Astronomy, Photography and Weather

General Category => Weather & Atmospherics => Topic started by: martinastro on June 28, 2009, 02:01:34 pm



Title: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on June 28, 2009, 02:01:34 pm
Thought I would make a start on this thread and will add to it on a daily basis. This is to the cover the potential for the week running Monday June 29th to Friday July 3rd 2009. There may well be some marginal convective potential at the start of the week, however later, from Wed onwards, models are indicating a high risk of thundery activity and even severe thunderstorms across parts of Ireland, N. Ireland and Britain with the areas further south most at risk due to high temps (heat wave) and humidity. There may be a risk of night storms also. Some parts of Ireland should see good storms however it's central Britain which can expect the chance of severe storms. Looks like an exciting period ahead which will no doubt produce some great images and a risk of funnels and tornadoes.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on June 28, 2009, 02:14:56 pm
Here's some of the CAPE and LI charts for Tues, Wed, and Thurs. No doubt these will chance signifcantly before then.

(http://i40.tinypic.com/296kfn5.jpg)

(http://i41.tinypic.com/1qqzp5.png)

(http://i44.tinypic.com/14ujghi.png)


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: markt on June 28, 2009, 02:35:29 pm
Great thread Martin!  Tuesday looks 'interesting' for us in the Midlands to say the least :p


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on June 29, 2009, 01:25:27 am
(http://i43.tinypic.com/20igv91.png)

Storm Forecast Issued: 2009-06-28 23:05:00
Valid: 2009-06-29 00:00:00 - 2009-06-29 23:59:00

Regions Affected
Wales, West Country, S,W+N Midlands, Northwest England, Central Southern Scotland ( parts of Central Southern England, Southwest England and much of Scotland are included in the WATCH )

Synopsis
High pressure over Scandinavia continues to affect the weather across the UK. Weak capping is likely to be in place initially, and so initiation of thunderstorms may take until mid/late afternoon in some parts. Mountainous areas are likely to benefit the most with both lifting mechanisms and local convergence zones present. Surface heating will be required significantly in non-mountainous areas for storm initiation. As a result, it seems any storms will be isolated but very slow moving, with the potential for flash flooding from prolonged torrential rain. Any storms that do develop during the day should move in a N/NW direction. Areas currently with the most favoured conditions are thought to be N/NE Wales and into NW England. Most storms will decay during the evening fairly quickly, but may persist a little longer across Northwest England. There is a risk of a thunderstorm across the Northwest Highlands, but the risk at the moment seems too limited for the THUNDERSTORM region to be extended here. There is also a small risk of elevated thunderstorms moving up from northwest France/Brittany area into SW/CS England late in the period, but similarly the risk is currently too low to be included on the map. We will monitor the conditions during Monday and may issue an update if necessary.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: Big Dipper on June 29, 2009, 01:34:30 am
Excellent news & thanks for posting Martin. I'm really looking forward to the week ahead now, weatherwise (bar the temperatures which do not suit me at all)!


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: markt on June 29, 2009, 07:39:53 am
Thunderstorms missed us yesterday, wonder how we will fare today?  I suspect it will be lovely while i'm at work, then when I get back and want to image the sun it will be torrential...  :P


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on June 29, 2009, 01:10:41 pm
Hey guys, here's the latest forecast from Tony Gilbert...

(http://i40.tinypic.com/288crvs.jpg)

Slight Risk of isolated Thundery Showers Wales, Midlands, NW UK and Scotland. 15Z-21Z

Marginal risk of Brief Tornado NW Wales (Red Box)

Ridging continues to build from the west, whilst the east side of the convective watch is now showing some better vertical lift derived from the upper trough. Strong capping will exist south of Thames Valley.

Today's convective outlook will be directly associated with the level of surface heating available, delivered under clear skys. Though given the sharp divergence at lower mid level we can expect any convective  initiation to pull aloft quite rapidly. Surface moisture is rather lean until late in the day. Hense a watch issued from 15Z onwards. Though orographic lifting could bring this slightly forward over N.Wales. I am encouraged by the dry air incursion above 600mb. Though with earlier lean moisture we can expect convection to remain rather scattered and isolated early in the period.

I do not really see any significant  convergence as has been mentioned earlier on this thread. Except for a small risk around NW Wales. It is here that we have a marginal risk of a brief tornado derived from low level vertical shear. I would also expect to see some good rotating cloud bases here. All dependent on an onshore breeze developing. This risk is considered brief due to lack of upper shear and the fact that storms are likely to be sustained for any length of time.

IMO and based on the most recent model output we can expect the Midlands to deliver the best sferic activity today.

PS. If I lived in NW Wales I would be taking the day of work in anticipation of a localised threat. Do we have any members in that location?


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on June 29, 2009, 01:13:05 pm
Check out this stunning funnel over the UK recently...

http://twitpic.com/8qmsu

and this wonderful video of a UK funnel on the 25th...

http://www.youtube.com/watch?v=yWEhQ8SbwVI


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: Tyler on June 29, 2009, 03:00:47 pm
based on the pic, you could call that a tornado. The condensation hasn't hit the ground, but it's so close that I'm 80% there is ground circulation on that.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: JohnC on June 29, 2009, 05:24:41 pm
Cheers, Martin. A chart I can, at last, understand re. CAPE. Would you mind posting the link please.?


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on June 29, 2009, 05:52:57 pm
Hi Tyler, I agree 100% with what you said about the funnel in the pic, being so low the vortex was probably on the ground for sure. I believe TORRO will be investigating this one, probable touch down.

John, I'm glad you found those charts useful. Here's the link...

http://www.netweather.tv/index.cgi?action=nwdc;sess=

These are the netweather GFS CAPE and LI charts which are very accurate. I use them all the time. Just click the + symbol and you can forward into the future and see which days are potential storm days, you can select a drop down menu and check for precip type etc too. They are updated at 18.00, 00.00, 06.00 and 12.00 each day so they need to be checked constantly to see if the CAPE has been updraded or downgraded. Hope this helps  :)


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on June 29, 2009, 10:08:55 pm
Outlook for Tues, will update what Tony Gilbert says when he gets a forecast sorted.

(http://i43.tinypic.com/2zgsww1.png)

Storm Forecast Issued: 2009-06-29 20:44:00
Valid: 2009-06-30 00:00:00 - 2009-06-30 23:59:00

Regions Affected
Northern England, Wales, N,W+S Midlands, West Country, parts of Southwest England ( much of mainland Scotland, Northern Ireland and remaining areas of Midlands and CS / SW England are included in the WATCH )

Synopsis
High pressure over Scandinavia continues to affect the weather across the UK. A plume of warm and moist air advects northwards out of NW France on Monday evening/night, and is likely to bring scattered showers or elevated thunderstorms to some southwestern/central-southern counties during the early hours of Tuesday morning, moving north into East Wales/W Midlands by dawn. Although these showers may weaken and decay during the morning hours, further thunderstorms are expected to develop within the THUNDERSTORM region on the map. Initiation should be sooner than on Monday due to a more favourable atmosphere and so from early/mid afternoon seems more likely. Slow moving storms are likely to pose a flash flooding risk, and also hail. Most storms should move in a N/NW direction. Some thunderstorms may persist for most of the evening, particularly in northern England, with a low risk of further elevated storms moving across the Channel in the late evening hours.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: scott86 on June 29, 2009, 10:09:12 pm
very thundery looking down in the lisburn area, nice boiling congestus and cbs in the vicinity and just had a brief shower, any chance of a storm do u think folks?


