Storm & Convective Discussion - 02/07/15 Onward - Heat & Plumes

[Paul]

They could well be two different model grids placed over different geographic regions, rather than one big 2KM grid. Probably a good example of how these models are quite sensitive to the initial conditions they are initialised with and their model configuration, physics, domain sizes etc.

 

Yep, tis important to bear in mind with these various flavours of the NMM etc is that there are a multitude of physics options and params within the model that can be changed/tuned + differences in the initial conditions, model used etc etc. 

[sparky1972]

Got a full tank of fuel ready to chase if need be. This is looking superb IMBY to be fair though!

However, we've all seen through experience what can happen, so I'm on standby to chase just incase.

Pretty much anywhere is in for a fair shout at a spectacular storm tonight though.

will be looking out towards your direction from here, we can normally see and hear the storms over your way, trying to encourage them to head towards us, lol

[Wilxy]

Tonight is going to be a headache for storm chasers including myself not even sure where to head to.

[Staffordshire]

Cirrus around here arm, moving quite briskly.

Really so undecided as to what to do later, head NW, S,E,SE? Guess I will have to wait till later, i will, however be sure to shoo the girlfriend out quickly come 10pm

[thunderhead 2005]

What is the SRH chart?

Storm Relivity Helicity, basically higher chance for Supercells.

[Andy Bown]

I'm wondering if these storms will quickly develop electrically and be quite high based giving a fine lightning show but little rain South of the M4 before developing precipitation wise as they head Northwards and merge into a large mass of thundery activity.

[Paul]

First little snippets of development down to our SW

 

[thunderhead 2005]

I'm wondering if these storms will quickly develop electrically and be quite high based giving a fine lightning show but little rain South of the M4 before developing precipitation wise as they head Northwards and merge into a large mass of thundery activity.

these will be elevated, there is not alot of surface base Cape.

[Karl83]

Tonight is going to be a headache for storm chasers including myself not even sure where to head to.

You are right. I may head North up towards Worcestershire judging by MO latest update but will have to wait and see.

[East_England_Stormchaser91]

will be looking out towards your direction from here, we can normally see and hear the storms over your way, trying to encourage them to head towards us, lol

Will do haha. Quite often storms here intensify once they're over the flat fenlands. Holbeach has always done well for decent storms, as my family tell me so!

[Wet'n'Dry]

Given that there may be an East/West split tonight with relation to the severity/frequency of storms, what would anyone prefer?

 

Frequent but moderate storms or Infrequent but violent storms?

 

I'm guessing the latter, that's also my preference, but if anything does show over here it won't matter so long as it does!

[Paul90]

MetO have upgraded the warnings;

 

Isolated heavy, and possibly severe, thunderstorms are expected to develop on Friday evening across parts of southern and southwest England. These are likely to become more frequent later and spread northwards across Wales, the Midlands and northern England overnight, and into southern Scotland by the early hours of Saturday. Some torrential downpours are possible leading to localised surface water flooding, with hail, frequent lightning and squally winds also likely hazards.

The public should be aware that there is a chance of some very localised significant disruption.

This is an update to the warning to extend the yellow area across southern Scotland and elevate the position in the risk matrix. This will be kept under review and further updates are possible closer to, and during, the event. On Friday evening another hot and increasingly humid airmass is expected to spread northwards from the continent. This airmass looks conducive to the development of isolated thunderstorms during the evening across southern and southwest England which are likely to become more frequent overnight as they spread northwards towards Scotland. With large amounts of energy again available in this atmosphere storms could be severe, with torrential downpours, hail and squally gusts of wind. 30 mm of rain is possible in less than an hour, with as much as 50 mm possible in 3 hours very locally.

Large uncertainty remains regarding areas most at risk from storms, and many areas will miss these altogether, staying largely dry. However, where they do develop, disruption is possible. The most likely area for disruption is considered to be Wales, parts of the Midlands and northern (especially northwest) England, but a lesser risk extends around the periphery of this region.

 

Matrix has been updated too.

 

No specific mention of the SE (primarily S and SW then moving N or NE). Same areas on the map under yellow warning, though have extended it further north.

 

paul90 likes this.

[DanN]

Storm Relivity Helicity, basically higher chance for Supercells.

 

Some of the forecast soundings do show some impressive SRH values with some rather large looping hodographs. I'm assuming this is due to the low level south-easterly flow (possibly 35kts at 925mb on some output) with veering winds above. Its almost a shame, as the boundary layer looks quite stable and with these storms rooted above, but a surface based storm in that environment could be very interesting.

[Wilxy]

What is the difference between 300hpa winds and 850hpa winds?

[Norfolk Sheep]

If you're on the road later then ABEA (anywhere but East Anglia) 

[Cloud 10]

I know this sounds silly, but we are going to put some padded covers over our cars tonight! We don't want any risk of adding to the dents we already have - I know it's unlikely that we'll get anything as severe as Wednesday night - but we're not taking any chances - and it means we can watch any developments without worrying.

 

For those of you who didn't get the large hail on Tuesday, please remember that if this happens again it is not something to be taken lightly - those things bend metal. That size of object could injure you if you are out in the open, and I don't even want to think about encountering it in a moving vehicle.

 

We all need to stay safe and enjoy anything that develops sensibly. With it being Friday night and most of us looking forward to a few bevvies we need to be extra careful.

 

I think you can tell that Wednesday night made a bit of a lasting impression on me...

 

Large hail is something i have not seen IMBY although it was less than a couple of miles away from me on Wednesday.

 

More than happy with "just" T&L.

[Harry]

Storm Relivity Helicity, basically higher chance for Supercells.

 

I did wonder...supercell chance is awesome across the SE question...but only where you get a storm to turn supercellular...our problem is is getting the storm in the first place.

[tomp456]

The moment you realise there's an East/West split and you're in the middle. 🆘

Edited July 3, 2015 by tomp456

[Harry]

The should do, as they will most likely be elevated thunderstorms, so most of the precipitation will evaporate before it reaches the ground. Wil be a lot of in-cloud lightning too:

 

ML.png Theta.png

 

These are interesting charts...suggests to me the plume hanging around a bit longer and making greater in roads than forecast earlier.

[Jordan Naylor]

So I live in chorley, slap bang in the middle of NW england, Lancashire. Are we looking at a repeat of the incredible wednesday storms? Worse? Or not as severe? BBC just saying heavy rain over night although they do have warnings for storms. 

[tomp456]

The latest BBC Sussex radio forecast didn't mention thunderstorms or even thunder, just the potential for torrential downpours

[ChezWeather]

NMM UKMO and GFS all going for storms developing in the SW and moving NE across the Midlands/NW England 

 

 

Edited July 3, 2015 by ChezWeather

[Harry]

Wow, MASSIVE upgrade on the latest NMM!!! 

 

 

Cop a load of that!

 

2KM though (which to me seems a complete outlier) says something completely different from the same time frame...advancement of the trough completely different too (look how much farther north it is than the other model)

 

Edited July 3, 2015 by Harry

[Azazel]

The moment you realise there's an East/West split and you're in the middle.

 

 

THIS

[tomp456]

Wow, MASSIVE upgrade on the latest NMM!!!

nmmuk-1-17-0.png

Cop a load of that!

Wow it'll be free beers all round if that comes off!!! Edited July 3, 2015 by tomp456