Convective / Storm Discussion Thread - 27th Feb onwards

[tomp456]

Looking NW about 30 minutes ago.

sky was much darker than what shows in pic

 

[NO LONGER POSTING]

9 minutes ago, Essex Easterly said:

Did you get much from Yesterday mornings wave Surrey?

No missed out yesterday but enjoyed some lovely weather so not fussed, I'm smack bang in the what the models are toying around with and the various warnings for tonight so hopefully I'll catch one tonight (=

[Sparkiee storm]

What's the DLS like tonight?

[Gordon Webb]

4 minutes ago, Mapantz said:

I wouldn't take too much notice of the warning - it's a blanket warning to cover their hiney's.

agree with this so if any part of the warning gets hit and with a warning area this wide there's a good chance of somewhere seeing at least something they can say they put out warnings covering themselves from criticism which I find odd Since when do anybody criticise the met office

OH WAIT

 

Edited May 28, 2017 by Gordon Webb
Correcting spelling errors again

[Wilxy]

Day 1 Convective Outlook: Sun 28 May 2017   

VALID 06:00 UTC Sun 28 May 2017 - 05:59 UTC Mon 29 May 2017

ISSUED 14:33 UTC Sun 28 May 2017

ISSUED BY: Chris/Dan

*Update at 1430z on Sunday to shift the main empahsis a little further west due to model trends* 

 

Upper trough approaching Iberia will advect a plume of high ThetaW air northwards across southern Britain through the course of Sunday evening and overnight into Monday. Destabilisation of this plume is expected, with upper forcing combining with isentropic upglide to allow areas of elevated thunderstorms to develop and expand in coverage - at least for a time - before general weakening/reducing trend is anticipated later in the night. 

 

Current thinking is activity will develop around the 19-22z timeframe over the English Channel / Channel Islands / SW England, growing upscale as the whole area of potential shifts NE-wards through the night. Steep mid-level lapse rates and reasonable CAPE suggests lightning will be notably frequent with any thunderstorms, especially farther east where such parameters will be more favourable.

 

As is often the case in such situations, there is some uncertainty as to the exact forecast evolution and position of areas most likely to experience thunderstorms - as such, the exact position of the SLGT/MDT is subject to some alterations. Some hail and strong gusts of wind will be possible with some of this convective activity.

Edited May 28, 2017 by tomjwlx

[tomdewey]

Will I get any thunder or lighting under this cloud or will is cloud turn into a home grow thunder storm?

[Mapantz]

Quote

Day 1 Convective Outlook

VALID 06:00 UTC Sun 28 May 2017 - 05:59 UTC Mon 29 May 2017

ISSUED 14:33 UTC Sun 28 May 2017

ISSUED BY: Chris/Dan

*Update at 1430z on Sunday to shift the main empahsis a little further west due to model trends* 

Upper trough approaching Iberia will advect a plume of high ThetaW air northwards across southern Britain through the course of Sunday evening and overnight into Monday. Destabilisation of this plume is expected, with upper forcing combining with isentropic upglide to allow areas of elevated thunderstorms to develop and expand in coverage - at least for a time - before general weakening/reducing trend is anticipated later in the night. 

Current thinking is activity will develop around the 19-22z timeframe over the English Channel / Channel Islands / SW England, growing upscale as the whole area of potential shifts NE-wards through the night. Steep mid-level lapse rates and reasonable CAPE suggests lightning will be notably frequent with any thunderstorms, especially farther east where such parameters will be more favourable.

As is often the case in such situations, there is some uncertainty as to the exact forecast evolution and position of areas most likely to experience thunderstorms - as such, the exact position of the SLGT/MDT is subject to some alterations. Some hail and strong gusts of wind will be possible with some of this convective activity.

[Gordon Webb]

2 minutes ago, Sparkiee storm said:

What's the DLS like tonight?

a) ... NW-France and S-UK ...

