Uk Convective General Discussion & Forecasts, 12th to 14th August 2012

[AWD]

Somewhere has got a moderate (MDT) from ukasf for tomorrow with an interesting forecast. However, i cannot see the map so don't know where the MDT is for.

I can't see the map either for some reason, but here is the text forecast.

Synopsis:

A surface low approaches from the Atlantic, beneath a broad extension of an upper trough. A plume of high ThetaE is advected northwards ahead of an eastward-moving cold front.

Discussion:Scattered showers and thunderstorms are forecast behind the eastward-moving cold front as 500-600J/kg CAPE develops in response to diurnal heating.

>20kts LLS and 30kts DLS will allow convection to become organised, with the potential for a tornado, especially (but not exclusively) over Ireland during the morning hours with up to 35kts LLS. There is also potential for low-topped supercells, again more likely over Ireland in the morning/early afternoon with sufficient helicity.

Hail up to 1.5cm in diameter is possible in stronger cores.

MDT areas have been chosen for regions of greatest CAPE and best shear, leading to most widespread coverage of sferics.

Along the cold front, embedded convection is also possible on the back-edge along the ThetaE axis

Going by that, I would hazard a guess that it would be Ireland.

[NorthYorksWeather]

Somewhere has got a moderate (MDT) from ukasf for tomorrow with an interesting forecast. However, i cannot see the map so don't know where the MDT is for.

Cant seem to save the map but central Ireland have moderate and central and western England have moderate. You are in moderate

[Supacell]

Cant seem to save the map but central Ireland have moderate and central and western England have moderate. You are in moderate

Thank you for that Vizzy. I had a feeling tomorrow may deliver after i saw this chart on lightning wizard:

[AWD]

I hadn't taken much notice in tomorrow as I wasn't expecting anything, and neither have my local BBC/Meto forecasts, but looking at the below charts, the South West and Wales look to have some decent ingredients there!

GFS has the above, but a but further North affecting the North West rather than the South West.

NAE has PPN over much of the Western Side of the Country

Something thats going to make me have a closer interest in tomorrow now for sure. I await some of the forecasts from our more knowledgable members!

[NorthYorksWeather]

Thank you for that Vizzy. I had a feeling tomorrow may deliver after i saw this chart on lightning wizard:

Yes you could get lucky, may have to take a trip up towards your end tomorrow afternoon

[I Cumbria Marra I]

OMG some of the heaviest rain i've ever seen falling over the last 10 minutes. amazing

[Cloud 10]

OMG some of the heaviest rain i've ever seen falling over the last 10 minutes. amazing

Had a brief heavy downpour here a short while ago which signals the end of this mini dry spell.

[Lynxus]

Morning.

And WOW!!! Check out Ireland this morning

Edited August 13, 2012 by Lynxus

[Supacell]

I had just noticed that myself Lynxus. Imagine waking up under that!!!

[Lynxus]

I had just noticed that myself Lynxus. Imagine waking up under that!!!

Would be awesome seeing that heading for me on the radar! Never know.. Wednesday may deliver. ( Unlikely ) but can only dream ehhe.

N-W hopepage has thunder for gloucester this afternoon. But it has had thunder day after day before and nothing but sunshine lol

Very convective.,., A lot of activity has been north this year.

Edited August 13, 2012 by Lynxus

[Nick F]

Storm forecast for today: http://www.netweather.tv/index.cgi?action=convective;sess=

I see it's going/gone bang across central Ireland this morning!

[Coast]

Nothing from ESTOFEX again for today (Euro holidays?) so here's UKASF:

Forecaster: Dan

Last Updated: 2012-08-13 06:40:00

Valid: 2012-08-13 00:00:00 - 2012-08-13 23:59:00

Synopsis:

A surface low approaches from the Atlantic, beneath a broad extension of an upper trough. A plume of high ThetaE is advected northwards ahead of an eastward-moving cold front.

Discussion:

Scattered showers and thunderstorms are forecast behind the eastward-moving cold front as 500-600J/kg CAPE develops in response to diurnal heating. >20kts LLS and 30kts DLS will allow convection to become organised, with the potential for a tornado, especially (but not exclusively) over Ireland during the morning hours with up to 35kts LLS. There is also potential for low-topped supercells, again more likely over Ireland in the morning/early afternoon with sufficient helicity.

Hail up to 1.5cm in diameter is possible in stronger cores.

MDT areas have been chosen for regions of greatest CAPE and best shear, leading to most widespread coverage of sferics. Along the cold front, embedded convection is also possible on the back-edge along the ThetaE axis.

Some of the relevant charts for today are looking like this:

Ireland and Western England getting the bulk of the MLCAPE:

Shear and convergence ahead of that in the Midlands and further North:

SBCAPE also to the West generally

Check out the higher level lapse rates in the SW!

Here's the flow:

Quite a large area to the West in a potential tornado/funnel/spout zone:

Looks like the NW is the place to be later today:

[Matty23]

So today is defo a day for radar watching???

[Lynxus]

So today is defo a day for radar watching???

Yeah worth keeping an eye on.

Could you add your location to your profile? ( Certainly helps knowing where you are to tailor replies )

[Matty23]

How do u change it as on my fone??

[Methuselah]

Click on your name, top right, and go into 'Edit Profile'...

[Matty23]

Done and cheers

[Supacell]

Rapid decline in sferics across Ireland after this earliers rash of them. GFS storm risk forecast going for a storm risk at 1am here, are we expecting something overnight?

[Coast]

GFS storm risk forecast going for a storm risk at 1am here, are we expecting something overnight?

Possibly......

A few chances coming up in the next few days:

Wednesday standing out for the South East currently, but be prepared for change as we approach it!

Next weekend across the country is also worth keeping an eye on.

[legritter]

Morning gang.

A line of rain now showing up to my far West and South-west, not sure what to make of that clear break showing over the sea. Perhaps its breaking up there or radar coverage is not covering that area. Looks like this band could develop as it runs N/east and East. Just going by this mornings update plenty of chances for some. Wednesday still posing some question marks about which areas will be affected by any severe weather, but certainly a spell of good action for some. There is also a worrying factor if this system stalls a little, resulting rainfall totals could be pretty high and with all that energy around till Friday we could again see some very good storm chances.

PS something is brewing across Quantock/Exmoor area right now, very dark clouds slowing down, also gone calm,

[legritter]

just a quick update ,now raining moderate and steady ,sky grey and more milky looking .does look like a very developing system as it pushes east and n/east . could also be interesting later today as the sun comes back out .cheers

[Supacell]

GFS is showing, and has been showing for a few runs, CAPE of around 300-500jkg this afternoon across western areas (which is moderate) but then a LI of -5 which i would normally associate with much higher CAPE values. What would this equate to with regards to the likelihood of storms?

[AWD]

Heavy shower here now, nought thundery about it though.

[Coast]

Muggy as hell out there and dewpoints are up around the late 15's °C. I'd love this to break down in to a storm but it isn't on the cards here.

http://www.netweathe...rrent;type=maxd

[A.J]

Nice thunderstorm near the Channel Isles...it's headed for the south coast somewhere in the area of Bournemouth to Southampton, worth keeping an eye on for folks on the south coast in the next couple of hours