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Severe T-Storm Risk UK & IRL June 29th-July 7th

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Author Topic: Severe T-Storm Risk UK & IRL June 29th-July 7th  (Read 5629 times)
martinastro
Martin Mc Kenna
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« 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.
« Last Edit: July 03, 2009, 06:22:29 pm by martinastro » Report Spam   Logged

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martinastro
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« Reply #1 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.





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markt
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« Reply #2 on: June 28, 2009, 02:35:29 pm »

Great thread Martin!  Tuesday looks 'interesting' for us in the Midlands to say the least :p
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martinastro
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« Reply #3 on: June 29, 2009, 01:25:27 am »



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.
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Big Dipper
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« Reply #4 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)!
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Remember:- If all else fails, read the Instruction Manual! Grin
 


Andy
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« Reply #5 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...  Tongue
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martinastro
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« Reply #6 on: June 29, 2009, 01:10:41 pm »

Hey guys, here's the latest forecast from Tony Gilbert...



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?
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martinastro
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« Reply #7 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...

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Tyler
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« Reply #8 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.
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« Reply #9 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.?
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martinastro
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« Reply #10 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  Smiley
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martinastro
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« Reply #11 on: June 29, 2009, 10:08:55 pm »

Outlook for Tues, will update what Tony Gilbert says when he gets a forecast sorted.



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.
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scott86
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« Reply #12 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?
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martinastro
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« Reply #13 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... Smiley
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scott86
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« Reply #14 on: June 29, 2009, 10:21:14 pm »

i think a late night may be in order to see if anything happens!
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