Ongoing thunderstorms from the previous night over the Bay of Biscay will start more elevated with 500-800 J/kg MUCAPE and 20 m/s DLS. Organized convection may already pose an isolated large hail threat.
Thunderstorms move to the NE and eventually onshore over NW-France during the daytime hours. There, a CAPE/shear space exists, favorable for organized DMC with 20-25 m/DLS and 800 - 1500 J/kg MLCAPE. Either expect onshore moving storms to root into the warm/moist BL air mass or expect CI onshore. Multicells/isolated supercells are possible over NW-France, which move off to the N/NE. Large hail, severe wind gusts and an isolated tornado risk is forecast with that activity. Thunderstorms weaken offshore over the English Channel with cooler LL air while crossing a sharp E-W aligned CAPE gradient. CI will be more isolated in nature, although upscale growing convection can't be ruled out with one or two clusters affecting the English Channel until sunset.

Confidence in more widespread CI increases during the night with the development of a diffuse/weak LL vortex over the W-English Channel in response to the approaching upper trough. This vortex pushes a wavy front east and a cluster of organized thunderstorms is forecast to evolve over NW-France and/or SW-UK. Forecast soundings reveal more elevated convection with MUCAPE of 1 kJ/kg and 20 m/s DLS. Also, 0-3 km shear increases to 15-20 m/s over far S-UK. Expect thunderstorms to grow upscale into a cluster of storms while crossing S-UK from WSW to ENE. Large hail will be the main risk. However, given amount of 0-3 km shear and persistent influx of moist/warm air from the S, a severe wind gust theat with a rapidly eastbound moving bowing line is possible. Weak mid-level height falls and the quasi-stationary nature of the evolving LL vortex over the W-English Channel lower the chance for a forced line of convection but indicate more of an internally organized (cold pool driven) event. Hence, the final outcome of that event depends on mesoscale impacts and nowcasting of the front's placement during the night and remains somewhat uncertain right now.
 

think answer is in there somewhere

[The PIT]

That little cell without any lightning in the south east is holding on in there isn't it. Plucky little thing.

[Sparkiee storm]

2 minutes ago, Gordon Webb said:

a) ... NW-France and S-UK ...

Ongoing thunderstorms from the previous night over the Bay of Biscay will start more elevated with 500-800 J/kg MUCAPE and 20 m/s DLS. Organized convection may already pose an isolated large hail threat.
Thunderstorms move to the NE and eventually onshore over NW-France during the daytime hours. There, a CAPE/shear space exists, favorable for organized DMC with 20-25 m/DLS and 800 - 1500 J/kg MLCAPE. Either expect onshore moving storms to root into the warm/moist BL air mass or expect CI onshore. Multicells/isolated supercells are possible over NW-France, which move off to the N/NE. Large hail, severe wind gusts and an isolated tornado risk is forecast with that activity. Thunderstorms weaken offshore over the English Channel with cooler LL air while crossing a sharp E-W aligned CAPE gradient. CI will be more isolated in nature, although upscale growing convection can't be ruled out with one or two clusters affecting the English Channel until sunset.

Confidence in more widespread CI increases during the night with the development of a diffuse/weak LL vortex over the W-English Channel in response to the approaching upper trough. This vortex pushes a wavy front east and a cluster of organized thunderstorms is forecast to evolve over NW-France and/or SW-UK. Forecast soundings reveal more elevated convection with MUCAPE of 1 kJ/kg and 20 m/s DLS. Also, 0-3 km shear increases to 15-20 m/s over far S-UK. Expect thunderstorms to grow upscale into a cluster of storms while crossing S-UK from WSW to ENE. Large hail will be the main risk. However, given amount of 0-3 km shear and persistent influx of moist/warm air from the S, a severe wind gust theat with a rapidly eastbound moving bowing line is possible. Weak mid-level height falls and the quasi-stationary nature of the evolving LL vortex over the W-English Channel lower the chance for a forced line of convection but indicate more of an internally organized (cold pool driven) event. Hence, the final outcome of that event depends on mesoscale impacts and nowcasting of the front's placement during the night and remains somewhat uncertain right now.
 

think answer is in there somewhere

Yeah I saw the answer in there haha, thank you :).

 

[ancientsolar]

Perhaps i'll try a 3 camera set up tonight ... It's just impossible to know whether or not i'll capture anything. ~ 
I saw the flashes from the lightning a 100 miles away when the storm erupted in Plymouth.. so that kinda give me a little ,., as long as i'm with in 70miles I should be able to see something  

[SteveB]

Is this crud coming up from the South part of the plan, or is it scuppering things?