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on June 29, 2009, 10:14:27 pm
Hi Scott, thanks for the report, I seen alot of weak mid level instability here...altocu castellanus. There's some rain moving up over Ireland from the SW, might be thundery in some parts but slim in the north. Of interest is the elevated unstable layer moving up from France, currently over Britain, which may arrive over eastern areas of NI late tonight/Tues morning..might just be rain though. Will wait and see what the experts think. Current charts show Wed, Thurs, and Fri (poss Sat too) as potential storm days for Ireland/N. Ireland but the charts keep changing like crazy with each update..very difficult to nail anything down. Let's see what Tony Gilbert says closer to the time. Certainly very warm and humid tonight. Fingers crossed... :)


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: scott86 on June 29, 2009, 10:21:14 pm
i think a late night may be in order to see if anything happens!


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: Padraig OBrien on June 29, 2009, 10:36:32 pm
I tought i heard a rumble of thunder during the band of rain that moved over ireland last night which was hefty enough here but the sound was drained by the ACDC Coldplay concert near me but i confirmed with me friend that he saw a flash of lightning


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: brianb on June 29, 2009, 11:44:42 pm
Quote
i think a late night may be in order to see if anything happens!
Far too warm to sleep. Or do anything else for that matter. Back to normal service PLEASE this heat is UNBEARABLE.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: Big Dipper on June 30, 2009, 12:35:02 am
Far too warm to sleep. Or do anything else for that matter. Back to normal service PLEASE this heat is UNBEARABLE.

Glad you posted that Brian - I was beginning to think it was just me! Just been out looking at the sky quality. Temperature far more pleasant nowbut the sky is too bright for me to bother setting up for imaging.
'Tis my cat I feel really sorry for................he's a long-haired moggy & to top it all, his coat is mostly black!


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on June 30, 2009, 01:07:01 am
Yes, warm, humid and very uncomfortable...not much sleep tonight.

Latest GFS is out at 00.00. Britain is still on go for storms however the Ireland/N. Ireland CAPE and LI has been downgraded big time. There will still be a chance for storms but the CAPE is nothing like it was progged earlier...grrr. However, it has upgraded Sat and Sun as the best days with just under 1000 CAPE on Sun with LI of -3 so this thundery period will extend for longer than expected. With the way the models are chopping and changing so much with each run anything is possible this week and weekend...let's wait and see.

In the meantime there have been some sferics over the W coast of Ireland tonight and Britain also. Something could explode over the S of the UK tonight with cells/storms crossing the channel.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on June 30, 2009, 09:47:39 am
(http://i39.tinypic.com/24fkaa8.jpg)

Storm Forecast
Valid: Tue 30 Jun 2009 06:00 to Wed 01 Jul 2009 06:00 UTC
Issued: Tue 30 Jun 2009 05:07
Forecaster: VAN DER VELDE

A level 1 was issued for the United Kingdom for excessive rainfall.

SYNOPSIS

Europe is largely free of synoptic scale low and significant high pressure systems, but the airmass is unstable over a large area. A weak upper ridge stretches from the Iberian Peninsula to Scandinavia, while 700 to 300 hPa heights are lower over the Balkan. A frontal system belonging to an Atlantic low will drag over Ireland and Great Britain.
Due to weak wind profiles, shear is less than 10 m/s virtually anywhere, and storms will tend to move very slowly, contributing to pulse type storms with local flash floods, to possibly more excessive convective rain events near persistent convergence zones. Isolated landspouts are also not ruled out.

...UK and Ireland...

A nearly saturated airmass with large precipitable water content is advected from the south and CAPE is predicted to develop, mostly over Wales and N England. Storm motion will be relatively slow and oriented along the source of lift. Regenerating convection may therefore keep training along a line for extended periods, leading to flash floods, while large scale models may underestimate precipitation. In Ireland the same moist airmass passes but with almost no instability (elevated), may need to be upgraded later on. The moisture load, weak lapse rates and deep warm cloud depth may reduce electrification.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: markt on June 30, 2009, 10:28:02 am
Makes for an interesting forecast for today!  Grey and drizzly here atm, the sun hasn't come out long enough to generate any real heat.  We have a 'new staff barbeque' after work at 3.30 this afternoon, so I reckon the cloud / rain Gods will probably look unfavourably on us for then  :P

They have 'planned' for it though and have a gazebo to put it under, though somehow I suspect it may be rather small scale for the size of deluge we're expecting...  ;)


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on June 30, 2009, 12:18:27 pm
Hi Mark, I hope it works out for you and that you get a good day, anything which does develop will likely be localized which usually is the case with these events. At this moment in time there are storms entering the S coast of Britain from the channel and moving N. Showers are breaking out further N too. Once the greatest heating period of day the occurrs then that's the main t-storm potential. Good luck...if you want a storm, or just a good day  :)


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: brianb on June 30, 2009, 12:33:47 pm
Quote
They have 'planned' for it though and have a gazebo to put it under, though somehow I suspect it may be rather small scale for the size of deluge we're expecting...
Lightning conductors? If not, better to lie face down in the mud....


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on June 30, 2009, 01:58:16 pm
Very intense rainfall over S. Ireland at the min moving NE, showing up red on the radar, no sferics though.

Latest update shows that the thunderstorm potential will last into late next week so the thread title will need to be changed at some point.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: markt on June 30, 2009, 05:11:48 pm
Nothing has really developed where I am today - very muggy, grey and with the occassional spot or 3 of rain.  Oh well  ::)


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on June 30, 2009, 07:16:24 pm
The main storms today have formed over S. Britain, N. Britain , Scotland, with the most intense storms over Wales..there will plenty of more chances to come  :)


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: markt on June 30, 2009, 08:30:34 pm
The main storms today have formed over S. Britain, N. Britain , Scotland, with the most intense storms over Wales..there will plenty of more chances to come  :)

It's ironic you know - the 'weather head' in me looks forward to exciting (read active) weather - however the astronomer in me yearns for clear skies (and hence realtively boring weather) - can't win em' all I guess  :P


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: brianb on June 30, 2009, 08:37:00 pm
Quote
the 'weather head' in me looks forward to exciting (read active) weather
The "weather head" in me hurts when there's thunder about. It's hurting now.

Quote
can't win em' all I guess
Don't see why not - it can do whatever it likes when the altitude of the Sun is in the range +6 to -9 degrees (approx) - just so long as it's cloudless in between times. And preferably around 0C, with a wind about force 3 is ideal.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: markt on June 30, 2009, 08:49:07 pm
Don't see why not - it can do whatever it likes when the altitude of the Sun is in the range +6 to -9 degrees (approx) - just so long as it's cloudless in between times. And preferably around 0C, with a wind about force 3 is ideal.


Lol, when you look at it like that I guess you're right.   ;D


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: JohnC on June 30, 2009, 10:39:35 pm
Great, thanks for that, Martin.

Our regional weather presenter tells us this evening that Thursday is going to be the day for heavy and frequent TS's. We'll see.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on June 30, 2009, 11:15:47 pm
Hey John, I don't trust the TV forecast that much as you know but it should be interesting to see what they go for. Here's Wed's outlook from ESTOFEX. There might be a low risk of thunder for Ireland also, but it's low.

(http://i41.tinypic.com/fe2p6r.jpg)

Storm Forecast
Valid: Wed 01 Jul 2009 06:00 to Thu 02 Jul 2009 06:00 UTC
Issued: Tue 30 Jun 2009 21:57
Forecaster: GATZEN

A level 1 was issued for the north-eastern British Isles for excessive rainfall.

SYNOPSIS

Large-scale weather pattern has not changed significantly across most of Europe. To the east of low geopotential over the northern Atlantic, the airmass is unstable over a large area in the range of weak geopotential gradients. A weak upper ridge stretches from the Iberian Peninsula to Scandinavia, while mid-level heights remain lower over the Balkan. A frontal system belonging to an Atlantic low will affect Ireland and Great Britain.

For most of Europe, weak vertical wind shear is forecast, and storms will tend to move very slowly, contributing to pulse type storms with local flash floods, to possibly more excessive convective rain events near persistent convergence zones. Isolated landspouts are also not ruled out.

