Convective Storm/Discussion thread - 11/06/16 onwards

[weather09]

No, was more in reference to recent comments that likelihood is storms will miss our shores.  

Anywhere along and E of the cold front in with a shout, and it doesn't look like moving east at any real rate, forming a wave along the boundary and holding EA/SE in the warm, moist air mass for Thurs.  

[A.J]

Just now, weather09 said:

No, was more in reference to recent comments that likelihood is storms will miss our shores.  

Anywhere along and E of the cold front in with a shout, and it doesn't look like moving east at any real rate, forming a wave along the boundary and holding EA/SE in the warm, moist air mass for Thurs.  

lol....that's alright then .....I was thinking 'hang on, I totally agree with W09 yet he's having a pop' ahahaha!.....

[dwalton]

34 minutes ago, ajpoolshark said:

NMM hi-res modelling infers that it's own output would have to be quite badly wrong for there not to be a plethora of elevated thunderstorms tomorrow night for parts of the SE quarter in the form of a mcs

        

     

 

Looking at them Sussex looks to be in for a good shout generally. 

[Ben Sainsbury]

45 minutes ago, ajpoolshark said:

NMM hi-res modelling infers that it's own output would have to be quite badly wrong for there not to be a plethora of elevated thunderstorms tomorrow night for parts of the SE quarter in the form of a mcs

        

     

 

Can someone explain what absolute vorticity means?

Edited June 21, 2016 by Ben Sainsbury

[Mapantz]

32 minutes ago, Ben Sainsbury said:

Can someone explain what absolute vorticity means?

I think that chart is the same as the 700hPa vertical motion chart on Wetterzentrale? not 100% sure. The scale on the right is slightly different:

Negative values indicate PVA, positive vorticity advection, a rising motion. Positive numbers are a falling motion, NVA, negative vorticity advection. A good tool for severe weather forecasting, such as supercells or even heavy rainfall.

As I said, I think the NW chart is the same one..

Edited June 21, 2016 by Mapantz

[Ben Sainsbury]

Just now, Mapantz said:

I think that chart is the same as the 700hPa vertical motion chart on Wetterzentrale? not 100% sure. The scale on the right is slightly different:

Negative values indicate PVA, positive vorticity advection, a rising motion. Positive numbers are a falling motion, NVA, negative vorticity advection. Good for severe weather forecasting, such as supercells or even heavy rainfall.

As I said, I think the NW chart is the same one..

Cheers much appreciated!

[Flash bang flash bang etc]

Oh poops I'm out at the pub tomo night so chasing in a vehicle would be a bad idea - especially since the vehicle is broken and at the local garage, and I don't think I'd be able to drive in a particularly straight line after several beers.

what sort of time are these storms likely to pass through during the night? If they are early hours at least I'd be able to watch from somewhere nearby with a good view.

Don't want to be sitting in a pub when there's decent lightning about!

[paul_montague]

Does anyone have a spare on off switch. My IOW storm shield generator Seems to be stuck in the on position. Was thinking of sending it to Kent but i think i get mobbed....

[William Grimsley]

Any more westward shift on this and we could see something towards SW areas but not this far west!

[A.J]

certainly a chance of eastern parts of the west country to see some rainfall tomorrow night, thunder riskl is very low though....Generally although from my experience, when an MCS fires ahead of a frontal boundary, most of the deep convection and associated thunderstorms occur on the eastern and SE flanks of the system, especially in this scenario where it seems here lays the greatest instability...not always the case though.......and excuse my clumsy phrasing as I'm typing whist having two other conversations....lol

[Ben Sainsbury]

8 minutes ago, ajpoolshark said:

certainly a chance of eastern parts of the west country to see some rainfall tomorrow night, thunder riskl is very low though....Generally although from my experience, when an MCS fires ahead of a frontal boundary, most of the deep convection and associated thunderstorms occur on the eastern and SE flanks of the system, especially in this scenario where it seems here lays the greatest instability...not always the case though.......and excuse my clumsy phrasing as I'm typing whist having two other conversations....lol

Even if this is the case, hopefully we could see some very interesting structures, we shall see tho! I'm in Bath so the further east the better!

[A.J]

Just now, Ben Sainsbury said:

Even if this is the case, hopefully we could see some very interesting structures, we shall see tho! I'm in Bath so the further east the better!

yep, defo Ben.....I'm about 25 miles east of you so I'll have my fingers, toes, everything crossed in the faint hope

[Harry]

Agree with AJ in that MCS generally reserve lightning activity to their eastern flank and I am going to suspect that will be the case tomorrow night. However, much like last July (3rd) I suspect there'll be pre-MCS cells firing which, if they do, could be very electrically active. Personally I think we have more chance at pre-MCS thunderstorms erupting on the edge of the plume than an MCS which I anticipate will run more along the coastline, perhaps giving Dungeness a show. Just a hunch...

[NO LONGER POSTING]

Anyone fancy a drive down to Dover?? 

