22nd into 23rd Aug 2011 - Storm/convective Forecast Discussion And Reports

[TheToastPeople]

Well. That was a whole lot of nothing

[Dorsetbred]

Go on tell me I missed something stormwise.......I'm sure I haven't.

3.6mm of rain no lightning and very light rain falling.

[Aceman]

should rename her Frenchie Poo Pants. so much potential, then nothing. hopefully something over the next few hours.

just some heavy rain would be nice, for my tomatoes anyway

[Damp and dreary]

And.... Thats the last post read! Took me almost an hour to read through all those (with frequent fags and coffees)

Thank goodness me and the good lady decided at 10.45 that we would go to bed and hopefuly wake up if any storms got here. What a shame though, amazing how that huge clump of heavy rain/storm just melted away as it got oh so close. Interesting too to read the exitement on here turn to negativity, then slowly peter out. Reminded me of Late night snow watches in the winter. Nice to see the forum so busy in August too. Oh well heres to the next one, maybe Friday?

[Nick F]

It looks like GFS may have been right all along with keeping any thunderstorms away over the near continent with just a few clipping the Kent coast, difficult call given UKMO and ECM wanted to produce some large rainfall totalls across the SE quadrant of England this morning and MetO forecasts were so keen to point out the risk thunderstorms and flash flooding. As ever, we miss out while France and Benelux get another hammering

Oh well, more storm potential later this week quite widely across the UK as the low moves in to the west.

[weatherobsuk]

Looks like epic fail lived up to its name lol. Finally got some shuteye for 2 hours from 4am, awoken to seeing the same thing everyone else is..rain, rain, and more rain on the radar. Can't win 'em all but there's still a CAT2 (soon to be stronger) Hurricane out there across the other side of the Atlantic to be watching. More late nights..sigh.

[Neilsouth]

Rubbish forecasts, 150 years of the met what a bloody joke!

No thunderstorms and no extensive rain, just a normal rainy day with some north east winds.

Going back to bed

Storms firing in the channel... COME ON LAST CHANCE SALOON!

[Harry]

Well what can I say....I'm glad I hit the sack when I did!! What a BUST! Feel bad for all those who stayed up or got in the car

Was always a difficult call but it appears GFS has been top dog yet again!!

[Polar Bear]

Well bit of a damn squid heh...altough with the intention of staying awake went to bed with laptop and window wide open...in five mins it seems I had gone..woke to hear someone say wow in the street so I assume some lightning and then slept til before 7am, It must have been raining hard as I only sleep that well when that happens! ....

Think I will flip back to the hurricane irene thread and see what is happening...found a great site too to watch progress on,,

see you some peeps there

Polar Bear

x

Edited August 23, 2011 by Polar Bear

[Typhoon Turner]

no its official i have moved the barton on humber stormshield.....

[Coast]

Storms firing in the channel... COME ON LAST CHANCE SALOON!

Well, last chance for today!

Was always a difficult call but it appears GFS has been top dog yet again!!

Yep busted again! To be fair, GFS did have this as marginal along the bit of SE coast but it was enough on the landward side to add to the other models that were showing it much further inland. Not sure if I have been let down by the charts or just wrongly interpreted them?

Here's what ESTOFEX have for the remainder of the day:

Storm Forecast

Valid: Tue 23 Aug 2011 06:00 to Wed 24 Aug 2011 06:00 UTC

Issued: Tue 23 Aug 2011 01:18

Forecaster: DAHL

A level 2 was issued across N France ... Benelux ... W Germany for damaging winds, large hail, excessive rainfall, and tornadoes.

SYNOPSIS

A deep upper long-wave trough is setting up over the eastern Atlantic, with several short-wave troughs crossing western Europe at its eastern periphery. One of these impulses will maintain a wave low along the main low-level baroclinic zone, which should stretch from western Iberia across southern England into the North Sea early on Tuesday. East of this front, a moist and rather unstable air mass is present. This air mass along with the frontal wave will likely be the focus for another episode of potentially severe convection on Tuesday.

DISCUSSION

... N France ... Benelux ... W Germany ...

Instability: It seems that instability will be a little weaker than in the same air mass on Monday, given CAPE consumption by the extensive convection over France and Benelux on Monday night, as well as lingering convective debris on Tuesday, which should limit insolation. Still, rather moist low levels and at least modest diabatic SFC heating should allow for MLCAPEs in excess of 1000 J/kg over western Germany and Benelux. Farther east, where the air mass should be unaffected by previous convection, somewhat higher MLCAPE may accumulate, possibly up to 2000 J/kg.

Shear: GFS suggests a broad region including much of France, Germany, and Benelux of 15 m/s DLS, and a somewhat localized region of 20 m/s over W Germany and Benelux. However, the best deep-shear and instability will become increasingly decorrelated as the day and evening progress. Much of the shear should be confined to the lowest 3 km, though the shear close to the ground (0-1 km) is somewhat marginal with 7-12 m/s.

Lift: Large-scale forcing for ascent will be provided mainly by a short-wave trough that will cross the region rather early in the day. As a result, convective development should ensue rather early, probably around local noon. Convective initiation will likely take place along outflow boundaries laid out by Monday nights convection, near orographic features, and/or along the synoptic-scale cold and warm fronts.

Storm mode: The reasonably strong shear profiles suggest convective modes ranging from well-organized multicells to supercells and bow echoes, with all modes potentially coexisting, although there will be the usual tendency for initially isolated cells to merge into a linear MCS given the deep-shear being largely parallel to the SFC cold front. The primary threats with this activity will be severe wind gusts, excessive rain, as well as large hail. A tornado or two are possible with isolated cells, especially if storms interact with outflow boundaries or orogenic circulations.

