Uk Convective General Discussion & Forecasts, 17th July 2012>

[Cloudwatcher]

NW forecast has us currently at 62% chance for tomorrow. Watch that plummet overnight haha!

[Chris.R]

Well there's over 1000 CAPE in parts of this regian tomorrow showing when I last looked, and that's usually the value to meet for me to think that we have a good chance. As I remember, almost all of the storms here have been when CAPE has been at or above that level. Anything below that means that storms just dy as they entre the thunder desert that is Merseyside, chesher and northwest into Liverpool bay up to the IOM and Anglesey..

[Cloudwatcher]

Well there's over 1000 CAPE in parts of this regian tomorrow showing when I last looked, and that's usually the value to meet for me to think that we have a good chance. As I remember, almost all of the storms here have been when CAPE has been at or above that level. Anything below that means that storms just dy as they entre the thunder desert that is Merseyside, chesher and northwest into Liverpool bay up to the IOM and Anglesey..

Lifted Index of minus 4 too....but we have had these figures quite a few times before and nothing comes of it. The cloud cover rolls in, we get a blanket and the temperature/ humidity isn't consistent enough to kick off decent convection. Hate to sound negative (and I do usually sound negative) but I honestly can't see tomorrow being any different. But fingers crossed and want to be proved wrong!

[Chris W]

It probably will go off in Cheshire tomorrow as I have taken my storm shield with me to the south east for the weekend. Ho hum.

[Cheshire Freeze]

Lifted Index of minus 4 too....but we have had these figures quite a few times before and nothing comes of it. The cloud cover rolls in, we get a blanket and the temperature/ humidity isn't consistent enough to kick off decent convection. Hate to sound negative (and I do usually sound negative) but I honestly can't see tomorrow being any different. But fingers crossed and want to be proved wrong!

That's the mindset that this lack of storms has got us into.....seen these CAPE figures before myself and not seen a bean when all said and done. Who knows though, maybe we'll get lucky for once!

[Cloudwatcher]

It probably will go off in Cheshire tomorrow as I have taken my storm shield with me to the south east for the weekend. Ho hum.

nah don't worry. Somehow I don't think you will be missing out! We will probably do the hard work of breeding them and then they will bugger off due east (Wheres due east of here...ohh thats right....Lincolnshire!! Roughly....)

*slinks off to the NSC to be storm starved and grumpy

[Thundery wintry showers]

Not much here in N Yorkshire today bar two sharp showers, but the GFS precipitation outputs didn't suggest much over England for today, with the weekend holding the majority of the potential. Not too surprised by the reports of a fine day btw; I think it's fairly common for central and eastern regions to get some generally dry sunny days out of this synoptic setup with the low pressure sat to the west, although it usually turns more showery as the low drifts eastwards.

The occluded front wrapped around the depression no longer looks to have much frontal cloud associated with it, and in fact coincided with some thundery activity over Ireland today, so I doubt that it will inhibit convection tomorrow over England and Wales.

[Aaron]

Having the lowest cape value doesn't mean you'll get thunderstorms.. or the most severe. Back on the 28th of June, I recall Newcastle had little in the way of cape but they got an amazing storm while we got nothing despite having really good cape values.. all will be revealed tomorrow.

[Cloudwatcher]

That's the mindset that this lack of storms has got us into.....seen these CAPE figures before myself and not seen a bean when all said and done. Who knows though, maybe we'll get lucky for once!

We won't. But taking this to the NSC and leaving this forum for people who actually get to experience storms! Good luck all for tomorrow. Stay safe,

[Chris W]

<p>How are the moisture levels, shear etc. looking for tomorrow? Looks to me like the occlusion started some decent storms in Ireland today.

Sunday looks just as good from a CAPE and LI point of view. That said, I for once do not want a lunchtime or afternoon storm in Stevenage or Letchworth tomorrow as I am attending my cousin's wedding. I am also planning to watch the Olympics in Hyde Park on Sunday bur could always run for cover so that is ok!

Edited August 3, 2012 by Chris W

[DubWeatherAddict]

Storm from Leitrim earlier on

....

[Chris D]

<p>How are the moisture levels, shear etc. looking for tomorrow? Looks to me like the occlusion started some decent storms in Ireland today.

Sunday looks just as good from a CAPE and LI point of view. That said, I for once do not want a lunchtime or afternoon storm in Stevenage or Letchworth tomorrow as I am attending my cousin's wedding. I am also planning to watch the Olympics in Hyde Park on Sunday bur could always run for cover so that is ok!

God people ain't half fussy these days

Expect nothing tomorrow (for NW England), I'm going to be negative about it all and see what happens lol. There's bound to be something limiting convection here isn't there? There usually is.

Edited August 3, 2012 by Chris D

[Chris W]

Estofex have a level 1 warning for marginally severe hail and tornadoes for almost all of England and Wales, plus Ireland, with 50% probability of lighting.

