Convective/Storm Discussion Thread - 1st August onwards

[Weather-history]

6 hours ago, Mokidugway said:

There's reports of flooding in greater Manchester this morning under horrendous conditions.

It was torrential this morning

 

[Thunderstruck]

Think that's it for the day now. Didn't take a direct hit thunder wise, but had some biblical rain, and also some deep, distant rumbles as well. That being said, it would be wrong of me to complain about it all being distant, it has been a great 2017, and I know others haven't been quite so lucky.

[Allseasons-Si]

There has been some lovely convective cloudscapes in the last few days in a cool west to northwesterly flow and although i didn't get any thunderstorms i wasn't too disheartened,

these first pics was of a Cb that got going to my NW saturday afternoon around 4pm,the first two are of ten minutes between then

then i fully zoomed out to capture these four shots ten minutes between them

another Cb was going up above my head but nothing came of it

now the best bit was a lovely evening sunset shining on these Cb's to my east,the last one is an anvil that was to my east this morning

also i am glad that some of you have had some storms over the last few days,September can deliver as i had a corker here last year

[Chris74]

Didn't expect the weather to turn out like it did today started of nice and sunny then turned about 5pm with thunder lightning and absolutely torrential rain not seen that amount of rain in a long time very nice though.

[LightningLover]

I've just seen a flash of lightning over the channel from an isolated cell.

[matt111]

1 minute ago, LightningLover said:

I've just seen a flash of lightning over the channel from an isolated cell.

Guess it came from this. 

[Robert Lewis]

Saturday was interesting in Reading, around 3-4pm it went from nice sunshine to very dark and ominous, I was at work trying to sell a house before the end of the day and I was driving to the east of Reading and thought this cell has all the makings for a thunderstorm, looked at the maps and there was nothing, suddenly 3-4 bolts of lightning came from the cell and it kicked off, had good regular lightning for about 20 mins before it passed over the east, had a few land relatively close to where i was, it stopped anyone coming to view this house till it passed so was cool standing in the doorway and watching it go over. Literally was nothing until it got to Reading and then it just started to unleash some real energy, pretty sure there was hail in a later storm shower that happened on Sunday too. 

[Stuart]

Day 1 Convective Outlook

VALID 06:00 UTC Tue 12 Sep 2017 - 05:59 UTC Wed 13 Sep 2017

ISSUED 06:21 UTC Tue 12 Sep 2017

ISSUED BY: Dan

Rapid deepening of a surface low as it drifts from Ireland and across the Irish Sea on Tuesday evening/night, to then be on the northern flank of the jet stream, combined with the dry intrusion should promote some deep convection on the wrap-around tip that crosses the Irish Sea late evening into NW England during the early hours. The location of this activity is subject to an error bar of +/- 80 miles N-S  but could result in some damaging gusts of wind in excess of 80mph locally - perhaps even capable of producing a tornado.

 

To the NW of this surface low, the approaching upper trough on Tuesday night will allow lapse rates to steepen, with numerous showers likely along western and northern coasts, some perhaps weakly-electrified.

 

http://www.convectiveweather.co.uk/forecast.php?date=2017-09-12

[Weather-history]

 

[Weather-history]

Mammatus visible from west Manchester

[Dangerous55019]

A stunning display of mammatus clouds here at the moment. 

[Weather-history]

 

[Summer Sun]

Day 1 Convective Outlook

VALID 06:00 UTC Wed 13 Sep 2017 - 05:59 UTC Thu 14 Sep 2017

ISSUED 05:27 UTC Wed 13 Sep 2017

ISSUED BY: Dan

Positively-tilted upper trough will slide gradually southeastwards across the British Isles on Wednesday, the associated cold pool aloft providing an environment with notably steep mid-level lapse rates. Showers will develop widely, some weakly-electrified in western exposed areas, and across parts of Ireland where better instability will exist as the upper cold pool approaches during the afternoon hours. Areas southeast of a line from The Wash to Devon may experience some heavy showers, but profiles will be capped somewhat with limited depth and hence lightning seems unlikely here, despite strongly-sheared profiles.

However, through the evening and night hours the cold pool and upper trough will continue to track southeastwards, and hence the environment will become increasingly unstable in SW Britain with showers developing more widely, along with a few thunderstorms - especially near west-facing coasts.

