Storms and Convective discussion - 1st August 2022 onwards

[Eagle Eye]

4 hours ago, SNOW_JOKE said:

A nice run-down by Metweather with their thoughts on this morning's Tornado at Great Hucklow, the team have access to higher-resolution data and can confirm (themselves) that it was indeed a Tornado by looking at the synoptic data & preliminary damage reports. 

https://twitter.com/alex_wx_

Would like to note that Metweather is just one person who's an enthusiast though I know him and he is very knowledgeable especially about using hodographs.

[Thunders]

This has started to produce heavier rain now.

[Rufus Butterfield]

First decent looking convection this year. Classic cold air showers.

[Eagle Eye]

A bit of late evening convection earlier here.

 

[CoventryWeather]

Hope this thread becomes a little more active later this week - the UKV showing some heavy, thundery showers in Ireland on Thursday, with much of England and Wales seeing them on Friday and Saturday. Want to hear others thoughts on this, but it seems that the storm season has finally arrived after what has been weeks of pretty rubbish weather! 

[Rufus Butterfield]

Some cape about on Friday/Saturday and ukv showing scattered heavy showers. Might be worth looking out for.

[The Tall Weatherman]

Could see something of interest on Friday afternoon around 15z if if the models follow through. Not a major event but we do have the ingredients there including reasonable Cape that could support some Heavy downpours with thunder around the Midlands area. Could also see a couple pop-ups on Saturday but let’s just wait and see

[Eagle Eye]

Slight risk by me and Jayy for tomorrow's event though lightning is likely to be mostly sporadic. He did the map, I did the discussion so here we go. Mostly a fairly low end slight risk but small chance of a Supercell.

"

Thursday 16th March - Convective Forecast ️

Here's the full explanation;

A warm front moves across Ireland around late morning to early afternoon and behind it the warm sector should clear any cloud and provide surface heating needed for convective initiation across central Ireland. 

Given supportive soundings for low based storms and SBCAPE values in excess of 400-500 J/KG they are likely to come with heavy precipitation. That is also supported by decent low-level characteristics for good moisture returns and mixing from the surface up to around 10,000 feet before the atmosphere stats losing moisture at a quicker rate.

As the storms push up the amount of moisture decreases and the air becomes dryer with perhaps a small dry warm nose in the mid-upper Troposphere but the main limiting factor is the moisture. 

The buoyancy and general kinematics aren't too favourable for vertical lifting beyond low-topped storms though sometimes shear can help increase storms height and a taller storm can mean more lightning. 35+ knots of 0-4 mile vertical shear may  allow for storms to be a bit taller than about 15,000 feet (according to the Swiss-EZ4 models) so slightly better lightning potential.

Strong lapse-rates, colder uppers and moderate updrafts with the strongest storms should allow for hail potentially a couple cm big. 

Given hodographs there is some support for a Supercell in one of the storms with the amount of vertical shearing and some support for rotating updrafts. Fairly strong upshear and downshear will separate the updrafts and downdrafts in the strongest convergence areas with storms and possibly Supercell(s) but still only a low probability. These will be low-topped Supercells if they do happen with heavy rain and low end severe hail. The energy in the lower atmosphere kinematics wise in terms of vorticity and SRH as well as the aforementioned characteristics does give some slight support for a funnel cloud/weak tornado as well though low-end threat.

Convergent boundary-layer vertical velocity is likely to be quite strong so forcing from convergence areas will be easily seen on radar with the tallest cells and likely producing the most lightning (though still sporadic). The latent heat release from the surface up to boundary layer will decide where upon the convergence zone the storms initially form from and where the most SBCAPE is taken up and where the strongest vertical tilting can take place given lifting. Early event lightning may be fairly frequent compared to as it mildly upscales given that its a surface heating event but if the storms are more popup rather than long-lasting on the convergence zone then cloud cover limiting surface heating possibilities may not matter as much.

Towards the middle to evening part of the event, the moisture at the surface-boundary later behind the warm sector begins to weaken with falling temps though latent heat flux from the sea heating may keep moisture from the south back up so that may allow for south-central Ireland to get a few showers and CS/SW England to also have a few showers capable of sporadic lightning on the back edge of the front. Mainly though, it's setting up the moisture for Friday's event.

As the Storms go into the evening they will touch towards central Scotland with a few remaining in Ireland and CS/SW England as the MUCAPE weakens and the storms mostly collapse in on themselves. Towards late evening there's very little risk remaining hence the risk ends.

These storms will come with the risk of some torrential rain and a small chance of localised flash flooding. Also the potential for sporadic CG lightning, hail (some low-end severe size) and a small chance of a Supercell."

[Windblade]

Looks like the storm seasons just beginning to spring into life! Early days yet but so far signs are encouraging. 

