Uk Convective General Discussion & Forecasts, 20th June 2012>

[tcc]

To me, this looks like the classic 3 fine days a Thunderstorm scenario. I'm not going to get excited or depressed until much nearer the time.

[Coast]

I hot-link a lot of charts on here and they do 'move on' during the following runs. I've downloaded these just so we can all get a teeny bit excited about potential and look back at them later in the week to see what actually became of them:

BOOM!!!!!

[Evening thunder]

Some of the models like the UKMO and GEM, and possibly the ECM just, show the 15C 850hpa line getting slightly further north than on the GFS:

UKMO (showing midnight as midday on Thurs not available)

GEM:

GFS shows this for the same time as that GEM chart:

Whether this means there would be more storm potential on the UKMO and GEM, I'm not really sure, but I'd prefer them to be showing that than them showing the set-up further east than the GFS still.

Note they also show 850mb pressure I think, rather than surface pressure, so the flow looks slightly more SW'erly on them.

[Coast]

Bank!!!

K Index = thunderstorm potential

<20 = none

20-25 = isolated

26-30 = scattered

31-35 = scattered to numerous

>36 = numerous

Poor correlation between KI values and severe weather events, good correlation KI < 26 and no thunderstorms.

TT = coverage of thunderstorm

44-45 = isolated

46-51 = scattered

52-55 = scattered to frequent

Good correlation between TT values > 48 and severe weather events.

PW = measure type of supercell thunderstorm

> 4,4 = high precipitation supercell

4,3-2,5 = supercell

< 2,50 = low precipitation supercell

Poor correlation between PW values and severe weather events, good correlation PW < 1 and no thunderstorms.

LI = measure of severity of thunderstorm

>0 = unlike potential for thunderstorms

0 - (-2) = possible potential with trigger (front, trough, orography).

-3 - (-5) = probable potential.

< -5 = strong potential

Good correlation between LI values < -5 and severe weather events.

CAPE = measure of severity of thunderstorm

<300 = little or no convective potential.

300-1000 = weak convective potential

1000-2500 = moderate convective potential

> 2500 = strong convective potential

Poor correlation between CAPE values and severe weather events.

Combination CAPE and 0-4km speed shear can give a hint on thunderstorm type

CIN = is the negative area on a sounding found between the lifting condensation level and level of free convection.

< 25 = associated with significant tornadoes

50 = associated with derechoes

> 100 = precludes thunderstorm development without significant forcing

EH = measure of rotation potential

SREH = measure of rotation potential for (thunder)storms

if they form:

150-300 = supercell development possible with large CAPE, risk for weak tornadoes (F0, F1)

300-450 = supercell development possible with small CAPE, risk for strong tornadoes (F2, F3)

>450 = large risk for supercell development, risk for violent tornadoes (F4, F5)

Poor correlation between SREH values and severe weather events.

http://www.skystef.be/forecast20m.html

[Lewis]

Bank!!!

Not so good for my area looking at the Custom skew-t charts.

Although 1000 cape and a LI of -4 cannot be too bad I suppose?

[Evening thunder]

Actually, I just remembered you can get many ECM model charts at 3 hourly intervals on Weather Uunderground, just go to www.wunderground.com then click the 'Maps & Radar' drop down menu and click 'Model maps'.

I took a few screenshots of some charts.

ECM precip and sea level pressure:

At 6am there is a showery looking precip signal through the SW and other area which moves NNE and really develops in the NE through the afternoon, probably indicating home grown more surface based storms there I'd guess. (most intense on the 6pm chart below)

But I notice a lack of a MCS import into the S/SE on these charts, and then guess what happens over the near continent? yep, you've got it.

Midnight precip:

GFS 850hpa temps (on the left) Vs ECM 850hpa temps at midday Thursday:

ECM shows 850hpa temps of 16-18C in the SE, though I notice the 850hpa air flow does appear to be a bit more SW'erly on the ECM by this time.

