Storms and Convective discussion - 20th March 2023 onwards

[matt111]

Nothing much going on today here but it’s been nice to see the convective skies. Currently not a lot on the radar in this area but some decent looking skies both to the north and south with clear skies overhead. 

[Thunders]

Just now, matt111 said:

Nothing much going on today here but it’s been nice to see the convective skies. Currently not a lot on the radar in this area but some decent looking skies both to the north and south with clear skies overhead. 

I mean, we are only at the beginning of this years storm season

[Thunders]

Nice view to my east

[The Tall Weatherman]

Looks like this black box could expect a storm in the next hour or two. Although it is weakening, daughter cells may form behind it.

[Thunders]

1 minute ago, The Tall Weatherman said:

Looks like this black box could expect a storm in the next hour or two. Although it is weakening, daughter cells may form behind it.

well, perfect for me, right in my viewing line

[Thunders]

2 minutes ago, The Tall Weatherman said:

Looks like this black box could expect a storm in the next hour or two. Although it is weakening, daughter cells may form behind it.

looks like its trying to expand west and might produce a daughter cell

[Sparkiee storm]

Some nice cloudscapes about again today. 

[Flash bang flash bang etc]

An unexpected surprise. Saw some sheet lightning on the way home from work, then a fork through the trees. Just parked up at the storm spot near home and caught a couple on camera, whilst admiring the beautiful moody clouds aloft

[Metwatch]

6 minutes ago, Flash bang flash bang etc said:

An unexpected surprise. Saw some sheet lightning on the way home from work, then a fork through the trees. Just parked up at the storm spot near home and caught a couple on camera, whilst admiring the beautiful moody clouds aloft

Lovely pictures! 

[Thunders]

6 minutes ago, Flash bang flash bang etc said:

An unexpected surprise. Saw some sheet lightning on the way home from work, then a fork through the trees. Just parked up at the storm spot near home and caught a couple on camera, whilst admiring the beautiful moody clouds aloft

Nice pics, would be better at night though

[Metwatch]

That's quite the hail storm! 

 

[Robbie Garrett]

 

Edited April 6, 2023 by Robbie Garrett

[Callie]

Heavy rain/hail earlier in the A23 from Crawley to Brighton and now think I’ve heard thunder near Eastbourne! Sky is very ominous to the north…

Edited April 6, 2023 by Callie

[Thunders]

34 minutes ago, Callie said:

Heavy rain/hail earlier in the A23 from Crawley to Brighton and now think I’ve heard thunder near Eastbourne! Sky is very ominous to the north…

I can also back this up, I’m in Eastbourne and we had a rumble or 2

[Eagle Eye]

Here's 9 timelapses from an extremely busy day with pictures to come later.

   

 

[Thunders]

Looks very dark in real life, my apple camera isn’t the best

[minus10]

1 hour ago, Flash bang flash bang etc said:

An unexpected surprise. Saw some sheet lightning on the way home from work, then a fork through the trees. Just parked up at the storm spot near home and caught a couple on camera, whilst admiring the beautiful moody clouds aloft

Just amazing and beautiful pics...

[Eagle Eye]

Okay so it's a bit of a dump of photos from today but these are some of the best I've taken.

Black and white because why not

Edited April 6, 2023 by Eagle Eye

[Eagle Eye]

[The Tall Weatherman]

Looks like next week there could be a few opportunities for some April Thunderstorms next week ! 
On Monday sufficient Cape should line up with some surface heating to create a few bangs

[Thunders]

1 hour ago, The Tall Weatherman said:

Looks like next week there could be a few opportunities for some April Thunderstorms next week ! 
On Monday sufficient Cape should line up with some surface heating to create a few bangs

Nice

 

[The Tall Weatherman]

Regarding Tomorrow it looks like the potential is there for Thunderstorms ! It looks like a band of rain should clear by the late morning allowing sufficient surface heating to take place across the many parts of England. Storms are expected to fire off around parts of the North/Central Midlands, Central Wales (isolated) and parts of the S/SE. These storms will have Reasonable Cape <700 and Strong lapse rates to play around with the potential to allow strong updraft development in turn making storms longer lasting and more severe, although the southern mode of storms may be more messy and pulse like but they have the risk to cause flooding wherever they train over for a period of time. Altogether the risk at the moment seems to be over portions of the North/East Midlands as the storms track more East and Wales if storms become more scattered. 

