Convective / Storm Risk Discussion - 21st June 2013 onwards

[VillagePlank]

Don't forget, the instability doesn't really reach our shores until much later on,

 

 

So not really expecting anything to survive the channel, nor be home grown until then.

Edited June 18, 2013 by Sparkicle

[Thundery wintry showers]

You know I don't really care if I get a direct hit here locally as photogenic wise its easier to watch a storm spitting out strobe lightning and anvil forks a hundred or so miles away, it can be just as fun.

Indeed, I remember feeling that way sometimes when I was down in Norwich- I had some good experiences of standing on the hill at the UEA campus with thunder and lightning displays passing by several miles to the west or south, and getting some good lightning captures on camera.  When the storm comes overhead it gets pretty exciting in other ways but then I have to run for cover!

 

I have to say that the outputs for North Yorkshire are hardly thrilling from a convection perspective- it's more likely to kick off in the south of England.

Edited June 18, 2013 by Thundery wintry showers

[Harry]

Don't forget, the instability doesn't really reach our shores until much later on,

 

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So not really expecting anything to survive the channel, nor be home grown until then.

 

That eastern shift clearly evident there over the past few days.

 

All we need now is a trigger to realise that potential, if indeed there is respective SB/MLCAPE in conjunction with the lifted indices.

[Neilsouth]

National Weather

Torrential downpours moving into south east england tonight/early hours, flashes of lightning....

Though going by how unreliable the beeb forecasts are, take it with a pinch of salt!

[Coast]

Just been for a wander and there is an eerie, muffled silence out there currently. Very humid and 'non weather freaks' at work are saying it will all end in a storm. Probably got a better idea than I have :winky:

[Harry]

Just been for a wander and there is an eerie, muffled silence out there currently. Very humid and 'non weather freaks' at work are saying it will all end in a storm. Probably got a better idea than I have

 

My partner text me earlier saying how muggy it is down in Sevenoaks. Quite a few people here have commented also on how close it is. Personally, I'm just not feeling like it's that bad at the moment.........like Coast, I think (and hope) they have a better idea than I!!!

 

Still little showing in France which would suggest imports of any description, indeed convection seems just as suppressed there by the cloud as it is here, perhaps why Estofex plumped only for a 15% zone there unlike yesterday. As I type actually, mugginess feels as if it has in fact jumped again (windows wide open here)

 

Edit - Hmmm just watched Nina Ridge's national forecast on the BBC website and she is certainly confident of some SE/EA activity tonight, although with that said there is quite a bit of evening sunshine to look forward to also which isnt on the cards at the moment (judging by the skies)

Edited June 18, 2013 by Harry

[Coast]

Edit - Hmmm just watched Nina Ridge's national forecast on the BBC website and she is certainly confident of some SE/EA activity tonight, although with that said there is quite a bit of evening sunshine to look forward to also which isnt on the cards at the moment (judging by the skies)

 

You can feel the background heat dissipating through the clouds like an electric blanket though, perhaps somewhere up there the little positives and negatives are starting to take shape and align themselves?

 

Still a mass of CB's over in France:

 

[Harry]

You can feel the background heat dissipating through the clouds like an electric blanket though, perhaps somewhere up there the little positives and negatives are starting to take shape and align themselves?

 

Still a mass of CB's over in France:

 

 

Hmm...might well be CBs popping up but certainly nothing of the electric variety showing up yet.

 

Running the satellite loop there is actually some pronounced breaks in the cloud forming over France, coinciding nicely with peak heating time of the day.........next 2-3 hours might be interesting down that way and will surely inform our chances for later.

Edited June 18, 2013 by Harry

[Coast]

Hmm...might well be CBs popping up but certainly nothing of the electric variety showing up yet.

 

From little acorns...... 

[Buzzit]

My Mr Fish pop quiz answer is no chance of anything exciting overnight. Is a big fail over most of France as well. Models struggling in the near term as expected.

 

[VillagePlank]

Here's the GooFuS 6z story ...

 

Firstly, theta-e includes both temperature and moisture, and if either of those rise, theta-e will rise with it, too; therefore, high theta-e values are nominally coincident with instability as it's a measure of how warm and how moist the air is. Consequent to this is that if the theta-e values higher up in the atmopshere are less than those lower down, lift will occur in the absence of a cap.

 

This is what's going on about now,

 

 

Here, you have the theta-e temperature at 850hPa, and 700hPa along with precipitation. If you look over SE Britain, you'll note the values are about the same, so you wouldn't expect much precipitation. However, on the western edge of this warm airmass, you can see that it isn't uniform, and in some places, the 700hPa theta-e value is less, thus lift will occur; the precipitation charts back that up.