Edited August 3, 2012 by Chris W

[Cloud 10]

UKASF forecast for today.

http://ukasf.co.uk/storm-forecasts/198

Edited August 3, 2012 by Cloud 10

[Nick F]

Saturday's Storm Forecast:

Valid: 04/08/2012 06:00 - 05/08/2012 06:00

Headline: ... THERE IS A RISK OF THUNDERSTORMS FORECAST...

Synopsis

Slow-moving upper and collocated surface low close to Sern Ireland on Saturday will drive an unstable cyclonic SWerly flow across the UK,

... IRELAND, SW ENGLAND, WALES, MIDLANDS, E ANGLIA, N ENGLAND & S SCOTLAND ...

Low to mid-level lapse rates are indicated to be a little steeper than Friday across a large swathe of the UK & Ireland thanks to colder air aloft INVOF upper cold pool/low now close by over S Ireland and slightly higher moisture advection beneath. Thus CAPE values will likely be higher today ... with a greater coverage of thunderstorms likely. Despite the lack of vertical shear ... there is potential for locally strong pockets of instability to develop in respoonse to surface heating, so some storms may be capable of small to modeate size hail (up to 2-3cm diameter or perhaps more in isolated instances), gusty winds and also producing torrential rain leading to localised flooding. Some local convergence zones are indicated over Ireland, Irish Sea and NW England ... so weak upper wind/surface wind confluence environment may favour the developemnt of funnels and perhaps one or two weak tornadoes. However, overall potential for organised severe weather seems to low to warrant a SLIGHT risk for any area.

Issued by: Nick F - Forecaster for Netweather

Also can be found here: http://www.netweathe...9d657b101567dc1

[Chris.R]

I like how as soon as I ppposted, I started all the other northwesterners posting too, as if they were weighting for someone to start a rant. LOL. BTW, Am I the only poster fromMerseyside on here? I feel like I'm all alone with no regular posters with in a radius of 10 miles and no storms either. Do people in merseyside not like storms then? or have they all just foregotten what a storm is, probably the latter! Come on, out of the woodwork you lot!

[Supacell]

Still looks like a good day for widespread convective activity today with numerous thunderstorms developing. I will be chasing, and was thinking of staying near to home.

However, the best area looks to be N Wales up into NW England (on GFS and Hirlam) and my question is as to whether the Pennines will shred any convection today as it heads towards me. A common occurence is for showers from the west to suffer this fate and then re-develop to my NE as they head up into North and East Yorkshire and it is this phenomenon that makes this area so void of storms.

If this is the case then I may be better to head west to the other side of the Pennines, and position myself around Lancashire (somewhere just north of Manchester). I think some of the members in storm starved areas of the NW may finally get there storm today (although please don't blame me if they don't hit your house directly )

EDIT: Could someone please post the ukasf map. I cannot see it and so cannot see where they have placed there Moderate risk.

Edited August 4, 2012 by Supacell

[Deluxe]

Could be a good day up here today. I'll be working outside for much of the day so will see any thunderstorms coming!

[Carl]

Could be a good day up here today. I'll be working outside for much of the day so will see any thunderstorms coming!

I'm not far away from you so will be keeping a close eye on events too!

[Lynxus]

Ok, So pretty much every site has me under a thunderstorms today.. this is normally a bad sign lol.

BBQ round mine then

[Stuart]

Good luck all for today

[Weather-Voyager]

I like how as soon as I ppposted, I started all the other northwesterners posting too, as if they were weighting for someone to start a rant. LOL. BTW, Am I the only poster fromMerseyside on here? I feel like I'm all alone with no regular posters with in a radius of 10 miles and no storms either. Do people in merseyside not like storms then? or have they all just foregotten what a storm is, probably the latter! Come on, out of the woodwork you lot!

I'm here quietly in the background!.. Keeping a eye on todays potential, it's been nearly a year since our last good storm here, so well over due for some action today...

Currenty scattered / broken skies and feels quiet nice in the sun.

WV

[Coast]

Great NW storm forecast from Nick this morning and although it doesn't cover my area, a few people might see the action today. So what are the others saying?

ESTOFEX have a level 1 for the Central area of England:

Storm Forecast

Valid: Sat 04 Aug 2012 06:00 to Sun 05 Aug 2012 06:00 UTC

Issued: Fri 03 Aug 2012 20:35

Forecaster: GROENEMEIJER

A level 1 was issued for parts of Ireland for marginally severe hail and for tornadoes.

A level 1 was issued for parts of the UK for marginally severe hail and for tornadoes.

SYNOPSIS

A broad WSW-ly mid-level flow over Europe is associated with a broad zone of lower-tropospheric temperature gradient stretching from northern Spain across France, southern Germany and Poland to the eastern Baltic States.On either side of this zone, convective storms are expected to develop. The WSW-ly jet is located ahead of a trough with an axis from a cold upper-level low over the British Isles towards the southwest, which slowly approaches western Europe.

Ireland and the UK....

