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Convective/Storm Discussion Thread - 1st August onwards


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Posted
  • Location: Mynydd - Isa , Nr Mold - North Wales
  • Weather Preferences: Foggy autumn days are the best! Although I does enjoy a good thunderstorm.
  • Location: Mynydd - Isa , Nr Mold - North Wales

Good afternoon all :)
Well, I don't know about others, but I for one have had enough of this winter now, I've had my cold and snow fix, and I'm starting to feel really quite storm starved.
So I thought I'd have a quick look at the Cape and LI charts to see if there is anything of interest showing on the horizon.
The 00z run from the GFS is showing this for Thursday afternoon! :D
Don't get me wrong, I'm not building my hopes up for this to produce a supercell, or even any thunder and lightning, but hey, its a start for very early in the season. :pardon:
As always, good luck to everyone in here, and lets hope that 2018 is a good and convective one for all of us. :friends::bomb:

Screenshot (1).png

Edited by Dangerous55019
Dyslexic fingers
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5 hours ago, Dangerous55019 said:

Good afternoon all :)
Well, I don't know about others, but I for one have had enough of this winter now, I've had my cold and snow fix, and I'm starting to feel really quite storm starved.
So I thought I'd have a quick look at the Cape and LI charts to see if there is anything of interest showing on the horizon.
The 00z run from the GFS is showing this for Thursday afternoon! :D
Don't get me wrong, I'm not building my hopes up for this to produce a supercell, or even any thunder and lightning, but hey, its a start for very early in the season. :pardon:
As always, good luck to everyone in here, and lets hope that 2018 is a good and convective one for all of us. :friends::bomb:

Screenshot (1).png

Can only hope after the none event winter in  my locale .

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Posted
  • Location: NW Bexley, Kent
  • Weather Preferences: Storms, rain, tornados, funnel clouds and the northern lights
  • Location: NW Bexley, Kent

Looking increasingly stormy this afternoon. Spotted this beauty of a cell to my north at 5.30pm (loads of other towers and cauliflower heads around in most directions). Doubt it'll amount to anything but nice to see all the same this early in the season.:)

20180327_173326.thumb.jpg.9006fd269b868bc013c3c9152f94d122.jpg

20180327_173331.thumb.jpg.0297354561ddca2f2aada55e655a8ebf.jpg

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Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

Day 2 Convective Outlook

VALID 06:00 UTC Wed 28 Mar 2018 - 05:59 UTC Thu 29 Mar 2018

ISSUED 20:51 UTC Tue 27 Mar 2018

ISSUED BY: Dan

Behind a frontal wave/low sliding eastwards across southern Britain on Wednesday morning, lapse rates will steepen with the approach of an upper trough from the west. In the wake of earlier rain, several showers are expected to develop during the afternoon, but with rather saturated profiles and skinny CAPE the lightning potential is considered fairly low.

 
Perhaps a greater chance of lightning will be over the Celtic Sea during the early hours of Thursday as heights fall from the west, cold air aloft then steepening lapse rates and generating a few hundred J/kg CAPE in response to SSTs. Given various forecast parameters, have issued a low-end SLGT for late Wednesday night - though some complications from what seemingly begins as deep convection eventually manifests itself into more of a frontal feature due to increasing baroclinicity by Thursday morning. Confidence is not particularly high for this SLGT, and trends will be monitored to remove it if necessary.
 
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Posted
  • Location: London
  • Weather Preferences: Hot
  • Location: London
20 hours ago, Windblade said:

Looking increasingly stormy this afternoon. Spotted this beauty of a cell to my north at 5.30pm (loads of other towers and cauliflower heads around in most directions). Doubt it'll amount to anything but nice to see all the same this early in the season.:)

20180327_173326.thumb.jpg.9006fd269b868bc013c3c9152f94d122.jpg

20180327_173331.thumb.jpg.0297354561ddca2f2aada55e655a8ebf.jpg

I'm liking the multicoloured houses.  

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Posted
  • Location: cleethorpes
  • Location: cleethorpes

Had hailstorm here not too large in diameter 3 to 4 mm sized hail.  Saw a beautiful cloud looked to have frontage rotation as it was turned inside itself was windy as it passed.  I would assume updraft.  Roughly about 4 pm although don't exact time must been good to see on radar.

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Posted
  • Location: Dorset
  • Weather Preferences: warehamwx.co.uk
  • Location: Dorset

 

 

Day 2 Convective Outlook: Thu 29 Mar 2018    
largethumb.php?date=2018-03-29

VALID 06:00 UTC Thu 29 Mar 2018 - 05:59 UTC Fri 30 Mar 2018

ISSUED 21:28 UTC Wed 28 Mar 2018

ISSUED BY: Dan

Upper low centred west of Ireland will drift slowly SE-wards to be over the Celtic Sea by Thursday night. Associated cold pool will result in steep mid-level lapse rates, which combined with SSTs and diurnal heating inland should generate 300-500 J/kg CAPE. The forecast is complicated somewhat by early deep convection over SW England / Celtic Sea / southern Ireland morphing into a more general band of showery rain as a result of increasing baroclinicity, this zone of showery rain (depicted as an occlusion) then pivoting gradually northwards and eastwards with time. 

