy rain Again! Hailstones, the lot, wowww

http://www.mebeam.com/Storm

Edited August 25, 2009 by JamieUK

[Harry]

C'mon, I think it's ok if we're surprised. A few days ago we had much more CAPE and much steeper lapses, Estofex issued a storm risk and nothing came of it. Today we have minimal CAPE and lapses are quite poor. The occluded front which has passed has probably brought the showers and the two storms today but even still, I certainly wasn't expecting anything in the way of heavy showers, and neither were the Met Office. They forecast for light showers and then quickly changed it to scattered heavy showers as they started breaking out.

If anything, this just goes to show how difficult it is predicting convective development. One day, the conditions are there, the forcing mechanism is there, but nothing much comes of it. And then you have today, where the important storm factors are poor but for some reason, an occluded front or trough has made the most of it, and created two small storms and a bunch of showers.

Well maybe this is a learning curve to be honest - I pay a fair bit of attention to the 'data', i.e CAPE, lapse rates etc, but as goes to show, they don't give you everything. No set of data I have seen gives you the 'x factor', the element which will ultimately decide yay or nay! T-skews give you a lot of information - some of the data indicates 'tornadic supercells LIKELY', where other information on the same chart says 'no single cell thunderstorms expected' - those are the terms used on the charts!

I work on both what the data is telling, and what I FEEL SHOULD happen! i.e. today, if it was my responsibility to issue some kind of forecast, I would have forecast "sunny spells with scattered showers, some heavy with a risk of thunder", because this is now a very common event after a cold front has trundled through. On days like this, the heaviest showers will readily develop towards the middle part of the day, early afternoon, and as you approach late afternoon, will very readily start to decay. I am intrigued to see what will end up happening, because like many, I have not paid close enough attention to the forecast, even at the moment!!. Based on many previous experiences of these setups alone, just this summer, this is what has happened and what is likely to happen in the future.

When cold fronts trundle through, they seldom leave a general mass areas of CAPE. What they do do however, is introduce cooler/colder air at different altitudes. This however does not mean ALL of the humid, more buoyant has been displaced - small pockets/areas remain. The sun comes out, the remaining moist and buoyant goes straight up and forms nice towering Cu/Cbs, bringing our showers. At the end of the day, the remaining relatively moist pockets have been displaced in the form of showers, leaving a wider area of stable, cooler air.

This is how I very much generalise it in my head (whether right or wrong - I am sure someone will tell me if I am wrong). There is little meteorological credit/knowledge here - this is just how I rationalise it based on recent years observations. CAPE charts, lapse rates will not show this, because they cover a wider area and do not account for the very much localised areas of difference.

This is why I am not surprised by todays thundery outbreaks. If there is another explanation for it, I am all ears, always ready to learn...

Edited August 25, 2009 by Harry

[NorthantsSnow]

Looks like the ex-Northampton storm has Peterborough's name on it.

[Coast]

Crazy country huh?

Big level 1 from ESTOFEX and indications of a chance of storms from other data/sites yesterday and nothing - not even much rain. All quiet on the www today and what do we get?

I should have stayed on in Essex earlier to watch it pass through - its the nearest I'm going to get at this rate!

[JamieUK]

Any1 who is East of me is in for a real treat, seems to be intensifying as it passed through, how intense can it get though, it was screaming it down with hail, constant thunder etc for the best part of 20mins...excellent stuff! :)

Oh and i was looking up at the clouds for ages lol and they were going in different directions, some actually moving oppositly into each other? and on the radars the rain is moving to a NE but many of the clouds to the NW? how come?

Edited August 25, 2009 by JamieUK

[sunny scunny]

Plenty of showers near my area, but the shield is working very well

[weatherobsuk]

Big Anvil tops spreading out over West Manchester towards the Peak District now. The Convective Cells are still only over Warrington/Northwich yet the tops are huge from here. Sun is also surprisingly hot and driving this thing like a furnace.

Anyone in Cheshire/Manchester also able to report on anything further upfield from my location?

[Harry]

Any1 who is East of me is in for a real treat, seems to be intensifying as it passed through, how intense can it get though, it was screaming it down with hail, constant thunder etc for the best part of 20mins...excellent stuff! :good:

Oh and i was looking up at the clouds for ages lol and they were going in different directions, some actually moving oppositly into each other? and on the radars the rain is moving to a NE but many of the clouds to the NW? how come?

Could be a few things, but I would imagine it is the downdraught from the within the cloud. Although the storm is moving NE, the downdraught would occur to the Western flank, thus moving the clouds in a W/NW direction. It could be the result of inflow winds - i.e. if the storm is still organising, it could be drawing on slightly moister air from the southern region, meaning the clouds along this path could be moving NW. It could also be rotation, keep your eyes peeled for possible funnels!

The air flow around any form of shower or storm can be so turbulent, the winds and therefore the clouds can move in really any direction.

[karyo]

Big Anvil tops spreading out over West Manchester towards the Peak District now. The Convective Cells are still only over Warrington/Northwich yet the tops are huge from here. Sun is also surprisingly hot and driving this thing like a furnace.

Anyone in Cheshire/Manchester also able to report on anything further upfield from my location?

Hi mate,

i've had a line of heavy showers that crossed slowly from west to east about an hour ago. Beautiful cloud tops! No thunder though...

More showers now but not as heavy. Still not electric!

Karyo