Within unstable air that surrounds the upper-level low, widespread storms are expected to develop in response to diurnal heating. Updraughts may become strong enough to produce some hail exceeding severe levels locally. Vertical vorticity may be stretched in the stronger updraughts of storms that develop in convergence lines circulating around the low, creating a modest risk of a few weak tornadoes.

UKASF have:

Storm Forecast Moderate

Forecaster: Chris

Last Updated: 2012-08-03 22:32:00

Valid: 2012-08-04 00:00:00 - 2012-08-04 23:59:00

Areas Affected:

England, Eire, Wales, S Scotland.

Synopsis:

A well developed, vertically stacked area of low pressure will be centred over the Celtic Sea and drift slowly eastwards through the day. Various occlusions and upper troughs will continue to rotate around the low providing the focal point for widespread convection.

Discussion:

There is a high confidence that numerous showers and thunderstorms will develop across Britain on Saturday. CAPE values over most of the SLIGHT risk area will be in excess of 500j/kg with values reaching in excess of 800j/kg across the MODERATE risk area. Shear is very limited with 20kts of LLS possible in parts of southern England being about all there is of note. However, this combined with developing updrafts and numerous convergence/outflow boudaries could still be enough to produce a brief spin-up funnel or weak tornado. Hail is also possible with the most well developed storms, especially those over Wales and the West Midlands were lapse rates will likely be steepest combined with 500mb temperatures of around -20C.

SkyWarn:

SKYWARN UK SEVERE THUNDERSTORM WATCH #045

ISSUED: 0900UTC SATURDAY 4TH AUGUST 2012 (GJ/SM)

SKYWARN UK HAS ISSUED A SEVERE THUNDERSTORM WATCH FOR THE FOLLOWING REGIONS: WALES CENTRAL ENGLAND NORTHERN ENGLAND

IN EFFECT FROM 0900UTC UNTIL 2300UTC SATURDAY 4TH AUGUST 2012

LOW PRESSURE OVER SOUTHERN EIRE FEEDING VERY UNSTABLE AIR ACROSS THE COUNTRY.

THERE IS A POSSIBILITY OF SEVERE WEATHER AFFECTING THE INDICATED REGIONS IN THE TIME PERIOD SPECIFIED. THREATS WITHIN THIS WATCH INCLUDE, BUT ARE NOT LIMITED TO:

HEAVY RAIN...LIGHTNING...HAIL...FUNNELS/WEAK TORNADOES

DISCUSSION:

THERE IS GOOD MODEL AND PARTNER AGENCY CONFIDENCE OF THE POSSIBILITY OF A SEVERE THUNDERSTORM THREAT DURING SATURDAY. SLACK LOW PRESSURE CURRENTLY CENTRED OVER SOUTHERN EIRE PROVIDES QUITE A RICH UNSTABLE ATMOSPHERE AND, COUPLED DIURNAL HEATING WITH SEVERAL HUNDRED J/KG OF CAPE, POSSIBLY EXCEEDING 1000J/KG ACROSS PARTS OF THE MIDLANDS AND EAST ANGLIA, THUNDERSTORMS ARE EXPECTED TO DEVELOP QUITE WIDELY ACROSS THE REGIONS MENTIONED ALTHOUGH CLOUD COVER MAY MIX OUT DEVELOPMENT. STRONG UPDRAUGHTS BRING HAIL WITHIN THE MORE POTENT THUNDERSTORMS ALONG WITH HIGH RAINFALL RATES.

THIS WATCH MAY BE UPDATED OR UPGRADED. PLEASE MONITOR WEATHER AND TRAVEL INFO AS NECESSARY.

21st OWS have a similar pattern:

Wow look at the spread of the MLCAPE!

and the SBCAPE up the Western side of the country:

Wales very likely storm central today?

But then convergence and shear right through the middle of the Country:

More rain in the North:

Low level LAPSE rates encouraging:

and the higher level ones, again more towards Wales and the Mid West in the middle of the afternoon:

Tornado alley in the blue area?????

Hi-Res HiRLAM has it more towards the East and Central later:

and they have various pockets of convergence breaking out which would be messy and widespread:

Their spout index shows possibilities right down the Eastern side of the UK mid afternoon, so keep an eye out!!!

Tornado chances to the Eastern side for them:

Simple GFS overview goes like this:

Wowsers!!!!!

I can think of a few people who will be pretty excited by today's chances and it's going to compete strongly with the Olympic coverage in some households!!!!

Good luck all

[Cloudwatcher]

Can't see us getting anything today, anything coming up from North Wales tends to get killed by the Clwydian Hills well before it gets to us. Getting my comfy seat ready in the NSC for another day of disappointment, Good luck all!

[A.J]

sods law isn't it?.....I'm in Torbay for the weekend (currently nursing a hangover from last night's excesses!...lol) and it looks like the Midlands could get some lovely thundertorms!......Well, I'm back home tomorrow afternoon, so hopefully might catch something up there then if the risk persists!