Convective/Storm Discussion Thread - 19th May 2018 onwards

[Summer Sun]

Day 2 Convective Outlook

VALID 06:00 UTC Thu 24 May 2018 - 05:59 UTC Fri 25 May 2018

ISSUED 20:28 UTC Wed 23 May 2018

ISSUED BY: null

 

Several episodes of thunderstorms are possible during this forecast period - in general, for England / Wales the risk of lightning is mainly across the southern half of the SLGT during Thursday daytime, the focus then shifting to the northern half of the SLGT on Thursday night / early Friday. Main focus for Northern Ireland / Republic of Ireland will be Thursday afternoon and early evening.

 

... THURSDAY DAYTIME: ENGLAND / WALES ...

Elevated convection will likely be ongoing at the start of this forecast period, associated with destabilisation of relatively high WBPT plume, over southern England / south Midlands, moving westwards into S Wales and parts of SW England. Some sporadic lightning continues to be possible with this activity, although instability reduces as storms continue to drift to the west, so probably with a weakening trend as they move into Wales / SW England.

 

By the afternoon, there is fairly good model agreement for any thunderstorm potential to become primarily focussed along the moisture plume, in a SE-NW corridor from Cen S England to S Wales. By this point, rain will be evolving into a messy mix of dynamic and embedded convection elements, though should any thunderstorms develop along this zone then they will quite likely be elevated - however, there is scope for some to become rooted in the boundary layer if enough surface heating can occur, either along or to the north of this frontal boundary. Some high-resolution model guidance suggests the potential for a couple of surface-based thunderstorms during the second half of the afternoon near or just north of the M4, drifting west into E / SE Wales towards evening. This area therefore has the potential to be upgraded to MDT; should thunderstorms develop here lightning could be quite frequent, accompanied by hail and gusty winds.

 

Main threats will be surface water flooding from prolonged heavy rain running over similar areas, particularly Cen S England and along the M4 corridor into the SW Midlands. Depending on developments, the SLGT may also need extending into parts of Devon and Cornwall.

 

... THURSDAY DAYTIME: NORTHERN IRELAND / REPUBLIC OF IRELAND ...

Remnants of mid-level convection / instability (from Wales) will drift westwards into southern and eastern Ireland on Thursday morning - this airmass then destabilising further in response to surface heating, yielding 500-900 J/kg CAPE. Low-level convergence will aid in the development of a few scattered surface-based showers and thunderstorms along a N-S line, starting on the eastern side of the SLGT mid-afternoon and drifting slowly to the west into the early evening, before decaying as nocturnal cooling of the boundary layer commences.

 

Shear is not particularly strong, and so most showers/storms will tend to be of the pulse variety, an individual cell lasting less than an hour etc. An isolated heavy shower / thunderstorm is also possible in western Northern Ireland.

 

... THURSDAY EVENING / NIGHT: ENGLAND / WALES ...

During the second half of the evening, a renewed pulse of high WBPT airmass will advect westwards towards East Anglia / SE England, and then into other portions of eastern England and the Midlands during the early hours, destabilising as a shortwave drifts from BeNeLux to eastern England around the northern periphery of the upper low over NW France. An increase in coverage of elevated showers and thunderstorms is expected with time, drifting WNW-wards across East Anglia - Midlands - southern N England - N Wales. This activity will tend to merge into a larger area of heavy rain with embedded lightning as the night progresses, and hence becoming a rather messy mix of dynamic and convective precipitation.

 

An upgrade to MDT may be required for parts of East Anglia in particular, if confidence on thunderstorm coverage improves - any thunderstorms that develop here will likely produce very frequent lightning given expected instability, with lightning frequency and coverage generally decreasing further west as profiles become saturated and instability reduces. 

 

http://www.convectiveweather.co.uk/forecast.php?date=2018-05-24

[Stuart]

Day 2 Convective Outlook
VALID 06:00 UTC Thu 24 May 2018 - 05:59 UTC Fri 25 May 2018

ISSUED 20:28 UTC Wed 23 May 2018

ISSUED BY: null

Several episodes of thunderstorms are possible during this forecast period - in general, for England / Wales the risk of lightning is mainly across the southern half of the SLGT during Thursday daytime, the focus then shifting to the northern half of the SLGT on Thursday night / early Friday. Main focus for Northern Ireland / Republic of Ireland will be Thursday afternoon and early evening.

