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Storms and Convective discussion- 7th August onwards


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At least this cheered me up when I turned Facebook on this morning. 1 year ago today on our Monsoon/Nonsoon chase last year some lovely twins in Colorado ahhhh take me back to 2019 please

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A beautiful altocumulus castellanus sunrise this morning. 

Oo she's a beauty 

My first attempt at storm shots 🤷‍♂️ (Please don't judge 🤣) The cells are impressive tonight! 

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3 minutes ago, Marcus_surfer said:

Well what a fantastic night here in Swansea.  Started off with a big cell to the north then from midnight had two very heavy cells push through and develop out of nowhere. Lots of lightning strikes but hardly any showed up on the detectors......do they not show up cloud to cloud or something?

Hoping for another round of storms tonight maybe

Intra-cloud lightning is definitely harder to pick up & it doesn't help that the thunderstorms were elevated meaning it was harder to detect.

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@Allseasons-si I cannot find your post as it is amongst the pages of posts from yesterday but I saw you asked about a storm near Belper.

I was not at home though. Yesterday I was, of course, our chasing again. By evening I was travelling into Birmingham from the south as lightning was flashing to my north and the M6 motorway was awash with flooding. I was behind a storm but they were moving slow and so I caught it up. 

I saw lots of storms yesterday but the highlight was a storm over Cannock and then Stafford. The lightning was not as frequent as the previous night, but when it did come the thunder was so loud. I didn't see as many CG's either. However, the rain and wind was intense. I am certain I experienced a proper microburst. Whilst driving in Stafford the visibility was almost nil and the roads were flooded. I would not be surprised to hear of wind or flooding damage from these storms. 

Videos to follow, but i now have over 8 hours of footage to edit from the 2 nights

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17 minutes ago, Dan the Man said:

Good morning everyone - terrible nights sleep. Loving the cooler and fresher conditions this morning - its a godsend!

Conditions prime once again, but more towards the South Midlands and South & East England today.

If there was an additional windshear ingredient...

Wish there was cooler, fresher conditions up here in stoke, 23C already and it's barely 8am.....  3C up on yesterday at the same time.... urgh..... I feel like a cooked chicken 🥵  Dew point is at 17C and rising way faster than the temp along with 75% humidity.  Urgh.... 🥵

 

Nice to see the thunderstorms already popping up though 😄 

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My little take for today.

Convergence zone looks like setting up around/just north of the M4 later this afternoon which should fire off thunderstorms from Cambridgeshire across the southern Midlands into South Wales. Showers breaking out north and south of here, but less "severe." My target zone for anything beastly would be around Oxford.

weather 13.08.2020.jpg

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Woke up to see a lot of lightning on the radar NE/E of London 👍🏼 Also there is a very active cell shooting out of France heading NW quickly and growing rapidly

1C2DA632-3DE6-4779-A499-49EBF1D0BD43.jpeg

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47 minutes ago, Paul Sherman said:

It means nothing though does it and is once again like the Met Office pure lazyness. Why not split the Level 2 into 2 parts and actually have a look at a bit of Meteorology. It's plainly obvious the flow is slack and these Storms will feed off each others outflow and along convergence lines. The one on Europe from Germany through to Belgium, the one in the UK London area across to Wales. The Met Office are the same lazyness and just slap a yellow risk box for 8 days when it's clear the plume of lapse rates and shortwaves would destabilise over Western parts first. At least other agencies actually put a bit of work into their forecasts including our very own Nick F - Dan at Convective Weather and Paul at Torro

It just winds me up as a lot of folk on here who are just starting out in this hobby get hoodwinked

Rant over on a positive note for Wales and the South Midlands and C Southern UK skies are clearing to my east. 

Skies definitely not clearing here....95% humidity and dank! Not complaining- the cap finally broke here yesterday and we had a short, but perfect little storm. Destroyed my dahlias, tho 😂 A lot cooler than recent days, so at least that's a bonus. Hopefully some of the rest of you will get your storms today

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6 minutes ago, Azazel said:

My little take for today.

