Convective/Storm Discussion Thread - 1st June onwards

[cheese]

We had a storm last year that produced hail the size of 1-pence coins here. The rain was enough to cause the roof at the local Sainsbury's and Boots to collapse. Nothing like that here this year, though that was certainly exceptional so I wouldn't expect a repeat.

[Summer Sun]

Day 1 Convective Outlook

VALID 06:00 UTC Mon 30 Jul 2018 - 05:59 UTC Tue 31 Jul 2018

ISSUED 04:42 UTC Mon 30 Jul 2018

ISSUED BY: Dan

Broad upper low continues to be centred south of Iceland, providing strong mid/upper level flow across the British Isles. Cold air aloft atop diurnal heating and SSTs will generate several hundred J/kg CAPE, with numerous showers affecting northern and western parts of the British Isles.

 

... NORTHERN IRELAND / NW REPUBLIC OF IRELAND ...

A little reluctant to issue a SLGT here given limited instability, but shear may be sufficient to aid in some sporadic lightning activity on Monday afternoon associated with scattered showers - though would prefer to treat point probability of lightning at less than 30% (i.e. sub-SLGT). A similar environment will also exist over western Scotland, both Highlands and islands.

 

... NORTHERN ENGLAND ...

Profiles look somewhat capped at 650/700mb for much of the day, limiting convective depth - however, an approaching shortwave should help to cool the mid-levels and remove most of this cap, allowing a greater depth of convection to become possible from mid-afternoon onwards. The strongly-sheared environment should allow for some cell organisation, with gusty winds and hail possible from the most intense cores, before the activity moves offshore during the evening.

 

... SE ENGLAND ...

Main focus here is late on Monday night into Tuesday morning. A pronounced shortwave over the mid-Atlantic will rapidly swing round the base of the broad upper low, approaching Brest around 00z, Cherbourg at 03z and inland Kent/Sussex by 06z, while intensifying. This increasingly strong forced ascent will allow a cluster of heavy showers to develop, drifting from the Channel Islands towards SE England during the early hours of Tuesday. Some lightning activity seems quite likely, with the potential for hail and gusty winds - in fact a tornado cannot be ruled out.

http://www.convectiveweather.co.uk/forecast.php?date=2018-07-30

[Supacell]

11 hours ago, East_England_Stormchaser91 said:

Definitely. It’s been a great year in that respect. Going on chases to capture amazing storms such as Thursday and Friday makes it worth every drop of fuel! 

Heres the departure of the storm that hit us. The frequency of thunder is unreal. If you’ve got earphones or headphones, plug them in! 

 

It was very similar with the storms that hit where I was. Almost constant thunder. Although until the evening most of the lightning was either very feint or not visible at all.

[Joey.G]

Zomg wall cloud over Matlock! Or not. Still, kinda looked mean enough for a bit of lightning but I think cloud tops a bit too low. Certainly be getting wet under it though! 

[NO LONGER POSTING]

Euro4.. 

Need to see the 12z really.. 

In house model disagrees.. 

[Ross B]

Thunderstorm currently moving into Durham 

[legritter]

Radar showing some activity moving n east towards Cornwall  , THINK this is a bit further north tracking than I read EARLIER today ,any one got any comments as I have been glued to paperwork today ,cheers gang .

[Harry]

Proper mackerel sky here with some Ac visible earlier. Maybe there’ll be enough instability for some isolated thunder and heavy downpours. Will keep windows open just in case (and it’s meant to be a fairly warm night) 

[Mokidugway]

1 minute ago, Harry said:

Proper mackerel sky here with some Ac visible earlier. Maybe there’ll be enough instability for some isolated thunder and heavy downpours. Will keep windows open just in case (and it’s meant to be a fairly warm night) 

Had some ac and flockus earlier ,clear blue sky now .

[Harry]

Just now, Mokidugway said:

Had some ac and flockus earlier ,clear blue sky now .

Just had a look at NetWx model and the NMM and they are having none of it. BBC, UKMO and Euro4 thinking yes. We’ll see.

[NO LONGER POSTING]

6 minutes ago, Harry said:

Just had a look at NetWx model and the NMM and they are having none of it. BBC, UKMO and Euro4 thinking yes. We’ll see.

NMM did really really bad last time round with storms... 

NetWx not so bad so that's why I'm being cautious 

[Mapantz]

NetWx is the NMM model. EURO4 is the NAE.

[East_England_Stormchaser91]

Hirlam and Euro4 nailed it on last Friday. NMM WRF was well off the money. We’ll see about this one though, as it’s a little fast mover, so would be quite a nightmare forecasting it. 

[Nick F]

Shortwave trough rounding the base of the upper low over the far N Atlantic, as seen on WV imagery below, will swing in across S England tomorrow morning and will induce an area of heavy convective rainfall, probably with some thunder embedded in it, before clearing E Anglia by mid-morning.

