Convective/Storm Discussion Thread - 1st August onwards

[Another Kent clipper]

1 hour ago, Windblade said:

So , when's the next event likely to be so I can expect another bout of disappointment? Wondering if this weekends upcoming warmth could produce some pulse storms? 

I thought that myself but when I looked at the gfs forecast on this website, I saw nothing for the next two weeks.  Northern France seems to be as close as the action will get

[Chris.R]

 Maybe something Monday evening? 

[Supacell]

45 minutes ago, Chris.R said:

 Maybe something Monday evening? 

Although the NMM suite from Netweather does want to break some heavy precipitation out across Wales and push it NE into NW England I cannot find any other models that do the same. GFS shows some light precipitation in a similar area but most show dry weather all the way. With high pressure in charge it is unlikely but there is low pressure moving in from the west with an associated weak cold front so who knows. I would like to see some more models on board to have greater confidence.

[The PIT]

Something maybe Tuesday with the air of a convergence zone moving eastward.

[Flash bang flash bang etc]

2 hours ago, The PIT said:

Something maybe Tuesday with the air of a convergence zone moving eastward.

We never do well with marginal setups so i’m not holding my breath about the next few day’s potential.

Was out last night /this morning watching out for the ETA Aquariid and it was a good reminder about what season we’re in - proper chilly - I had 2 coats on!

Until we get humidity of some sort I think it’ll just be pleasant & dependable fine weather for the next few days - which isn’t a bad thing!

[Supacell]

I think ridging will be too strong tomorrow for there to be any thundery activity. If there is anything at all then it will be a few large raindrop type showers from the high ground of Central Wales up into north-west England but really I expect it will be a glorious sunny day tomorrow for most of us. On Tuesday there may be some showers and possibly thunderstorms across Eastern England forming ahead of a cold front moving in from the west. The Met Office have been mentioning this and some convection is showing up in the models but again it is a very small risk (although a higher risk than is the case tomorrow).

[The PIT]

16 hours ago, Flash bang flash bang etc said:

We never do well with marginal setups so i’m not holding my breath about the next few day’s potential.

Was out last night /this morning watching out for the ETA Aquariid and it was a good reminder about what season we’re in - proper chilly - I had 2 coats on!

Until we get humidity of some sort I think it’ll just be pleasant & dependable fine weather for the next few days - which isn’t a bad thing!

T shirt weather here even overnight. Will be interesting if the convergence zone is still there and weather it'll be strong enough to create showers.

[Summer Sun]

Day 2 Convective Outlook

VALID 06:00 UTC Tue 08 May 2018 - 05:59 UTC Wed 09 May 2018

ISSUED 19:11 UTC Mon 07 May 2018

ISSUED BY: Dan

An upper trough will slide eastwards across central/northern Britain on Tuesday with a surface cold front drifting slowly eastwards. Ahead of this front, a corridor of high dewpoint air (14-17C) will exist, providing the focus for some convective potential given strong heating (air temperatures likely to reach 24-27C over E / SE England during the afternoon hours, with 600-1,00 J/kg CAPE as a result) and increasing low-level wind convergence.

Model guidance varies markedly on convective initiation, with some generating numerous showers while others remain virtually dry. Forecast profiles are very dry, with a nose at about 600mb which may inhibit deep convection. That said, forcing will subtly increase aloft as the upper trough approaches from the west.

 

Current thinking is an isolated heavy shower / thunderstorm may develop over Durham / North Yorkshire during the first half of the afternoon in combination with low-level convergence and some orographing forcing over the North York Moors - this then moving out to the North Sea. Other showers may develop further south along this N-S boundary during the afternoon, but particular focus is given to East Anglia during the late afternoon / first half of the evening where one or two thunderstorms may develop and clear to the NE. 

 

Deep layer speed shear will be increasing towards the evening as the flow aloft strengthens on the forward side of the approaching upper trough - though directional shear looks a little messy. If a thunderstorm can develop (despite the limiting factors mentioned above), given the magnitude of instability it could produce hail up to 1.5cm in diameter and some localised surface water issues given PWAT 25-30mm. Have reluctantly issued a low-end SLGT to better highlight this potential, despite low confidence at present.

 

http://www.convectiveweather.co.uk/forecast.php?date=2018-05-08

[Flash bang flash bang etc]

Looks like a downgrade to only really affect East Anglia (if anything can get going at all).

Shame as I was up for hanging about NE London area after work to see what would happen - but not worth it now.

Interesting to see what happens though

[NO LONGER POSTING]

1 minute ago, Flash bang flash bang etc said:

Looks like a downgrade to only really affect East Anglia (if anything can get going at all).

Shame as I was up for hanging about NE London area after work to see what would happen - but not worth it now.

Interesting to see what happens though

Yes risk was low before, but now most high RES models not interested at all its because the first front moving in is decaying to quickly 

[NO LONGER POSTING]

Hold the phone... Currently travelling from Marlow to Great missinden and serious lift going on... Big towering clouds going up 

[NO LONGER POSTING]

Pit stop, still going up... 

Anyone east of say Aylesbury into Norfolk and Norwich hot spots up north into Cambridge etc good location if these can continue to grow.. 

 

 

[Flash bang flash bang etc]

43 minutes ago, Surrey said:

Pit stop, still going up... 