 
Ahead of this occlusion, some marginal instability may develop as a result of diurnal heating and thermal trough aloft, with scattered showers possible from late morning onwards over East Anglia / north Midlands / northern England before the showery rain arrives from the southwest later in the day. Some isolated lightning activity may be possible from these heavy showers.
 
Behind the occlusion, an uptick of instability is expected and here the better chance of some sporadic lightning is more likely. However, any such convection will be rather disorganised given a lack of any notable shear, and mainly forced by areas of low-level convergence - such as the north Devon / Somerset coast into south Wales, and close to the surface low centre over S/SW Ireland. Hesitant to issue SLGTs given the uncertainty, not least with how quickly the occlusion will lift north to allow sunshine to return to the W Country, for example - but have issued 2 low-end SLGTs for now to highlight areas with the best overall potential for some sporadic lightning activity.
The strongest cells will be capable of producing some hail up to 1.0cm in diameter, and perhaps a weak tornado.
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Posted
  • Location: NW Bexley, Kent
  • Weather Preferences: Storms, rain, tornados, funnel clouds and the northern lights
  • Location: NW Bexley, Kent

With us still feeling the effects of the ssw I wonder if we will get our annual April showers/storms this year? Every year I look forward to this event as it marks the start of the storm season but with all this talk of more cold coming up and possibly lasting til mid April/May I wonder if we will not get our April showers this year and what this means for the storm season moving forward?

Edited by Windblade
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Posted
  • Location: Mynydd - Isa , Nr Mold - North Wales
  • Weather Preferences: Foggy autumn days are the best! Although I does enjoy a good thunderstorm.
  • Location: Mynydd - Isa , Nr Mold - North Wales
20 minutes ago, Windblade said:

With us still feeling the effects of the ssw I wonder if we will get our annual April showers/storms this year? Every year I look forward to this event as it marks the start of the storm season but with all this talk of more cold coming up and possibly lasting til mid April/May I wonder if we will not get our April showers this year and what this means for the storm season moving forward?

Morning @Windblade :)

I’m thinking exactly the same. But trying to look on the positive side, the sun is now that much higher in the sky, and I’m hoping that this coupled up with the instability could give us an impressive start to the storm season. :bomb::D

As always, only time will tell, but it’s good to see convective outlooks already being issued.

Here’s hoping. :good:

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Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
1 hour ago, Windblade said:

With us still feeling the effects of the ssw I wonder if we will get our annual April showers/storms this year? Every year I look forward to this event as it marks the start of the storm season but with all this talk of more cold coming up and possibly lasting til mid April/May I wonder if we will not get our April showers this year and what this means for the storm season moving forward?

Well, normally the classic April Showers involves cold air aloft, like today, creating steep lapse rates, with a moist maritime flow warmed in the sun to build the shower clouds, so some cold air around is not a bad thing, as the sun's energy will create steep lapse rates and support showers, so long as there is some moisture around, which is not an issue normally in our maritime climate.

Anyway, have issued a convective / storm forecast for today, for showers, perhaps with hail and thunder locally, becoming more widespread through the day, as the sun warms the surface up beneath cold air aloft. Should hopefully be some good photogenic convective cloudscapes today and again tomorrow and Saturday.

https://www.netweather.tv/weather-forecasts/uk/convective

Storm & Convective Forecast

convmap_290318.thumb.png.2c1779bf176bac73c8bd8bc0bf4e1afc.png

Issued 2018-03-29 07:21:52
Valid: 29/03/2018 6AM TO 30/03/2018 6AM

CONVECTIVE / STORM FORECAST - DAY 1 (THURS 29TH MARCH)

Synopsis

Upper low / cold pool orginiating from southern Greenland will drop SE over the far N Atlantic to be centred just west of Ireland Thursday afternoon. Surface low pressure system with multiple centres to west of Ireland will over spread western UK with an unstable S to SEly flow covering Ireland, N. Ireland, England and Wales.

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

Increasingly cold mid-level air spreading out from upper cold pool moving in across the far west, AOB -35C at 500mb across Ireland, will create steep lapse rates across UK and Ireland, steepest towards the west. This will create an unstable atmosphere, increased by surface heating in sunny spells, which will support development of heavy showers containing hail and occasiotnal thunder locally from late morning. A shortwave trough rotating NE ahead of the upper low to the west will likely bring an organised area of heavy showers and few thunderstorms NE across Ireland, England and Wales through the afternoon, which may bring an enhanced risk of localised flooding, the risk increased by recent heavy rainfall saturating the ground in some southern areas. Risk of stronger convection with risk of thunder and heavy rainfall should subside after dark as surface heating fades.

