Convective/Storm Discussion Thread 25/5/16 onwards

[Harry]

31 minutes ago, Stormyking said:

Latest 12z has got my interest suddenly for Sunday night into Monday, an area of Elevated showers/ storms develop in the channel and push up from the South East, its only 1 run but theres been a bit of a trend on something being picked up, still early days. Wasn't that interested in monday morning before but confidence has gone up a touch,  reminds me a little of June 2013

As for the rest of the uk its looking like an interesting few days coming up

 

This only shows precipitation remember - NMM MUCAPE projections are uninspiring so would not be too confident of much steric activity. 

[Stormyking]

28 minutes ago, Harry said:

This only shows precipitation remember - NMM MUCAPE projections are uninspiring so would not be too confident of much steric activity. 

As I said too William in my last post, im taking this with a pinch of salt, I know there are alot more ingredients you need, ive checked all other things like MUCAPE , its okay but still time for improvements, wind shear could be quite important though i haven't that yet. id rather be chasing the mainland stuff to be fair

[Supacell]

There is at least some interest over the weekend. On both days the winds are very light and from the same direction all the way through the vertical profile and so wind shear is virtually non-existent. CAPE values are quite juicy in a line from NW England to Essex on Saturday and then even more so in S and W areas on Sunday, especially Wales and areas near the western M4 corridor and Bristol Channel. Moisture is abundant, we will be under a warm, humid air mass with plenty of water locked up ready to be released should any storms develop. However, will there or won't there be storms and is it worth chasing?

If any thunderstorms do develop this weekend then they will likely be very slow moving, if not appearing almost stationary, and contain torrential rainfall. Lightning could be quite prolific for a brief time (especially on Sunday) as each storm matures, but will quickly fall away as the storms quickly choke on their own downdrafts. Whether any storms form though as a big if. It looks like weak troughs and convergence zones will be the trigger. Saturday and Sunday fax charts from the Met Office show a trough feature on both days in different places.

        

http://www.metoffice.gov.uk/public/weather/surface-pressure/

The Netweather Extra wind charts show that wind convergence in SW parts on Sunday evening

Precipitation charts for both Saturday and Sunday show the areas most likely to see storms, and models seem to agree on these areas being at the highest risk

  

Showers and storms will require surface heating and without enough of it storms won't develop. I am also concerned that some models still don't break out any precipitation on either day. There is still much scope for change though, be it downgrade or upgrade.

Regarding chasing. With very little wind shear any storms that do develop will have a short shelf life. If you find yourself close to a storm then getting into position will be easy as they will be slow moving and getting under one could prove rewarding, especially on Sunday as even if we only see half of the CAPE values being shown by GFS, there will still be some power in those storms. If you find yourself any distance from a developed storm then it is more likely you will drive into it, get into position just to watch what was once a thunderstorm drop a bit of drizzly rain on top of a very wet ground! Skill will be in getting into position before a storm matures. The best way to do this would be to sit near the convergence zones (if you can find them) and watch the clouds, constantly check the radars. However, is it worth it, storms may not even develop?

Well you have to be in in to win it, and if you don't chase and rely on a storm coming to your front door then you reduce the chances of seeing anything. If you are short of money and petrol costs will kill you then don't drive far. A local chase should not lead to disappointment as even if you don't see anything you are still getting out and about and enjoying the scenery. When you put more money on it, such as I did last week, you kind of want that storm to make the trip worthwhile. 

I cannot chase Saturday, but i look fairly well placed at home (although if I lived about 30 miles further west i'd have been more confident). I can chase Sunday but would I risk driving all the way to the West Country? That's a decision to be made on Sunday morning

 

Edited June 3, 2016 by Supacell

[weather09]

Difficult one to call tomorrow, but likely an isolated to scattered risk. Models developing a relatively narrow region - generally from the SE, across central parts and towards the NW - of substantial instability (several 100J/kg MLCAPE, per recent outputs) where expected good insolation heats a decently moist boundary layer within the warm sector. Both Euro4 and GFS are progging dewpoints to 16-17C, which seemed a little high initially. But the fact that a meso. model is showing these values lends confidence that these will be realised.

Little support aloft given stagnant flow under weak heights, with vertical wind shear non-existent. Though recent UKM synoptic outputs do show a disturbance (trough) pushing west throughout the day, so likely focus for any developments. Question mark over cloud cover, but looks increasingly likely there will be clearing skies from the east so reason why models are maintaining instability outputs as temps reach low 20s.

 

Edited June 3, 2016 by weather09

[Supacell]

33 minutes ago, weather09 said:

Difficult one to call tomorrow, but likely an isolated to scattered risk. Models developing a relatively narrow region - generally from the SE, across central parts and towards the NW - of substantial instability (several 100J/kg MLCAPE, per recent outputs) where expected good insolation heats a decently moist boundary layer within the warm sector. Both Euro4 and GFS are progging dewpoints to 16-17C, which seemed a little high initially. But the fact the a meso. model is showing these values lends confidence that these will be realised.

Little support aloft given stagnant flow under weak heights, with vertical wind shear non-existent. Though recent UKM synoptic outputs do show a disturbance (trough) pushing west throughout the day, so likely focus for any developments. Question mark over cloud cover, but looks increasingly likely there will be clearing skies from the east so reason why models are maintaining instability outputs as temps reach low 20s.

