Convective/Storm Discussion Thread - 1st August onwards

[Summer Sun]

Day 2 Convective Outlook

VALID 06:00 UTC Wed 25 Apr 2018 - 05:59 UTC Thu 26 Apr 2018

ISSUED 19:13 UTC Tue 24 Apr 2018

ISSUED BY: Dan

Cold pool associated with broad upper trough drifting eastwards across the British Isles on Wednesday will be accompanied by markedly steep mid-level lapse rates and some marginal instability. Numerous showers will move eastwards across many areas, some with small hail.

Best instability will exist in a zone from the Republic of Ireland - Wales - Midlands - East Anglia where lapse rates will be steepest, yielding up to 500 J/kg CAPE in response to diurnal heating. These regions will also benefit from 20-40kts DLS, which may compensate for the low levels of CAPE, especially across southern counties of England.

 

Theoretically lightning could occur almost anywhere given widespread deep convection (hence large LOW threat level), but given a reasonable overlap of CAPE and shear over these aforementioned regions, have introduced a low-end SLGT to suggest slightly better overall conditions for lightning activity. High-resolution models suggest convective gusts of 50mph may be possible.

One inhibiting factor across these areas could be true convective depth, with forecast profiles suggesting deep convection may be restricted to tops near 400/450mb (even shallower across southern England, while deeper over northern England but here CAPE will be much taller/skinner with less DLS).

http://www.convectiveweather.co.uk/forecast.php?date=2018-04-25

[Woollymummy]

On 22 April 2018 at 19:35, Stormhog said:

That was a pretty intense storm that tracked across East Anglia. The hail core scored a bullseye on my mothers village of Redgrave. 

My parents in Diss got actually bruised by the hail, fearing for their windows too, super storm!

[Nick F]

Storm & Convective Forecast

Issued 2018-04-25 08:08:54
Valid: 25/04/2018 0600z - 26/04/2018 0600z

THUNDERSTORM OUTLOOK - DAY 1 (WEDNESDAY 25TH APRIL 2018)

Synopsis

Broad upper troughing covers the far north Atlantic, with a shortwave in the upper flow passing Scotland during the day and a cyclonic southwesterly flow covering the UK, which will be unstable to surface heating - supporting diurnal heavy showers with a risk of hail and thunder.

... IRELAND / N. IRELAND, SW SCOTLAND, WALES and ENGLAND ...

Returning Polar maritime airmass across the UK and Ireland will be characterised by steep lapse rates thanks to increasingly cold air aloft created by upper troughing edging in from the Atlantic. Instability will be greatest  across Ireland + central and southern parts of UK - where surface heating and moisture will be greatest beneath cold air advection aloft. This will support the development of diurnal heavy showers and some scattered weak thunderstorms capable of producing small hail and gusty winds - which may reach 40-50 knts locally. Thunderstorm risk should fade after dark.

Issued by: Nick Finnis

[Jordan S]

[Another Kent clipper]

A couple of shots from the Orkney islands, between st Margaret's hope and kirkwall

[Dangerous55019]

Distant grumbling of thunder. 

And it looks like we’ve got some activity over on the Wirral. 

[Marko1690]

Couple of small thunderstorms heading away from mourne mountains out to irish sea, dunno if they will gather any more energy before they contact the rest of the country?

[East_England_Stormchaser91]

One of the best April shower days in a long time. Cracking cumulonimbus shooting up all over and a few real loud rumbles heard earlier with some decent IC lightning. Bravo! 

[Weather-history]

Some good convective skies

[Weather-history]

Big hail shower passing through

[Flash bang flash bang etc]

Midhurst storm died off on approach. Found a nice little spot to view it on the way home but alas i’m left sitting in a rain shower watching pheasants 

Edited April 25, 2018 by Flash bang flash bang etc

[Thunderstruck]

Very dark sky to the NW which is apparently producing lightning. Haven’t seen any yet but keeping my eyes peeled...

Edit: Just saw a little CG! Might skirt me to the north though. We’ll see

Edited April 25, 2018 by Thunderstruck

[Weather-history]

19 minutes ago, Weather-history said:

Big hail shower passing through

 

[Thunderstruck]

Think it’s died now, so still waiting for my first rumble of 2018. Did see my first lightning though. 

[Flash bang flash bang etc]

Pulse storms I fear. Though that one near Milton Keynes did alright wow

[toggerob]

Nice CB and TCu landscapes around the Peaks this afternoon, caught up in one that gave torrential rain with pea-sized hail and just the one lightning strike. Warm April sunshine one minute and lashing down with rain the next.

[Weather-history]

At last thunder.

[Polar Maritime]

Some very heavy showers rattling through here just now.

[Supacell]

Intercepted a storm near to Worksop. Two flashes and bangs, some gusty winds and quite decent hail of about marble sized. With the winds it was really crashing into the car windscreen.

Edit: This about an hour ago.

Edited April 25, 2018 by Supacell

[Robbie Garrett]

Huge CB to my SW tracked over Kingston Upon Thames 10 minutes ago moving due east.  No sure if electrical?

Edited April 25, 2018 by Robbie Garrett

[Chris.R]

A typical April showers day here today watching cells explode inland whilst it remains sunny but cool here on the coast in the on-shore flow. The fewer days like this I get this year the better. 

[TropicThunder]

Had a few rumbles from the little storm that passed over here around an hour ago. Tried to chase but was defeated by the rush hour traffic. Did see a nice double rainbow though.

Edited April 25, 2018 by TropicThunder

[Flash bang flash bang etc]

7 minutes ago, Chris.R said:

A typical April showers day here today watching cells explode inland whilst it remains sunny but cool here on the coast in the on-shore flow. The fewer days like this I get this year the better. 

Wasn’t sure if the on-shore breeze might aid the formation of CZs around your parts?

 

edit: don’t read that as ‘around your parts’ 

Edited April 25, 2018 by Flash bang flash bang etc

[Lincs Observation]

Several storms have passed through Lincs today as I type we have very heavy hail thunder and lightening

LO

the hail is coming down that hard it's shredding the leaves on the trees as it falls marble size wow

Edited April 25, 2018 by Lincs Observation

[Supacell]

28 minutes ago, Lincs Observation said:

Several storms have passed through Lincs today as I type we have very heavy hail thunder and lightening

LO

the hail is coming down that hard it's shredding the leaves on the trees as it falls marble size wow

Same thing around Worksop. My car was covered in leaves.