Anyone east of say Aylesbury into Norfolk and Norwich hot spots up north into Cambridge etc good location if these can continue to grow.. 

 

 

Yeah in Purfleet at the moment, and only a few little fluffy clouds about but it’s very warm here and though small they do have that look about them...

[NO LONGER POSTING]

55 minutes ago, Flash bang flash bang etc said:

Yeah in Purfleet at the moment, and only a few little fluffy clouds about but it’s very warm here and though small they do have that look about them...

Yep they have really gone up but can so they can't rise anymore here, maybe areas further east like I said will have a suprise nothing in radar yet 

[Flash bang flash bang etc]

It’s ‘should I stay or should I go’ time...

I’m in Brentwood, and those skies are teasing me 

[Thunderstruck]

Cloud and humidity absolutely soared in the past couple of hours. Definitely wouldn’t rule anything out in Essex, even if not directly in my area

[NO LONGER POSTING]

22 minutes ago, Flash bang flash bang etc said:

It’s ‘should I stay or should I go’ time...

I’m in Brentwood, and those skies are teasing me 

Don't do it, I can see the back edge of that stuff over London I'm coming down the m4 east bound, they can't break through the cap at moment tops are flat as pancake I think if anything happens now it will be Norfolk or the North Sea that gets it 

Edited May 8, 2018 by Surrey

[Eye to the sky]

Threatening skies in the north midlands.Gone from blue skies to dark and stormy skies.Breeze picking up too.

[Flash bang flash bang etc]

12 minutes ago, Surrey said:

Don't do it, I can see the back edge of that stuff over London I'm coming down the m4 east bound, they can't break through the cap at moment tops are flat as pancake I think if anything happens now it will be Norfolk or the North Sea that gets it 

Yeah I do see that, although one sferic appeared on Blitzortung - could be a false strike as no precip for that area on the radar

[Summerstorm]

4 minutes ago, Eye to the sky said:

Threatening skies in the north midlands.Gone from blue skies to dark and stormy skies.Breeze picking up too.

That'll just be the front passing through and the rain associated with it nothing convective about it probably. 

[NO LONGER POSTING]

43 minutes ago, Flash bang flash bang etc said:

Yeah I do see that, although one sferic appeared on Blitzortung - could be a false strike as no precip for that area on the radar

By now the high RES models showing anything today had storms breaking out about an hour half ago.. 

[Summer Sun]

Day 2 Convective Outlook

VALID 06:00 UTC Sat 12 May 2018 - 05:59 UTC Sun 13 May 2018

ISSUED 20:04 UTC Fri 11 May 2018

ISSUED BY: Dan

Sharpening upper trough will drift slowly across Ireland, while digging south over Biscay. Within the trough axis, cold air aloft will result in steep mid-level lapse rates, generating 300-600 J/kg CAPE in response to diurnal heating. 

Deep convection will be ongoing at the start of the forecast period over the Celtic Sea, associated with a slowly-filling cut-off upper low. This convection will tend to weaken during the morning hours, with the focus then shifting northwards across the Republic of Ireland and eventually Northern Ireland. Under the trough axis, shear will be fairly weak and so pulse-type showers/storms are most expected - hence any lightning will tend to be short-lived and sporadic. Worth noting that subsequent model guidance have tended to make showers increasingly isolated compared to earlier runs, causing some uncertainty over likely coverage.  Showers/storms will gradually decay through the evening, though further showers are likely close to Atlantic coasts overnight.

 

On the forward side of the upper trough, a frontal wave will develop over France, pushing rain northwards into SE England and East Anglia. The exact track / shape of this wave remains uncertain, and hence timing and areas affected. Either way, on the eastern flank some weak instability may be present, with perhaps an isolated lightning strike - hence the inclusion of a LOW threat level.

 

http://www.convectiveweather.co.uk/forecast.php?date=2018-05-12

Edited May 11, 2018 by Summer Sun

[Nick F]

Storm & Convective Forecast

Issued 2018-05-12 09:51:06
Valid: 12/05/2018 0600z - 13/05/2018 0600z

THUNDERSTORM OUTLOOK - DAY 1 (SATURDAY 12TH MAY)

Synopsis

A deep upper trough extends south from Iceland across E Atlantic / Ireland and on down to northern Iberia. There is a risk of isolated thunderstorms developing on the edge of this upper trough across Ireland, N. Ireland and SW England today.

... N. IRELAND, IRELAND and far SW of ENGLAND ...

Cold mid-levels of upper trough overlapping far west will overspread the above areas, creating steepening lapse rates with surface heating, which combined with surface breeze convergence will allow bands of heavy showers and isolated thunderstorms to develop, which maybe accomapanied by hail and heavy rainfall which may lead to localised flooding. Deep layer shear will be weak of Ireland/N. Ireland, stronger over SW England but CAPE forecast to be weak here, so no severe weather is expected. Showers/storms should fade after dark as surface heating wanes.

... E ENGLAND ... 

A low risk of isolated lightning from embedded mid-level convection within pulses of rain spreading north across E England later and overnight.

[Mercury Rising]

oi oi ! ?  

[BlueHedgehog074]

Some embedded convection within the front to my East (had rained a bit earlier here)

Also took a recent screen capture of the Netweather radar, which is showing a line of some very torrential rain just to the East and North-East of London, with some red echoes. And maybe some thunder?

Looks wild down their!