Convergence zone looks like setting up around/just north of the M4 later this afternoon which should fire off thunderstorms from Cambridgeshire across the southern Midlands into South Wales. Showers breaking out north and south of here, but less "severe." My target zone for anything beastly would be around Oxford.

weather 13.08.2020.jpg

I'd be surprised. Far cooler than yesterday and very humid in the incubator 😂

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CW Forecast:

image.thumb.png.2b3633821c07c0380eef3d148a9c9507.png

Day 1 Convective Outlook

VALID 06:00 UTC Thu 13 Aug 2020 - 05:59 UTC Fri 14 Aug 2020

ISSUED 07:25 UTC Thu 13 Aug 2020

ISSUED BY: Dan

Clusters of showery rain, some with embedded lightning, are likely to be drifting westwards across parts of Ireland, southwest England and south Wales on Thursday morning, forced by a shortwave / PV lobe which will clear the west coast of Ireland by early afternoon. This may leave rather extensive cloud in its wake, but assuming this thins and breaks to allow some surface heating, then increasing instability may allow scattered showers and a few thunderstorms to develop in its wake across southern Ireland, aided by low-level convergence in the slack surface pattern but also by a minor shortwave arriving from the east during the afternoon. These will likely weaken as they clear westwards during the evening hours. Hail 1.0-1.5cm in diameter may be possible from the strongest cells, but shear is rather weak. Other clusters may arrive from the Irish Sea during the overnight period.

Elsewhere, there may be a slight uptick in elevated shower/thunderstorm activity across parts of East Anglia and SE England first thing on Thursday morning as a minor shortwave swings northwestwards then westwards from the southern North Sea to the Midlands. Depending on cloud cover associated with this feature, diurnal heating could yield 1,000-1,500 J/kg CAPE across Wales, southern England and East Anglia, which in combination with low-level convergence zones due to the slack surface low will provide the focus for scattered thunderstorms developing, some with frequent lightning. The exact location of these convergence zones is handled differently amongst model guidance, and so pinpointing exactly where shower/thunderstorms may occur, with the zones also likely to move through the day, is difficult. A MDT has been issued where there is reasonable consensus for at least one convergence zone to become established.

 

Similar to Wednesday, weak shear suggests pulse-type storms are likely, with individual cells having a relatively short life but downbursts and outflow helping to spawn daughter cells nearby. PWAT around 40mm with storm motion of 15-20mph to the NW could result in prolonged downpours and local flash flooding. Overall, the severe threat is somewhat lower than previous days - the magnitude of CAPE may be supportive of some marginally severe hail, 2-3cm in diameter, and some strong wind gusts of 35-45mph. A SVR has been introduced, primarily for the flash flood threat and to a lesser extent for hail and wind, but overall severe conditions are not expected to be too widespread. Forecast profiles suggest temperatures around 28-30C will be required to develop surface-based convection, and given a weaker cap and smaller dewpoint depression cloud bases will likely be somewhat lower (around 4,000ft initially) compared with previous days.

 

Surface-based convection will gradually weaken towards late evening as nocturnal cooling of the boundary layer occurs, but some late-day thunderstorms could evolve from west London late evening and run westwards along the M4 corridor. Further scattered elevated showers/thunderstorms will be possible through the night as minor shortwaves arrive from the east, with a particular focus over East Anglia and extending into the Midlands. Extensive low cloud, mist and hill fog will likely develop at the surface, with showers raining through this from aloft.

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So no more Death Valley then 😅

I think the Cone and Triangle can add another day to be honest but Mapantz the SOR gotta, be raising those shields to a level 3 later mate. Keeping ours on level 1. If you take a quick peek at the radar the triangle and cone have perfectly deflected those Storms away and it's why we put so much money into our defences 😂

Seriously though the rest of you enjoy the Storms today could be some stunners again with cold pool mergers. 

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1 minute ago, Paul Sherman said:

So no more Death Valley then 😅

I think the Cone and Triangle can add another day to be honest but Mapantz the SOR gotta, be raising those shields to a level 3 later mate. Keeping ours on level 1. If you take a quick peek at the radar the triangle and cone have perfectly deflected those Storms away and it's why we put so much money into our defences 😂

Seriously though the rest of you enjoy the Storms today could be some stunners again with cold pool mergers. 