Across north-western Russia, rather strong vertical wind shear is expected in the range of an amplifying short-wave trough moving eastward, and vertical wind shear will likely overlap with instability. Mid-level winds will also increase compared to yesterday over extremely western Europe as the Atlantic trough slowly moves eastward, but low-level cold air advection is expected to limit convective potential there.

UK

A nearly saturated airmass with large precipitable water content is advected from the south and CAPE is predicted to develop especially over the central portions. Storm motion will be relatively slow and oriented along the source of lift. Regenerating convection may therefore keep training along a line for extended periods, leading to local flash floods. In Ireland the same moist airmass passes but with almost no instability due to rather cool low-level air masses.

The UKASF forecast has a wider area in the watch box.

http://ukasf.co.uk/module-Storm/


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on July 01, 2009, 12:52:07 pm
Here's the CAPE and LI charts for today. Britain is on go for t-storms and TORRO have a tornado watch out for central and N areas of Britain.

http://www.torro.org.uk/site/forecast.php

Note also that the instability has been upgraded for N. Ireland today during the afternoon with central and W areas showing the best values. If there's any solar heating then some heavy showers should develop and perhaps an isolated thunderstorm, there is a risk of funnels here also.

(http://i41.tinypic.com/2wfmyc9.png)

Thurs should see the risk of severe weather for Britain, Ireland, and N. Ireland due to an advancing cold front colliding with this unstable air.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on July 01, 2009, 05:32:47 pm
Bridge collapsed in County Durham due to heavy rain.1 person trapped.

http://news.bbc.co.uk/1/hi/england/wear/8128977.stm


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: markt on July 01, 2009, 08:03:45 pm
Been another muggy and humid day here in the West Midlands, somewhat overcast which is rather annoying as i've just got a barlow and focal reducer to use for Ha imaging of the sun.   Will be interesting to see how quickly tomorrows weather will push in from the west :)


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on July 01, 2009, 08:16:00 pm
The following is a Convective Watch issued by the Irish Weather Network on 01 July 2009 at 19.00 Hrs. The risk remains valid at present until at least 12 Hrs on Thursday 02 July 2009.

Convective Watch - Issued at 19.00

For the coming 24 Hours, a southerly flow containing extremely humid air will cover Ireland. Dewpoints will be very high within this flow & conditions will remain humid to exceptionally humid. Later tonight and into tomorrow, there is at least a 40%-50% risk of thundery rainfall spreading into southern and southeastern districts. Such thundery rainfall, along with the possibility of embedded thunderstorms will then transfer due north over the course of the morning, affecting many eastern areas whilst continuing to transfer northwards. There is the potential for localised flooding in some areas along with the prospect of a difficult morning commute. Later into the afternoon, whilst conditions should gradually begin to clear across eastern districts, there is a threat of heavier showers or thunderstorms further north and west.

The first developments in terms of thundery rainfall are expected to arrive in southern and southeastern areas at approximately 03 Hrs on Thursday morning. Thundery rainfall is quite likely to develop, transferring northwards on a gradual basis. There is also a risk of embedded thunderstorms, leading to localised downpours and potentially localised or spot flooding in some areas, especially further south and east at first.

Predicated Rainfall At 6 Hrs - Thursday

(http://i42.tinypic.com/vnnjtw.png)

The morning commute may well be particularly difficult across many eastern areas tomorrow morning, with thundery rainfall & isolated thunderstorms, making for very difficult driving conditions. Localised accumulations of in excess of 20mm of rainfall are quite possible during this period, most especially across southeastern, eastern and northeastern districts.

Present indications suggest the risk to be most significant towards 12 Hours, before diminishing later into the afternoon in eastern areas.

Predicted Rainfall At 9 Hrs - Thursday

(http://i40.tinypic.com/1zvtkea.png)

However, it should also be noted that there is a risk of thunderstorms breaking out further northwest into the late afternoon in the very humid conditions.

Summary

In summary, thundery rainfall will spread from the variable south overnight, arriving in southern and southeastern districts during the early morning before spreading further northwards to affect many eastern districts towards 09 Hrs. Embedded thunderstorms are possible along with the potential for localised flooding and significant surface water accumulation. Driving conditions may become very dangerous in eastern and southeastern areas during the morning commute. The risk also transfers to northeastern areas by 10Z, with the potential for thunderstorms further north and west later into the afternoon. A further update will be issued when more guidance becomes available.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: Padraig OBrien on July 01, 2009, 08:18:31 pm
I  just got notified that one of are friends down it Wexford county had a bad thunderstorm last Sunday evening and about 5 km form them two horses were killed by lightning so unfortunate


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: Padraig OBrien on July 01, 2009, 08:24:41 pm
Hi Martin im smack down right in the middle of that yello on the map


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on July 01, 2009, 08:53:49 pm
Thanks for the report Padraig...that's terrible about the horses!. There was a 17 year old killed by lightning in Birmingham recently. Here's an interesting forecast from ESTOFEX...

(http://i41.tinypic.com/2qmg9hz.jpg)

Storm Forecast
Valid: Thu 02 Jul 2009 06:00 to Fri 03 Jul 2009 06:00 UTC
Issued: Wed 01 Jul 2009 19:31
Forecaster: PUCIK
A level 1 was issued for Great Britain and Ireland mainly for excessive precipitation

SYNOPSIS

Rather inconspicuous synoptic setup has established over Europe and no major changes are anticipated during this forecast period. A ridge of slightly higher geopotential heights at midlevels will stretch from SW Mediterranean into Scandinavia. To the east, a shallow trough will reside over Russia, Ukraine and Balkan states. The only apparent change to the setup is an approaching short-wave trough, which is predicted to affect the weather across Great Britain, Western France and Spain. Frontal system, associated with it, will cross the area in the late evening and night hours.

Widespread diurnally driven thunderstorms are expected over most of Central, Western and Southeastern Europe. In weak wind shear, thunderstorms will stay mostly poorly organised. Due to the slow motion of individual cells, high moisture content , local heavy rainfall event is quite possible, especially over the mountainous areas.

DISCUSSION

...Great Britain...

Ahead of the approaching cold front, soundings suggest that an unstable air mass has developed over the islands.
air-mass or air mass, not airmass, as far as I know Thunderstorms have already commenced (as of 18Z Wednesday) and for this forecast period, two rounds of convection are possible. GFS suggests that an MCS will affect southern parts of England, Wales and Ireland by early morning and noon hours, developing in vicinity to the cold front and moving northwards. Another round is possible in the afternoon and evening hours, mainly over Scotland and England, where models hint on enhanced CAPE values. Due to the high moisture content of the troposphere, slow motion and predicted formation of convective system, it seems possible that significant precipitation amounts could accumulate locally.

Poland, Czech republic, Southern Germany, Eastern Austria, Italy and Balkan states...

12Z Tuesday soundings have shown that moderate instability has developed in this region, with MLCAPEs even above 1500 J/kg at a few locations. A very similar situation will also develop this forecast period, with rapid destabilization as surface heating commences. Warm, well-mixed and humid airmass will therefore allow for another round of convection. Wind shear will stay very weak, so the storms will not become better organised than in multicell clusters. Nevertheless, slow storm motion and high moisture content (Tds approaching 20C) will allow for localized heavy rain events, especially in the mountainous areas. In multicells, we can not even rule out a large hail event, mostly over Poland or northern Italy, where the highest values of instability should be realised. Enhanced Delta Theta-E values ( locally over 16 K) suggest that slightly severe wind gusts might also occur (again, with Poland being the place with the highest probability of this threat when compared to the rest of Level 1 regions). Due to low LCLs, weak wind fields and high CAPE release in the lowest 3 km, landspout type tornadoes might occur, especially tied to the local convergence zones.

... Vologda oblast and surroundings....