Issued by: Nick Finnis

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Posted
  • Location: King’s Lynn, Norfolk.
  • Weather Preferences: Hot and Thundery, Cold and Snowy
  • Location: King’s Lynn, Norfolk.
1 hour ago, Windblade said:

With us still feeling the effects of the ssw I wonder if we will get our annual April showers/storms this year? Every year I look forward to this event as it marks the start of the storm season but with all this talk of more cold coming up and possibly lasting til mid April/May I wonder if we will not get our April showers this year and what this means for the storm season moving forward?

Feels good to be coming out of hibernation ready for storm season! 

I personally don't think it will make much of a difference. 2013 saw a similar theme, and despite a low quantity of storms, they were worth the wait, truly spectacular in places. As for April showers, it all depends on the pattern setup. The best scenario for April showers is a PM westerly, or even better if you like a PM southwesterly, with the cold sourced Atlantic air flowing around the low, met by diurnal heating in the strengthening sun. 

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Posted
  • Location: Mynydd - Isa , Nr Mold - North Wales
  • Weather Preferences: Foggy autumn days are the best! Although I does enjoy a good thunderstorm.
  • Location: Mynydd - Isa , Nr Mold - North Wales

Although a long way from me, I see that there have been a few lightning strikes around the Surrey area. :)

F7173219-14BE-45B6-80D2-918E6068BD4E.png

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Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

Day 2 Convective Outlook

VALID 06:00 UTC Fri 30 Mar 2018 - 05:59 UTC Sat 31 Mar 2018

ISSUED 19:27 UTC Thu 29 Mar 2018

ISSUED BY: Dan

Broad upper trough covers northwest Europe on Friday, with the upper low centre drifting from the Celtic Sea to the English Channel. Various features will be rotating around a multi-centred surface low over Biscay/northern France, adding complications between areas of convective potential vs bands of more dynamic precipitation. 

Given differences over timing and position of these features between various model guidance, it becomes difficult to pinpoint areas most favourable for lightning activity - in either case, it is not expected to be widespread, and generally rather isolated/sporadic given marginal instability.
 
In a general sense away from areas of showery rain, sufficient insolation and steep mid-level lapse rates will help generate a few hundred J/kg CAPE, capable of producing scattered showers - some perhaps weakly-electrified. Reluctant to issue a SLGT for previously mentioned reasons, but have included a low-end SLGT for parts of C + E Ireland where one or two isolated thunderstorms could occur during the afternoon, and perhaps another area of focus could be the Midlands towards Glocs/SE Wales - but very much dependent on the position and timing of the front approaching from the south. Some small hail will be possible with the strongest cells.
 
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Posted
  • Location: NW LONDON
  • Weather Preferences: Sun, sleet, Snow
  • Location: NW LONDON

had thunder lightning and hail, was a surprise

Edited by lassie23
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Posted
  • Location: South Devon
  • Location: South Devon

Checking in on a local FB group and there are reports of a possible tornado in the Follaton/Totnes area yesterday afternoon. I wonder if it was picked up elsewhere? Could also have been a downburst I guess, either way the garden furniture will be off for a walk :D

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Posted
  • Location: Bexhill-on-sea, East Sussex (11.8M ASL)
  • Weather Preferences: Thunderstorms, snow, and wind storms
  • Location: Bexhill-on-sea, East Sussex (11.8M ASL)

Missed this last night :( apparently there was a rumble of thunder from this:

4A22AC76-D5AF-452F-AABF-10061875FC11.jpeg

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Posted
  • Location: St Leonards-on-Sea, East Sussex. 81 metres asl
  • Weather Preferences: Thunderstorms.
  • Location: St Leonards-on-Sea, East Sussex. 81 metres asl
41 minutes ago, LightningLover said:

Missed this last night :( apparently there was a rumble of thunder from this:

4A22AC76-D5AF-452F-AABF-10061875FC11.jpeg

There were some pretty potent showers drifting up from the Channel last night producing some heavy downpours in our area. I didn't hear any thunder though , the nearest lightning strikes at the time were apparently near Heathrow and in north west London.

So far today it's just cold, wet and windy here, making it a miserable start to the Bank Holiday.

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Posted
  • Location: NW LONDON
  • Weather Preferences: Sun, sleet, Snow
  • Location: NW LONDON
1 hour ago, SenlacJack said:

There were some pretty potent showers drifting up from the Channel last night producing some heavy downpours in our area. I didn't hear any thunder though , the nearest lightning strikes at the time were apparently near Heathrow and in north west London.

So far today it's just cold, wet and windy here, making it a miserable start to the Bank Holiday.

Yes I was under one of those potent showers, there was lightning, thunder and hail here.

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Posted
  • Location: St Leonards-on-Sea, East Sussex. 81 metres asl
  • Weather Preferences: Thunderstorms.
  • Location: St Leonards-on-Sea, East Sussex. 81 metres asl
3 hours ago, lassie23 said:

Yes I was under one of those potent showers, there was lightning, thunder and hail here.

Yes I saw your post about that in the regionals Lassie. Given the torrential downpours here around the same sort of time I was hoping we might be in luck as well but it wasn't to be.

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