 

Moving on the 18z today,

 

 

You can see that the 'plume' has now properly entered the SE quadrant. Notice the close theta-e lines around the middle of the country. The 45C line is 'resisting' the inward motion of the plume at 700hPa, so you get a difference with height. This means you'd expect lift to occur producing rainfall, which the precipitation charts go onto show. Note that since the pattern for Western France hasn't really changed, nor has the precipitation; it isn't moving North since the higher 700hPa theta-e's are effectively blocking it's progress. If we go onto look at midnights charts,

 

 

You can easily, now, see the 55C on the 850 chart and the 50C on the 700 chart. Lift is going to happen over the Southern North Sea, Dover Straits, E Kent, etc

 

Insolation/Surface heating is not required, so, one would expect, mechanical lift (the difference in theta-e's) will set things off. Problems for forecasting are where the differences over height occur. NAE has the whole thing about 100 miles West and is plum for E Sussex, W Kent, and London. GFS has the activity over the Dover Straits and North Sea.

 

Watching the radar should give a good guide to how close it's following the charts.

 

(I hope I've got that about right)

Edited June 18, 2013 by Sparkicle

[Coast]

NAE has the whole thing about 100 miles East and is plum for E Sussex, W Kent, and London. 

 

 

[VillagePlank]

Sorry, Coast, I meant "NAE has the whole thing about 100 miles West and is plum for E Sussex, W Kent, and London." I've edited my post, so your one now looks like you're lying!

Edited June 18, 2013 by Sparkicle

[Harry]

Couple of sparks in France recently

Sorry, Coast, I meant "NAE has the whole thing about 100 miles West and is plum for E Sussex, W Kent, and London." I've edited my post, so your one now looks like you're lying!

 

NAE in the short term is meant to be quite reasonable isnt it? Well, I suppose we'll find out within the coming hours

[Coast]

Sorry, Coast, I meant "NAE has the whole thing about 100 miles West and is plum for E Sussex, W Kent, and London." I've edited my post, so your one now looks like you're lying!

 

As long as my plums remain in Sussex, that will do for me!  

[VillagePlank]

Herstmonceaux sounding, vs GFS 6z Heathrow skew-t,

 

 

Looks pretty spot on to me.

Edited June 18, 2013 by Sparkicle

[Coast]

NW Forecast Skew T for 06z tomorrow slightly better, but not dramatic:

 

 

What lies between the hours though?

 

 

[VillagePlank]

BBC going for widespread thunderstorms in early hours - the video

 

http://www.bbc.co.uk/weather/me1

Edited June 18, 2013 by Sparkicle

[Neilsouth]

Sparkicle

Thankyou for a great read!

[PolarWarsaw]

BBC going for widespread thunderstorms in early hours - the video

 

http://www.bbc.co.uk/weather/me1

 

In the south east.*

[VillagePlank]

In the south east.*

 

Does anywhere else exist ?

[Harry]

That is my concern - was thinking about the potential in the last half hour or so and my inclination is for an E Kent/E Sussex/E Essex event, striking a median between the NAE output and the GFS.

 

Again hoping I'm very wrong and look forward to setting my alarm (again) for say 3am in case we do get lucky......oh no, Miranda moment coming on, cant stop myself.....I'm up all night to get lucky, I'm up all night to get lucky, we're up all night to get lucky.....

In the south east.*

 

His link is caveated to be fair with the ME1 postcode

Edited June 18, 2013 by Harry

[JK1]

Chance for West Sussex? I'm so desperate lol 2 false hopes so far

Edited June 18, 2013 by JK1

[VillagePlank]

Less hope the further West you are, I think. Waiting on the 12z's GFS, GEFS, to be honest, before I do a 'risk-map' Given that this looks, to me, like an airmass thunderstorm, exact locations are going to be exceptionally difficult to pin down anyway.

Edited June 18, 2013 by Sparkicle

[Harry]

Woof!!!! Latest MetO precip forecast will suit many I feel....

 

http://www.metoffice.gov.uk/public/weather/forecast/#?tab=map&map=Rainfall&fcTime=1371556800&zoom=5&lon=-4.00&lat=54.63

 

If this comes off will be happy for both me and many others in the SE quadrant.

 

Critically, if the attached link is fairly accurate it does not show initiation over France until around 10pm....so patience will be everything!!!!

Edited June 18, 2013 by Harry