Storm risk - Monday 9th May onwards

[Harry]

Ukcw forecast out;

Day 2 Convective Outlook

VALID 06:00 UTC Mon 09 May 2016 - 05:59 UTC Tue 10 May 2016 

ISSUED 20:39 UTC Sun 08 May 2016

ISSUED BY: Dan

Large cut-off low will be located west of Iberia, providing a feed of of high WBPT air around its northern and eastern flanks across central/southern Britain. Assuming enough insolation occurs (questionable cloud cover) then pre-frontal troughing will be the main focus for deep convection, associated with a zone of low-level wind convergence providing the necessary forcing. Have issued a low-end SLGT to highlight areas of greatest interest, but even here it is uncertain as to how much lightning activity may actually materialise. High-res models also suggest a cluster of active thunderstorms moving N-wards from Brest peninsula towards the Channel Islands late Monday afternoon/early evening, hence the inclusion of a SLGT here. 

Showers/thunderstorms that do occur will move generally towards the WNW along this boundary. DLS is rather weak, and therefore limiting the overall severe risk, with the main threat being from minor surface water issues given potential for shower training over similar areas, especially farther west (i.e. towards Wales and Ireland).

[William Grimsley]

14 minutes ago, Harry said:

Ukcw forecast out;

Day 2 Convective Outlook

VALID 06:00 UTC Mon 09 May 2016 - 05:59 UTC Tue 10 May 2016 

ISSUED 20:39 UTC Sun 08 May 2016

ISSUED BY: Dan

Large cut-off low will be located west of Iberia, providing a feed of of high WBPT air around its northern and eastern flanks across central/southern Britain. Assuming enough insolation occurs (questionable cloud cover) then pre-frontal troughing will be the main focus for deep convection, associated with a zone of low-level wind convergence providing the necessary forcing. Have issued a low-end SLGT to highlight areas of greatest interest, but even here it is uncertain as to how much lightning activity may actually materialise. High-res models also suggest a cluster of active thunderstorms moving N-wards from Brest peninsula towards the Channel Islands late Monday afternoon/early evening, hence the inclusion of a SLGT here. 

Showers/thunderstorms that do occur will move generally towards the WNW along this boundary. DLS is rather weak, and therefore limiting the overall severe risk, with the main threat being from minor surface water issues given potential for shower training over similar areas, especially farther west (i.e. towards Wales and Ireland).

That looks good. We may see some nice sheet lightning to the south tomorrow night then, I wonder if those thunderstorms will make it across?

[Mapantz]

I'm sure that shape looks familiar, just can't put my finger on it..

[Allseasons-Si]

1 minute ago, Mapantz said:

I'm sure that shape looks familiar, just can't put my finger on it..

gods finger

[Allseasons-Si]

26 minutes ago, Mapantz said:

I'm sure that shape looks familiar, just can't put my finger on it..

i hope that risk tranfers further north this week.

Edited May 8, 2016 by Allseasons-si

[Harry]

On my walk to the station and skies looking distinctly thundery to my south. Dark complexion, hints of aspiratus undulatus together with bands of Ac (some of which is AcCas). You will all know the sort of sky I'm talking about. 

Touch more humidity in the air today too 

[NO LONGER POSTING]

9 minutes ago, Harry said:

On my walk to the station and skies looking distinctly thundery to my south. Dark complexion, hints of aspiratus undulatus together with bands of Ac (some of which is AcCas). You will all know the sort of sky I'm talking about. 

Touch more humidity in the air today too 

Certainly a more "thundry feel" to the weather today

 

Does look okay(ish) for the South later today and more so over night and into tomorrow.. I expect Estofax will have a report out soon  

 

 

Edited May 9, 2016 by Surrey

[Ben Sainsbury]

The BBC said; "By the afternoon, the rain will turn heavier with the odd rumble of thunder possible, particularly over the higher ground" I'm not sure how this works? Considered orographic lifting, but the SW isn't exactly know for it's "huge mountains" even though there are a few larger hills?

