Storms and Convective discussion - September 2023

[Jamie M]

YT video from yesterday

[Eagle Eye]

3 hours ago, Jamie M said:

Pictures from yesterday's storm which had supercellular characteristics

Im going to be riding on the "possible Supercellular characteristics" forecast for a while. 

[Southern Storm]

19 hours ago, Jamie M said:

YT video from yesterday

Great video, it looked like it was really spinning, very nice to watch

Now we finally have some settled weather, and things are starting to heat up, I wonder if we have some decent storms to look forward to.

Or are we going to have the heat fade away without any convective breakdown? It's something that has happened a few times in recent years

In the 90s you'd have a couple of day of 25 degree heat culminating in some big storms, nowadays it seems it can be hotter and have no real breakdown to speak of, I'm hoping for the former 90s scenario

Only time will tell

[ChannelThunder]

52 minutes ago, Southern Storm said:

Great video, it looked like it was really spinning, very nice to watch

Now we finally have some settled weather, and things are starting to heat up, I wonder if we have some decent storms to look forward to.

Or are we going to have the heat fade away without any convective breakdown? It's something that has happened a few times in recent years

In the 90s you'd have a couple of day of 25 degree heat culminating in some big storms, nowadays it seems it can be hotter and have no real breakdown to speak of, I'm hoping for the former 90s scenario

Only time will tell

Models look pretty promising into the latter part of the week, but after the year we've had I'm not counting any chickens.

[WeatherArc]

A thundery breakdown is looking possible at the end of next week, at the moment i would think Fri to Sun are the main days of focus.

We still need some things to go right for us in the models though.

Looking at Sunday we can see that cape is pretty marginal, i would say the max is about 1000 j/kg in Cornwall, near Bristol and in South Wales. 

The problem is that the GFS is thinking that the heat being pumped up from the south will be relatively dry. Relative Humidity values in some parts of the country on Saturday will be below 35%. 

We also have to keep an eye on where that high pressure sets up. I don't think it will be a problem by the end of the week though. 

In my opinion and experiences with forecasting American storms the GFS really underdoes cape values, it's only when more short range high-res models get into range that we get a better idea of the thunderstorm potential. In terms of location right now i would favour the west for surface based homegrown storms with the south getting imports from France. 

Massive difference on Saturday between the GFS and euro with the dew point values. The only problem here is that the Euro has much lower temperatures, limiting cape. 

 

Comparison of GFS and Euro for Sundays cape. 

Interesting sounding from around Gloucester on Sunday, the wind profile really stands out, plenty of directional shear with winds at the surface being south easterly, 850s being direct southerly and 500s being from the south west. Nice looking hodograph. Obviously the speed shear, cape, low level lapse rates and cin leave a lot to be desired. 

So overall, I genuinely think the potential is there for some very good late summer thunderstorms however we need quite a few things to go our way. We are still 150+ hours out so expect we will see a few different solutions on how this heat will breakdown, hopefully not with frontal rainfall from the Atlantic.  

Edit-The 12z Gfs has come out and looks much better for t-storm potential on Sunday, could be the start of cape values being upgraded over next few runs. 

 

[viking_smb]

16 minutes ago, WeatherArc said:

A thundery breakdown is looking possible at the end of next week, at the moment i would think Fri to Sun are the main days of focus.

We still need some things to go right for us in the models though.

Looking at Sunday we can see that cape is pretty marginal, i would say the max is about 1000 j/kg in Cornwall, near Bristol and in South Wales. 

The problem is that the GFS is thinking that the heat being pumped up from the south will be relatively dry. Relative Humidity values in some parts of the country on Saturday will be below 35%. 

We also have to keep an eye on where that high pressure sets up. I don't think it will be a problem by the end of the week though. 

In my opinion and experiences with forecasting American storms the GFS really underdoes cape values, it's only when more short range high-res models get into range that we get a better idea of the thunderstorm potential. In terms of location right now i would favour the west for surface based homegrown storms with the south getting imports from France. 

Massive difference on Saturday between the GFS and euro with the dew point values. The only problem here is that the Euro has much lower temperatures, limiting cape. 

 

Comparison of GFS and Euro for Sundays cape. 

