Storms and Convective Discussion - 20th April 2019 onwards

[Zak M]

Just now, ChezWeather said:

What did you expect? they were absolutely through the ceiling, showing values that people in the heart of Tornado Alley would be happy to see!

 

 

Yeah true. I said yesterday too about areas not going to see CAPE values as high as 3,000j/kg next week.

[ChezWeather]

1 minute ago, zmstorm said:

Yeah true. I said yesterday too about areas not going to see CAPE values as high as 3,000j/kg next week.

Do not worry my friend, as Ben mentioned, we are talking about SB Cape here anyway

Fear not, there will be plenty of opportunities for storms in the upcoming week 

[Another Kent clipper]

8 minutes ago, Ben Sainsbury said:

That is for SB CAPE and not ML CAPE as we're likely to see more elevated storms rather than surface based.

This gives me hope.  By being likely elevated the storms might wait for me to finish work at 8.30pm

[Flash bang flash bang etc]

46 minutes ago, Another Kent clipper said:

My four days off have fallen on yesterday, today, tomorrow, and Sunday!  

... however, having just checked the GFS, tue-wed-thu are already scaled down for Cape from what they were. Can't speak for other charts

The London area and far SE are more likely to benefit toward the end of the week. That’s not to say you won’t get bits and pieces earlier than that.

Also like Ben says it’s not all that simple - basic CAPE isn’t necessarily all we need

Final point is that there’s a lot of guesswork and speculation at the moment based on data that’s hasnt been nailed-down yet. Yeah they’ve got a vague idea but anything could happen so don’t give up hope!

 

Edited June 21, 2019 by Flash bang flash bang etc

[Sparkiee storm]

What's the Max SB CAPE values now it has downgraded?

[Zak M]

Just now, Sparkiee storm said:

What's the Max SB CAPE values now it has downgraded?

For Tue-Thurs, I think it doesn't go above 2,000j/kg CAPE

[Sparkiee storm]

2 minutes ago, zmstorm said:

For Tue-Thurs, I think it doesn't go above 2,000j/kg CAPE

Okay thank you, plus still a lot of ML CAPE 

[Flash bang flash bang etc]

4 minutes ago, zmstorm said:

For Tue-Thurs, I think it doesn't go above 2,000j/kg CAPE

Still nuts, really

[Mapantz]

The 12Z UKV looks absolutely nuts for parts of England on Monday night, early Tuesday morning.

[Flash bang flash bang etc]

2 minutes ago, Mapantz said:

The 12Z UKV looks absolutely nuts for parts of England on Monday night, early Tuesday morning.

Oooh where?

[Wilxy]

6 minutes ago, Mapantz said:

The 12Z UKV looks absolutely nuts for parts of England on Monday night, early Tuesday morning.

What about Sunday night?

[Mapantz]

5 minutes ago, Flash bang flash bang etc said:

Oooh where?

Roughly..

Don't take that as gospel though. Much to be resolved before we get there.

[Chris.R]

 Don’t like 12Z at all. Hope it’s not going wrong. Only GFS anyway and that’s useless, rubbish, throw it in the bin. WRF coming into range now. 

Edited June 21, 2019 by Chris.R

[IanR]

Anyone get the feeling all this is just getting hyped up,  probably end up just being a bog standard southerly warm spell wlth heavy rain , sometimes thundery in places and sunny spells , like we get most years ,  BBC week ahead forecast has temps in the 21 to 23 range for NW England up until Wednesday, we nearly got to that in Febuary this year

 

Run along, nothing to see , well in Wigan for sure      

[AnvilCrawlers]

I've just read PJB analyst on ukww,things could get interesting sunday.here's hoping

[Met4Cast]

57 minutes ago, Mapantz said:

The 12Z UKV looks absolutely nuts for parts of England on Monday night, early Tuesday morning.

How do you have access to the UKV?

----

The ECM K-Index shows how the main risk moves SW>NE through Sunday evening into Monday morning 

Of course this doesn't take into account absolutely everything so it can only be used as a guide but Wales, Midlands, N Wales into N England and later NE England the main areas of potential as the warm moist air undercuts a broader area of rain associated with the low to the West. 

Unlikely to see widespread severe thunderstorms but could see one or two MCS storms developing, particularly after midnight Sunday across N Wales and NW England.

[Flash bang flash bang etc]

28 minutes ago, Met4Cast said:

How do you have access to the UKV?

----

The ECM K-Index shows how the main risk moves SW>NE through Sunday evening into Monday morning 

Of course this doesn't take into account absolutely everything so it can only be used as a guide but Wales, Midlands, N Wales into N England and later NE England the main areas of potential as the warm moist air undercuts a broader area of rain associated with the low to the West. 

Unlikely to see widespread severe thunderstorms but could see one or two MCS storms developing, particularly after midnight Sunday across N Wales and NW England.

I was wondering if Herefordshire might be a good spot to head for for about 9pm.

Any thoughts?

[Met4Cast]

6 minutes ago, Flash bang flash bang etc said:

I was wondering if Herefordshire might be a good spot to head for for about 9pm.

Any thoughts?

Timing is a little bit tricky, especially for specific locations because different models are faster with the initiation of storms. Herefordshire at the moment looks to be on the boundary between general thundery showers and the possibility of more severe storms initiating a little North of the area. Again though pure speculation at this stage, events like these are nigh on impossible to nail down with any real accuracy. 

[Mapantz]

38 minutes ago, Met4Cast said:

How do you have access to the UKV?

Part of being a moderator. 