 

Looking at that Great Hucklow damage, I would put money on that being Tornado damage, it's almost textbook. 

 

[Eagle Eye]

 

[mountain shadow]

Storms building across Monaghan and Armagh moving North East.

Already some torrential rain with lightning.

 

[Rush2019]

54 minutes ago, mountain shadow said:

Storms building across Monaghan and Armagh moving North East.

Already some torrential rain with lightning.

 

Grabbed a screenshot of this from Lisburn about 20 mins or so ago, credit to Meteoblue weather cams.  Beautiful.

[CoventryWeather]

2 hours ago, Rush2112 said:

Grabbed a screenshot of this from Lisburn about 20 mins or so ago, credit to Meteoblue weather cams.  Beautiful.

They look stunning! 

Looks v.interesting for tomorrow. Hopefully we can get some decent cell development, anyone placing any graphics here later? I'd say a slight risk is likely across much of the Midlands and into northern England. 

[Eagle Eye]

Me and Jayy's forecast for tomorrow (I once again wrote the discussion and he did the map)

"

Convective outlook  

Friday 00:00 - Saturday 00:00

An occluded front moves across Ireland early morning on Friday sparking a few showers capable of a strike or two of lightning. Though that's a very conditional risk for lightning at about a 5% risk of even 1 strike.

However, in the afternoon across western Ireland the risk ramps up behind the front with fairly buoyant air and latent heat release from surface heating. The air remains moist up until around the 500MB parcel layer. Given good kinematics storms could reach to around 20,000 feet. Though shearing is unlikely to be that strong, 500-700+J/KG of MUCAPE may be able to overcome that and storms can become relatively tall.

There's also backing from the lapse-rates for hail given fairly cold but moist upper air. A lot of moisture has the potential to be condensed in the atmosphere given the time of year and the models suggest quite a lot of the PWAT will be saturated. The forecasted high relative vorticity along a lobe on the west coast suggests horizontal convergence and upper-level divergence, a sign of ascending motion or convection  that forms thunderstorms. Thus, a slight risk has been added at a 35% chance of lightning within a 25 mile radius.

In the UK the risk is similar but strong WAA after a clearing cold front in the morning will give rise to temperatures strong enough to break any of the CIN and vertical motion increases. Similar lifting especially surface based to the west Ireland risk, even better lapse-rates and better supportive shearing but drier air in the mid Troposphere and the boundary layer dynamics are much less good may limit potential. Depending on the timing of the cold front, MUCAPE could be anywhere between 300 J/KG max or 800+ J/KG max so we decided to limit the slight risk to a low-end slight risk to the main area (around 30% chance of lightning within 25 miles).

Later on in the evening, showers could fire up along the southern edge of the advancing occluded front along the southern/southeast coasts and the risk for a strike or two in the channel/coasts is possible given 200-300 J/KG of MUCAPE. Update will follow on this rather early hours Friday or in the afternoon.

These will come with the risks of heavy rainfall, some hail and sporadic to some organised lightning.

"

[The Tall Weatherman]

Seeing some real potential for tomorrow for some isolated storms. Surface Heating will be strong with relatively Mild and sunny weather. This should yeild around 700 Cape widely Around the midlands area which should be enough to set off some bangers around the afternoon. We should wait and see but it seems mostly like a small hail/ Thunder threat. 

[matty40s]

On 15/03/2023 at 22:32, Eagle Eye said:

Slight risk by me and Jayy for tomorrow's event though lightning is likely to be mostly sporadic. He did the map, I did the discussion so here we go. Mostly a fairly low end slight risk but small chance of a Supercell.

"

Thursday 16th March - Convective Forecast ️

Here's the full explanation;

A warm front moves across Ireland around late morning to early afternoon and behind it the warm sector should clear any cloud and provide surface heating needed for convective initiation across central Ireland. 

Given supportive soundings for low based storms and SBCAPE values in excess of 400-500 J/KG they are likely to come with heavy precipitation. That is also supported by decent low-level characteristics for good moisture returns and mixing from the surface up to around 10,000 feet before the atmosphere stats losing moisture at a quicker rate.

As the storms push up the amount of moisture decreases and the air becomes dryer with perhaps a small dry warm nose in the mid-upper Troposphere but the main limiting factor is the moisture. 

The buoyancy and general kinematics aren't too favourable for vertical lifting beyond low-topped storms though sometimes shear can help increase storms height and a taller storm can mean more lightning. 35+ knots of 0-4 mile vertical shear may  allow for storms to be a bit taller than about 15,000 feet (according to the Swiss-EZ4 models) so slightly better lightning potential.

Strong lapse-rates, colder uppers and moderate updrafts with the strongest storms should allow for hail potentially a couple cm big. 