[Harry]

Not entirely sure I follow that either Ben...sounds like the presenter muddled their words a little lol.

 

Edited May 9, 2016 by Harry

[MattTarrant]

It is said on the Met office summary aswell 

[William Grimsley]

Yes, that is strange, probably incorrect. Anyway, I woke up to thunder being mentioned on the local weather forecast for today which was a nice surprise. Quite a thundery looking sky this morning with a rainbow off to the west of here. The Met Office are forecasting a 3 hour thunderstorm for me tomorrow afternoon. Get in.

Edited May 9, 2016 by William Grimsley

[alexisj9]

50 minutes ago, Ben Sainsbury said:

The BBC said; "By the afternoon, the rain will turn heavier with the odd rumble of thunder possible, particularly over the higher ground" I'm not sure how this works? Considered orographic lifting, but the SW isn't exactly know for it's "huge mountains" even though there are a few larger hills?

Sometimes that's all it takes, guess we'll see later. 

[knocker]

Wales possible hotspot?

[Dami]

10 hours ago, Mapantz said:

I'm sure that shape looks familiar, just can't put my finger on it..

That pic is one eye short of a troll face, just came from the school run and it looks very stormy to my south.

[Mapantz]

19 minutes ago, Dami said:

That pic is one eye short of a troll face, just came from the school run and it looks very stormy to my south.

The clouds look ominous here too, but there's a little bit of sunshine. 

[Harry]

Sun out in force in London at the moment 

[Nick F]

Bit of an uncertain day to forecast storms for me, given cloud spilling up from south and CINH north of the Midlands, but surface convergence, some sunshine and a shortwave moving north out of France later could trigger some storms across central and southern England along with Wales. Also some storms likely to develop over EIRE again today.

My Full forecast here: http://www.netweather.tv/index.cgi?action=convective;sess=

Edited May 9, 2016 by Nick F

[Azazel]

very muggy here this morning and the "smell" of thunder in the air

[MP-R]

1 hour ago, Ben Sainsbury said:

The BBC said; "By the afternoon, the rain will turn heavier with the odd rumble of thunder possible, particularly over the higher ground" I'm not sure how this works? Considered orographic lifting, but the SW isn't exactly know for it's "huge mountains" even though there are a few larger hills?

Obviously mixing up thunder and snow risk 

[NO LONGER POSTING]

Sun out here too and some lengthy cloud breaks and thinning of cloud on Sat especially for the south East 

[Ben Sainsbury]

Again 20'c over a few areas already along the Western areas and parts of Central areas, got a feeling if the sun breaks, this could be another day of underestimated temperatures. Dewpoints looking decent too touching 13-14'c in parts of the SE.

Edited May 9, 2016 by Ben Sainsbury

[MattTarrant]

Temperatures here peaked at 22'c yesterday at like 10:30 yesterday and then slowly decreased after that.

The rain is already starting to develop across northern France

[Ben Sainsbury]

11 minutes ago, MattTarrant said:

Temperatures here peaked at 22'c yesterday at like 10:30 yesterday and then slowly decreased after that.

The rain is already starting to develop across northern France

On top of what Matt said, this is where we could see developments begin as we see breaks into the cloud ahead of this band?

[Chris K]

2 hours ago, Ben Sainsbury said:

The BBC said; "By the afternoon, the rain will turn heavier with the odd rumble of thunder possible, particularly over the higher ground" I'm not sure how this works? Considered orographic lifting, but the SW isn't exactly know for it's "huge mountains" even though there are a few larger hills?

You don't need huge mountains - just think for example the height difference between sea level and the moors of Exmoor/Dartmoor etc. This could be enough to force warm, moist air to rise and therefore if sufficient forcing takes place, showers and possibly storms can develop (My assumption is these would mainly be surface-based...???) Obviously other factors will affect the overall risk too.

Edited May 9, 2016 by Chris K

[Flash bang flash bang etc]

Where does one find maps pertaining to wind convergence areas?