 

Storm & Convective Forecast

Issued 2018-07-30 21:02:20
Valid: 31/07/2018 00z - 01/08/2018 00z

THUNDERSTORM OUTLOOK - TUESDAY 31ST JULY 2018

Synopsis

An upper level low will continue to sit over the far north Atlantic, centred just south of Iceland, blocked to eastward progress by upper-level high over NE Europe. A shortwave trough rounding the base of upper low will move NE across southern Britain on Tuesday morning, creating a wave in the cold front clearing east across eastern England – which will induce an areas of heavy rain, with possible thunderstorms embedded, tracking NE across S England and E Anglia early morning.

… S ENGLAND and E ANGLIA …

Convection supporting heavy showers with isolated lightning across UK during Monday will generally fade in the evening / night as surface heating wanes. However, a shortwave trough, clearly visible on WV imagery rounding base of upper low over Atlantic, will swing NEwards across southern Britain, engaging cold front slowly edging east across England, developing a wave along it as it tries to clear SE England in early hours of Tuesday, which will combine to increase forced ascent of moist airmass ahead of the front. This will support an area of convectively driven heavy rainfall to spread NE S England and E Anglia Tuesday early PM. Models indicate sufficient instability for thunderstorms, with the potential to organise, given 0-6km effective-shear of 40-50 knots, to produce hail, strong wind gusts and briefly intense rainfall that may lead to localised rainfall. Although a very small risk, backing surface winds ahead of the approaching shortwave and veered winds with height may produce enough low-level helicity to allow more buoyant updrafts to rotate to produce  a brief tornado too.

Issued by: Nick Finnis

 

[LightningLover]

4 minutes ago, Nick F said:

Shortwave trough rounding the base of the upper low over the far N Atlantic, as seen on WV imagery below, will swing in across S England tomorrow morning and will induce an area of heavy convective rainfall, probably with some thunder embedded in it, before clearing E Anglia by mid-morning.

 

Storm & Convective Forecast

Issued 2018-07-30 21:02:20
Valid: 31/07/2018 00z - 01/08/2018 00z

THUNDERSTORM OUTLOOK - TUESDAY 31ST JULY 2018

Synopsis

An upper level low will continue to sit over the far north Atlantic, centred just south of Iceland, blocked to eastward progress by upper-level high over NE Europe. A shortwave trough rounding the base of upper low will move NE across southern Britain on Tuesday morning, creating a wave in the cold front clearing east across eastern England – which will induce an areas of heavy rain, with possible thunderstorms embedded, tracking NE across S England and E Anglia early morning.

… S ENGLAND and E ANGLIA …

Convection supporting heavy showers with isolated lightning across UK during Monday will generally fade in the evening / night as surface heating wanes. However, a shortwave trough, clearly visible on WV imagery rounding base of upper low over Atlantic, will swing NEwards across southern Britain, engaging cold front slowly edging east across England, developing a wave along it as it tries to clear SE England in early hours of Tuesday, which will combine to increase forced ascent of moist airmass ahead of the front. This will support an area of convectively driven heavy rainfall to spread NE S England and E Anglia Tuesday early PM. Models indicate sufficient instability for thunderstorms, with the potential to organise, given 0-6km effective-shear of 40-50 knots, to produce hail, strong wind gusts and briefly intense rainfall that may lead to localised rainfall. Although a very small risk, backing surface winds ahead of the approaching shortwave and veered winds with height may produce enough low-level helicity to allow more buoyant updrafts to rotate to produce  a brief tornado too.

Issued by: Nick Finnis

 

I know this was unintentional, but... 'briefly intense rainfall that may lead to localised rainfall' ...Who would have guessed? 

Edited July 30, 2018 by LightningLover

[Nick F]

Quite an active line of storms rolling through SE England this morning, woke me up 5.20am with an almighty close flash and crash.

 

[matty40s]

There is rain is far more North than forecast and just enjoying the unexpected morning lightning storm west of Northampton.

One each side of me from Blitz lightning map

 

Edited July 31, 2018 by matty40s

[Team Jo]

Raining torrentially here and some very vivid lightning, even against the daylight. Thunder woke us all up about half an hour ago, all very exciting!

[Farmer Dave]

Just heard thunder here in Upchurch, Kent

[Nick F]

Didn’t expect storms in south Midlands too, if anything, the line of storms across the SE getting more active lightning-wise as they cross Essex and N Kent

5 minutes ago, Team Jo said:

Raining torrentially here and some very vivid lightning, even against the daylight. Thunder woke us all up about half an hour ago, all very exciting!

Now Paul Sherman has flown back stateside, the storms are returning to south Essex.

[Thunderstruck]

Well, that’s me woken up then. Definitely more thunder than I was expecting in this and the rain has been absolutely torrential

[LightningLover]

Has Hastings activated some form of storm shield...? This is the 4th time in the space of 2 weeks any potential t-storm activity has grazed us, and is just too far away to hear/see. 

Edited July 31, 2018 by LightningLover

[Farmer Dave]

Well that was quite a show for a while! Quite frequent lighting, loud thunder and torrential rain!

[Htid]

5 minutes ago, LightningLover said:

Has Hastings activated some form of storm shield...? This is the 4th time in the space of 2 weeks any potential t-storm activity has grazed us, and is just too far away to hear/see. 

Eastbourne aswell. I felt sure it couldnt  miss us but I was wrong. 

[shaky]

Defo way more north and more widespread than forecasted!!its chucking it down here in leicester!!