[Jamie M]

AROME has some nice shear on its 6z run with cloud tops tapping into the shear at 400 mb (23.5k ft) if I have hopefully read it right!

All dependant on how much heating can be got and if the convection can get high enough. 

[Eagle Eye]

A cold front clears to the east with a double edged shortwave trough behind it providing the lift needed for strong buoyancy and under general surface heating with the general synoptic scale features looking fairly conductive for pulse thunderstorms however as usual defining a single area is difficult.

 

Gravity wave features that make local environments 'the most' conductive for thunderstorm development should theoretically be handled best by models such as the UKV and AROME so we have mainly based our forecasts in terms of coverage in terms of those models. I find that they tend to forecast saturation and sometimes storm mode quire different to other models and sometimes reality.

 

Cloud clearings on a surface heating day is a very important factor in heat buildup and the release of heat properly into a conductive environment. Given the timing of the clearing front still being handled badly by the models it is difficult to tell what will happen in the eastern part of England.

 

If the cold front can clear early such as the UKV and Swiss models suggest then we may see the surface forcing and shearing parallel to the cold sector allow for a cluster or even a small squall if the cloud can clear. According to the Swiss 4x4 model, while the clouds may not clear fully, the significant shearing along the channel and south and then the parallel DLS at 50-70 knots along the London to east area in the early afternoon and the strong forcing likely given the PV lobe along the western side of moisture tongue then a squall line or cluster could easily form there. The UKV has a similar idea but with a couple clusters and visibily weaker clearings and therefore CAPE buildup. 

 

Very few of the models support this though given the cold front timing to be later. There still could be some clustering up in the east into the evening with cloud clearings but perhaps weaker and with a lot less CAPE build up. 

 

In the daytime across the 'slight risk' and 'area of interest' areas and SBCAPE is likely to buildup above 300 J/KG widespread and locally around 800 J/KG and given fairly strong lift with the subtle shortwave forcing and convergence supported by a couple of small-scale PV lobes: pulse thunderstorms and perhaps some clustering in the more sheared zones appears likely. Saturation is unlikely to be a major problem and therefore cloud clearings should be fairly widespread and good enough for the low-level lift needed. Though the northern half of the slight risk appears more saturated and may struggle a little bit for clear cloud clearings for storms to form.

 

So this supports moderately tall pulse thunderstorms quite widespread across the UK and Ireland. Low-level lapse-rates are very strong and given weak low-level shearing hail is supported fairly well but deep-layer shearing being weak should limit that to 1-2 cm's max unless the southern side of the slight can get tall storms then that may support bigger hail perhaps up to 3-4cm but only for a short time if the shearing increase times well.

 

Supercells are not supported much by the synoptic scale pattern except a small chance in the southern mode. Soundings and hodos tend to favour more single cell or multicellular storm modes with most of the little shearing going speed rather than directional.

 

The further south you go and the more directional it gets with the vorticity being more streamwise than crosswise also supporting tornado's. There is also less amount of CAPE which is storm energy and less support there is for storms overall.

 

The best chance for a Supercell may be in the Cornwall region but there is very low support for a storm and I suspect will rely on gravity wave forcing that doesn't appear to be there that much.

 

Perhaps the best region for tornadic development is on the southern portion of the slight risk. With vorticity becoming increasingly streamwise and low-level shearing becoming more directional and actual storms likely to form in that area then a tornado may be possible in that area.

 

So general support is for sparodic lightning which may organise for a time and small hail. An isolated tornado or two may be possible. Perhaps some torrential rainfall and strong winds as well at 60+ km/h in some areas.

[ChannelThunder]

JFF of course, but there's the slightest hint of a plume end of next week on ECM, not that'd it be much of one in mid-April.