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Convective/Thunderstorm Discussion : Spring/Summer 2020

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Just starting new thread for the season(s). Nothing to report!

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Thepillowman

MikeD22 wrote: »

Thunderstorm over castlecomer now. Quite a strong one as well. Very slow moving. Tried to get some video but phone is letting me down big time

Watching it lighting up the sky in East Clare.

MikeD22

Thepillowman wrote: »

Watching it lighting up the sky in East Clare.

Lightning has eased significantly now. Very heavy rain at the moment. Currently with my two year old who isn't a fan of thunderstorms at all.

Danno

Certainly a lively little cell that brewed over central Laois and pushed down over the north Kilkenny hills. Seems to have died out now. Plenty of thunder and lightning with a peak of around three strikes per minute, but consistent at that level for well over 1hr.

sweet_trip

one hour of gopro footage and apparently whatever settings i had didn't register a single bit of lightening???? :(despite seeing with my eyes what spookwoman posted.

Danno

No rain from that cell reached this part of South Laois, but we managed a brief shower that just dampened the ground around 7.50pm

Danno

MikeD22 wrote: »

Thunderstorm over castlecomer now. Quite a strong one as well. Very slow moving. Tried to get some video but phone is letting me down big time

https://www.facebook.com/LaoisWeather/videos/172738637408946/

JJayoo

Could do with some rain in South Sligo, I planted a load of trees and I have been watering the ones planted on dryer soils and it's wrecking my head

km79

JJayoo wrote: »

Could do with some rain in South Sligo, I planted a load of trees and I have been watering the ones planted on dryer soils and it's wrecking my head

Rain in sligo ?
Nope you will never get any

Meteorite58

A record of today's lightning and track of rainfall. Note not all strikes show up on maps . Not a drop of rain at my site here near Tralee. Lot of thunder heard during the afternoon.

spookwoman

Some slow motion strikes from today Waterford

https://www.youtube.com/watch?v=jyEhJ3sqxCQ

Vlak

Some great cover of todays storms across the country, and thanks to all who've contributed.

Having watched back the radar returns and lightning strikes one thing I've noticed with these storms which I haven't seen before is the limited areas in which they 'fired'. The likes of the storms in Cork & Kerry, and later in Monaghan seemed to 'spawn' in the same place, then head east before fading, and almost as soon as they've faded another storm seemed to 'spawn' in the same place as the last and head east, in virtually the same pattern and lineation, and thus the cycle continued during the afternoon.

I would be interested to hear some analysis - if possible regarding this set-up from today and why the storms seemed to fire from specific locations as they did repeatedly, rather than them firing up across the country more randomly. I understand the graphs seemed to indicate CAPE was more prevalent in the south of the country, but the 'pocket' in Monaghan / North Cavan seemed pretty isolated in comparison to the rest of the activity.

Was it the case that these areas in Kerry / Cork and Monaghan had 'pockets' of CAPE which enabled thunderstorms to fire in these locations time after time, or were there other factors involved which led to these specific locations in particular to produce almost like a thunderstorm factory for the afternoon, while other areas didn't?

mickger844posts

The Storm that passed over Waterford City yesterday evening was quiet active. Very slow moving but did loose energy pretty fast.
A little sample of some cloud to cloud Lightning and over the top reaction ðŸ˜€
https://youtu.be/ugEMPRmM_Do

Chris_5339762

Not fair! Was just too far south of it and if it hadn't been for COVID lockdowns I'd have gone to Killarney storm chasing.

[Deleted User]

Chris_5339762 wrote: »

Not fair! Was just too far south of it and if it hadn't been for COVID lockdowns I'd have gone to Killarney storm chasing.

I enjoyed listening to the approaching thunder as I raced to finish a water butt and then looking at out torrential rain accompanied by thunder and lightening for an hour.

Fascinating watching the the amount of water increase on my sensor as I had a nice cup of coffee

20mm of rain, 330ml of freshly brewed coffee in an hour

Say my name

Vlak wrote: »

Some great cover of todays storms across the country, and thanks to all who've contributed.

Having watched back the radar returns and lightning strikes one thing I've noticed with these storms which I haven't seen before is the limited areas in which they 'fired'. The likes of the storms in Cork & Kerry, and later in Monaghan seemed to 'spawn' in the same place, then head east before fading, and almost as soon as they've faded another storm seemed to 'spawn' in the same place as the last and head east, in virtually the same pattern and lineation, and thus the cycle continued during the afternoon.