GFS Vs ECM temps at 3pm:

I forgot to get the scale in but ECM is more detailed and has a larger area of temps in the 24-28C catagory (yellow colour). Dew points are also shown as contours with them touching 20C in Kent and a few other E/SE spots.

Shear (not sure what 'type' this chart shows) seems relatively low altough there is an increase around the NE coinciding with the heaviest precip shown at 6pm:

ECM 3pm cloud cover percent:

Though one chart that unfortunately doesn't seem to be available from the ECM which would be really useful, is CAPE/LI charts.

Edited June 25, 2012 by Stormmad26

[Coast]

The GFS 06z run is out and keeps things right on track:

The lightning ensemble probability also makes interesting viewing as EA and to the North of there seems to be in a high risk area currently:

[Harry]

Still a bit knife edge for my liking with the GFS easterly creep! What is encouraging is the UKMO and GEM holding things slightly further west!

Timing will be crucial...an MCS would be nice Weds or Thurs night

Reads better on the MetO at the moment though

Outlook for Wednesday to Friday:

Wednesday warm and humid, with bright or sunny spells, risk of heavy or thundery showers developing. Thursday becoming very warm, perhaps thunderstorms arriving later. Friday cooler, windy, spells of rain.

Edited June 25, 2012 by Harry

[Supacell]

How long before we can actually start believing?

The charts show a widespread homegrown storm day on Wednesday before imports moving into the SW on Weds night move NE on Thursday and amalgamate with homegrowns that set off through the afternoon across the Midlands, giving eastern areas a very noisy evening.

Chance of channel imports into the SE also and i would be very surprised to see the channel killing off convection with CAPE of over 2000J/kg and a LI of -7/-8!!!

Its then all over by midnight Thursday with a standard fare of sunshine and heavy, thundery showers on Friday.

[Coast]

How long before we can actually start believing?

Wednesday night/early Thursday morning? If those indicators currently showing from France into the SW start occurring on Wednesday, I'll be checking out the radar for direction like a hawk!

A long way to go yet and I'll feel more comfortable when the Hi-res charts start coming into the timescale.

[Kain]

I wish the east of the UK gets wiped off the map...then we would have to have some storms in the west :o

Looks like it could go boom for you guys though!

[Carl46Wrexham]

Same old story happening YET again it seems.

This is not natural variation....this is the same scenario playing out time after time. Getting nothing year on year is not an example of natural variation, but more of an unwelcome pattern becoming established. The fact that many of us in the west have seen nothing storm wise for between 4 and 6 years is growing evidence of this for me.

Before anyone pipes up that the Eastern side always gets more, yes, as I have previously acknowledged, I realize that and accept that as fact. Nothing unusual about that. It is undeniably unusual however that many of us this side of the UK are seeing NOTHING year on year. That is my issue here. If this pattern continues, I can easily foresee posters such as myself on here 5 years from now, bemoaning the fact that no storms have been experienced for nigh on a decade.

Edited June 25, 2012 by Carl43Wrexham

[samadamsuk]

Looking extremely promissing at the moment! I'm flying to Turkey on friday lunchtime from Gatwick, so I've booked a cheap hotel so I can drive deom Cirencester to Gatwick thursday night - hopefully a good light show.

Wednesday night looks interesting for the SW, with a 500mb wind max pushing in and good jet support, but it looks like the mucape doesnt push in until the morning hours, so might not come together - I'll wait for the expert forecasts though here as I'm not quite sure -

Sam

[AWD]

Same old story happening YET again it seems.

This is not natural variation....this is the same scenario playing out time after time. Getting nothing year on year is not an example of natural variation, but more of an unwelcome pattern becoming established. The fact that many of us in the west have seen nothing storm wise for between 4 and 6 years is growing evidence of this for me.

Before anyone pipes up that the Eastern side always gets more, yes, as I have previously acknowledged, I realize that and accept that as fact. Nothing unusual about that. It is undeniably unusual however that many of us this side of the UK are seeing NOTHING year on year. That is my issue here. If this pattern continues, I can easily foresee posters such as myself on here 5 years from now, bemoaning the fact that no storms have been experienced for nigh on a decade.

