Convective Discussion

[Harry]

Oooh...I do love my imports, though sadly on this occasion, appears nothing doing

I feel a video coming on...

Least we have some home grown potential, either on Thurs or as those charts above suggest, Friday also. Oh to be in Holland on Thursday though! Can't even get a sudden annual leave as I have a meeting thursday morning, boooo!!

[Paul Sherman]

Gonna be an interesting 4 days of fishing from Wed to Sunday on the Norfolk Broads, better pack me tripod, camera and Remote Cable

Paul S

[Coast]

Look at those lapse rates, just across the water!

It wouldn't be much to ask for that lot to be positioned more over the SE of the UK would it?

Friday afternoon into the evening currently looking best for us, according to the current GFS:

21st OWS don't have anything 'local' for Thursday yet, but look at the area coming in from the North Atlantic:

[Costa Del Fal]

GFS seems to place a fairly strong Cap over the next few days, particularly France etc.

[Harry]

GFS seems to place a fairly strong Cap over the next few days, particularly France etc.

With a cold front rattling in, and signs that a trough MAY develop, I'd of thought that is a good thing.

[NorthNorfolkWeather]

Gonna be an interesting 4 days of fishing from Wed to Sunday on the Norfolk Broads, better pack me tripod, camera and Remote Cable :lol:

Paul S

Wednesday had better be quiet, in fact I'm pretty certain it will just be hot, as the Cromer carnival is on, with the Red Arrows performing over the sea at 11:30 (great views from the cliff top).

I have my doubts as to whether we'll actually get anything, if we do, it will be late Thursday/early Friday when a camera and tripod may bag you something.

The Cape numbers suggest that something could happen, but most models seem to suggest it will slide south west to north east along a diagonal quite a bit further west than Norfolk

[dogs32]

sometime's a strong CAP can have good result's IF it eventually break's causing an explosive updraught with all that energy stalled up...wishfull thinking..

[Thundery wintry showers]

Current outputs have what looks like heavy/thundery showers developing over East Anglia and the southeast late on Thursday, just ahead of the main frontal system which couold be interesting.

Yes, re. earlier posts, stagnating and stabilising warm air can be an issue in thunderstorm setups, then again I can't remember many instances when an Atlantic system came racing eastwards and brought much of the way of thundery activity. A lot depends on the stability of the airmass itself, whether any cap can be overcome etc (Dogs32 is right, a modest cap can actually result in pretty severe storm activity if convection can break through it). I remember that the southerly regime at the beginning of the month was mostly cloudy in south-eastern areas, ahead of the front, which won't have helped.

I was thinking of the southerly plume events on dates like 3 August 1994, 11 July 1995, 7 June 1996, 25 August 2000, 2 June 2002, 31 August 2005 etc. when an Atlantic system made relatively slow progress eastwards and heavy thundery downpours broke out on and just to the east of the cold front. But as some earlier posts here have shown, even that kind of setup isn't always reliable.

[Harry]

Current outputs have what looks like heavy/thundery showers developing over East Anglia and the southeast late on Thursday, just ahead of the main frontal system which couold be interesting.

Yes, re. earlier posts, stagnating and stabilising warm air can be an issue in thunderstorm setups, then again I can't remember many instances when an Atlantic system came racing eastwards and brought much of the way of thundery activity. A lot depends on the stability of the airmass itself, whether any cap can be overcome etc (Dogs32 is right, a modest cap can actually result in pretty severe storm activity if convection can break through it). I remember that the southerly regime at the beginning of the month was mostly cloudy in south-eastern areas, ahead of the front, which won't have helped.

I was thinking of the southerly plume events on dates like 3 August 1994, 11 July 1995, 7 June 1996, 25 August 2000, 2 June 2002, 31 August 2005 etc. when an Atlantic system made relatively slow progress eastwards and heavy thundery downpours broke out on and just to the east of the cold front. But as some earlier posts here have shown, even that kind of setup isn't always reliable.

BBC/MetO forecast precip charts have some very heavy/thundery rain running up across the SW, Wales, NW England and into Scotland during the early hours of Thursday and throughout the course of the morning.

[chrisbell-nottheweatherman]

I didn't know the Cromer carnival was tomorrow - let us hope for good weather for that. Certainly, the Look East forecast this lunchtime suggested storms/heavy showers developing infront of the CF on Thursday late afternoon into the evening.

[NorthNorfolkWeather]

I didn't know the Cromer carnival was tomorrow - let us hope for good weather for that. Certainly, the Look East forecast this lunchtime suggested storms/heavy showers developing infront of the CF on Thursday late afternoon into the evening.

OT I know, but Red Arrows (hopefully in a brilliant blue sky) tomorrow at 11:30.