 

I will have my eyes on the skies over Derby tomorrow afternoon, although if it is going to happen I feel you are better positioned.

[William Grimsley]

Thanks for your analysis, @Supacell. Bristol looks a bit far for me to travel on Sunday especially as it will be late evening by the time everything has fully kicked off. Do you think they'll still be a good chance across more southern areas of Somerset?

[MattTarrant]

14 minutes ago, William Grimsley said:

Thanks for your analysis, @Supacell. Bristol looks a bit far for me to travel on Sunday especially as it will be late evening by the time everything has fully kicked off. Do you think they'll still be a good chance across more southern areas of Somerset?

Just wait until the day 

Edited June 3, 2016 by MattTarrant

[William Grimsley]

Grrr, I shall have to. Zzzzzzz.

[dwalton]

Looking ok for potential this weekend but I'm more looking to Monday to Wednesday. Tuesday looks the most widespread potential at the moment. All to play for which I think is the best potential for some years as we have an easterly component to it all

[William Grimsley]

Certainly the best potential since 2014 I've seen.

[Harry]

4 minutes ago, William Grimsley said:

Certainly the best potential since 2014 I've seen.

Seriously??

[MattTarrant]

8 minutes ago, Harry said:

Seriously??

For us thunderstorm desperate folks down here in the south west I think he means

[Wilxy]

Was planning on going chasing on Sunday but potential not as good as Monday but am working that day.

[Mapantz]

 

Pick of the bunch from the weekend:

 

I'm hoping for a dry weekend, here. I'd rather let the warmth build up for a few days to be honest, next week is where i'd be looking to. It seems to be a recurring theme though, I like it!

[Harry]

@Mapantz what does you super storm tool say for 15z-16z tomorrow??

Im curious as to how different models are projecting the evolution of this E-W trough through tomorrow  

[Mapantz]

3 minutes ago, Harry said:

@Mapantz what does you super storm tool say for 15z-16z tomorrow??

Im curious as to how different models are projecting the evolution of this E-W trough through tomorrow  

15Z:  

16Z: 

Feel free to have a gander: http://www.warehamwx.co.uk/cumulus/ewn/forecast/map.php

[Nick F]

Interesting period coming up, warm front moving west tonight introducing  warmer and more humid air, DPs of 16-17C over northern Belgium and Holland tonight:

So on Saturday some quite moist air around, as per PWAT charts and hence decent CAPE

... ridging and light winds aloft and lack of upper forcing tomorrow - but strong surface heating where cloud breaks occur and breeze convergence or orographic lift looks to trigger isolated heavy showers and storms which will be slow-moving, BUT many will stay dry, so unless you are prepared to travel to them, most will be disappointed!

Sunday, best moisture will be confined to western areas - where storm risk will be too, but again storms they will be isolated.

But, moisture returns from the S/SE early next week, as the flow comes off the near continent, the surface flow rather moist given the amount of rain that's fallen over France, Benelux and Germany recently resulting in the flooding.

Shortwave mid-upper trough and strengthening upper flow arriving from SW on Tuesday could trigger more substantial storms acros parts of England And Wales, as upper shear and forcing increase to organise convection.

 

Edited June 3, 2016 by Nick F

[William Grimsley]

Hmm, this is tough. I think I'm going to make my decision tomorrow evening on whether I chase or not, but to say the risk is isloated, if I wasn't so hungry for thunderstorms I wouldn't chase, but I may have too...

[Harry]

10 minutes ago, Mapantz said:

15Z:  

16Z: 

Feel free to have a gander: http://www.warehamwx.co.uk/cumulus/ewn/forecast/map.php

Cheers mate.

[Speedway Slider]

Ok peeps, to water or not to water.....? Speedway track that is, spent all afternoon getting rid (puddles/lakes) from rain early week, what chances for West Leicester tomorrow afternoon/evening copping a storm or convective rain episode??

[Flash bang flash bang etc]

The stampervan will be out on Sunday - maybe a jolly jaunt over to the west a little. Gonna be fun waiting and watching to see where these pesky storms crop up :-D

[Wilxy]

13 minutes ago, William Grimsley said:

Hmm, this is tough. I think I'm going to make my decision tomorrow evening on whether I chase or not, but to say the risk is isloated, if I wasn't so hungry for thunderstorms I wouldn't chase, but I may have too...

What day? Sunday or Monday?

[William Grimsley]

8 minutes ago, Flash bang flash bang etc said:

The stampervan will be out on Sunday - maybe a jolly jaunt over to the west a little. Gonna be fun waiting and watching to see where these pesky storms crop up :-D

Sunday preferably but I can make Monday too.

[StormChaseUK]

Not bad

[A.J]

1 hour ago, MattTarrant said:

For us thunderstorm desperate folks down here in the south west I think he means

But this is so factually incorrect unless you're talking from a totally IMBY perspective...many places in the SW had a very good 2015 season.......On a bigger scale, I feel the problem some have is that if they don't have numerous thunderstorms dropping CG's on their houses then it's been a bad season for their entire region!