Convective Weather Discussion Uk

[Harry]

Who wants to waite ten minutes between discharges lol, ok sumtimes we get great storms from imports, as its uncommon it makes it even more noteworthy,at least the sky is interesting today.

In my experience, imports are often more electrical than homegrowns!?!? While I have no statistics to prove it, they often bring more positive strikes also, adding to the event

PS - Happy Birthday, Ryan!

Edited May 5, 2011 by Harry

[Stormyking]

In my experience, imports are often more electrical than homegrowns!?!? While I have no statistics to prove it, they often bring more positive strikes also, adding to the event

PS - Happy Birthday, Ryan!

Thankyou Harry

[Harry]

Hmmm...the 06z GFS has only added to the ambivalence lol!

[Stormyking]

Oh and Thankyou Coast and I think everyting might be legal :L well most things

I prefer Imports as In my opinion they last a lot longer and you get a lot more lightning with them most of the time and especially as they happen mostly over evening and Night time, it makes it that just bit more better knowing that you can relax, chill out with a beer or something and jsut watch the show

[Coast]

I prefer Imports as In my opinion they last a lot longer and you get a lot more lightning with them most of the time and especially as they happen mostly over evening and Night time, it makes it that just bit more better knowing that you can relax, chill out with a beer or something and jsut watch the show

I like the imports as I can sit high on Beachy Head and watch the progress as they come across the channel. The only time I successfully got any real lightning shots was from an import and with unrestricted views almost to France, it was quite exciting.

I have a miniature, MicroSD card based digital movie-cam this year and although only 1.3 Megapixels and 16GB max, I might just strap it to the top of my digital stills camera and see what I can get when the great day arrives!

[andymusic]

Just started to rain here lightly - drought is finally broken

[UKVoodoo]

I get the feeling today will be where everything looks great for storms but we miss 1 ingredient to see them unless very lucky

However I do feel tomorrow and Saturday will have a much stronger chance of widespread thunderstorms across GB

[A.J]

I get the feeling today will be where everything looks great for storms but we miss 1 ingredient to see them unless very lucky

However I do feel tomorrow and Saturday will have a much stronger chance of widespread thunderstorms across GB

I'm naturally lucky, so I'm a shoe-in for a thunderstorm...lol

Well, real pot-pourri of sky here today, generally overcast, a high cirrus veil, some low level crud, but in the chinks, some nice convection bubbling up with numerous Cu Congestus towers....Lower level atmospheric energy & bouyancy are on the rise as are dew points in my region...A little kink in the isobar patterns suggest a wave running up though the occluded front straddling the Irish Sea coastlines, this might just be the forcing required to spark off showers and weak thunderstorms through the west midlands into NW England this afternoon

[Arnie Pie]

Well the haze is finally lifting an i am beginning to see convection all around me....

and it feels nice and muggy

The image below is the recent view from Brumcam ( I would have normally waited until the helicopter passed...but sometimes its good to remind yourselves of the reasons these "inconveniences" are here at the QE.)

Edited May 5, 2011 by windypants

[Stormyking]

I like the imports as I can sit high on Beachy Head and watch the progress as they come across the channel. The only time I successfully got any real lightning shots was from an import and with unrestricted views almost to France, it was quite exciting.

I have a miniature, MicroSD card based digital movie-cam this year and although only 1.3 Megapixels and 16GB max, I might just strap it to the top of my digital stills camera and see what I can get when the great day arrives!

That sounds pretty amazing, down here on the Island we got some amazing views, I normally go up to this place called Culver Downs, I can just go up there and shows around Half of the Island, miles and miles out to sea and I can see as far as Brighton from there and alot of the other parts of the mainland, Im still yet to capture my first Lightning photo so hopefully that will change this year My friend said I can use his camera next time, hes a big storm lover too and he has an amazing Camera not sure what its called but it takes pictures instantly

[Lauren]

Grey and cold outside. But will it rain?

[Wivenswold]

A surprising lack of optimism on here again before the forecast event has even started.

Some perspective is needed I think. It's the 5th day of May, some 19 days before the official start of the summer and we're looking forward to the 3rd potentially thundery spell with hints in the models that a 4th event could be a week away. Estofex is positive, Met Monkey is positive, the Bracknell fax charts look good and the NAE output shows promise.

I'm wondering whether it'll be best to split the storm threads into areas so that those lucky enough to get a storm can discuss it in great detail without winding-up members of the no-storms club.

[Coast]

A surprising lack of optimism on here again before the forecast event has even started.