[alexisj9]

I fancy a drive in the other direction.

[Chris K]

Even those further west may see thundery showers develop in the following few days, even though more hit and miss. The risk is there at least.

[Tom Jarvis]

.

Edited June 21, 2016 by Tom Jarvis

[Tom Jarvis]

5 minutes ago, Surrey said:

Anyone fancy a drive down to Dover?? 

 

Come to the Ashdown forest has great views to the south and se 

[alexisj9]

1 minute ago, Tom Jarvis said:

Come to the Ashdown forest great views to the south on there and plenty of parking. 

Went there quite a few years back now, beautiful. Actually there was a storm one of the nights I was there, lasted hours.

[stainesbloke]

9 minutes ago, Surrey said:

Anyone fancy a drive down to Dover?? 

I fancy it, in fact I'd prefer to keep going and head to the northeast of France but the Channel Tunnel is experiencing more problems again, could take a while to get home. Chasing in France would be fun; the motorways are so much quieter compared to here and there are rest stops every 20kms or so (good storm viewing). 

[Summer Sun]

Moderate chance of thunderstorms tomorrow 

http://www.convectiveweather.co.uk/forecast.php?date=2016-06-22

[alexisj9]

12 minutes ago, Summer Sun said:

Moderate chance of thunderstorms tomorrow 

http://www.convectiveweather.co.uk/forecast.php?date=2016-06-22

I really do not like the last paragraph.

[Ben Sainsbury]

1 minute ago, alexisj9 said:

I really do not like the last paragraph.

Any we should take this extremely seriously, all parameters are in place and could see widespread extremely frequent lighting, severe flooding, moderate sized hail. These forecasts not only provide forecasts for us storm lovers, they provide neccesary warnings!

[Harry]

Storm Forecast
Valid: Wed 22 Jun 2016 06:00 to Thu 23 Jun 2016 06:00 UTC
Issued: Tue 21 Jun 2016 21:55
Forecaster: PUCIK

A level 2 was issued for NW France mainly for large to very large hail, severe wind gusts and to the lesser extent for excessive precipitation and tornadoes.

A level 1 was issued for extreme N France, SE England, Belgium and Netherlands mainly for severe wind gusts, excessive precipitation and to the lesser extent for large hail.

A level 1 was issued for S Italy mainly for marginally large hail.

A level 1 was issued for W Balkans through Romania into Ukraine mainly for large hail, severe wind gusts and excessive precipitation. 

SYNOPSIS

With several days of extremely severe thunderstorm activity over parts of E Europe, situation will finally begin to ease off over this region. Primary reason will be the weakening of mid-tropospheric flow as trough over Central Europe fills up, coincident with a decrease in the DLS. Northern part of the trough will continue moving eastwards, along with the cold front, across W Russia. A cut-off low will remain almost stationary just to the SW of Sicily. A change in the pattern is forecast over W Europe with an amplifying trough over the Atlantic. SW-ly flow will advect a plume of steep lapse rates over moist airmass over W and Central France. 

Several areas, both in W and E Europe require closer inspection with enhanced probability of severe weather. 

DISCUSSION

... NW France ...

All models agree on the increase in the low-level moisture over the area while already at Tuesday 21 UTC, surface observations reveal dewpoints up to 18 deg C. In conjuction with the steepening lapse rates from the south, moderate CAPE values are forecast over the area (1000 - 2000 J/kg). Strengthening mid and upper tropospheric flow will yield high values of DLS (20 - 30 m/s), so that very well organised convection can be anticipated. Supercell convection will be also supported by an increase in SRH as surface flow backs to easterly with low pressure south of the area. Forecast soundings display favourable veering of winds with height and by 18 UTC, 200 - 400 m2/s2 of SRH is forecast in the 0-3 km layer especially in the NW part of the Lvl 2. Parallel mid to upper tropospheric flow to the boundary suggest that storms may have tendency to cluster, but any storm that manages to stay out of the boundary could remain in the form of isolated supercell, capable of large to very large hail. A brief window will exist in the evening also for tornadoes as boundary layer stabilizes but low level shear ramps up. It is likely that storms progress along the boundary in the form of a cluster or small MCS in the night hours towards NE, being capable of severe wind gusts and/or excessive precipitation. Detrimental factor, especially across the northern parts of the Lvl 2 may be lingering cloudiness.

... Belgium, Netherlands, SE England ...

Lower CAPE values forecast for this area decrease the overal risk of severe weather. Nevertheless, if some storms manage to initiate during the day, they may become supercells with a threat of marginally large hail due to the strong vertical wind shear. Region may be also impacted during the night hours by the convective clusters (or MCS) moving in from France. Such system would pose predominantly a risk of severe wind gust or an excessive rain event. 

[Ben Sainsbury]

In connection with ESTOFEX Forecast...

Seems like the only thing preventing a lvl 3 from NW France is the excessive cloud cover.

Edited June 21, 2016 by Ben Sainsbury