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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 5737 times)
martinastro
Martin Mc Kenna
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« Reply #30 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.



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/
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martinastro
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« Reply #31 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.



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.
« Last Edit: July 01, 2009, 12:55:03 pm by martinastro » Report Spam   Logged

martinastro
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« Reply #32 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
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« Reply #33 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 Smiley
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martinastro
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« Reply #34 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



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



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.
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« Reply #35 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
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« Reply #36 on: July 01, 2009, 08:24:41 pm »

Hi Martin im smack down right in the middle of that yello on the map
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martinastro
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« Reply #37 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...



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.

« Last Edit: July 01, 2009, 09:09:55 pm by martinastro » Report Spam   Logged

martinastro
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« Reply #38 on: July 01, 2009, 09:42:58 pm »



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.
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« Reply #39 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
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martinastro
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« Reply #40 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.
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martinastro
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« Reply #41 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.
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« Reply #42 on: July 02, 2009, 04:11:39 am »

Very strong activity here
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« Reply #43 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
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« Reply #44 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
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