Measured I think, but still looking forward! We have had a couple of relatively duff years on the whole and whilst I appreciate that no amount of enthusiasm will influence nature and its weather, I am strongly in favour of a positive attitude and keeping the old eyes peeled for something 'out of the blue' - it's an interesting part of our hobby after all!

I'm wondering whether it'll be best to split the storm threads into areas so that those lucky enough to get a storm can discuss it in great detail without winding-up members of the no-storms club.

It might be worth spiting this convective thread into two: general conversation and more detailed forecasts/thoughts - but we already have regional threads available. What do members think?

[Neilsouth]

Will post more a little later in the week, but for now get ready for some major action by Friday and into the weekend. The ingredients are coming together to produce a decent risk of some thunderstorms and some major precipitation events, the setup is almost Spanish-plume type in terms of origins of the air mass etc...

Matt.

Synopsis - Synoptic Evolution - Thunderstorms, Showers and Thundery Rain - Weekend

Anticylonic conditions prevail across much of Scandinavia and Western Europe with a vortex to the West/South West of the United Kingdom gradually strengthening and under going cyclogenisis. Slight retrogression of this vortex towards Western Britain will introduce a strengthening WAA regime from the deep South drawing in moisture and additional heat. As the pressure gradient between low and high pressure strengthens through the weekend so the jet stream running the Southern base of the vortex begins to strengthen running from N Iberia. A warm plume advected N towards S England during Friday Night running Saturday should begin to engage with the encroaching vortex and lowering geo-potential from the Atlantic leading to increasing shower and thunderstorm activity. Later in the period and perhaps during Sunday full engagement of the plume axis could be realised with elevated convection becoming a risk. This could introduce a more significant threat of widespread heavy rainfall and some embedded thunderstorms. Focus on convection would be along the warm plume axis just ahead of the dry-line. Current multi-model bias GFS/ECM and UKMO blend projects main engagement to be around Reading running into much of Eastern England and the East Midlands into Northern England. A elevated mix layer set-up would be most likely with excessive rainfall the greatest risk. Also worth noting will be the risk of thunderstorms during Saturday, especially for the North Midlands running into the Pennine regions. A relatively strong lower level jet running increasingly moist and unstable airmass is likely to lead to the development of 300-600j/kg MLCAPE which if realised could lead to a few stronger multi-cell storms capable of a brief spin up and some large hail and gusty winds. This additional threat will be covered in more detailed convective watches.

The overall consensus is growing in multi-model support with growing consistency beginning to be seen in the single-model GFS multi-run analysis. GFS12Z ensembles at the time of writing shows very good correlation within the perturbed members suite P1-20 running T850 values up-to or perhaps in excess of +10. This combined with decreasing T500 thickness will also aid in enhancing mid level lapse rates and subsequent forcing. The finer detail will need to be added closer to the forecast period within T+48 due to mumerous vorticity eddies/lobes likely to be tied into this WAA training.

All in all the weekend looks like becoming increasing wet for quite a few of us with some much needed rain. Some of this rain likely to be thundery with elevated lightning. More updates will be added as we close in on Friday.

PRELIMINARY WATCH

Risk of Tornadoes and Stronger Thunderstorms on Saturday

Saturday is being monitored and the first in the start of the potential of severe thunderstorms. The general thunderstorm threat will likely increase quite significantly at this stage with the kinematic environment also strengthening. Latest GFS06Z guidance as of 5 May 2011 shows strong WAA being transported Northwards from the South as a strengthening vortex to the SW/W edges closer to the Western shore. To the East of the United Kingdom high pressure remains assertive and the squeezing effect of the vortex to the West will likely strengthen the pressure gradient. Due to the synoptic positioning of high and low pressure this only enhances warm air advection processes, leading to increasing moisture loading and as a result greater potential instability.

06Z output runs a jet around the base of the vortex from N Iberia into Western and Northern parts of Britain during Saturday. The combination of lowering heights at 500mb and increasing moisture/heat advection will only aid in steepening mid-level lapse rates and CAPE in the order of 500-800j/kg should be realised. Lower level moisture advection and LCL(s) 800M< will favour tornadogenisis and some storms could route to the boundary layer. A jet streak in the order of LLJ 72kts will aid in increasing multi-level windshear and it appears that ingredients are coming together for the potential of some stronger multi-cell thunderstorms, perhaps more organised in nature. The main threat at this early stage will be across Wales, The Midlands, running into Derbyshire and the Peak District and perhaps becoming more widespread across Northern England running into the North East.

