Thunderstorms and Convective Potential

Danno

http://durrow.athost.net/lightning/ <<< Strike shown near Dublin/Wicklow area.

Trogdor

Danno wrote: »

http://durrow.athost.net/lightning/ <<< Strike shown near Dublin/Wicklow area.

Looks about right but nearer the coast:)

chalkie

20:20ish, Shankill - directly overhead.

Loudest thunder I've heard! I posted on this under Current conditions. I received a reply from someone that it was most likely a Positive Lightning bolt which is more powerful and common in Winter. Hadn't realised there was such difference but definitely by the explosive bang of this one, there was something unique about it!

Joe

ian_m

Seems to be further heavy rain heading north east towards Wicklow/Dublin

Snowbie

More than likely that it was a -CG. If thunder is heard very loud and from a distance, it is because there is little in the way of obstacles muffling or blocking out the sound. In this case the lack of tall buildings and rain.

Due to some cold air aloft and other factors, i'm not surprised that there was not a couple more strikes but not anticipating a thunderstorm either. There is little in the way of energy in the atmosphere. The odd strike can crop up in the next few hours around the Dublin Wicklow area due to conditions below.

In the attach below shows how the strike may have occured.

1.The radar shows the single but very weak cell.
2.Deep level shear
3.Vertical vorticity
4.Surface winds direction
5.800-1000 foot winds.

Due to an evironment created not only by the wind, the Dublin/Wicklow mtns aided in the convergence. Surface winds and lower atmosphere winds created slight convergence with topography(mtns) forcing. Deep level shear would give the cloud some tilt to allow the forcing to updraft quick enough. There is ML inhibition so a cap on convection is in the middle atmosphere.
More than likely the -CG built up in the lower part of the TCU cloud which delivered the strike. I don't see by sat pics that a CB was evident.

chalkie

Hi Snowbie.

Thanks for that information on the lightning and conditions. Only returning to this thread now.

I had consulted with someone else and from the description I gave them they were fairly sure it was the rarer positive discharge. I've been around lightning storms in many locations, open(!) and urban, home and abroad, and I can truthfully say that while I have witnessed CC or very close CG discharges I had never heard anything close to the 'bang' this one made.

It was simply...different...!!?

Makes for interesting research since then!

I do note your point about a CB not being evident. Presumably then the cloud heights would not have been that great thus restricting the length of the path the lightning could have travelled? This would counter the argument that it was positive I suppose.

Joe

Snowbie

Hi Joe,

I had one of those strikes myself in late February also when a belt of thundery rain moved up from the south. The house literally shook it was that loud.
That single strike was heard in Sandyford where Docarch lives and vica versa when a strike down his way was heard clearly from here(unfortunately it hit a house which Docarch knew the occupants)

I'll try and explain a little more why i think it was a negative cloud to ground (-CG). We all know that when the majority of lightning strike occurs the heat of the lightning expands the air vigorously and the air expands out omni directional from the strike.
The thunder that we hear can be muffled out by buildings but more by hills/mtns and most of the time rain. The more intense the rain the more it can absorb the sonic.

As the rain was not torrential and the cloud tops where capped to the towering stage or TCU (towering cumulus) there was just enough static allowed to build in the lower atmosphere in a relatively small window if you like to produce the strike. The strike i would say be the common fork and had a couple of stepped leaders producing several but close and higher sonic boom with little in the way of amplification.

With the less than common +CG in this country (more common in Winter/Spring than Summer though due to more colder air in the upper atmosphere) when the strike originates up in the Anvil at 30,000 feet approx in this country(60,000 feet in tropics), are the more powerful stirkes with the greatest length of travel to the earth. These can create a certain high boom too but again if there is enough to muffle out the thunder, it can just sound the same as any other strike unless we have an extremely rare dry storm in this country.

shamwari

Snowbie, have you a recollection of a (dry?) storm in August 1997 when something blew in of the Irish sea over Dublin? IIRC it kicked off around 10.30pm on a Sunday night, but don't know exact date. The lightning was brilliant white and "blasts" of thunder. All in all, it lasted about and hour

Danno

@shamwari

Would that have been the end of June or thereabouts?

I think I can remember what I would have described as a "silent" storm, no thunder, but brilliant lightning from storms that tracked up the Barrow valley and obviously over the east of Ireland.

There was purple and white lightning. Portlaoise would have gotten it bad with thunder also on the same night... began at 10.30pm and went on for two to three hours.

Hal1

The lovely Evelin is forecasting some hail and TS's in the whest tonight, but all places at risk she said.