With the approaching trough from NW and associated PVA, cyclogenesis is forecast by models and a low level flow should strenghten considerably, resulting in high LLS values, locally up to 15 m/s as forecast by GFS. Moreover, prominent veering of the winds with height will result in high SREH values. Slight instability, with MLCAPE values less than 1000 J/kg will develop in vicinity of the surface low. As models show that instability will overlap with enhanced LLS and SREH, slight chance of tornadoes is forecast for the region in Level 1.



Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on July 01, 2009, 09:42:58 pm
(http://i41.tinypic.com/2mpxtfq.gif)

Look at the large white cloud over France, that's a Mesoscale Convective System (MCS), a huge storm system which is currently moving N towards the UK with another further W which will track up through Ireland. It might make land fall during the early morning hours and move across the country. Thurs can go either one of two ways, the first is a non event with just heavy rainfall, the second being a spectacular storm event, possibly the best since 2005/6. Time will tell, although I'm only expecting rain here tommorow, anything sparks would be a bonus.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: Padraig OBrien on July 01, 2009, 09:53:16 pm
ye im always it will hit the coast full force and then weakean over land but i have high hopes


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on July 02, 2009, 01:39:17 am
Padraig, if you are still up, there's lightning from those storms off the SE coast of Ireland, the flashes should be visible at night.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on July 02, 2009, 03:54:31 am
It's almost 04.00 in the morning, the radar is crazy over the Republic of Ireland, absolute torrential rainfall, red and white on radar, and producing lightning. Thunder being reported and big flashes, it's moving N and might cross into N. Ireland by day break.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: Padraig OBrien on July 02, 2009, 04:11:39 am
Very strong activity here


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: Padraig OBrien on July 02, 2009, 04:47:55 am
just wathing the radar carefully very loud thunder here earlier  but im starting to see more lightning in the distance south of me torrential rain i woke and there was alarms going off so i knew something big hit the area im seeing a lot of flashes coming form the dublin area


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: Padraig OBrien on July 02, 2009, 05:32:31 am
Wat an early morning ive had ive heard dublin got hit bad around 4 o clock met eireann reporting heavy thunderstorms around Dublin and county suburbs


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: Padraig OBrien on July 02, 2009, 06:02:06 am
Large parts of Dublin, Kildare,Wicklow,Wexford have been affected by flooding the rain is torrential with these storms

Just heard that the M50 Motorway the main motorway around Dublin is flooded and closed on one side

Rail services are also affected by flooding

One of Dublins main hospitals (The Matter) roof has partially collapsed

Very heavy surface water on all main Motorways into Dublin

Over 40mm of rain in one hour around dublin and eastern parts of Kildare county

Power is out in some suburban areas

Over two weeks of rain just one hour

Many Motorways and roads around Dublin are now declared impassable commuters told to stay at home

Reports of that the entire Dublin coast road is impassable and that theres a watch that conditions could get worse due to high tide at 08:40

Most flooding has now subsided around the greater Dublin area but damage has been caused in many areas


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on July 02, 2009, 12:21:26 pm
Hi Padraig, the Dublin area got hit really bad didn't it. I knew from the radar last night that a significant event was taking place. I'm just after seeing 'Midday' on TV3 and a man was interviewed who had his backgarden destroyed by severe flooding, so much so that the sheds had been ripped from the ground. He also reported giant hail stones and terrible thunder. Those storms traked up the E coast of Ireland into NI today.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on July 02, 2009, 12:24:19 pm
One of the halls in Maghaberry Prison, NI is flooded according to the BBC.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on July 02, 2009, 12:39:53 pm
(http://i42.tinypic.com/29qnwig.gif)

Here's the sferic chart from this morning, you can see the S-N path of that storm up the E side of the country!

I heard intense rainfall here around 05.30.

TORRO have issued a tornado discussion for all of Ireland today.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: Padraig OBrien on July 02, 2009, 12:44:43 pm
That certainly explains the spectaculur display i witnessed last night


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on July 02, 2009, 01:05:13 pm
Just seen RTE news, a guy reported water half way up his stairs in Dublin.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: scott86 on July 02, 2009, 01:22:10 pm
i got woke up this morning at around 6.am with a huge clatter of thunder and the heaviest rain ive seen in a long time! the lightning was quite obscured by the rain but the thunder was extremely loud!


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on July 02, 2009, 01:50:33 pm
Thanks for the report Scott. This from the BBC NI site...

Warnings of severe or extreme weather in some parts of Northern Ireland have been issued by the Met Office.

Heavy and thundery rain is likely to affect all six counties on Thursday morning.

There will be further pulses of heavy rain in the afternoon and the risk of thunderstorms.

The Met Office has said there is the potential for some localised flooding because the system is very slow moving.

Parts of the north and east will hold onto dryer conditions for a time but the wet weather is slowly shifting across towards the Irish Sea and there will be some heavy showers in that area later.

People asre being advised to take extra care on the roads.

One of the visits halls in Maghaberry Prison is flooded following heavy rain last night.

The Prison Service has temporarily closed the hall for urgent remedial work to be carried out.

It is contacting visitors who will be affected by the flooding to re-arrange their appointment.

The flooding incident phoneline is 0300 2000 100.



Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: scott86 on July 02, 2009, 01:54:31 pm
fingers crossed for something later! Much happening up in your direction?


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on July 02, 2009, 01:56:05 pm
Not a thing here Scott, just light rain, maybe something will kick off from those showers behind the cold front....

(http://i44.tinypic.com/2hd2zcm.jpg)

TORRO CONVECTIVE DISCUSSION 2009/020

A TORRO CONVECTIVE DISCUSSION has been issued at 11:15GMT on Thursday 2nd July 2009

Valid from/until: 11:15-21:00GMT on Thursday 2nd July 2009 for the following regions

Parts of (see map)

SW England

Midlands

NW England

Scotland

Wales

Eire

N Ireland

THREATS

Marginally severe hail; isolated tornadoes; gusty winds; heavy rain; CG lightning.

DISCUSSION

Three potential areas of convective development seem possible today: West of the cold front, across Eire and western parts of N Ireland; along the cold front, through SW England, Wales, and western Scotland; in the moist plume ahead of the cold front, from the Midlands through parts of NW England into central Scotland.

West of the cold front, several hundred J/Kg of CAPE are forecast to develop across western Eire/W N Ireland, with reasonable shear. Loosely organised clusters may develop with a marginal severe hail/wind threat.

Along the cold front axis, elevated and perhaps embedded surface based showers/storms are possible, although the overall coverage of thunderstorms may be fairly low. Any storm which develops will do so in an environment favourable for gusty winds/marginal hail, as well as producing heavy rainfall.

Ahead of the cold front, there are indications that isolated storms may form across parts of the Midlands and then move NNW into NW England. Shear may be sufficient for a small loosely organised cluster capable of producing marginally severe hail, along with frequent CG lightning.

In the same airmass across Scotland, there is likely to be somewhat stronger shear, perhaps enough for weak mesocyclone development. This would enhance the wind/hail threat, and given an increasing low-level flow, a tornado is possible too.

Lack of stronger shear precludes a WATCH

Overnight tonight, there is a risk of thunderstorms spreading into southern counties of England, along with increasing deep-layer flow. These could bring the risk of marginally severe hail and winds.