The main threat will be widespread thunderstorms with an attendant threat of a few stronger severe cells capable of producing tornadoes and large hail. Downpours, flash flooding and gusty winds also becoming a problem. This development does need close monitoring. Also worth mentioning will be the cloud equilibrium projections below -50, very favourable for very active lightning within the cells. Should model guidance continue to stengthen for Saturday a HIGH risk of thunderstorms would appear likely with perhaps a moderate risk of Severe storms for some. A tornado watch is anticipated for the weekend. An offical warning and update will be issued closer to the time-frame.

null Forecaster/Site Owner

two ^

Edited May 5, 2011 by Victor Meldrew

[Harry]

Measured I think, but still looking forward! We have had a couple of relatively duff years on the whole and whilst I appreciate that no amount of enthusiasm will influence nature and its weather, I am strongly in favour of a positive attitude and keeping the old eyes peeled for something 'out of the blue' - it's an interesting part of our hobby after all!

Indeed Coast

I do feel things are turning increasingly less widespread with opportunities for severe storms decreasing also, based on the latest models.

Nevertheless, there will be scope for severe weather and a few potent thunderstorms, plus rashes of convective showers/thundery showers.

My decrease in optimism is not such that there will be hardly any storms, but instead of 100 locations getting thunderstorms, perhaps more like 30-50 will.

But as ever, what will happen and what the charts say will on 99.999999% of occasions never match, especially more than 24-36 hours before any widespread events are expected to unfold.

EDIT - LOL! I post this just after "I don't believe it" posts those texts comparable with that of storm porn!!! Who will be right? I seldom like being wrong, but on this occasion, I will be more than happy

Edited May 5, 2011 by Harry

[matt_in_dudley]

Been a warm muggy day here so far, overcast (but that bright kind of overcast) no rain from what i have seen of the day, been up since 6am. I'm thinking about putting some washing out just because of how warm it is.

[Harry]

Not seen this on this thread so far, but here's Estofex's view of tomorrow (pretty much in line with what I predicted earlier, lol)

A level 1 was issued for Portugal and Spain mainly for large hail and severe wind gusts. An isolated significant hail event can't be ruled out over south-central Spain, e.g. Madrid southwards.

A level 1 was issued for NW-France mainly for large hail and an isolated severe wind gust/tornado risk.

A level 1 was issued for S-Turkey mainly for flash flood producing thunderstorms.

SYNOPSIS

CAA continues over east-central/east Europe with a quasi-stationary longwave trough still in place. Strengthening ridging over central Europe further assists in the advection of a well mixed, dry and cool air mass far to the south, even affecting parts of the central/eastern Mediterranean with negative surface dewpoints. A north-south aligned air mass boundary has established to the east of that feature and attendant surface high pressure are with a sharpening moisture gradient present over far eastern Ukraine and parts of Russia.

Over the far northeastern Atlantic, an extensive deep cyclonic vortex is anchored with little eastward movement forecast. However, a significant impulse along its southwestern fringe is about to assist in the development of a sharp mid-/upper trough with a much shorter wavelength. This feature circles around the southern part of the main vortex and approaches Portugal as a significant vorticity lobe from the west during the night hours. Brisk SW-erly flow covers regions from the Iberian Peninsula all the way to UK, atop gradually moistening LL. Hence, a more widespread thunderstorm risk is in store for the upcoming forecast period.

Stable conditions persist beneath increasingly tilted high pressure/ridge features over central Europe.

Models agree reasonably well with the main pattern, revealing some discrepancies within the BL qualitiy...especially over NW-France.

DISCUSSION

... Portugal and Spain ...

Brisk southwesterly flow affects all of the Iberian Peninsula all day long. However, as aforementioned vorticity lobe approaches from the west, wind field at mid-levels ramps up significantly during the early afternoon hours onwards with shear magnitude increasing by roughly 10 m/s at lowest 3 and 6 km to 20 and 25 m/s respectively. According to a deep WAA pattern, veering is expected within the mid tropospheric layer and widespread 200 m^2/s^2 SRH-3 occur, increasing betimes over E-Spain. Also, a 35-40 m/s diffluent high-level streamline pattern (~300 hPa) covers the forecast area, also persisting as sharpening trough approaches from the west.

