Convective/Storm Discussion Thread - 1st June onwards

[Cambridgeshire Weather]

Why is it thundering in Peterborough ? Was not expected to be woken up by thunder as did not know the conditions were right wow !

[Team Jo]

1 hour ago, Nick F said:

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

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

I know! He is literally a one man stormshield

[Summer Sun]

Day 1 Convective Outlook

VALID 06:00 UTC Tue 31 Jul 2018 - 05:59 UTC Wed 01 Aug 2018

ISSUED 06:03 UTC Tue 31 Jul 2018

ISSUED BY: Dan

A potent shortwave, and associated area of precipitation, will continue to clear northeastwards across east/southeast England on Tuesday morning. Steep mid-level lapse rates and strong forcing will continue to bring the risk of lightning, small hail and gusty winds.

http://www.convectiveweather.co.uk/forecast.php?date=2018-07-31

[Harry]

Pleasant surprise waking up to thunder and lightning - of course it was forecast by some and by some models, but it’s always nice when it happens as forecast

 

[Windblade]

I woke up at 5.45am to a terrific storm. Lightning was infrequent but the thunder was LOUD. The rain was absolutely pounding. The lightning was all IC but had a pint tint. Wonderful. It was so relaxing I went back to sleep. Unfortunately that's probably the last storm for me for a while as we're now going to see the return of the disgusting, sweaty, stinking, opressive, energy-sapping unbearable heat as we near the weekend. 

[Summer Sun]

Day 2 Convective Outlook

VALID 06:00 UTC Wed 01 Aug 2018 - 05:59 UTC Thu 02 Aug 2018

ISSUED 19:33 UTC Tue 31 Jul 2018

ISSUED BY: Dan

Some minor forcing aloft, associated with a dry intrusion in the mid/upper levels, may encourage mid-level instability release embedded within more generic frontal precipitation as a series of fronts move northeastwards across Scotland, Northern Ireland and NW Republic of Ireland - especially later in the day. Lightning potential is considered rather low given the lack of any notable instability and rather saturated profiles.

http://www.convectiveweather.co.uk/forecast.php?date=2018-08-01

[Summer Sun]

http://www.convectiveweather.co.uk/forecast.php?date=2018-08-02Day 2 Convective Outlook

VALID 06:00 UTC Thu 02 Aug 2018 - 05:59 UTC Fri 03 Aug 2018

ISSUED 20:53 UTC Wed 01 Aug 2018

ISSUED BY: Dan

Orographic forcing combined with an upper-level disturbance may allow one or two isolated but locally heavy showers to develop over NE Scotland late Thursday afternoon / early evening, moving NE-wards offshore. Forecast profiles suggest convection may be a little stunted in depth somewhat, so questionable as to how much (if any) lightning activity there will be.

 

On Thursday night, a mid-level dry intrusion atop very moist low-level air may encourage some mid-level instability release as showery outbreaks of rain develop along a pre-frontal trough, primarily from the Irish Sea across Cumbria / NE England and perhaps S Scotland. Skinny CAPE profiles and somewhat limited depth of convection suggests any lightning activity should be fairly isolated.

 

http://www.convectiveweather.co.uk/forecast.php?date=2018-08-02

[Ben Sainsbury]

Looks like a possible plume event indicated by NMM & GFS for Tuesday into Wednesday, one to keep an eye on.

[Summer Sun]

Day 1 Convective Outlook

VALID 06:00 UTC Fri 03 Aug 2018 - 05:59 UTC Sat 04 Aug 2018

ISSUED 05:10 UTC Fri 03 Aug 2018

ISSUED BY: Dan

An embedded shortwave within the strong upper flow across the British Isles will track across northern England / southern Scotland on Friday morning, inducing a wave along the trailing cold front. This forced ascent may result in mid-level instability release, with the chance for some sporadic lightning - perhaps most likely near the coast of NE England and then points offshore. Some reasonable speed shear will exist to enable cells to become somewhat organised. Confidence on lightning coverage is not particularly high, so will refrain from issuing a SLGT for now.

 

Profiles by the afternoon become more capped to surface-based convection as upper ridging builds in the wake of the earlier shortwave - though still sufficiently deep to allow a few heavy showers to develop over northern England and / or southern Scotland.

The main exception is eastern Scotland where profiles look more favourable for deeper convection for a longer period of time, perhaps overlapping with daytime heating. A surface low will also form in the area during the afternoon hours, with low-level convergence and orographic forcing aiding in the development of scattered heavy showers, some capable of producing sporadic lightning. Some uncertainty over how much lightning activity there will be given gradual subsidence developing aloft, but weak, converging surface flow may allow a few funnel clouds to form.

 

http://www.convectiveweather.co.uk/forecast.php?date=2018-08-03

[Nick F]

Don't be fooled by the GFS showing CAPE across a lot of the  UK today, England and Wales mostly capped by anticyclonic circulation towards south, though cold front moving down across N England expected to develop some heavier pulses that may bring the odd rumble of thunder. Greatest risk for thunder across eastern Scotland from heavy showers developing here in post-frontal airmass. 