 

Hail to 1.5cm in diameter and gusty winds will be possible with the strongest cells, rain accumulations limited somewhat by strong steering winds. Overnight a band of showery rain will drift south over the North Sea, grazing some NE and E coastal counties of England and perhaps bringing an elevated threat of lightning here too - though confidence is not high enough to upgrade to SLGT for now.

 

http://www.convectiveweather.co.uk/forecast.php?date=2017-09-13

[Nick F]

Storm & Convective Forecast

Issued 2017-09-13 09:13:43
Valid: Weds 13 Sept 6am to Thurs 14 Sept 6am

Day 1 Convective / Storm Forecast

Synopsis

In wake of Storm Aileen - which will move across Denmark early afternoon, a potent upper shortwave trough in strong belt of upper westerlies will swing in across western Britain today, enhancing the instability of cool and unstable westerly flow across the UK. Much of Scotland will see cloud and general rainfall, limiting convective potential.

... IRELAND, N. IRELAND, ENGLAND and WALES ...

Increasingly cold mid-levels will spread in from the west with arrival of mid-level cold pool/shortwave trough ... steepening lapse rates and supporting heavy showers and increasingly scattered thunderstorms, as surface heating in sunny spells allows convective cloud to attain more height for charge separation. Heavy showers intially across western areas this morning, fuelled by seasonally warm SSTs and steeper lapse rates before becoming more widespread further east as surface heating and increasing lapse rates destabilise atmosphere. Thunderstorms most likely across Ireland, Wales, N and W England ... though anywhere across England may see storms this afternoon. Vertical deep-layer shear will be generally weak away from S England (underneath strong jet stream) and CAPE modest in cool Pm flow (a few 100 j/kg), so generally showers/storms will tend not to organise or be prolonged to bring a severe threat. Heavier showers and t-storms may bring hail and enhanced strong wind gusts.

Across S England/S Wales lines of showers/storms may organise and align into linear clusters with westerly streamlines to bring a risk of localised flooding and perhaps isolated strong, maybe damaging, convective wind gusts - particularly across SW England and S Wales - where have delineated a MARGINAL risk.

[Dangerous55019]

A little bit of convectivity going at the moment to my north.

Not really that surprising being as we're now in an unstable airmass in the wake of Storm Aileen. 

[LightningLover]

I just had a very unexpected and squally shower! It lasted for about 5 mins, with one gust of roughly 30mph. A moment ago it was completely clear, with a nice sunset. No electrical activity though.

After the shower: (notice the developing towers in the distance )

Edited September 13, 2017 by LightningLover

[Weather-history]

 

[toggerob]

NW 7 Day Weather Forecast is indicating a 52% risk of storms between 4 and 7 am into the morning. Possible trough development?

[Chris.R]

11 minutes ago, SNOW_JOKE said:

 

Edited September 13, 2017 by Chris.R

[LightningLover]

1 minute ago, Chris.R said:

Yeah been watching out. A bit of cake buildup, especially the light Liverpool Bay yeah been watching that. A bit of CAPE buildup, especially at Liverpool Bay. Already some activity in the Irish Sea and still a few hours to go. 

Cake buildup? Nice! (i'm presuming auto-correct is being a pain)

[Chris.R]

12 minutes ago, SNOW_JOKE said:

NW 7 Day Weather Forecast is indicating a 52% risk of storms between 4 and 7 am into the morning. Possible trough development?

Yeah I've been watching that. A bit of CAPE buildup later especially in Liverpool bay. Already some sferics in the Irish sea. 

[Chris.R]

4 minutes ago, LightningLover said:

Cake buildup? Nice! (i'm presuming auto-correct is being a pain)

Yeah really don't know what happened there! Have re-done my post. . 

[LightningLover]

According to Lightningmaps.org, there has just been some lightning very close to the shore, but no thunder/lightning seen or heard...

[LightningLover]

5 minutes ago, LightningLover said:

According to Lightningmaps.org, there has just been some lightning very close to the shore, but no thunder/lightning seen or heard...

EDIT: may have been a false positive.

[matt111]

2 minutes ago, LightningLover said:

EDIT: may have been a false positive.

Or was it... Another one appeared just as you posted that.