Interesting sounding from around Gloucester on Sunday, the wind profile really stands out, plenty of directional shear with winds at the surface being south easterly, 850s being direct southerly and 500s being from the south west. Nice looking hodograph. Obviously the speed shear, cape, low level lapse rates and cin leave a lot to be desired. 

So overall, I genuinely think the potential is there for some very good late summer thunderstorms however we need quite a few things to go our way. We are still 150+ hours out so expect we will see a few different solutions on how this heat will breakdown, hopefully not with frontal rainfall from the Atlantic.  

Edit-The 12z Gfs has come out and looks much better for t-storm potential on Sunday, could be the start of cape values being upgraded over next few runs. 

 

its too far ahead yet, like you said, I would rather wait till weds at the earliest to see what happens 

[Shaunado]

That's quite the storm outbreak in Latin America!

https://www.weatherandradar.co.uk/weather-map?center=-8.64,-65.04&zoom=2.48&layer=lr

[Ben Sainsbury]

Well... Wednesday night into Thursday is looking good on the UKV, for the western half of the UK anyway.

Moderate CAPE in a high sheared environment with steep mid-level lapse rates. Good signs, we just need some consistency.

[ChannelThunder]

00z ECM is fantastic for Cornwall.

[Ben Sainsbury]

11 hours ago, Ben Sainsbury said:

Well... Wednesday night into Thursday is looking good on the UKV, for the western half of the UK anyway.

Moderate CAPE in a high sheared environment with steep mid-level lapse rates. Good signs, we just need some consistency.

Still no consistency... as @ChannelThunder says, ECM looks great for Cornwall! Elevated convection is one of the most difficult challenges for NWP models at this point in time, so it seems Wednesday night may throw some surprises!

On the flip side, nothing may develop at all, but I know which scenario I'd prefer.

Edited September 4, 2023 by Ben Sainsbury

[Windblade]

I was hoping we'd escaped the worst of the usual Summer Heatwaves this year but here we go again.  Not sure why people claim "We haven't had much of a Summer".   It's been sunny here almost every single day since April, with hardly any convective activity this year whatsoever.  I haven't seen a storm since the beginning of May I think and anything I have seen has been barely extremely rare and barely active. Any remote chance after this disgusting heat finally buggers off we'll be in for a thundery breakdown? Desperate for something substantial this year. Haven't seen a single fork for over a year. 

Edited September 4, 2023 by Windblade

[Neilsouth]

15 hours ago, Shaunado said:

That's quite the storm outbreak in Latin America!

https://www.weatherandradar.co.uk/weather-map?center=-8.64,-65.04&zoom=2.48&layer=lr

 

Check this out! That's a lightning strike every second

 

https://www.weatherandradar.co.uk/weather-map?center=16.38,-11.04&zoom=9.31&layer=lr

[The Tall Weatherman]

Don’t mind if I do ! 

[WeatherArc]

The 06z GFS run looks very good for us storm lovers, thunderstorm potential for multiple parts of the country from Wednesday till Tuesday. 

 

11 minutes ago, The Tall Weatherman said:

Don’t mind if I do ! 

I'll take that 

[Shaunado]

54 minutes ago, Neilsouth said:

 

Check this out! That's a lightning strike every second

 

https://www.weatherandradar.co.uk/weather-map?center=16.38,-11.04&zoom=9.31&layer=lr

Awesome! Looks like an even more lively storm has developed in S Sudan, several each second...

https://www.weatherandradar.co.uk/weather-map?center=1.74,30.96&zoom=4.53&layer=lr

[Ben Sainsbury]

42 minutes ago, The Tall Weatherman said:

Don’t mind if I do ! 

Bloody beat me to it! Looks impressive nevertheless. Typical the only night shift I have this week, is on Wednesday night. Would be willing to chase this otherwise.

Edited September 4, 2023 by Ben Sainsbury

[The Tall Weatherman]

31 minutes ago, WeatherArc said:

The 06z GFS run looks very good for us storm lovers, thunderstorm potential for multiple parts of the country from Wednesday till Tuesday. 

 

I'll take that 

I would not say very good. Of course it will change but much of the Cape seems situated way farther west and over the mountains and also a serious amount of CIN is modelled over much of the higher Cape values. So far I think Wednesday (locally), Sunday and Monday have the highest risk. 