Forecaster: RPK.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: scott86 on July 02, 2009, 02:01:17 pm
Thanks for posting that Martin, half of the weather websites are firewalled on this computer! lol


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: Padraig OBrien on July 02, 2009, 02:05:41 pm
About  8kms from me there are reports that the area had hailstones the size of 20cents coins for a brief time last night


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on July 02, 2009, 02:24:42 pm
Check out the weekend forecast here from Michael Fish on Netweather tv...

http://www.netweather.tv/index.cgi?action=michaelfish;sess=

Would love to see him back on tv again.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: scott86 on July 02, 2009, 02:50:58 pm
will have to have a look later,, being in work is like living in the stone age again as far as computers go! lol


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on July 02, 2009, 04:41:50 pm
Thunderstorms currently over W Ireland and moving N. Not much over N. Ireland other than some patchy rain moving north. N. Scotland and parts of Britain have storms also. Serious looking cells are crossing the Channel and headding for the S coast of Britain, they could produce some action this evening and tonight.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: scott86 on July 02, 2009, 05:05:12 pm
its just been a few spits and spots in belfast all day, extremely humid, which doesnt go well with the warmth, it was like walking into a wall of water when i walked outside, i feel sorry for the folks down in england, there was a picture on the bbc site of a guy who made his own cold room in his bathroom!


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: R Newman on July 02, 2009, 06:58:53 pm
There was severe Thunder storm to the west of me an hour ago in Ballina, but just like a week ago it missed me by several miles, the actual cell itself must be at least 40 miles wide see http://www.met.ie/latest/rainfall_radar.asp. Was very dark in that direction. wanted to drive into it but Babysitting so could not move :'( :'(

I really enjoy this site well done to Martin and his regular updates

Ronan Newman


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on July 02, 2009, 07:11:54 pm
Thanks very much for the feedback Roman and the report. There sure looked to be some big cells/storms in parts of Ireland today, all I want now is a few in the north so we can get some of the action.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: Padraig OBrien on July 02, 2009, 10:54:37 pm
Things a are starting to look very thundery down here id say somethings brewing to my south and pushing this way


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: R Newman on July 03, 2009, 12:02:12 am
Thanks Martin, Its Ronan, I know there is a Roman here on the boards, took two images two weeks ago  while driving home of a Cb and a possible Funnel cloud as I noticed a Wall Cloud lowering (more cows martin ;))


http://www.flickr.com/photos/galwayastronomyclub/3682285917/sizes/l/

http://www.flickr.com/photos/galwayastronomyclub/3682285923/sizes/l/in/photostream/

Ronan Newman


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: Padraig OBrien on July 03, 2009, 12:09:19 am
Lightning displays to my south now but no thunder


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on July 03, 2009, 12:40:39 am
There are storms in Ireland tonight again  :)

Friday's outlook....

(http://i39.tinypic.com/2ynmphj.jpg)

...THERE IS A SLIGHT RISK OFSEVERE THUNDERSTORMS FORECAST...

Synopsis
An upper ridge lies N across central Europe and the North Sea, upper low to the west of Ireland finally starts to shift eastwards towards UK. 22z analysis shows cold front lying St Malo-Swansea-Belfast, with thundery troughs across Normandy/E English Channel, W Ireland and N Scotland. By 12z Friday, cold front moving NE expected to lie Great Yarmouth-Edinburgh-Isle of Skye, by 24z Atlantic low and fronts approaches Ireland, while cold front clears NE from N Scotland with SW flow across UK.

... CENTRAL-S ENGLAND, MIDLANDS, SE ENGLAND, E ANGLIA, N ENGLAND, IRELAND & SCOTLAND...

Trough over Nern Scotland will bring further heavy downpours with isol. sferics over next few hours before fading. Some uncertianties to how quickly the cold front will clear through the UK during Friday after coming to a virtual standstill over SW UK during Thursday and not much movement this evening. However, approaching upper trough moving in from the SW will finally push the cold front NE towards the east coast by the afternoon, introducing less humid but still warm air in its wake. Tonight, thundery rain with isolated embedded t-storms will slowly edge east across SW England, Wales and eventually W Scotland and NW England. Post frontal airmass is also unstable across Ireland with further t-storms possible here overnight.

Further east, attention is drawn to thundery trough/vortex drifitng north out of Nern France which has developed MCS areas in response to slightly increased speed of upper winds on approach of upper trough to the SW and meso sfc low crossing the east English Channel ... one MCS area will likely push across Sussex/Kent and inland across the London area towards E Anglia, the other area clipping E Kent though it may merge. Storms within theses MCSs will be capable of producing torrential downpours capable of flash flooding, frequent cloud to ground lightning, hail to marble size and isolated wind gusts to 40-50kts. Therefore issue a SLIGHT risk of severe weather mainly for Friday AM as these storm areas move NE across SE England and E Anglia.

Further NW and W, forcing along cold front has weakened somewhat this evening, however, isolated t-storms may redevelop along the cold front as upper trough arriving from SW sharpens as it moves slowly NE across central England, N England and Scotland during the morning. These storms will mainly pose a threat with heavy downpours and cloud-ground lightning. This heavy thundery rain with isol t-storms will tend to become confined to Scotland and the east coast north of the Wash as the cold front continues NE, clearer less humid but still warm condtions will push in across much of the rest of the UK in the afternoon/evening. However, in post frontal airmass across Ireland, GFS develops several 100 j/kg of SBCAPE over the N and W as shortwave troughs in cyclonic SW flow help to create instability with sfc heating. So some thunderstorms are possible here in the afternoon and evening.

Issued by: Nick F - Forecaster for Netweather

ESTOFEX going for a larger risk area...

http://www.estofex.org/


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on July 03, 2009, 12:46:15 am
Hey Ronan, sorry about the name mix up  :). Thanks for sharing those two images which are great. That's a lovely looking cell, definitely looks like some kind of wall cloud or inflow feature in the first image, that storm is close to the ground too, the Cows really add to the scene. Love the images  :)


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on July 03, 2009, 12:57:27 am
Here's the current sferic (lightning) activity tonight....

(http://i41.tinypic.com/208tkcg.gif)

Active night t-storms in Ireland, Scotland, and a monster MSC moving across the channel towards the S and SE coasts of Britain..highly electrified!. Someone is going to have a wild night.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: Big Dipper on July 03, 2009, 01:11:38 am
Martin, just to second what Ronan said earlier on about keeping us updated. The only criticism that I have is that none of your storms have come my way as out yet  ;D - though that lot crossing the channel at the moment gives me some hope.

Anyway, thanks again for the time and effort that you've put in to this thread. The icing on the cake would be if I had something exciting to report, weatherwise like many others here.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on July 03, 2009, 03:34:01 am
Thanks very much Andy, I'm glad the convective outlooks are proving useful. I'm in the same boat as yourself, eveything seems to be missing here lately, maybe Fri afternoon will produce something. Fingers crossed.

Observed distant white flashes of lightning here between 02.30-03.00 BST.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on July 03, 2009, 10:27:19 am
Updated forecast from Tony Gilbert

(http://i41.tinypic.com/2rcl7kk.jpg)

Moderate Risk Thundery Showers 09Z-18Z Ireland & East Anglia UK

Thunderstorms continue effect SE UK through the morning and into early afternoon. These are primarily elevated and it is uncertain if these will become surface based given cloud cover reducing heating.

Ireland looks in line a stormy day. Conditions are enhanced by marginal vertical shear and mid level dry air moving north. Deep upper troughing from the west will sustain better lapse rates at all levels


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on July 03, 2009, 10:31:03 am
TORRO CONVECTIVE DISCUSSION 2009/022

http://www.torro.org.uk/site/forecast.php (risk map)

A TORRO CONVECTIVE DISCUSSION has been issued at 08:35GMT on Friday 3rd July 2009
Valid from/until: 08:35-21:00GMT on Friday 3rd July 2009 for the following regions of the United Kingdom & Eire:

Scotland

N England

Midlands & E Anglia

Eire

N Ireland

THREATS

Isolated funnels/tornadoes, marginally severe hail, CG lightning, torrential rainfall, gusty winds.

SYNOPSIS

High theta-e/w plume is slowly progressing NE across Great Britain. This will bring the chance of both embedded mid-level thunderstorm activity, and the chance of surface-based storm development through the remainder of today, from E Anglia NW'wards through much of N England into Scotland. Shear is marginally sufficent in these areas for loosely organised clusters, posing a slight wind/hail threat, along with heavy rain/CG lightning.