... THURSDAY DAYTIME: ENGLAND / WALES ...
Elevated convection will likely be ongoing at the start of this forecast period, associated with destabilisation of relatively high WBPT plume, over southern England / south Midlands, moving westwards into S Wales and parts of SW England. Some sporadic lightning continues to be possible with this activity, although instability reduces as storms continue to drift to the west, so probably with a weakening trend as they move into Wales / SW England.

By the afternoon, there is fairly good model agreement for any thunderstorm potential to become primarily focussed along the moisture plume, in a SE-NW corridor from Cen S England to S Wales. By this point, rain will be evolving into a messy mix of dynamic and embedded convection elements, though should any thunderstorms develop along this zone then they will quite likely be elevated - however, there is scope for some to become rooted in the boundary layer if enough surface heating can occur, either along or to the north of this frontal boundary. Some high-resolution model guidance suggests the potential for a couple of surface-based thunderstorms during the second half of the afternoon near or just north of the M4, drifting west into E / SE Wales towards evening. This area therefore has the potential to be upgraded to MDT; should thunderstorms develop here lightning could be quite frequent, accompanied by hail and gusty winds.

Main threats will be surface water flooding from prolonged heavy rain running over similar areas, particularly Cen S England and along the M4 corridor into the SW Midlands. Depending on developments, the SLGT may also need extending into parts of Devon and Cornwall.

... THURSDAY DAYTIME: NORTHERN IRELAND / REPUBLIC OF IRELAND ...
Remnants of mid-level convection / instability (from Wales) will drift westwards into southern and eastern Ireland on Thursday morning - this airmass then destabilising further in response to surface heating, yielding 500-900 J/kg CAPE. Low-level convergence will aid in the development of a few scattered surface-based showers and thunderstorms along a N-S line, starting on the eastern side of the SLGT mid-afternoon and drifting slowly to the west into the early evening, before decaying as nocturnal cooling of the boundary layer commences.

Shear is not particularly strong, and so most showers/storms will tend to be of the pulse variety, an individual cell lasting less than an hour etc. An isolated heavy shower / thunderstorm is also possible in western Northern Ireland.

... THURSDAY EVENING / NIGHT: ENGLAND / WALES ...
During the second half of the evening, a renewed pulse of high WBPT airmass will advect westwards towards East Anglia / SE England, and then into other portions of eastern England and the Midlands during the early hours, destabilising as a shortwave drifts from BeNeLux to eastern England around the northern periphery of the upper low over NW France. An increase in coverage of elevated showers and thunderstorms is expected with time, drifting WNW-wards across East Anglia - Midlands - southern N England - N Wales. This activity will tend to merge into a larger area of heavy rain with embedded lightning as the night progresses, and hence becoming a rather messy mix of dynamic and convective precipitation.

An upgrade to MDT may be required for parts of East Anglia in particular, if confidence on thunderstorm coverage improves - any thunderstorms that develop here will likely produce very frequent lightning given expected instability, with lightning frequency and coverage generally decreasing further west as profiles become saturated and instability reduces. 

http://www.convectiveweather.co.uk/forecast.php?date=2018-05-24

 

[alexisj9]

Looks on radar like storm incoming soon. Can't hear it yet, but sky looks ripe too.

[Guest]

Has to be said looks like a bit of wet mess moving into the south east opposed to anything particularly well organised. Time will tell.

[Flash bang flash bang etc]

Just now, Alderc said:

Has to be said looks like a bit of wet mess moving into the south east opposed to anything particularly well organised. Time will tell.

Give it til hour 23

[East_England_Stormchaser91]

Very promising forecasts, and this could just be the start of things to come. Over the weekend, we could be seeing several reloads piling into Southern England in the form of potential MCS’s anywhere from the SW, all the way to the SE and E anglia. Some of those CAPE and LI values especially from Saturday through to Tuesday look incredible, especially across the channel in France and BeNeLux. 

