Convective / Storm Risk Discussion - 14th June 2013 onwards

[Panayiotis]

Today is looking good! Showers have pepped up at the time expected with multiple squall lines developing over Wales and the SW:

http://www.netweather.tv/index.cgi?action=radar;sess=

Edited June 15, 2013 by Panayiotis

[ZONE 51]

Yes need to keep watch on thunderstorms today I was focused on the thundery plume event would have done a post later for today but getting on with time, actually are just go and get some charts... So much interest in the weather at the moment!

230am radar from weather online

[ZONE 51]

GFS 18z other not updated yet

1)

2)

 

Today unstable air, yellow area is the most unstable.

 

3)

CAPE shows that thunder a risk today.

 

4)Surface wind flows for midday.(larger image so can view closer)

 

Surface wind flows for midday(above)

 

5)UKMO 12z - low pressure

 

UKMO 12z

Low pressure today

 

Not looks closely so are leave it to other to say where storms could be today(or look back a page or two for recent model runs) Heavy showers and thunder likely, not sure exactly at this stage what develops later but could be some surprises in there.

Edited June 15, 2013 by ElectricSnowStorm

[Supacell]

The latest GFS charts have downgraded CAPE a little but there is still more than enough to produce scattered thunderstorms amongst the heavy showers today, and these will still likely make use of a plethora of other parameters to bring the risk of organised storm activity.

 

At 3pm, which looks to be peak time (although storms will start much earlier than this) it looks like GFS and NMM have the highest CAPE being over Lincolnshire and East Anglia, the downgrade means that CAPE values of around 500-700j/kg to be utilised. GFS CAPE is shown below, and Parcel Layer Depth looks quite decent too.

 

 

 

As has been mentioned, any storms that develop will be able to take advantage of 30-60 knts of deep layer shear (especially in the southern area of the higher CAPE) along with 15-25knts of low level shear with a moderate tornado risk parameter being shown across East Anglia and the southern East Midlands.

 

 

Helicity across the same area to allow those storms to rotate and bringing the risk of supercell's in the same areas as mentioned above.

 

 

However, ELT's look to be better further north (up to -40c around the Humber) but still decent enough across most of the country to promote lightning and hail.

 

 

I know it is not meant to show up storm probabilities etc but the NMM TT index is very impressive for Lincolnshire this afternoon. Values of 60 indicate scattered severe storms which would tie in well with what is showing on the charts.

 

 

So my thoughts are that there will be widespread showers today across the UK with most areas at risk of some thundery ones. The area I have highlighted within the red box is where there is a risk of severe thunderstorms, possibly even a supercell, bringing a risk of squally wind gusts, hail to 2cm in diameter and even the risk of a tornado. Peak time looks to be mid morning through to around 5pm, after which most of the best conditions move out into the North Sea. There is a risk of CG lightning anywhere within the yellow box, especially to the east.

 

 

Needless to say I will be out storm chasing from this morning onwards

Edited June 15, 2013 by Supacell

[Stuart]

the met office Take the word risk of thunder off for the Highlands forecast  so still in NSC 

[Norfolk Sheep]

Hmmmm, looks like Vinnie the Vito could have his first chase outing later today. Will follow developments closely

[Coast]

UKASF's take on today:

 

 

Moderate

Forecaster: Dan

Last Updated: 2013-06-14 17:12:00

Valid: 2013-06-15 00:00:00 - 2013-06-15 23:59:00

 

 

 

Synopsis:

 

Upper trough migrates eastwards across the British Isles through Saturday. At the surface, a cold front will clear eastwards through the early morning hours, followed by a very showery/convective scenario.

Discussion:

 

A cold front will migrate eastwards across England and Wales through the night-time hours, at the beginning of the forecast period (forming a wrap-around occlusion over Scotland). Under the left-exit region of the jet on the forward side of the upper trough, some 40-60kt DLS will allow embedded convective elements to develop, with the possibility of occasional broken convective lines/QLCS capable of producing locally very strong gusty winds and short periods of very heavy rain. Low-level helicity generated from backed surface winds ahead of the main surface front, rapidly veering westerly along/behind the front increases the threat of a tornado as the front continues to track eastwards. Isolated lightning/thunder is possible along the cold front, but given expected convective depth to be fairly shallow, this is likely to be rather isolated, if any at all.

 

Shortly behind the front, a cluster/area of heavy showers is expected to pass through, particularly across Wales and SW England, this having a greater chance of producing local thunder given MLCAPE values of 200-300 J/kg.

 

Through the day on Saturday scattered showers and a few thunderstorms will become widespread across many parts of Britain, with up to 800 J/kg SBCAPE by afternoon. Particular attention is given to E England where longest land track coupled with best diurnal heating and organisation from 30-50kts DLS is likely to lead to more widespread sferic activity. However, wrap-around occlusion debris with areas of more dynamic rain will tend to result with a rather messy situation in places, reducing surface temperatures (and SBCAPE) locally. 

The strongest cells (for organisation and longevity) are expected to be across the Midlands, Lincolnshire and East Anglia during the afternoon, with hail possibly >2.0cm in diameter in any stronger cells. Sufficient low-level helicity may allow for one or two low-topped supercells, capable of producing a tornado. Thus, these aforementioned areas will need monitoring for potential upgrade to SVR threat level through Saturday, although any severe threat should tend to be quite localised.

 

 

 

[Coast]

NMM puts some good structure to things in East Anglia this afternoon:

 

 

 

Very good surface CAPE and LI:

 

 

TT index also has good potential:

 

 

Aviation weather shows the jet and that area of possibilities:

 

 

 

 

 

 

Edited June 15, 2013 by Coast

[Coast]

Latest obs:

 

[Darren Bown]

Looks like a good storm risk for most today, but being in the midlands to Lincs/EA seems to be most favourable for anything severe.