Back on topic, I think we've been let down a few times by the local forecast, but I will admit I wasn't about for some of the thundery Thursdays on July. Interesting that again it's progged fro a Thursday, seems to be repeating on a 7 day theme or a harmonic of 7 days

[chrisbell-nottheweatherman]

OT I know, but Red Arrows (hopefully in a brilliant blue sky) tomorrow at 11:30.

Back on topic, I think we've been let down a few times by the local forecast, but I will admit I wasn't about for some of the thundery Thursdays on July. Interesting that again it's progged fro a Thursday, seems to be repeating on a 7 day theme or a harmonic of 7 days

I find the LE forecast often gives more accurate detail than the national one.

[Harry]

12Z has given the SE a shot at imports, just.

Thursday now looking less impressive however.

[NorthNorfolkWeather]

12Z has given the SE a shot at imports, just.

Thursday now looking less impressive however.

That's an understatement, Thursday looks very poor, everything seems to have been shunted eastwards.

there's some very impressive CAPE in France and the low countries

[Harry]

This is very much a long shot, but Estofex have upgraded their forecast for today (naff all for us by the way, just for early clarification)

What I have noticed is that the area of thunderstorms across N Spain/S France has been expanded. This just gives me the inkling that the forecast area of instability to our S is in fact larger than first thought. With this area set to move N/NE over night and through tomorrow, it MAY (just MAY) present us with a little more chance tomorrow night/early Thursday.

This is very desperate, lol, but you never know!

[Mike Storm]

re Friday afternoon into the evening currently looking best for us, according to the current GFS: by Coast

NO not friday afternoon, im suposed to be going 'solo' on my flying training! not likely to happen if theree are giant cb's all over the place!

[maidstone weather]

tomorrow evening seems OK on the 12z, all it needs is a shift of 10-20 miles or so and we could be in the goods :lol:

[maidstone weather]

what's those speckles of blue on the BBC maps at 9pm tomorrow? :lol: (which happens to coincide with the GFS)

[Harry]

what's those speckles of blue on the BBC maps at 9pm tomorrow? (which happens to coincide with the GFS)

Judging by the video forecast there isn't much to be expected tomorrow night will have to see what the next run of GFS throws up.

This trough could come close - at this stage the trough is over N France, 12 hours later it runs from Scandinavia towards Holland. Slight jump N and W of this trough could us something...although as we know with troughs, they can appear, and disappear!

[Harry]

Kaddy just said the front is to bring no more rain than dribs and drabs to the SE!!

YES.....yes yes yes yes yes yes....thank the lord...storms are coming people

[dogs32]

Kaddy just said the front is to bring no more rain than dribs and drabs to the SE!!

YES.....yes yes yes yes yes yes....thank the lord...storms are coming people

all storm's will hit Glos and Worcestershire with full impact

possible MC'S

[Jane Louise]

They will happen,they will happen Lol

And lucky for some tomorrow

Storm Forecast Issued: 2009-08-18 21:28:00

Valid: 2009-08-19 00:00:00 - 2009-08-19 23:59:00

Regions Affected

extreme Southeast England ( all of the UK, excluding Outer Hebrides and SW England are including in the WATCH )

Synopsis

A complex area of LOW pressure between Scotland and Iceland, and a large area of HIGH pressure over the continent will dominate the weather across the United Kingdom on Wednesday. Ahead of a cold front, aligned through central Scotland and the Irish Sea at midday Wednesday, a very warm and humid airmass is advected northwards from France. A strong cap appears to be present over France for much of the daylight hours, preventing convection from occurring - however, during the evening hours the pressure gradient over northeast France is expected to slacken, creating a surface LOW to develop. This may cause initially scattered or isolated thunderstorms to develop. There is a risk of one or two of these clipping the extreme southeast corner during the mid-late evening hours - this is uncertain due to disagreement between the models. Later in the night the storms are expected to expand and merge into an MCS-type feature across Benelux and the southern North Sea. These storms pose a risk of supercellular characteristics. Elsewhere, although some heavy and locally torrential pulses of rain are expected to move northeastwards along the cold front, the risk of embedded thunderstorms seems unlikely given rather limited cloud height.

http://ukasf.co.uk/module-Storm/mode-forecast/id-252/

[dogs32]

supercellular characteristics

[*Stormforce~beka*]

Believe it when I see it ...

[NL]

http://www.estofex.org/

Extended Forecast

Valid: Thu 20 Aug 2009 06:00 to Fri 21 Aug 2009 06:00 UTC

Issued: Tue 18 Aug 2009 21:51

Forecaster: TUSCHY

... UK, Ireland and Scotland ...

Beneath cold mid-levels,daytime driven thunderstorms are forecast. Shear is too marginal foranything severe, but the potential for augmented LL CAPE release has tobe monitored, which dictates the tornado / funnel risk.