[Chris.R]

 Oh well better than nothing. I’ll take heavy rain with possible sporadic lightning on Thursday night for now. 

[alexisj9]

46 minutes ago, Alderc said:

Has to be said looks like a bit of wet mess moving into the south east opposed to anything particularly well organised. Time will tell.

Yeah it seems to have died for now.

[Allseasons-Si]

Good luck to you guys down in the south but it looks like the storms have died away,but  i cannot tell you if you will get a storm IYBY(in your back yard),things could develope later and i hope they do

signing out now as i am up at 5am

looking forward to some reports when i get in tomorrow after 2pm

night guys.

[Flash bang flash bang etc]

Sat24 not showing it yet (I can’t seem to zoom on the U.K. at the mo) but check the rain radar and you can see the PPN area springing into life over the channel.

Waitig for some sferics from that lot still - but looks like the steering winds will pull these storms along a route roughly in line with the south coast - maybe even a little northerly, tracking up towards South wales.

First couple of hours probably quite sporadic but gathering in energy a little as they pass into Wiltshire and clustering into short-lived storms for a while in the wee hours.

Personally think a couple of places along the way may do surprisingly well from this, but in general it will be less active than the storms we are expecting at the weekend...

Then again, this is just a roughly educated guess by a sleepy storm-starved southerner waiting patiently in a van by the coast - so anything could happen

[Allseasons-Si]

There is life SE of Lille IF that's any consolation

got to go.

[Ǝssex Ǝasterly]

The rain is nearly here! 

[Norfolk Sheep]

4 hours ago, Allseasons-si said:

You can see the cells exploding over the Belgium/Dutch borders on here

new cell developed north of Antwerp.

https://en.sat24.com/en/nl/visual

 

good look to those in the south later

I really hope Holland isn't using up its storm allowance for 2018 before I go there in August 

[Flash bang flash bang etc]

It’s very hard to nap in a Fiat Fiorino

No way to get comfy there’s too many edges on everything

[Norfolk Sheep]

47 minutes ago, East_England_Stormchaser91 said:

Very promising forecasts, and this could just be the start of things to come. Over the weekend, we could be seeing several reloads piling into Southern England in the form of potential MCS’s anywhere from the SW, all the way to the SE and E anglia. Some of those CAPE and LI values especially from Saturday through to Tuesday look incredible, especially across the channel in France and BeNeLux. 

Or, as is usually the case, a load of left over muck and clag from France every morning 

[alexisj9]

Rain seems to be getting heavier, west of here, wouldn't be surprised if it gets electrified again soon.

[Flash bang flash bang etc]

2 minutes ago, alexisj9 said:

Rain seems to be getting heavier, west of here, wouldn't be surprised if it gets electrified again soon.

Hope so - thinking of heading home soon so a few farewell flashes before it follows me back would be nice

[A.J]

some hefty showers tracking westwards along the M4 corridor....we've just had one

[LightningLover]

What does everyone think? Is it worth staying awake any longer, or should i get some kip? (I have to get up at 07:00 for school)

[Flash bang flash bang etc]

Wind is picking up

[Flash bang flash bang etc]

My worry is that the lightning will start right where I am and make me jump out of my skin

[convector]

1 minute ago, LightningLover said:

What does everyone think? Is it worth staying awake any longer, or should i get some kip? (I have to get up at 07:00 for school)

i wouldn't bother, there's plenty of better setups this week and the next

[Flash bang flash bang etc]

Eek rain cell right next to me apparently

[LightningLover]

2 minutes ago, convector said:

i wouldn't bother, there's plenty of better setups this week and the next

I was thinking the same. I'll leave the curtains/windows open, and if  anything noteworthy occurs, ill hopefully get woken up.

 

Good luck everyone!

[Zephyr]

9 minutes ago, ajpoolshark said:

some hefty showers tracking westwards along the M4 corridor....we've just had one

Same here been quite a temperature drop as well starting to feel a little cold.