I would be interested to hear some analysis - if possible regarding this set-up from today and why the storms seemed to fire from specific locations as they did repeatedly, rather than them firing up across the country more randomly. I understand the graphs seemed to indicate CAPE was more prevalent in the south of the country, but the 'pocket' in Monaghan / North Cavan seemed pretty isolated in comparison to the rest of the activity.

Was it the case that these areas in Kerry / Cork and Monaghan had 'pockets' of CAPE which enabled thunderstorms to fire in these locations time after time, or were there other factors involved which led to these specific locations in particular to produce almost like a thunderstorm factory for the afternoon, while other areas didn't?

I haven't looked at a map. Nor do I want this to go into a 5G thing.

But have a look at the sites of origin to see if there's a correlation with television transmitters in these areas.
I noticed a tentative link one time during a previous dry time and outbreak of thunderstorms.

highdef

Say my name wrote: »

I haven't looked at a map. Nor do I want this to go into a 5G thing.

But have a look at the sites of origin to see if there's a correlation with television transmitters in these areas.
I noticed a tentative link one time during a previous dry time and outbreak of thunderstorms.

Most of the storms developed due to orographic lift over mountain ranges/high ground. Television transmitters tend to be placed at the highest point in any given area therefore it goes without saying that when storms form due to orographic lift, a television transmitter can usually be "linked" however there is no further link to be made, period.

Say my name

highdef wrote: »

Most of the storms developed due to orographic lift over mountain ranges/high ground. Television transmitters tend to be placed at the highest point in any given area therefore it goes without saying that when storms form due to orographic lift, a television transmitter can usually be "linked" however there is no further link to be made, period.

There's your answer Vlak. period.

PukkaStukka

highdef wrote: »

Most of the storms developed due to orographic lift over mountain ranges/high ground. Television transmitters tend to be placed at the highest point in any given area therefore it goes without saying that when storms form due to orographic lift, a television transmitter can usually be "linked" however there is no further link to be made, period.

Wales had a similar preponderance of storms on Saturday which also occurred over the mountains.

Also Television Masts get struck by lightning, not cause it!

Mortelaro

PukkaStukka wrote: »

Also Television Masts get struck by lightning, not cause it!

Funnily enough,cloud to ground strikes are actually ground to cloud
So tv masts that are struck ,strike the cloud and not the other way round
That I learned some moons ago at the theatre of electricity in Boston
They have a faraday cage in which they invite you to stand inside whilst they generate lightning strikes on it
Not for the faint hearted!

https://www.youtube.com/watch?v=4WxD4PEBinQ

https://www.mos.org/live-presentations/lightning

Say my name

Just for the cod,,Vlak.

Was that area on the Cavan/Monaghan border near here?

sweet_trip

From Saturday.

Meteorite58

A good detailed account of Saturday 9th May Thunderstorms from Met Eireann, have reproduced it in full for the record.

Just to note also that here near Tralee we heard numerous rumbles of Thunder over 3 hours or so and sometimes for extended periods of about every 30 seconds to a minute yet very few sferics showed up on the maps in this part of Kerry, possibly only the biggest strikes were being captured .

Convection in Ireland: Thunderstorms on Saturday the 9th of May 2020
by Alan Hally, Meteorologist in the Research, Environment and Applications Division, Met Éireann

On the 9th of May, Ireland was under the influence of a high-pressure system with temperatures in the high-teens and low to mid-twenties countrywide. Dynamically, i.e. in the highest levels of the atmosphere, there was very weak forcing due to the presence of the high-pressure. Given the location of the initial thunderstorms in the south-west, orographic forcing (i.e. upwards motion of air due to mountains) was likely a very important contributory factor to these thunderstorms. The atmospheric conditions followed a conceptual model known as "convection in fair weather conditions". Using a combination of satellite photos and vertical cross-sections of the atmosphere, we can get a very clear picture of what was occurring on Saturday the 9th of May.

In order for a surface based thunderstorm to occur, the dew-point temperature must be 12C or higher. Figure 1 below shows a satellite photo of Ireland at 1pm on Saturday the 9th of May in the infra-red along with an overlay of the 12C dew point isotherm (in purple) from an analysis provided by the European Centre for Medium Range Weather Forecasts (ECMWF) weather model. This clearly illustrates that Munster was perfectly primed for the development of strong thunderstorms.