[Ben Sainsbury]

6 minutes ago, The Tall Weatherman said:

I would not say very good. Of course it will change but much of the Cape seems situated way farther west and over the mountains and also a serious amount of CIN is modelled over much of the higher Cape values. So far I think Wednesday (locally), Sunday and Monday have the highest risk. 

Setups like these are our high risk, high reward scenarios. Often in the UK, our convection isn't capped, so it freely goes up without much explosivity, generally producing weaker storms. Whereas later this week, we're more akin to the US, where if we can break the cap, we could be looking at some particularly explosive thunderstorms!

Edited September 4, 2023 by Ben Sainsbury

[CoventryWeather]

2 minutes ago, Ben Sainsbury said:

Setups like these are our high risk, high reward scenarios. Often in the UK, our convection isn't capped, so it freely goes up without much explosivity, generally producing weaker storms. Whereas later this week, we're more akin to the US, where if we can break the cap, we could be looking at some particularly explosive thunderstorms!

Is it too early to get soundings on when the cap goes (ie, at a certain temperature)? Seems interesting nonetheless. Let's hope for some decent action later this week.

[WeatherArc]

34 minutes ago, The Tall Weatherman said:

I would not say very good. Of course it will change but much of the Cape seems situated way farther west and over the mountains and also a serious amount of CIN is modelled over much of the higher Cape values. So far I think Wednesday (locally), Sunday and Monday have the highest risk. 

Gosh thats annoying, ill completely admit i dont often (if ever) look at CIN charts for the UK, im too used to the non cap setups we often have. Still as Ben said it looks like it could be akin to a more American setup where the potential cap would break mid-day leading to explosive convection, I guess this is one of those setups where we are going to have to watch model trends such as the amount and spread of instability as well as what that CIN does closely,  I completely agree with you about Sunday, Monday being the main days though. Another point is that the shear aint great, while i would take any kind of thunderstorm it would be nice to have some longer lasting cells producing prolific lightning.

Still we are 153 hours out from Sunday on the models, things will change. Lets just hope for the better 

[Sunny76]

2 hours ago, Windblade said:

I was hoping we'd escaped the worst of the usual Summer Heatwaves this year but here we go again.  Not sure why people claim "We haven't had much of a Summer".   It's been sunny here almost every single day since April, with hardly any convective activity this year whatsoever.  I haven't seen a storm since the beginning of May I think and anything I have seen has been barely extremely rare and barely active. Any remote chance after this disgusting heat finally buggers off we'll be in for a thundery breakdown? Desperate for something substantial this year. Haven't seen a single fork for over a year. 

We didn’t have very good summer between early July until the middle part of August. 
 

Yes, it did improve as August went on, but July was appalling for its lack of sunshine and long sunny warm days.

For people who hate the heat, I think Summer 23 has been the ideal season for people who hate hot sunny weather.

The current weather this week looks to be the only good sustained period of warm sunny days since June for people who enjoy summery weather.

[WeatherArc]

GDPS has a pretty decent setup for Sunday.

 

Edited September 4, 2023 by WeatherArc

[Alderc 2.0]

18 hours ago, Shaunado said:

That's quite the storm outbreak in Latin America!

https://www.weatherandradar.co.uk/weather-map?center=-8.64,-65.04&zoom=2.48&layer=lr

Why does Realtimelightning and BlitzortungLive not pick up all the strikes in equatorial areas?

[alexisj9]

26 minutes ago, Alderc 2.0 said:

Why does Realtimelightning and BlitzortungLive not pick up all the strikes in equatorial areas?

They don't pick up all the strikes in Europe either.

[Sparkiee storm]

This time last year quite a few of us were about to see those overnight storms that happened on 2 consecutive nights for some of us and some daytime cells at times too.

  

Looking to this week and into the weekend, like others, will be keeping an close eye on developments, first for Wednesday Night and then for the weekend. I remember September storms in 2010, 2014, 2016, 2022 and now hopefully this year. The 2016 storms were pretty vicious here.

Best of luck to all for some late season pyro. 

Edited September 4, 2023 by Sparkiee storm