And again... nothing for the south east even when in a level 2 risk

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@staplehurst forecast leaving me feel somewhat deflated. Whilst I’m well in the SLGT area, the narrative (and modelling) seems fairly clear that initiation will generally be away from E/SE of London. Increasingly falling on the pessimistic side with Mr @Paul Sherman 😢👎

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12 minutes ago, Jamiee said:

CW Forecast:

image.thumb.png.2b3633821c07c0380eef3d148a9c9507.png

Day 1 Convective Outlook

VALID 06:00 UTC Thu 13 Aug 2020 - 05:59 UTC Fri 14 Aug 2020

ISSUED 07:25 UTC Thu 13 Aug 2020

ISSUED BY: Dan

Clusters of showery rain, some with embedded lightning, are likely to be drifting westwards across parts of Ireland, southwest England and south Wales on Thursday morning, forced by a shortwave / PV lobe which will clear the west coast of Ireland by early afternoon. This may leave rather extensive cloud in its wake, but assuming this thins and breaks to allow some surface heating, then increasing instability may allow scattered showers and a few thunderstorms to develop in its wake across southern Ireland, aided by low-level convergence in the slack surface pattern but also by a minor shortwave arriving from the east during the afternoon. These will likely weaken as they clear westwards during the evening hours. Hail 1.0-1.5cm in diameter may be possible from the strongest cells, but shear is rather weak. Other clusters may arrive from the Irish Sea during the overnight period.

Elsewhere, there may be a slight uptick in elevated shower/thunderstorm activity across parts of East Anglia and SE England first thing on Thursday morning as a minor shortwave swings northwestwards then westwards from the southern North Sea to the Midlands. Depending on cloud cover associated with this feature, diurnal heating could yield 1,000-1,500 J/kg CAPE across Wales, southern England and East Anglia, which in combination with low-level convergence zones due to the slack surface low will provide the focus for scattered thunderstorms developing, some with frequent lightning. The exact location of these convergence zones is handled differently amongst model guidance, and so pinpointing exactly where shower/thunderstorms may occur, with the zones also likely to move through the day, is difficult. A MDT has been issued where there is reasonable consensus for at least one convergence zone to become established.

 

Similar to Wednesday, weak shear suggests pulse-type storms are likely, with individual cells having a relatively short life but downbursts and outflow helping to spawn daughter cells nearby. PWAT around 40mm with storm motion of 15-20mph to the NW could result in prolonged downpours and local flash flooding. Overall, the severe threat is somewhat lower than previous days - the magnitude of CAPE may be supportive of some marginally severe hail, 2-3cm in diameter, and some strong wind gusts of 35-45mph. A SVR has been introduced, primarily for the flash flood threat and to a lesser extent for hail and wind, but overall severe conditions are not expected to be too widespread. Forecast profiles suggest temperatures around 28-30C will be required to develop surface-based convection, and given a weaker cap and smaller dewpoint depression cloud bases will likely be somewhat lower (around 4,000ft initially) compared with previous days.

 

Surface-based convection will gradually weaken towards late evening as nocturnal cooling of the boundary layer occurs, but some late-day thunderstorms could evolve from west London late evening and run westwards along the M4 corridor. Further scattered elevated showers/thunderstorms will be possible through the night as minor shortwaves arrive from the east, with a particular focus over East Anglia and extending into the Midlands. Extensive low cloud, mist and hill fog will likely develop at the surface, with showers raining through this from aloft.

MDT in Hampshire now you have my attention

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See we are already looking at today being a downgrade on earlier days, and we’re losing the top end of the heat - relying once again on the next few days to provide that all-elusive convective ‘event’.

Reading Dan’s writeup I’m not massively confident about the chances for southern counties. The all-night storms we were seeing forecasted keep disappearing, and now we are seeing increased cloud each day whereas we had fine conditions for the best part of a week.

This is precisely why it bothers me when the first opportunity busts in a situation where it’s several days of predicted severe weather. You then clutch straws for a second and invariably that fails and after that you’re desperate for anything.

I have a bad feeling that come Monday we will just have had visiting thundery showers and the odd sporadic storm, then for the south we will be looking at settled conditions for the next 6 months.

REALLY REALLY hope I’m wrong 😕

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1 minute ago, Harry said:

@staplehurst forecast leaving me feel somewhat deflated. Whilst I’m well in the SLGT area, the narrative (and modelling) seems fairly clear that initiation will generally be away from E/SE of London. Increasingly falling on the pessimistic side with Mr @Paul Sherman 😢👎

Aye, Harry, I quite agree... And the Beeb's app-thingie's forecast of 'thundery showers from 11am onwards' is looking more and more like a 'pile of shi'ite'!

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