Given hodographs there is some support for a Supercell in one of the storms with the amount of vertical shearing and some support for rotating updrafts. Fairly strong upshear and downshear will separate the updrafts and downdrafts in the strongest convergence areas with storms and possibly Supercell(s) but still only a low probability. These will be low-topped Supercells if they do happen with heavy rain and low end severe hail. The energy in the lower atmosphere kinematics wise in terms of vorticity and SRH as well as the aforementioned characteristics does give some slight support for a funnel cloud/weak tornado as well though low-end threat.

Convergent boundary-layer vertical velocity is likely to be quite strong so forcing from convergence areas will be easily seen on radar with the tallest cells and likely producing the most lightning (though still sporadic). The latent heat release from the surface up to boundary layer will decide where upon the convergence zone the storms initially form from and where the most SBCAPE is taken up and where the strongest vertical tilting can take place given lifting. Early event lightning may be fairly frequent compared to as it mildly upscales given that its a surface heating event but if the storms are more popup rather than long-lasting on the convergence zone then cloud cover limiting surface heating possibilities may not matter as much.

Towards the middle to evening part of the event, the moisture at the surface-boundary later behind the warm sector begins to weaken with falling temps though latent heat flux from the sea heating may keep moisture from the south back up so that may allow for south-central Ireland to get a few showers and CS/SW England to also have a few showers capable of sporadic lightning on the back edge of the front. Mainly though, it's setting up the moisture for Friday's event.

As the Storms go into the evening they will touch towards central Scotland with a few remaining in Ireland and CS/SW England as the MUCAPE weakens and the storms mostly collapse in on themselves. Towards late evening there's very little risk remaining hence the risk ends.

These storms will come with the risk of some torrential rain and a small chance of localised flash flooding. Also the potential for sporadic CG lightning, hail (some low-end severe size) and a small chance of a Supercell."

I have to say you called this pretty well EE, lots of lightning up the Irish central and Eastern side today, 

[JR319]

The sun feels really strong today in any breaks of cloud. Probably the warmest it’s felt all year - even the breeze feels slightly warm! 
 

Hopefully will aid well for later on

[Nick F]

THUNDERSTORM WATCH - FRIDAY 17TH MARCH 2023

 

Issued 2023-03-17 07:40:14
Valid: 17/03/2023 0600 to 18/03/2023 0600

Forecast Details

Upper trough to the west of Ireland Friday morning will shift east across western Britain through the forecast period, becoming diffuse. Low 100 miles west of Shannon 983mb at 06z expected 50 miles west of Ireland 997mb by midnight tonight. A mild, moist southerly flow covers the UK and Ireland on Friday, unstable to surface heating.

A frontal wave moving northeast out of France will bring a spell of rain across SE England / E Anglia this morning, clearing out into the North Sea by noon. Otherwise, widespread showers developing across the UK and Ireland through the day, spreading north/northeast, and turning increasingly heavy in places, with hail and thunder, as surface heating in sunny spells increases lapse rates / instability beneath middle level airmass falling as low as -25C spreading northeast. Despite weak vertical shear, occluded fronts spiralling around low moving into the west of Ireland and lobes of vorticity moving north ahead of the upper trough approaching the west may organise showers / thunderstorms into bands or clusters – bringing the risk of localised flooding.

Tonight, some high resolution models are indicating some mid-level instability pushing northeast across southern areas of England – which may support heavy showers spreading north, perhaps with the odd rumble of thunder.

Issued by: Nick Finnis

Forecast on the website: https://www.netweather.tv/weather-forecasts/uk/convective

 

[CoventryWeather]

Starting to see some convection to my south, in terms of cumulus developing in the sunshine. 

Let's hope for some thundery activity somewhere today! 

Edited March 17, 2023 by CoventryWeather

[Eagle Eye]

West Ireland 

Compared to the Midlands

Clearly, the midlands is worse placed for when instability gets in with a sharp dry layer at the 700MB depth level and also a warm nose compared to west Ireland only having that much further up but I expect that dry air at the mid-levels to somewhat erode and become moister on the next analysis towards mid-day so we'll say how we fo.

[Arnie Pie]

A chance of something stormy passing through later this afternoon

already some convection occurring

just in case

 

[Metwatch]

Decent convection with some cumulus mediocris about. 

Not much in terms of heavy showers heading this way so far though. 

Edit: Raining now 

Edited March 17, 2023 by Metwatch

[Scuba steve]

Some cumulonimbus towers over east Cumbria Yorkshire way  welcome back ,lol

[Arnie Pie]

19 minutes ago, Metwatch said:

Not much in terms of heavy showers heading this way so far though. 

Early days I'm hoping, there's plenty of ppn to the SW to keep us interested

On a separate note: anyone knowing of a horse running in the Gold Cup that is good with storms and prefers the softer ground?

[Rufus Butterfield]

Watched this cumulus grow when walking back from college