Figures 2 (a), (b) and (c) are what we call vertical cross-sections. These figures demonstrate respectively; rising motion (known as omega), convergence/divergence (very important for illustrating areas where thunderstorms can occur) and relative humidity. These images detail the conditions of the atmosphere from the surface up to a height of approximately 12km. Image 2 (a) displays a large area of red from approximately 1000hPa to 300hPa. This represents the very strong updrafts, or upward motions of air in the atmosphere. Images 2 (b) and (c) compliment this perfectly as they show both convergence of air at the surface (in red on 2(b)) and high values of relative humidity in the upper atmosphere (green lines on image 2 (c)). The combination of all these factors; the mountains of the south-west, the high dew-point values, the strong rising motion and the moist air in the upper atmosphere led to very heavy downpours throughout the afternoon of Saturday the 9th of May. A satellite animation of the development of the storms can be seen below in what is known as the "Day Natural Colours RGB". The presence of tall convection producing cumulonimbus clouds can clearly be seen by the blue/cyan colours in Munster and areas over the south-east.

https://twitter.com/MetEireann/status/1259154102212268033?s=20

9LCWjSQ.jpg?1

One of our Twitter followers, Martin O'Brien, tagged us in a series of 4 photos which clearly show a well-formed funnel cloud. He took these while passing through the scenic Blueway region in Carrick-on-Suir, Tipperary on Saturday afternoon 9th May, during this period of convection described above.

Paul Downes, Forecast Meteorologist, Central Forecasts and Applications Office, Met Éireann, provided the following explanation.

This funnel, while not reaching the ground is a great example of the conservation of angular momentum. There are three main ingredients needed to get this.

1.Moisture. While you might not see it until it transforms into a cloud, moisture is all around us. The more humid the air the more moisture that is being suspended in the air. Saturday was a warm humid day.

2.Instability. Like a hot air balloon, the air inside a cloud has to be warmer than the air outside it, so when the sun heats the earth, 'bubbles' of warm air rises.

The air in the cools as you go up in the atmosphere, e.g. when you see ice crystals grow on the outside of an air plane window- its very cold out there! But the rate at which it cools is always changing. The air in the 'bubble' will cool too at a constant rate as it rises, the key here is if it cools slower than then atmosphere, we call this instability. The atmosphere is unstable and the bubble can continue to rise.

At a point called the Tropopause, approximately 10km above our heads, the atmospheric temperature begins to rise again and the air becomes stable once more. So If you have (1) moisture then as the invisible bubble rises and cools it will eventually condense into a cloud. If it is still unstable the cloud will continue to rise into a cumulonimbus (cumulus- a towering cloud, nimbus - with rain).

So that is what starts the process. The final ingredient is:

3. Shear. This can have several forms but for now we will just look at directional shear. If winds change direction along a front, such as a sea or lake, breeze shear can exist along the front, this can cause the air to turn. Alone it will do very little and is quite common. However if you place it under an updraft (a cloud going upwards) it acts like an ice skater in a spin. When an ice skater spins and their arms are out they rotate slowly, if they want to spin faster they pull their arms in - this is called the conservation of momentum and it works in nature just the same. If a large eddy of rotation exists along a boundary and a shower accelerated the air upward, it will tighten the rotation below it. This causes pressure to decrease and to condense, thus forming the funnel cloud we see in the photo above. In extreme cases it can produce powerful tornadoes. However more of every ingredient would be needed- which is something we rarely ever see here- as well as a lot of help from the jet stream which didn't really play a major role on Saturday.

Meteorite58

Thunderstorms possible today, more so the SW and Kerry could come out with top activity.

SlowBlowin

Meteorite58 wrote: »

Thunderstorms possible today, more so the SW and Kerry could come out with top activity.

Hows it looking now ? Am still plugged in at the moment but poised to unplug !!

Meteorite58

SlowBlowin wrote: »

Hows it looking now ? Am still plugged in at the moment but poised to unplug !!

Never got going, Convective weather mentioned that an inversion layer could affect the growth of convection and it looks like that along with the other modest parameters just didn't come together to do the business.

JCX BXC

Quick shower with abrupt hail in West Clare.

igCorcaigh

Disappointing lack of sparks.

highdef

igCorcaigh wrote: »

Disappointing lack of sparks.

There shouldn't really be any disappointment for something that wasn't expected to happen much, if at all.

[Deleted User]

A nice bright flash of lightening followed quickly by a loud clap of thunder a few mins ago here in the NW then a very heavy brief shower.

Carol25

Lighting flash just south of Athenry and loud rap of thunder.