Nothing no one on here or on the planet can do about it though. Mother nature will do what mother nature wants to do.

I keep a little hope for my location now after receiving a couple of tweets from my local forecaster suggesting that whilst the east will see the enhanced threat, there is still enough instability for the South West to see something thundery too! Anything thundery will do for me!

[Mapantz]

Storms could pop up in many places on Thursday, but the bias is towards the east for something better.

[Mapantz]

I can easily foresee posters such as myself on here 5 years from now, bemoaning the fact that no storms have been experienced for nigh on a decade.

I haven't had a thunder storm here since 2005. It is frustrating, but part of the reason that it seems to be the east that get it, is just purely down to being closer to the continent, that's also a reason for a lot of other types of weather too. I'm sure there's people int he east as well though, that have not seen much storm activity. Storms are sparse in nature, it's not like a weather system that covers three countries at a time.

It's just unfortunate, things will probably change again at some point though.

Edited June 25, 2012 by Mapantz

[Methuselah]

This is not natural variation....

Well if it ain't 'natural' what is it?

[Harry]

I wish the east of the UK gets wiped off the map...then we would have to have some storms in the west

Looks like it could go boom for you guys though!

And a warm welcome to NetWeather's very own Mahmoud Ahmadinejad

[Gavin P]

My video today looks at the possibililty of Thundery Thursday for the UK : http://gavsweathervids.com/

Looks like there could be some pretty interesting, unstable weather to say the least.

Edited June 25, 2012 by Gavin P

[Coast]

Lets be honest here, this potential is going to waver West and East for a good few runs more yet and no doubt increase and decrease in potency right up to the last minute. There's no use in getting concerned about where and when exactly yet, there are just general hints of something really quite good for somewhere in the UK on Thursday, maybe Wednesday.

I can hear the wise-words ringing in my ears about 'run-to-run analysis' and how far out is accurate and many, far more knowledgeable folk on here will tell us that TStorms are one of the most difficult things to pin down, along with snow. I have been guilty on here already today of taking mostly GFS output and consecutive runs to try and verify my own excitement of what could happen (and currently where!!). So I guess we need to just wait a while and enjoy the potential shown, without taking it as specific guidance to where and who will get what.

Here is a great place to moan about lack of TStorms in your area, I'm not going to join in because sooner or later - a humdinger will crack open the heavens above me and I will be smiling like a silly idiot again!!!!

http://forum.netweat...orms-club-2012/

[Kain]

And a warm welcome to NetWeather's very own Mahmoud Ahmadinejad

LMAO Not quite that bad since you would all be welcome to come and live in the west!

[ardsar]

Just got my website up and running in time for the "storms" this week. It is based in Plymouth, Devon and includes a Boltek Lightning detector.

www.bearsbythesea.co.uk

It is still work in progress, but hopefully informative and useful. Feedback and suggestions welcome!

Good luck all for later this week.

[Coast]

www.bearsbythesea.co.uk

It is still work in progress, but hopefully informative and useful. Feedback and suggestions welcome!

Nice work ardsar, welcome aboard the good ship Netweather and the madness that is the convective threads too!

[Mapantz]

Just got my website up and running in time for the "storms" this week. It is based in Plymouth, Devon and includes a Boltek Lightning detector.

www.bearsbythesea.co.uk

It is still work in progress, but hopefully informative and useful. Feedback and suggestions welcome!

Good luck all for later this week.

Good work! I used to use weather display myself, but fancied a change and so i moved to Cumulus. I'll bookmark your link though, i find it handy to have info from independent stations in the south west.

[Lewis]

Same old story happening YET again it seems.

This is not natural variation...

06Z is very good, someone above mentioned when should we start to believe, I would leave it until Tuesday 18Z, if it's showing the same, BELIEVE