A small chance exists that storms form along the warm front and briefly tap air N of the front, before becoming elevated. At this stage, the storms would ingest strongly-sheared low-level air and would have increased potential for tornadoes. However, this scenario is rather uncertain.

Overall, the convective threat justifies a level-2 risk. The activity should begin rather early in the day and may last into the late evening hours.

Yet again, so near but so far!!!!

UKASF update:

Forecaster: Dan

Last Updated: 22:02 Monday, 22nd August 2011

Valid: 00:00 Tuesday, 23rd August 2011 - 23:59 Tuesday, 23rd August 2011

Areas Affected:MDT: CS + SE England, Home Counties

SLGT: East Anglia, E + S Midlands, SE + CS England

Synopsis:A complex synoptic pattern is forecast during Tuesday as frontal systems associated with a convective area of low pressure drift northwards out of France and affect many Central, Southern and South-eastern areas of England during the day. Increasingly cyclonic conditions are expected further north and west with some scattered showers and perhaps longer spells of more frontal rain across Ireland later, despite some reasonable drier and brighter conditions at times.

Discussion:

A noteworthy MCS has, as expected, developed across northern France this evening, producing a very high rate of lightning. It will, over the coming hours, move NE/NNEwards across the English Channel. Despite the fact that sferic activity has recently begun to decrease in intensity, dewpoints across and on either side of the Channel are 15/16C, with SST's currently at 17-19C. This would perhaps indicate that lightning might be sustained/reinvigorate on it's track across the Channel, but of major consideration is the lack of CAPE/LI etc once it leaves mainland France. Nevertheless, it will continue to move in an environment with very high ThetaW values, and there is some support for well organised thunderstorms to move across the English Channel and affecting southern areas overnight.

For now, we issue a MDT threat level to those areas that are likely to see an increased coverage of lightning as the MCS and other cells move across the area during Tuesday. It is prudent to add that this kind of synoptic setup is notorious fickle and extremely difficult to forecast.

As the day progresses the convective risk is likely to reduce and any heavy precipitation is forecast to gradually clear away out into the North Sea. At the moment the primary risk of severe weather is from frequent lightning activity and torrential downpours leading to localised flooding. The severe thunderstorm threat, with a risk of large hail, severe wind gusts and tornadoes, is forecast to remain over in the near continent with the majority of the forecast models keeping the severe DLS and helicity values again over in France.

It is anticipated that all lightning should cease on mainland UK around 11/12z.

[vortex_liam]

So i missed it all

Im up for a chase today, come on LAST CHANCE

[Paul Sherman]

Looks like epic fail lived up to its name lol. Finally got some shuteye for 2 hours from 4am, awoken to seeing the same thing everyone else is..rain, rain, and more rain on the radar. Can't win 'em all but there's still a CAT2 (soon to be stronger) Hurricane out there across the other side of the Atlantic to be watching. More late nights..sigh.

Feel for you guys, just got back to the hotel (Nearly Midnight here) and was expecting to see pictures but all I see is doom and gloom, what happened this time ??

Btw If any of you have any spare cash get on a plane to S Carolina (Not that dear and Major Hub) and rent a car to see this thing make Landfall, I am sooooo tempted as I am out here until Sunday myself. The coverage on the Weather Channel is spot on and they are going with S Carolina over Florida.

[Coast]

How comes Belgium always gets our storms?

On its way now:

Away from us!!!!

Still a bit of rain left to come:

[Norfolk Sheep]

Oops, smiley Carol says "we're not seeing as much rain as we thought" Better hike off and explain to the local fire brigade that they've been on stand by for nothing.... I have some nice undulatus this morning and it seems to have rained a little overnight......

[Harry]

Nice to see estofex spring to life coinciding with better model agreement! Grr

[SteveB]

Well nothing here, not even rain.

This one is a total bust for here (hey what's new)

[Norfolk Sheep]

http://www.meteogroup.co.uk/uk/home/weather/radar/belgium.html

Look at the strike intensity, I think there's one in there saying 489

[chionomaniac]

A frustrating bust. I'm glad that I am not as tired as some will be this morning!

[Coast]

Look at the strike intensity, I think there's one in there saying 489

That had my name on it

[Norfolk Sheep]

That had my name on it

With that amount it had everyone's names on it

[Typhoon Turner]

went to bed expected to get a good nights sleep... and got one

how many more times!!

[Nick F]

Steady heavy rain here in south London is small consolation for what it could have been like as per MetO/BBC forecasts last night.

Anyway, with GFS having a feather in its cap this morning, perhaps its new found reliablity for storms may stoke some interest with its widespread coverage of storms indicated on Friday as the upper trough moves east across the UK:

[pinball wizard]

It looks like GFS may have been right all along with keeping any thunderstorms away over the near continent with just a few clipping the Kent coast, difficult call given UKMO and ECM wanted to produce some large rainfall totalls across the SE quadrant of England this morning and MetO forecasts were so keen to point out the risk thunderstorms and flash flooding. As ever, we miss out while France and Benelux get another hammering

Oh well, more storm potential later this week quite widely across the UK as the low moves in to the west.

Morning Nick. The NAE wasn't keen on developing much in the way of PPN either, certainly no more than 12mm at best was forecast when i last checked it so I think its a pat on the back for that and the GFS and a case of should have known better from some of the more esteemed forecasters at the Met and other agencies?

[Sprites]

Okay, MCS 2 is now 'Epic Fail'

Since posting that, Epic fail is still intensifying

LOL , in France they named it Epic Display.