DWCommuter

Just spotted lightening here in Naas co. Kildare. No thunder that I could here. There's no rain or hail. It was in the SW.

darkman2

Thanks for that. Am keeping a look out. Very squally outside now with heavy rain. The showers seem to be dieing so im not expecting much in my area. Some nasty showers in the west though.

gally74

have ye all here folks,

on the couch today watching the tv, ulster on,

wind really pciked up. then some hail stones started.

then the mother of all flashes and like a shot gun went off in the house,

really load thuned.

all esb phone gone, in fact the telecom white box in the hall is in bits and black, all over the hall

Sierra Oscar

Just after having a few flashes here.

rc28

gally74 wrote: »

have ye all here folks,

on the couch today watching the tv, ulster on,

wind really pciked up. then some hail stones started.

then the mother of all flashes and like a shot gun went off in the house,

really load thuned.

all esb phone gone, in fact the telecom white box in the hall is in bits and black, all over the hall

The lines outside your house were struck- this happened at our place a few years ago when we got home to find every eircom 'white box' socket in the house had exploded. Incredibly lucky that curtains etc hadn't caught fire.

shamwari

Danno wrote: »

@shamwari

Would that have been the end of June or thereabouts?

I think I can remember what I would have described as a "silent" storm, no thunder, but brilliant lightning from storms that tracked up the Barrow valley and obviously over the east of Ireland.

There was purple and white lightning. Portlaoise would have gotten it bad with thunder also on the same night... began at 10.30pm and went on for two to three hours.

I could be wrong about the date but the storm to which I refer blew in off the Irish Sea and headed inland. It didn't come up from the south as such. It was a cracker though!

Another "spectacular" I can recall was at the end of August 2000 - I think U2 was playing at Slane that weekend. Anyway I was in Newry around 2.30pm on the Friday and when a good storm kicked off. As we headed back towards Dublin there was some spectacular CG strikes and the RTE mast on Clermont Carn took a direct hit. Radio1 went off air but everything else radio-wise stayed on the air. When I got back to Dublin, the storm eased off around tea-time and I went to collect my good wife from work. Just as she got into the car, the storm kicked off again with rain bucketing down!

Later that night, I was in a church practicing for my brothers wedding (I was best man!) The storm outside was going full-tilt and the thunder sounded truly apocalyptic in the church! I got home around midnight as the storm was wrapping up. I put on my airband radio and listened to what the pilots had to say and one pilot in particular was very informative. He briefed the tower about violent turbulence and hail, but he "fell" out of the storm around 7000ft and everything was manageable thereafter.

The wedding next day took place in bright sunshine. When we were at the reception, I enquired if there were any faxes for the happy couple. The manager apologised and said that their fax machine died in the previous nights storm and pointed to a charred blackened box in the corner :eek: I did the decent thing and quoted him for a replacement

Sierra Oscar

Is it me, or is there a little thunderstorm on the way to the West Coast at the moment?

Mr Benevolent

From met.ie:

A band of thundery rain, preceded by sleet in places, will extend northeastwards this evening and early tonight; southeast winds will increase strong to gale force for a time also.

Another "spectacular" I can recall was at the end of August 2000

I remember it well, I have a suspicion it was an MCS. Went away and returned a few hours later. Four bolts hit the ground simultaneously - it sounded like a Space Shuttle launch!

shamwari

Looks like a few sFerics on the Kerry coast at the mo

CrowdedHouse

Anyone know if there was thunder around Galway at around 4 am ?

The dogs were going mad as they do when there is thunder,I was fast asleep - thought I heard a rumble - not sure

Mr Benevolent

Bringing this thread back from hibernation, looks like there's a reasonable chance of a bit of action over the next few days. Anybody got the expertise to confirm or deny this?

Hal1

Met.ie are going for some scattered TS for tuesday night. 12z is also supportive of this and the risk continuing on into wensday for western areas at first, but all areas at risk during wensday. Most likely to be accompanied by snow.

Mr Benevolent

Snunderstorms! I like it.

nacho libre

Thundersnow would be most welcome!! Certainly this week will make up for that dreadful azore high which afflicted us during the second half of February.

Said azores high delivered a lot of sunshine here to East Wicklow..so I'm not complaining.

Thundersnow is possible.
We had it on feb 2nd.I reckon the local insurance offices are still dealing with the deluge of claims from the accidents I saw on arklows main st that day..
It's a hilly street and people just don't know how to drive in snow :rolleyes:

Anyway back to the thunderstorms... at the moment estofex don't rate the risk too highly..but then they didnt on monday feb 2nd either.Their analysis may change tomorrow but then again it might not.

An intense cold front from Greenland approaches Scotland and Ireland during the afternoon/evening hours. Temperatures at 500hPa drop to -40°C or below, so convection will be widespread. Showers and an isolated thunderstorm are possible but expected coverage does not justify an highlighted area.

Mr Benevolent

Estofex is warning of thunderstorms for the west of Ireland today.

Redsunset

nice few strikes over donegal coast

maquiladora

Storm Forecast
Valid: Tue 03 Mar 2009 06:00 to Wed 04 Mar 2009 06:00 UTC
Issued: Tue 03 Mar 2009 06:33
Forecaster: VAN DER VELDE

...More clustered convection should occur on shortwave troughs affecting Ireland, with isolated thunder possible....

http://www.estofex.org/

ian_m

maquiladora

valid from 04.03.2009 06:39 CET Until 04.03.2009 18:59 CET

Thunderstorms

Awareness Level: Yellow

lightning-risk "Moderate to high risk of thunderstorms today with hail and sleet in places."