BL quality is still the main concern with yesterday's soundings revealing high T-Td depressions and inverted-V typed profiles. However, persistent influx of better moisture from the Mediterranean assist in further BL recovery and better LL moisture to work with. The pattern is also not supportive for widespread, thick cirrus, so expect again another round of good diabatic heating and orographically bound initiation. CIN remains weak with rapid mix out of any nocturnal stabilization, so scattered thunderstorms evolve around noon, increasing during the afternoon hours in coverage and strength. Large hail is well possible with any multicell/supercell thunderstorm. During the later afternoon, an isolated significant hail risk evolves over central/south-central Spain with any discrete supercell, given favorable parameter overlap ( ~800 J/kg MLCAPE, 30 m/s DLS and increasing SRH). Strong to severe wind gusts are also forecast as BL remains deeply mixed and 0-3 km shear increases betimes.

During the night, thunderstorms move slowly towards the east, as upper trough approaches. However, BL stabilization results in rapidly decreasing CAPE, although steep lapse rates may offset that effect with modest MUCAPE present all night long. Anyhow, expect severe risk to diminish rapidly until 00Z.

An upgrade to a level 2 may become necessary, if CAPE/shear overlap remains in place during upcoming model outputs....mainly over central/south-central Spain. The main risk would be signficant hail.

... W-France ...

Models still diverge regarding the final BL moisture content. ECMWF and GFS all indicate an ongoing moisture advection regime during the forecast with dewpoints increasing to 10°C and more. GFS remains very bullish, developing sfc. dewpoints in the upper tens all the way to the W-English Channel with ECMWF showing a modest solution. Nevertheless, all models indicate modest MLCAPE of at least 500 J/kg, probably maximized over NW-France during the afternoon. Shear remains weaker compared to Spain, but roughly 15 m/s DLS and somewhat enhanced SRH-3 indicate a large hail risk with stronger thunderstorms, next to isolated severe wind gusts. Also, LCLs around 1000 m and somewhat enhanced LL shear may also cause an isolated tornado event. As thunderstorms spread to the N/NE during the night, decoupling from the BL results in a mainly elevated thunderstorm risk over SW-UK. Despite an isolated marginal hail risk, no severe is forecast.

This is what I predicted earlier - I hope that it will change.

What is clear, is that there is a lot of chopping and changing going on (as ever!) and the finer details are to be ironed out. But where previously I was thinking fairly decent severe risk, estofex level 1 (at least), I am more inclined to go with a blanket estofex yellow zone, with level 1 over the continent and a risk (nothing more) of fairly widespread heavy and possibly thundery showers.

Edited May 5, 2011 by Harry

[conor123]

Some weak mammatus moving toward here now with dark skies to the south, nothing on the radar though of interest?

Does seem something is brewing though.

[Darren Bown]

I've not posted for a while on here, but have been reading intently for the last few days. Estofex seem to have given quite a significant chance of storms today. Feels humid here, a lot of cloud about, and a breeze picked up recently.

[Kain]

Just been to vote for the AV thing and had some nice whales mouth above me. Its gone very humid here and it really does feel like something is about to kick off

[Adi F]

I am somewhat ambivalent regarding the coming three days.

Me too mate. Partly why I have focused on the start of nextweek and the possibility of widespread storms and potential for some tornado’s.I know it is a long way out and the charts may well change but the risk inconstantly being highlighted in consecutive runs. Yes the minutia of the datais all over the place at the moment but the trend has not changed that much andwhen we are looking that far out it’s the trend that counts.

We might all be wrong, the snow may return tomorrow and not stop for 6 months!

[matt_in_dudley]

Gone quite dull here in Brownhills, grey over towards Bloxwich and Willenhall, wind has picked up a little bit too. I do love weather like this, will it? Wont it?

[A.J]

Some weak mammatus moving toward here now with dark skies to the south, nothing on the radar though of interest?

Does seem something is brewing though.

Just been to vote for the AV thing and had some nice whales mouth above me. Its gone very humid here and it really does feel like something is about to kick off

Very similar skies here as well chaps.....A stark difference to about 30 mins ago with bright, warm sunshine,....now leaden skies, quite angry looking infact, the humidity's risen markedly since the clouds rolled in

[Kain]

Just starting to rain here now...wierd though the rain is warm!

[Adi F]

Me too mate. Partly why I have focused on the start of nextweek and the possibility of widespread storms and potential for some tornado’s.I know it is a long way out and the charts may well change but the risk inconstantly being highlighted in consecutive runs. Yes the minutia of the datais all over the place at the moment but the trend has not changed that much andwhen we are looking that far out it’s the trend that counts.

We might all be wrong, the snow may return tomorrow and not stop for 6 months!

I think i need to clarify I am not saying there will be no thunder storms before Sunday, there is a good chance of thunderstorms tomorrow and Saturday but I am focusing more on the tornado potential.

I may be wrong but I don't think there is enough heat for anything today but i may be wrong.