[ChezWeather]

From PJB on UKWW:

Convective Outlook / Advisory Sunday 23rd June 2019 
Period 15:00 BST Sunday 23rd June until 13:00 Monday 24th June 2019 
Issued Friday 21st June 
Paul Blight 

Outlook / Advisory Risks 

Red Box = Moderate to High Risk (60%) of T-Storms developing generating high electrical discharges in the form of frequent C/G Lightning and Torrential Rainfall Rates 
Purple Box = High Risk (70%) of Thunderstorms developing and moving north during the late evening and overnight into Monday, organising into an organised convective system with frequent lightning, torrential rain, gusts to 55-60Knts . Primary Risks - Travel Delays & Disruption, Local Flooding & Power Disruption. 

Detail 

Broad upper level trough moves towards the UK at the same time as a strong deep layer ridge develops over the Western Mediterranean, this 700mb ridge and 850mb ridge is quite pronounced and during the early part of next week extends upwards in the atmosphere to become a significant area of warm well subsided blocking air. The first pulse of warm advection at 925mbs and 850mbs arrives during Sunday and provides the recipe for some late day development of thunderstorms as at the same time the upper trough at 500mbs and 300mbs arrives into the west. A Southerly Jet on the eastern flank of this trough will be propagating north on the eastern side of this trough during the day, and will split later in the day to contain 2 jet Maxes. One will speed north and then NE over Scotland, and another will arrive in the SW of England overnight into Monday. As the upper trough moves closer, a shortwave trough will move north and increase the Southerly convergence at 700mbs and 500mbs up through the western and later northern parts of the UK. Along with the increase in forward velocity of the air, the deep layer shear will increase through the rest of the atmosphere along with both some directional and speed sheer and divergence aloft in the right entrance of the initial Jet core. As the Jet core splits it will move NNE and the right entrance will be taken NE across Scotland. At 850mbs there will be a steady push of warm advection through the day on Sunday will some cooling above that. An increase in Theta-W to around 12/14C occurs early in the day and then a further advection of 16C WBPT plume arrives by the end of Sunday. At the surface daytime heating will occur and as temps approach 25-27C we then start to have the enough heating to initiate convection given the moisture aloft, and the cooling taking place through the differential thermal advection. During the afternoon streamline forecasts indicate some surface confluence and convergence will occur along the M4 or around the Severn Estuary across to the Centre of England. At the same time convergence occurs over the Southern part of Northern England, towards Merseyside and down to the West Midlands. This additional forced ascent from the surface will initiate convection and then the convection will be able to tap into the relatively strong upper level thermodynamics and kinematics, steered by the flow at 700mbs where additional southerly confluence will focus the rising air even more and 700mb/500mb vertical velocity fields indicate that the storms once developed will grow quite rapidly and head across Northern England and then able to further organise themselves given the favourable upper level venting pattern of Deep Layer Shear and the added Jet stream divergence field. The strong convective developments also able to tap into a filament of vorticity propagating north and possibly also a filament of north south vorticity lying down N/S on the eastern flank of the trough which will have swung north around the base of the trough and become aligned to the flow as it meets the developing deep layer block to the east. This favourable upper level environment will continue through to Monday morning as the storms move out into the North Sea. The UK will then sit under the left entrance region until a further area of enhanced upper level thermodynamics and Kinemetics arrives in the South and across the Channel Islands as we go into Monday night and early Tuesday. 

Thunderstorms are highly likely to develop from 15:00 around the Welsh Marches, North of the M4 Corridor and across the Midlands up towards Merseyside and Greater Manchester. These then growing and advecting northwards as the evening progresses and gathering further organisation. Frequent lightning developing, torrential rain and as the storms gain latitude and organise then we can expect potentially SEVERE weather to develop including torrential heavy rain, giving 40-60mm & 125mm/h rainfall rates and straight-line gusts over 55knts and PROB30 of over 60knts. Strike rates over 10,000 strikes and possibly nearer to 20,000 strikes possible through the late evening and night. Hail also becomes possible. Tornado development is not likely due to the topography of where the storms will be advecting into. Once the storms are routed from the surface they will move north in the 700-800mb steering 
flow and be lying off the NE Coast of Scotland by Monday Morning 07:00 

Primary Risks 

Dangerous Cloud to Ground Lightning, Torrential Rain, Local Flooding, Gusts and damage to trees. Delays and Disruption to the Power Grid and Travel Network. 

Further updates will be issued through Saturday and Sunday. 

Fig 1 - Convective Outlook / Advisory Risk Box V1 (Risk is to 13:00 Monday not 07:00)

Issued Paul Blight 
19.45 21st June 2019.

[Met4Cast]

2 minutes ago, Mapantz said:

Part of being a moderator. 

Sign me up!

[Flash bang flash bang etc]

9 minutes ago, Met4Cast said:

Timing is a little bit tricky, especially for specific locations because different models are faster with the initiation of storms. Herefordshire at the moment looks to be on the boundary between general thundery showers and the possibility of more severe storms initiating a little North of the area. Again though pure speculation at this stage, events like these are nigh on impossible to nail down with any real accuracy. 

Coventry?

[Chris.R]

Definitely doing an all-nighter Sunday night. Anything better than the 28th June 2012 would do nicely (2 rumbles)!

[ChezWeather]

1 minute ago, Chris.R said:

Definitely doing an all-nighter Sunday night. Anything better than the 28th June 2012 would do nicely (2 rumbles)!

I have a feeling that i'll be suffering from a severe lack of sleep next week, no time off work and likely pulling all-nighters on Sunday and Monday 

[matt111]

Just to whet the appetite (or in case of disappointment) I've been watching YouTube videos of some past storms. Some great footage from Eastbourne the other night on there now.