Across N Ireland, surface front is moving NE with some convective activity - a stronger storm is possible along this line before it moves into W Scotland.

Across Eire, vort max is moving into the SW ATTM and will move NNE through today. Surface based instability is expected to develop around and just ahead of it. Shear profiles are supportive of weak rotation, which could enhance a wind/hail threat. In addition, low-level shear profiles suggest a slight risk of a tornado.

Forecaster: RPK.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: scott86 on July 03, 2009, 10:52:31 am
looking very promising indeed!!


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on July 03, 2009, 03:49:36 pm
Storm in central Ireland moving NE, may arrive to the SE of Lough Neagh later.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 3rd
Post by: martinastro on July 03, 2009, 05:02:16 pm
Thunderstorm approaching SE NI visible to the SW.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 03, 2009, 06:26:15 pm
Thread title has been changed to accomodate the continuing t-storm threat which lwill ast until at least Tues July 7th.

Today was a complete bust up north, rubbish infact, the convection here was weak, heavily capped, and too dry looking despite hots temps and sunny sky producing intense solar heating. Very disappointing. Sun and Mon currently look really good for Ireland, N. Ireland and parts the UK...although that could change.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: Padraig OBrien on July 03, 2009, 11:33:24 pm
had a lot of action last night lots of lightning to my south


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 03, 2009, 11:35:30 pm
(http://i41.tinypic.com/2zfqwj5.png)

Storm Forecast Issued: 2009-07-03 23:21:00
Valid: 2009-07-04 00:00:00 - 2009-07-04 23:59:00

Regions Affected
Northern Ireland, Ireland, Scotland (excluding Shetland), Northern England, North Midlands, N + C Wales ( all of the UK, excluding SE England, are included in the WATCH )

Synopsis
An area of LOW pressure centred to the west of Ireland in the Atlantic will be the main dominating feature of the weather across the United Kingdom on Saturday. Numerous showers and thunderstorms are expected to rapidly develop during the morning across the western side of both islands (Ireland and Britain) becoming more widespread and moving eastwards into the afternoon. A broad area has been highlighted on the map due to the widespread nature of the showers, although not all of the showers will be electrified. Moderate winds will ensure the showers/storms should move through fairly quickly, so the flash flooding risk is somewhat limited to areas most prone to frequent showers. Ireland/Northern Ireland appears to have the most favourable environment, but since these showers will move eastwards, courtesy of embedded troughs and weather fronts within the westerly flow, local thunderstorms cannot be ruled out across Wales/Northern England/Scotland. Showers/storms will rapidly decrease in coverage and intensity during the evening, especially inland, whilst persisting across many western coasts into the night hours, especially over western Scotland and Ireland where they may remain electrified into the night.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: Padraig OBrien on July 04, 2009, 10:22:28 am
torrential rain here at the moment with one flash of lightning


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 04, 2009, 10:28:41 am
Thanks for the report Padraig, that rain looks nasty on radar.

Met Office have warning out for N. Ireland...

Heavy and thundery rain will develop this afternoon. 5 to 10mm could fall within an hour with 20mm or more in 3 hours.

The public are advised to take extra care and refer to the NI Rivers Agency for further advice on flooding and also to Traffic Watch (NI) for further advice on road conditions.

Issued at: 0952 Sat 4 Jul


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: Padraig OBrien on July 04, 2009, 10:37:47 am
Ye i heard that should be interesting very heavy rain down here i wasnt expecting this


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: markt on July 04, 2009, 11:26:50 am
Semi overcast and 'fresher' here for me today.  I'm sat waiting it to clear up a bit so I can go out and get a look at the new sunspot grouping that has appeared.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 04, 2009, 11:32:32 am
(http://i42.tinypic.com/1igck2.jpg)

Slight Risk of Strong Thunderstorms Northern Eire 12Z-21Z

Cold front already bringing heavy rain to eastern regions of Ireland. It is expected that convective showers will develop this afternoon on the flank of this current activity. Vertical shear up to 600 mb is quite pronounced and divergent allowing for good updraft / downdraft separation and dynamic lift. GFS develop strong CAPE values based on a very moist boundary layer and progressive solar heating as cloud clears from the west. Very dry mid level air overruns this surface moisture enhancing a rapid increase in lapse rates. Surface convergence is also increased as dry air from the west moves in behind the cold front.

Based on the current model detail it is possible that we may see a split cold front become apparent as the day progresses. ATM shear looks fairly straight lined, but given the mix of strong dynamic forcing,potential instability and vertical straight lined shear we can expect a defined risk for large hail reports & strong gusting wind (non severe)

Please Note; the above forecast is based on the GFS model. NNM differs in the main!



Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: scott86 on July 04, 2009, 12:00:36 pm
seen the remainder of that storm yesterday skirting the edge of belfast, it had somewhat weakened, no lightning,  but still had an impressive structure to it! a nice end to the day!


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: Padraig OBrien on July 04, 2009, 12:03:41 pm
Just had very heavy rain and hail embedded in some parts had one flash of lightning but that happened earlier


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 04, 2009, 01:11:49 pm
Very heavy rain here. More from Tony Gilbert...

Can't rule tornadoes out. But doesn't look like there will be enough low level shear! Though, potential instability could become very impressive indeed.

Risk box is extended into SW & west Ireland. Some Sferic already initiating NW Ireland



Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 04, 2009, 01:16:36 pm
Forecast from Netweather...

http://www.netweather.tv/index.cgi?action=convective;sess= (risk box)

IRELAND, N and W SCOTLAND & N ENGLAND...

Post frontal airmass in wake of occluding front moving NE is characterised by steep lapse rates given proximity of upper low and associated colder air aloft. As a result, with sfc heating and moist martime airmass, GFS develops several 100 j/kg of CAPE across Ireland also N & W Scotland this afternoon with heavy showers and t-storms likely to develop in an uncapped environment. Forced ascent of warmed moist air will likely be enhanced by upper level divergence within left exit region of a 100mph+ jet streak and associated shortwave troughs moving NE across Ireland and W Scotland. Presence of these stonger upper winds and tongue of dry mid-level air may see organisation of storms into multicell clusters or line segments capable of producing isolated marginally severe wind gusts reaching 40-50 mph. Also storms maybe accompanied by hail of up to pea-marble size and cloud-ground lightning. Given this threat for strong storms will issue a slight risk for Ireland. Overall shear will be fairly weak with little turning of winds up through the cloud layer, however, there maybe enough low-level shear over Ireland this afternoon - combining with any strong updrafts to allow an isolated weak tornado. A few thunderstorms may develop amongst the heavy showers across N England later this afternoon too, isolated storms may develop elsewhere outside the 'boxed' areas over N and W UK.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 04, 2009, 01:48:52 pm
Here's the gust front which arrived over my area last night at dusk from the W. It turned the sky black and was huge and evil in appearance. I had my family out looking at it. Some whale's mouth could be seen below it and behind where tall towers catching the Moonlight with stars above which was a nice sight. It only produced a light shower, although earlier in it's life it was a t-storm over central Ireland during the evening. Images at ISO400 and a few sec's.

(http://i43.tinypic.com/29oqsuv.jpg)

(http://i40.tinypic.com/nwaoe9.jpg)


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 04, 2009, 02:07:33 pm
Convection building rapidly here now that the Sun has broke out. Large towering cu shooting up at an impressive rate and moving at a very swift pace across the sky. Things certainly look more dynamic here today!


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: Padraig OBrien on July 04, 2009, 02:37:04 pm
Nice shots Martin reminds me of thursday evening when i could see flashes to the south the sky was very like yours not much action here since this morning


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 04, 2009, 03:15:27 pm
Cheers Padraig, there are storms moving up into NI now.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: markt on July 04, 2009, 04:41:49 pm
Squall line is just passing over here now.  Very black skies and very strong downdraughts...  No T&L tho...


