Thunderstorms and Convective Potential

Deep Easterly

Cursed, I tell you, this place is cursed. Raining a bit more heavy now. Thunder heard over Tuam, but to outta town here. :mad:

Edit: Storm over. 0.1mm total. One for the records?

Storm 10

Hi Snowbie

How many Lightning strikes have you recorded, I have counted at least thirty if not more (visually I mean)

Snowbie

What town are you in or near in Galway?

Storm 10

The City

Snowbie

206 strikes recorded since first detected over Limerick/Clare border. Roughly 86 in and around the Bay and near the city when the storm was at it's peak.
Has dropped well off now with only a couple of strikes now and again.

Storm 10

Jez I did not think there were that many around you should post that one on the UK Weather Forum, there was one about ten minutes ago over the City but only heavy rain now, some times as the storm moves off you can get lightning form the tail end of it like it was as it approached from over the Bay.

Deep Easterly

Downpour now. At least something.

Snowbie

I replayed the time when it was heading over the Bay from Clare and heading towards the city. 84 in total.
Mostly IC+ (+ Intra cloud or sheet lightning) but mostly running through the cloud so you would have seen very little of it but all in the vicinity of Galway Bay.
CG+ 3
CG- 11
IC+ 41
IC- 29

to be exact:D

RoisinD

Had very bad thunder and lightning here in north west Clare ( just across the other side of Galway Bay). Rainfall measuring 26.7mm.

I understand that there has been serious flooding in Ennis - some shops including Tescos had to close.

Deep Easterly

A small break in the clouds to the northwest is revealing a blood red sky. Sky looks demented just to my west over the lowlands. It looks like some serious rain is falling over Headford/Cong area approx. Rain has eased to more moderate levels here. Of course. :rolleyes:

Edit: Cloud up towards the Claremorris area beginning to look very threatning. Turning into a black grim evening.

Edit Edit: weak flash of lightning, dimmed the lights for a second!

nacho libre

it seems that Galway city and bay get most of the lightning action in this part of the country:mad:

Snowbie

Nothing as exciting in the charts as was this time last night for today Thursday. Risk is mainly for the midlands later transferring east. Convection will only occur if sun gets to work on the ground heating it early on and which is forecast to happen. Cloud is also forecast to spill down from the NW later on in the day but might bump up the showers ahead of it aided by weak convergence.

No significant convergence from the 18Z, slight if any compared to 24hrs ago unfortunately.

Storm 10

Hi Snowbie

Would please explain to me how to read the Cape Chart, I read so much about it but I dont know how to read the chart and where the weather is likely to be bad.

I only came across the cape charts recently I have no problems with any other weather charts etc.

Snowbie

I'll try and simplify this as i can.
Cape is basically the potential energy of the atmosphere in a given area. Cape varies across an area but at it's greatest over flat regions where particles of air/droplets can rise undisturbed.

We measure cape as surface based (SB) or midlevel(ML) and in joules per kg (j/kg) The higher the value the better the potential.

SB cape will indicate an unstable atmosphere at surface level (energy) and this will give rise to cumuli formations but is only one parameter in the forecasting of Ts. High or very high SB cape does not mean Ts will occur.

ML cape will also indicate unstable conditions through mid level regions (850-700mb region) Most of the time but not always we can asscociate SB and ML cape together with a good indicator of heavy showers/storms. But if we ever find ML cape without SB, it is a good indicator of elevated storms or high based storms mainly from warm moist humid plumes from the south.

If there is high SB cape and no ML cape, there is a cap or inhibition in the atmosphere so the cloud will not build up to higher regions in the troposhere.No CB will form just cumulus congestus giving showers untill the cap/inversion level clears.

These are just 2 parameters in the forecasting of storms. Both values need other ingredients for Ts to occur but the main ones we look for first before moving onto the next.

Hope this helps, don't hesitate to ask if you need any more info.

Storm 10

Thanks Snowbie for that info certainly helps to understand the chart a bit better

darkman2

Some big thunderstorms likely to develope across the Midlands and North and they may extend East later. I expect to see some flash flooding especially in the North Midlands.

Deep Easterly

nacho libre wrote: »

it seems that Galway city and bay get most of the lightning action in this part of the country:mad:

Nacho, when are you ever going to realise that Galway is better in everything full stop?

The West Awakes!

Snowbie

darkman2 wrote: »

Some big thunderstorms likely to develope across the Midlands and North and they may extend East later. I expect to see some flash flooding especially in the North Midlands.

GFS does not agree, risk downgraded somewhat for the east and north midlands.
South midlands most a risk transferring to the SE later. Little more of a convergence than yesterdays output but still slight and most important no sun or very little.

Very little convection is occuring and now with the front starting to throw general cloud now down over the country. All from 06Z output but as always we shall see.

darkman2

We are seeing development increasing now so we will see how it goes but there is a convergence zone across the center of the country and lapse rates continue to steepen. With the wind SWrly in direction below the convergence zone (where Dublin is) then we are in the firing line. Like I say I think we will have storms this afternoon but we will see how it goes.

Most of the development so far seems to be in the same area as yesterday ie in the mid west.

Snowbie

Yes there seems to be convergence but still slight atm. That is the occluded/cold front re-developing across the centre of the country. With the air moist SW ahead of it been some what advected in, it's peeping up the front with cumulus visible on satellite. Some heavy bursts are likely along it with some cold air aloft with the chance of a rumble. Nowcasting as GFS did not get a grips with this.

Watch radar and sat during the afternoon to see the developing front and see if it becomes more active. I still think as it moves more south east where the convection will be greatest with the approaching front, this be the best chance for a storm.
Then as the front clears some beefy showers might develop to the north of the front.

maquiladora

Looks like some activity over Carlow.

darkman2

Disappointing so far in the midlands and East but Cork and North Leinster on radar look like having possible storms.

DOCARCH

Looks like something mushrooming over the Waterford/Dungarvan area?

http://www.sat24.com/frame.php?html=view&country=gb

Snowbie

South was always favoured best today ahead of the front from 06Z. Big downgrade from the 18Z and 00Z for the rest of the country but was right in the end. No prolonged sunny spell here and mostly cloudy which limited convection occuring.

Nice convection there over Waterford and east Cork, a few strikes from it too.

A bit of sun creates surface warming and moist warm air being forced to rise quicker ahead of the front will create some explosive convection but really if it where only that easy too, some other parameters involved in the setup.

Edit:Wind convergence in the attach over the south and the link above from the satelitte, more lift from Wicklow mtns.

Snowbie

Some increasing cape values over the east in the last hour upto 350j/kg. LI -0.5
Modeate downpour in the last hour from a shower. Max rain rate 47.8mm/hr.
Looking at sat, some embedded CB have recently grown in the N Dublin area.

Hal1

I would have driven through that rain shower at its peak, as discussed over in the 'current weather conditions' thread. It was one serious heavy shower.

nacho libre

Deep Easterly wrote: »

Nacho, when are you ever going to realise that Galway is better in everything full stop?

The West Awakes!

We'll see by Sunday evening:p

Snowbie

Still a bit away but GFS consistent on it's Ts potential this Wednesday.

For Ireland, the midlands and NW of the country are in good location for a Ts while over the Wales has the highest risk. The risk over Wales later moves into the Irish sea and across the east coast but by then it's around midnight before it gets here and Cape has decreased. Surface heating will be minimal at night but there is high humidity and warmth in a slack SE flow forecasted for Tuesday night and into Wednesday so the chance of an import to the east looks possible later Wednesday. Will update this as we get closer the time.

Storm 10

Hi Snowbie

Whats the chances of a TS in the West this coming weekend