Edited June 15, 2013 by Darren Bown

[Coast]

One problem I can see, is that surface heating may not be quite what we want:

 

 

This is the 15z forecast

[WillinGlossop]

http://www.estofex.org/

Level one warning issued for central uk....

Edited June 15, 2013 by WillinGlossop

[Supacell]

Some sferics detected off the east coast recently but other than that no sferics yet. I have decided to get an early start today and I am already just outside Nottingham heading east towards Lincolnshire. Once there I will position myself somewhere near the A1 to get a good run both north or south so I can intercept west to east moving bands of showers and hopefully thunderstorms.

 

Sferic near to Norwich too.

Edited June 15, 2013 by Supacell

[Coast]

I have decided to get an early start today and I am already just outside Nottingham heading east towards Lincolnshire. Once there I will position myself somewhere near the A1 to get a good run both north or south so I can intercept west to east moving bands of showers and hopefully thunderstorms.

 

I'd go for somewhere like Kings Lynn or Wisbech

[Coast]

Kicking off already:

 

[Methuselah]

Can see it from here, Coast...A line of anvils roughly aligned SSW-NNE...

[Stuart]

good luck all i missing out for today

Edited June 15, 2013 by Stuart

[Methuselah]

Just heard a distant rumble...Will it all be gone for this afternoon, anyone?

[Supacell]

Just heard a distant rumble...Will it all be gone for this afternoon, anyone?

 

No i doubt it will be gone for this afternoon, peak time looks to be this afternoon, particularly eastern areas.

 

Nice cell has fired up around Norwich and heading NE, spitting out quite a number of sferics and can hear lots of distant sferics on AM radio (which will be this cell). 

 

Thanks Coast, I am thinking somewhere like that too. Currently just outside Grantham and so will soon have a clear route towards Wisbech/Kings Lynn. Have to be back in Belper by 7-8pm though, but I expect most of the activity will begin to die very quickly from around 5pmish.

[Captain Shortwave]

Thunderstorm in Great Yarmouth right now, looks like they could get going quite well here today

[Nick F]

Storm & Convective Forecast - Issued 2013-06-15 09:40 Valid: 15/06/2013 1000z to 16/06/2013 0600z

Headline: ... THERE IS SLIGHT RISK OF SEVERE STORMS FORECAST ...

Synopsis
Unseasonably deep upper and collocted surface low move NE across northern Britain on Saturday, with a deeply cyclonic and unstable southwesterly flow across the UK.

.. ENGLAND and WALES ...

Unseasonably cold mid-levels (AOB -25C at 500mb) associated with upper low will overspread the UK during Saturday, creating very steep lapse rates. Scattered heavy showers and thunderstorms will increase in coverage across England and Wales as diurnal heating reaches its maximum during the afternoon in any sunny spells. 300-400 j/kg CAPE forecast by GFS sufficient for scattered thunderstorm development. Any storms will likely organise towards central and eastern England, given  strong 50-70mph westerly winds at 500mb and 40-60 knts of DL shear towards southern Britain, so there is a risk of strong convective wind gusts of 40-50 mph lowering to the surface given dry air aloft and also a risk of hail along with torrential rain leading to flooding.

A minor wave/trough passing through in the flow may allow winds to back towards the surface sufficiently for rotating updrafts/mesocyclones to develop in any storms, and with low LCLs there is scope for an isolated tornado to develop if sufficient low-level buoyancy can occur. 

Therefore have issued a SLIGHT risk across central, southern and eastern England

 

Issued by: Nick F

Edited June 15, 2013 by Nick F

[Staffordshire]

No i doubt it will be gone for this afternoon, peak time looks to be this afternoon, particularly eastern areas.Nice cell has fired up around Norwich and heading NE, spitting out quite a number of sferics and can hear lots of distant sferics on AM radio (which will be this cell). Thanks Coast, I am thinking somewhere like that too. Currently just outside Grantham and so will soon have a clear route towards Wisbech/Kings Lynn. Have to be back in Belper by 7-8pm though, but I expect most of the activity will begin to die very quickly from around 5pmish.

Good luck today mate, do you do your chases on your own?And for whatever its worth ill edge my bets on the best action in a square between Kings Lynn, Kettering, Grantham, Boston. But obviously one single badboy going right over the city of Lincoln as per usual. Edited June 15, 2013 by Staffordshire

[Norfolk Sheep]

No i doubt it will be gone for this afternoon, peak time looks to be this afternoon, particularly eastern areas.

 

Nice cell has fired up around Norwich and heading NE, spitting out quite a number of sferics and can hear lots of distant sferics on AM radio (which will be this cell). 

 

Thanks Coast, I am thinking somewhere like that too. Currently just outside Grantham and so will soon have a clear route towards Wisbech/Kings Lynn. Have to be back in Belper by 7-8pm though, but I expect most of the activity will begin to die very quickly from around 5pmish.

 Just gone past here, nothing heard or seen but it was developing en route. Intend to head up the A47 later to a favoured location and see what happens! (actually what normally happens is nothing, whilst at home all hell breaks loose...)

[Supacell]

Good luck today mate, do you do your chases on your own?

 

I do mate yes. Have to keep stopping to check updates on forums etc but can watch netweather extra radar as i am driving as it updates automatically. 

 Just gone past here, nothing heard or seen but it was developing en route. Intend to head up the A47 later to a favoured location and see what happens! (actually what normally happens is nothing, whilst at home all hell breaks loose...)

 

We may end up chasing a similar area, but from different directions 

[Ben Sainsbury]

Showers beginning to spread in for SW England now and I expect these to develop as they move further east.