[Evening thunder]

Ok so after seeing some charts/suggestions that things will be further east than me including a tweet from Ian F about the latest Met Office assessment.. the Convective Weather update shifts west and places me firmly in the moderate zone!

Not sure what to think. They have done well in the past so hopefully that continues

[Daniel*]

 

We'll see....

 

[sparky1972]

temp rising and humidity falling here at the mo, weather station currently reading 27c and humidity 47%

[Wilxy]

1 minute ago, SteveB said:

Is this crud coming up from the South part of the plan, or is it scuppering things?

Its part of the plan it should clear north of us by evening then its all eyes to are south!

[UKSupercell]

Can someone tell me if the south-east (Chilterns/greater London area) is in for any storms tonight? The forecast looks promising, but it's just started raining here yet there's no sign of thundery activity from this crap moving north, and little sign of any significant storms currently over France. 

[Windblade]

Darkening to my southwest. Looking on radar there appears to be a moderate cell headed this way. No sparks yet but it could produce, maybe.

[Mapantz]

1 minute ago, Evening thunder said:

Ok so after seeing some charts/suggestions that things will be further east than me including a tweet from Ian F about the latest Met Office assessment.. the Convective Weather update shifts west and places me firmly in the moderate zone!

Not sure what to think. They have done well in the past so hopefully that continues

It shows how complicated this one is. 

*Watches radar and move the animations back and forth to work out trajectory*

[Gordon Webb]

1 minute ago, Evening thunder said:

Ok so after seeing some charts/suggestions that things will be further east than me including a tweet from Ian F about the latest Met Office assessment.. the Convective Weather update shifts west and places me firmly in the moderate zone!

Not sure what to think. They have done well in the past so hopefully that continues

was about to comment on that myself but got hung up on mutliple quoting , it seems even now no one is quite sure what is going to happen later tonight and overnight , even Dan from convectiveweather highlighting the uncertainty

[Rob Walker]

9 minutes ago, tomdewey said:

Will I get any thunder or lighting under this cloud or will is cloud turn into a home grow thunder storm?

No, look toward later on this evening for developing storms this is just left overs from biscay.

[Summer Sun]

15:45 update

Day 1 Convective Outlook

VALID 06:00 UTC Sun 28 May 2017 - 05:59 UTC Mon 29 May 2017

ISSUED 14:45 UTC Sun 28 May 2017

ISSUED BY: Chris/Dan

*Update at 1430z on Sunday to shift the main empahsis a little further west due to model trends* 

Upper trough approaching Iberia will advect a plume of high ThetaW air northwards across southern Britain through the course of Sunday evening and overnight into Monday. Destabilisation of this plume is expected, with upper forcing combining with isentropic upglide to allow areas of elevated thunderstorms to develop and expand in coverage - at least for a time - before general weakening/reducing trend is anticipated later in the night. 

Current thinking is activity will develop around the 19-22z timeframe over the English Channel / Channel Islands / SW England, growing upscale as the whole area of potential shifts NE-wards through the night. Steep mid-level lapse rates and reasonable CAPE suggests lightning will be notably frequent with any thunderstorms, especially farther east where such parameters will be more favourable.

As is often the case in such situations, there is some uncertainty as to the exact forecast evolution and position of areas most likely to experience thunderstorms - as such, the exact position of the SLGT/MDT is subject to some alterations. Some hail and strong gusts of wind will be possible with some of this convective activity.

http://www.convectiveweather.co.uk/forecast.php?date=2017-05-28

[SteveB]

3 minutes ago, tomjwlx said:

Its part of the plan it should clear north of us by evening then its all eyes to are south!

Cheers Tom, can't quite believe I will see another storm within a couple of days of each other, but like buses maybe two come along together

[ancientsolar]

for those of us left in storm limbo,. at least it's supposed to be moving towards us earlier in the night.. rather than 4-5am .. hoping for a good nights sleep!

[Thunderstruck]

Hmmm. Westward shift in the MDT there. Still in the slight though, and I do feel like we'll see something tonight...