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 04, 2009, 05:14:23 pm
Lots of t-storms over W NI, moving NE. The area around W and S Lough Neagh watch out soon.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: scott86 on July 04, 2009, 05:16:58 pm
send some over to belfast martin! lol :D


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 04, 2009, 05:21:21 pm
Huge cells reported from NI at the moment and active storms!. I forgot to mention...

No storms here but they might approach me soon. I have been out for a good while, great towering cu around, very hight and solid. Take this with a BIG pinch of salt, I noticed miles away to my SW a very large lowering shaped like a dark inverted bowl with on my horizon to the S side of the Sperrin Mountains, I watched it move dynamically for 10 min's until I lost it from view. It was just too far away for a decent image but it looked alot like a large wedge type tornado, it could have been low scud from a shelf but I didn't look like it to me, again just too far away, I would be interested to see if any other reports come in, I don't know for sure where it was located but from my view point looking at the SW horizon, it would have been between the W side of Slieve Gallion and the S side of the Sperrins...VERY far away. It looked very


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 04, 2009, 07:07:07 pm
Well, I went out after a tip off from Greg on te UKWW who mentioned the cell approaching here from 50 miles away, I looked above my house and was amazed to see the anvil directly overhead, it was HUGE!! with some mamma on it. This was blown many miles downwind from the storm itself. It took a long time to see the storm but when it arrived it was nasty!, deadly blue c-gs...very dangerous hitting outside the precip area, my nerves were on a knife edge, the thunder was like a gun shot then later like continuous rumbling. The rain from it was incredible, even frightening looking as it approached falling from the gust front over Slieve Gallion. Behind it was a double rainbow with thunder booming...fantastic. Now, there's another storm approaching....



Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 04, 2009, 07:20:24 pm
Anyone who lives in central or W N. Ireland might want to go chasing, there's a line of storms moving up from SW to NE and Tony Gilbert believes these are severe cells. The one which hit Maghera was photographed from 50 miles away with an overshooting top.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: brianb on July 04, 2009, 09:22:48 pm
A few flashes of ligntning & rumbles of thunder here this evening, and a prolonged but light shower of rain, less than 1mm in total.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 04, 2009, 09:44:17 pm
Just to follow up, 2nd storm passed through with stunning flanking line which produced a distant brief white rope funnel which didn't last long at all. However the convection was definitely severe looking!. Rock solid 'monster' cbs with mammatus and overshooting tops above Sperrin mountains all evening, I was in pursuit of these but they were too distant. I suspect another funnel or even a tornado report may yet come in if there are others with their eyes on the sky today. Quite a stunning evening!


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: Padraig OBrien on July 05, 2009, 09:59:41 am
Lokks like to be a very heavy shower to me south very like yesterday evening


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 05, 2009, 11:08:14 am
(http://i44.tinypic.com/fk2qg9.png)

Storm Forecast Issued: 2009-07-04 21:33:00
Valid: 2009-07-05 00:00:00 - 2009-07-05 23:59:00

Regions Affected
Northern Ireland, Ireland, Scotland (excluding the far east), NW England, Wales and SW England ( all of the UK is included in the WATCH )

Synopsis
Similar to Saturday, an area of LOW pressure centred just to the west of Ireland in the Atlantic will be the main dominating feature of the weather across the United Kingdom on Sunday. Numerous showers will be present even at daybreak across quite a few areas thanks to embedded troughs and fronts within the anticyclonic flow around the area of LOW pressure. Further showers and thunderstorms are expected to become very widespread across Ireland and Northern Ireland for much of the day, and increasingly so across Wales and Southwest England later in the afternoon and throughout the evening, due to an approaching occlusion. The showers will move in a northeastward motion across the UK - yet again a broad area has been highlighted, but not all of the showers will be electrified. Moderate winds will ensure the showers/storms should move through fairly quickly, so the flash flooding risk is somewhat limited to areas most prone to frequent showers (western parts of both islands in particular). Ireland/Northern Ireland, and later Wales/SW England appear to have the most favourable environment for thunderstorm development. Showers will decrease in coverage across eastern areas rapidly during the evening hours, but will persist across many western areas throughout the night, and so will the associated risk of thunder and lightning.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: Padraig OBrien on July 05, 2009, 11:24:25 am
Thanks for that Martin im hoping to get more significant stuff today just very heavy shower here at the moment lots of heavy showers in south leinster pushing northwards


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: brianb on July 05, 2009, 12:14:36 pm
Very odd here, there are signs of instability at upper and lower levels but maybe an inversion at mid level, though the fair weather cumulus have a lumpy top with no obvious signs of butting into a very stable air layer.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 05, 2009, 12:36:40 pm
There very well could be some kind of cap Brian which is one of today's restrictions. Strong solar heating or another form of lift will be needed to break through it. CAPE values over Ireland and N. Ireland this afternoon are between 1000 and 1200 with a lifted index of -3 and -4 so it's an extremely unstable enviornment out there today, as long as the cap can be broken through later. Tony Gilbert mentioned that the upper atmosphere is saturated which could inhibit growth. Worth keeping an eye on the sky today for funnels/waterspouts/tornadoes.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: Padraig OBrien on July 05, 2009, 01:17:12 pm
just had a very heavy hail shower up to pea size i can hear thunder rumbling to my east


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 05, 2009, 01:40:30 pm
Just checked the sferics charts Padraig, I can see those lightning strikes plotted to your E. There's more in central and N areas. Currently Ireland and N. Ireland is covered in showers, radar looks very busy, many of these have intensifed since the last update and are turning into storms.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 05, 2009, 02:06:15 pm
Convection is exploding up here, awesome towering cu with mushroom heads arranged in long lines and expanding in the hot sun. I'm surrounded by large anvils on either side of me here, although they are a little too wispy is profile for my liking. Judging by the updraught quality visible now I think there could be good action today somewhere. Shame about the lack of wind shear though.

Met Office have weather warning out for NI for Mon already.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 05, 2009, 02:18:51 pm
Here's a video still from Sat...

(http://i39.tinypic.com/2ce6uxw.jpg)

Note the c-g hitting down ahead of the approaching rain/gust front.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: Padraig OBrien on July 05, 2009, 02:31:06 pm
Ye i know its a really crazy radar my friend in Dublin said theres lightning there thats were im hearing the thunder from why is Dublin getting all the activity latly? :-\


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 05, 2009, 02:36:17 pm
No one knows the answer to that I'm afraid  ;)

Giant rock solid anvil W of Slieve Gallion, cells and convection are looking serious now. Bound to be a chance of a vortex from these.

Funnel cloud captured on webcam over S. Britian shore.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 05, 2009, 02:38:33 pm
Met Office warning for NI issued for today...

Showers will become locally heavy and thundery this afternoon and evening, with 15mm within a 3 hour period generally, and up to 30mm in places. Showers will slowly ease during the course of the evening.

The public are advised to take care and refer to the NI Rivers Agency for further advice on flooding and also to Traffic Watch (NI) for further advice on road conditions.


Issued at: 1318 Sun 5 Jul


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: scott86 on July 05, 2009, 02:50:36 pm
some serious convection down here in lisburn! the towers were shooting up at 10 this morning! havnt had a direct hit yet but some nice cells just passing to my east.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 05, 2009, 02:58:51 pm
Thanks for the report Scott. The convection is serious again today. The cells are producing gusty winds which are lifting my attic door up and down. Storms to the W and SW of NI at moment and wide spread showers. I haven't had thunder yet but the cells and updraughts are incredible, good chance of a tornado from those I should think.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 05, 2009, 03:06:15 pm
Current storms and large anvils over NI and SW Ireland...