Storm & Convective Forecast

Issued 2018-08-03 08:08:56
Valid: 03/08/2018 00z - 04/08/2018 00z

THUNDERSTORM OUTLOOK - FRIDAY 3RD JULY 2018

Synopsis

A broad scale upper trough / Vortex covers Greenland, Iceland and much of the far North Atlantic, the upper flow will be cyclonic SWly across northern Britain, anticyclonic across southern Britain. A weakening cold front will slide slowly SE across England and Wales - an unstable airmass will follow cold front across Scotland and northern England, supporting heavy showers and a few thunderstorms. 

... SCOTLAND and N ENGLAND...

Cold front moving SE will bring a narrow band of rainfall slowly down across northern England through the day. Although fragmented and light rainfall at the moment, models indicate pulses of heavy rainfall developing along the front, likely in response to upper shortwave ejecting NE ahead of upper trough to the NW of UK inducing subtle waves along the front and thus enhancing lift of humid air ahead/along front. Some of the heavier burst of rainfall will be convectively-driven and updrafts maybe robust enough for isolated lightning, pusles of heavy convective rainfall may lead to some localised flooding. 

To the north of the cold front, airmass will be unstable to surface heating, more especially so across southern and eastern Scotland along with the far north of England - where greatest residual moisture is likely to pool along likely breeze convergence zones overlapped by cooling air aloft of upper trough to the NW creating steep lapse rates. So sunny spells will likely yield anywhere in the region of 300-700 j/kg CAPE, which will support development of heavy showers or thunderstorms during peak heating. Vertical shear will be fairly weak, so storms will tend to be short-lived pulse-type, the instability may be sufficient for hail along with gusty winds. A few funnel clouds can't be ruled out with stronger updrafts in storms that form along along the convergence zones. Storms will tend to clear out into the North Sea in the evening.

Issued by: Nick Finnis

Edited August 3, 2018 by Nick F

[Chris.R]

 Wow it seems the cold front has electrified.  Didn’t think that was going to happen. I have now looked at the charts and see there is a bit of potential really did not think anything was going on for a few days yet.  Will teach me not to take my eye off the ball. 

Edited August 3, 2018 by Chris.R

[Mokidugway]

23 minutes ago, Chris.R said:

 Wow it seems the cold front has electrified.  Didn’t think that was going to happen. I have now looked at the charts and see there is a bit of potential really did not think anything was going on for a few days yet.  Will teach me not to take my eye off the ball. 

I can hear distant thunder direct hit by looks of it 

[Chris.R]

11 minutes ago, Mokidugway said:

I can hear distant thunder direct hit by looks of it 

 Yep well done. Looks like I’m going to be too far south. 

Edited August 3, 2018 by Chris.R

[sunnijim]

Interesting UKMO fax chart for Tuesday lunchtime.

Unstable and baking hot air flow over SE England and a feature shown in that flow which could set off some bangers and crackers?

[Gray-Wolf]

Wow! that was close/loud! Shotgun lightning to the west of Hebden bridge out of that little streamer of cloud currently flowing over us!

Saw the flash and was thinking " Nah" when the windows/doors were rattled by the thunder ( then the car alarms set off!).

[Mokidugway]

Just now, Chris.R said:

 Well done. Looks like I’m going to be too far south. 

Conditions changed from drizzle to storm almost instant, temperature also climbed  by 3 c  in heavy rain !

[Ben Sainsbury]

On 02/08/2018 at 11:24, Ben Sainsbury said:

Looks like a possible plume event indicated by NMM & GFS for Tuesday into Wednesday, one to keep an eye on.

Never mind, the models looking a lot more progressive now and thundery breakdown looks unlikely.

[LightningLover]

31 minutes ago, sunnijim said:

Interesting UKMO fax chart for Tuesday lunchtime.

Unstable and baking hot air flow over SE England and a feature shown in that flow which could set off some bangers and crackers?

Hastings will most likely miss out again... lol

[Chris.R]

 Closest sferic of the day, 25 miles, but it’s to my north-east. Haha always happens. 

[Stozzy]

Few flashes and rumbles here 

[Chris.R]

50 minutes ago, Ben Sainsbury said:

Never mind, the models looking a lot more progressive now and thundery breakdown looks unlikely.

 Oh well. At least we are under a trough then there will hopefully be some chances for polar-maritime thundery days like last Saturday. I do well from them around here anyway and plumes don’t seem to deliver any more. 

[Another Kent clipper]

7 minutes ago, Chris.R said:

 Oh well. At least we are under a trough then there will hopefully be some chances for polar-maritime thundery days like last Saturday. I do well from them around here anyway and plumes don’t seem to deliver any more. 

Agreed, in my experience of being in Manchester over the last seven years, the Aprils and Septembers seem to yield more results.  And by more I mean more than nothing!

 

Radarwise right now, I'm interested in this little spec:  Edit: it's now disappeared. How embarrassing

 

Edited August 3, 2018 by Another Kent clipper
Grammar

[Mokidugway]

All over now was a few rumbles but nothing interesting, long gone are the days of air mass storms ,plumes and morning wallclouds approaching  from  the south

[Chris.R]

Looks like a small window  of opportunity  this afternoon for surface based airmass storms, although I think I’m probably out of  the game due to the wind direction. I would need something to develop over the sea. We have a yellow warning out now. 

[Eskimo]

Not sure where these storms are going to come from within the warning area.