Storm & Convective Discussion - 16/07/15 onwards

[steve86]

Nice bit of convection here in Gosport

[Chris K]

Question - why is SBCAPE/LI so drastically reduced during August in the model outputs when compared to similar set ups in July? Is it the gradual reduction of the strength of the sun? 

 

For example GFS 0z shows Low pressure moving up from the South with moderate values of CAPE. Compare it to something similar showing up in June/July and we would have those silly red/white CAPE values.

 

I know there are many factors required for storms - it was just something interesting I noticed.

Edited August 17, 2015 by Chris K

[Dean E]

Nice bit of convection here in Gosport

 Can see this too! 

 

Being shown as a small convection area on the Satellite as well

 

[Speedway Slider]

Looking at Wednesday 19th Aug, Poole in Dorset....

Is there enough in the forecast to say if they are gonna get a lot of heavy, perhaps some thundery stuff, especially late afternoon/early evening down that end of the UK?

Ball park I realise....

[East_England_Stormchaser91]

Question - why is SBCAPE/LI so drastically reduced during August in the model outputs when compared to similar set ups in July? Is it the gradual reduction of the strength of the sun? 

 

For example GFS 0z shows Low pressure moving up from the South with moderate values of CAPE. Compare it to something similar showing up in June/July and we would have those silly red/white CAPE values.

 

I know there are many factors required for storms - it was just something interesting I noticed.

I personally think its undercooking. I've seen some brilliant convection in August over the years. August 25th 2012 was a typical UK storm day with a low pressure right over us, and it delivered some cracking storms countrywide, with notable ones in Ely/Littleport, Bristol and Sheffield way. Some really quite memorable storms took place particularly in the Augusts of 2003, 2004, 2005 and 2006 also. 

[Nick F]

00z GFS says risk of storms Saturday/Sat night, as heat and humidity builds with the trigger a thundery trough/low moving north ahead of slow-moving/wriggling front across the west, before fresher conditions spread east Sunday. ECMWF not having any of it. Be nice if GFS is right ... but sod's law ECMWF probably closer to the truth.

[Stormyking]

You dont always need lots of SB Cape for really good convective days, there is a lot of other factors to that is also good for some awesome convective weather, especially August and September.

Other factors also include Wind sheer

Mid Level cape and lifted

Transitional weather fronts too, such as cold fronts and stuff.

 

Also During End of Summer and through Autumn, good surface based cape confines back to mainly coastal waters, due to the land is becoming  and the Sea is Warmer, this tends to happen more During Evening, Night and Early hours

 

Hope I have explained this ok

[Supacell]

I suppose I can dream. It has been over 6 weeks now since I last saw a storm!

 

[Winter Cold]

That looks good for Sheffield and Derby doesnt it! We can keep our fingers and toes crossed lol 

[Dorsetbred]

Looking at Wednesday 19th Aug, Poole in Dorset....

Is there enough in the forecast to say if they are gonna get a lot of heavy, perhaps some thundery stuff, especially late afternoon/early evening down that end of the UK?

Ball park I realise....

NAh, I live in Poole and it doesn't look that heavy from an overall outlook perspective.

[JamieUK]

Saw these clouds in Aylesbury today. I thought these were Mammatus clouds but they're only associated with severe thunderstorms right? Can anyone clarify?

[Thunderbolt_]

Not a bad pub run from the GFS this evening, with surface-based CAPE values of 800-1,000 joules/kg quite widely, with some pockets of CAPE going up to about 1,400 joules/kg. There is also moderate instability, with LI values of -3 to -4. Furthermore we have some pretty decent air temperatures at 850hpa and lapse rates.

 

 

We could see some very beefy surface-based thunderstorms.

[Panayiotis]

Saw these clouds in Aylesbury today. I thought these were Mammatus clouds but they're only associated with severe thunderstorms right? Can anyone clarify?

Theyre amazing! Not necessarily, I have seen mammatus on countless occasions where they were just passing through without any thunderstorms/rain around...

[Nick F]

Saw these clouds in Aylesbury today. I thought these were Mammatus clouds but they're only associated with severe thunderstorms right? Can anyone clarify?

 

No, you don't need thunderstorms to produce mammatus, just the right atmospheric conditions. such as temperature difference, wind shear etc. Great photo btw, they showed similar photo on BBC London News Weather last night taken over the northern Home Counties.

 

Weekend looking interesting for storms potential atm, as a plume of very warm, humid and increasingly unstable air gets sucked up across central and eastern parts on Saturday ahead of a cold front moving in from the west, though some disagreement between models (ECM and GFS) with regards to how quickly they clear the frontal boundary east.

 

00z GFS clears a band of thundery rain/storms along this boundary out into the N Sea Sunday morning after a hot day across central and eastern England on Saturday, with thundery rain developing along the boundary further north and west. ECMWF slower to clear this frontal boundary, with its thundery rain/storms (not till Monday), developing an area  of low pressure along the boundary - which further slows the clearance of the boundary and its thundery rain - so would produce some large rainfall totals for some.

Edited August 19, 2015 by Nick F

[Thunderbolt_]

Here is a quick guide on how to interpret the BBC/Met Office's forecasts, since last time it turned out to be a total fiasco with some poeple:

 

https://forum.netweather.tv/topic/83800-how-to-interpret-and-use-the-bbcmet-office-forecasts/

[Gordon Webb]

well some MIGHT get there wish this weekend for heat or storms ?

 

considering this has been pushed on the main page and elsewhere since last weekend after the so called failure of last THURSDAY / FRIDAY this forecast should cheer some up but it's still 3 days away and models appearing to be chopping and changing every run to some degree  I won't hold my breath on this coming to pass

[William Grimsley]

I'm a little not with it with what is coming up this weekend. Is the south west affected by this?

[MP-R]

I'm a little not with it with what is coming up this weekend. Is the south west affected by this?

 

After last week, I'm not expecting anything regardless of what the forecasts say!

[Gordon Webb]

there is a chart showing possible potential for saturday Northern England and the Midlands which you should take with a pinch of salt , if you cannot find it that's because it's the model thread which of course IS THE IDEAL place for convective discussion

[A.J]

there is a chart showing possible potential for saturday Northern England and the Midlands which you should take with a pinch of salt , if you cannot find it that's because it's the model thread which of course IS THE IDEAL place for convective discussion

actually it was model discussion so it was posted in the correct thread, if the poster thought prudent, he would've also posted in this thread

[Winter Cold]

there is a chart showing possible potential for saturday Northern England and the Midlands which you should take with a pinch of salt , if you cannot find it that's because it's the model thread which of course IS THE IDEAL place for convective discussion

 

Just for you then Gordon, GFS 12z is an upgrade for storm potential on Saturday for those parts

 

[Costa Del Fal]

The West Midlands region through and up north towards Manchester looking prime spots for now though inevitable to change.

[Flash bang flash bang etc]

actually it was model discussion so it was posted in the correct thread, if the poster thought prudent, he would've also posted in this thread

I regularly check both - I consider the model thread to be the best place for early signals.

I also like to look at models - especially hot ones ;-)

[Darren Bown]

I actually am hoping for a dry Saturday, or if there's a storm risk, it's showers rather than persistent rain!

[Stormyking]

Im quite liking the look of this Weekend more than last week, there is a few other factors showing on this compared too last week, this time there seems to be a lot more heat further West across the majority of the Country and also convergence zones, along with decent ML cape and even some SB cape too. Should be some good cloud structures with the good wind sheer if this pulls off