(http://i44.tinypic.com/ig9fz7.jpg)

Credit: Sat 24

Current lightning activity from ATD sferics

(http://i39.tinypic.com/2eeynf6.gif)


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: Padraig OBrien on July 05, 2009, 04:04:02 pm
We just got hit by a bad enough storm i wasnt interested in the thunder and lightning but the wind that came with this was unreal and it so dark i was surprised theres wasnt a funnel cloud or tornado with it here some pics just taken now
(http://i727.photobucket.com/albums/ww271/pad199207/P05-07-09_154001.jpg)
(http://i727.photobucket.com/albums/ww271/pad199207/P05-07-09_1541.jpg)
(http://i727.photobucket.com/albums/ww271/pad199207/P05-07-09_1540.jpg)
(http://i727.photobucket.com/albums/ww271/pad199207/P05-07-09_1537.jpg)


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 05, 2009, 04:14:48 pm
Great stuff Padraig, that looks like a nasty gust front you had passing through, no wonder those winds were violent!.

Here's a video from Sat showing the approaching storm...

http://www.youtube.com/watch?v=jrBIDNiaTeY


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 05, 2009, 05:14:10 pm
The forecast is going for showers tonight, it might be a good time to watch for moonbows.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: Padraig OBrien on July 05, 2009, 06:42:42 pm
another gud storm to my east yet again wi gud rumbles of thunder and a bit of a shelf upfront but not heading my way


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: scott86 on July 06, 2009, 09:47:06 am
looks like the east is favoured for thunderstorms! hope something comes my way!


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 06, 2009, 10:26:16 am
(http://i41.tinypic.com/k3ur5x.jpg)

Moderate Risk of General Thundery Showers 06-21Z UK & Eire

Slight Risk Severe Thunderstorm Southern Ireland, Wales and Southern UK 06-18Z

Slight Risk of Strong Tornadoes Southern UK, Wales, E.Anglia and South Midlands 06-18Z

Probably the most serious forecast that I have posted to the UKWW so far this year;

Deep break away upper trough moves east through Monday increasing lift with steep lapse rates at all levels. Moderate divergent upper jet stream further increases lift with primary focus to the front left exit region. Increasing low level jet at 850mb establishes strong low level shear. Models currently develop high CAPE values as heavy surface moisture advects east mixing with mild air from the south. Potential instability is utilised as dry incursion pushes through inline with the predicted surface trough. Strong vertically stacked PVA max builds over Wales and moves east  adding to stronger convective potential.

Quite a day in store with potential for non severe convective gusts of around 30kts based on mean average values from 800mb to 600mb. Threat of large hail and defined risk of one or more strong tornado events are possible.

Particular attention is given to south Midlands  late in the day where the low level jet is shown to increase and overrun lighter winds at surface. Whilst winds would seem to be straight lined the speed shear should compensate to increase low level field vorticity. Upper winds are strong but show only slight increase with height hense a SLIGHT risk of Severe Thunderstorms is expected ATM.


UPDATE

As per earlier forecast with enhanced tornado risk zone (blue box) 15Z-18Z

Additional risk box added Scotland for enhanced risk of Convergence Zone Tornadoes.

Based on the most recent model update there would appear to be an enhanced risk for tornadoes this afternoon from north Dorset arcing through to E.Anglia where surface vector is reduced increasing LL shear. Upper dry air incursion times in nicely and pushes in from the west creating an arcing line of isolated strong convective cells. It is within this line that severe weather potential today will peak.

It is however noted that due to lack of any considerable veer at surface the risk for meso derived tornadoes today remains SLIGHT. A reminder that the broad coverage box does not mean that everyone in that box will see a storm today, but just that there is a defined risk. In fact I do not expect the thundery activity to be widespread in nature!


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: Padraig OBrien on July 06, 2009, 10:44:19 am
very interesting indeed lets hope for the best love to be over in the middle of the UK


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: Padraig OBrien on July 06, 2009, 04:26:04 pm
well today so far has certainly lived up to its forecast we had a very bad storm earlier on today cudnt take anything my phone went dead it was very solid structure but didnt last very long  im hearing further thunder to my NW and heading my way the sferics on the irish weather network over Kildare and Laois Countys


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: scott86 on July 06, 2009, 05:17:21 pm
barely a drip over belfast today  :(


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: scott86 on July 06, 2009, 05:51:21 pm
spoke too soon, mammoth shelf cloud right over head now! just waiting for some sparks!!!


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 06, 2009, 06:06:27 pm
Seen a wall cloud earlier but that was it. Instability is very week over NI this evening, storms everywhere else though. Any pics of the shelf Scott?


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: Paul on July 06, 2009, 06:12:36 pm
Quite extraordinary what a difference a few miles can make - torrential rain in Antrim - wipers on full speed, then from Ballyclare onwards, just 10 miles away, no evidence of any rain at all! Sunny here on the coast 20 miles from Antrim.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 06, 2009, 06:15:34 pm
I know what you mean Paul. Very sunny and hot here with some cbs over the Sperrins...yet others are getting hammered by storms today. Check out the lightning activity over the UK so far today...

(http://i40.tinypic.com/72vaj9.gif)


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: scott86 on July 06, 2009, 06:18:07 pm
unfortunately not,,everyday there has been some action i have been in work,, im constantly having to nip outside to get a quick look to see whats happening, the main area of rain just missed me but it looked very nasty over towards black mountain! it all seems to be dissipating now, but a lovely sight all the same! any action over your direction?


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: Padraig OBrien on July 06, 2009, 06:26:45 pm
Torrential rain here again but no thunder very active day here


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 06, 2009, 08:01:52 pm
Nothing of interest here Scott, there was great updraught towers early in the day and a wall cloud but then everything died out. I never expcted any t-storms in NI today due to building stability by the afternoon. I'm happy with what I seen on Sat though..I got my fix lol. This could be the end of the current thundery period until the next event. Chance of something on Tues for Britain but I think NI is out the game for the time being. Still plenty of more chances in Aug and Sept.  :)..glad you seen a cool shelf cloud though!


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 07, 2009, 12:41:27 pm
(http://i31.tinypic.com/15iatcz.jpg)

Moderate Risk of General Thundery Showers 09Z-21Z Central, SE and eastern regions of UK

Probably the last decent run of thunderstorms for a few days.

Occluded front looks to trigger further convective showers through Tues as CAPE values rise once again within a moist unstable climate. Upper cold pool moves slowly east but continues to influence central and eastern regions as surface temps rise. Vertical shear rather limited at all levels and upper levels are saturated up to the trop decreasing risk of any severe weather event. In addition to this we can expect some rather heavy cloud cover reducing insolation in many areas. Prime threat looks to be further localised flooding with slow moving storms.

UPDATE

As per earlier forecast. Whilst risk of Tstorms remains fairly moderate, the level of organisation within these storms looks rather poor. As mentioned by Paul, the whole set up looks to deflate by early evening as surface temps drop within the broad parameter of the outflow. A stray cell may venture toward the southern region of E.Anglia which could utilise some convergence and wind veer but not much else ATM.

Current CAPE overload looks based primarily on moisture advection. Though with expected cloud cover I'm not sure whether GFS predicted surface temps will be realised. Hense the predicted CAPE level is unlikely to be realised (opinion). This could well become evident on the next model output as the indices is adjusted likewise.


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: Padraig OBrien on July 07, 2009, 10:52:26 pm
I heard on the radio today that there was a tornado spotted down in Wexford County


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: martinastro on July 08, 2009, 01:21:16 am
Thanks for the info Padraig!, let us know if you hear any further details about it. John T from TORRO will probably be investigating that one. Cheers.  :)


Title: Re: Severe T-Storm Risk UK & IRL June 29th-July 7th
Post by: Padraig OBrien on July 08, 2009, 12:01:56 pm
Hi Martin just found this link it explains a couples house damaged by a tornado in Wexford County
http://www.irishtimes.com/newspaper/ireland/2009/0708/1224250237597.html