Convective/Thunderstorm Discussion: Autumn/Winter 2017-18

Meteorite58

Met Eireann mentioning Saturday night: Outbreaks of rain in all areas, heavy and possibly thundery, with a risk of spot flooding

So not very familiar with this kind of set up but very interested in piecing together from the charts trying to understand why and how Thunderstorms might develop in this scenario.

What I am seeing from the charts is an approaching upper shortwave trough and the remnants of Post Tropical Cyclone Ten laden with humidity and moisture and warm air advection . In the post frontal region with high Theta E and wet bulb readings aided by convergence to produce instability and reasonable lapse rates coming on to the SW coast and possibly getting height from the mountains leading to some thunderstorms with heavy rainfall late Sat night early Sun morning. Will see.

Meteorite58

https://twitter.com/severeweatherEU/status/904319559620022274

Meteorite58

Just a couple of sferics showing up last night near Dunmanway and Birr.

Cantona's Collars

Any reports from North Wexford/South Wicklow. Gone really dark up that way.

Meteorite58

zerks wrote: »

Any reports from North Wexford/South Wicklow. Gone really dark up that way.

The conditions today are not conducive for Convection / Thunderstorms. Potential for patchy rain and drizzle is forecast.

Meteorite58

Possibility of some thunderstorms tomorrow, best chance in the afternoon probably S, SE and midlands I would think.

Upper Vortex and cool pool of air aloft, Jet nearby leading to some but not a lot of shear, decent lapse rates and introducing cool 850hpa temps as the day goes on, warm SST's and should be good clear spells allowing for heating.

degsie

Hail, thunder and lightning in Lucan

IvySlayer wrote: »

Hail, thunder and lightning in Lucan

Yup, nasty out there!

Big thunder kicking off right now in Dublin 12...

Which thread is the one for current reports? I figured it'd be the Autumn one now?

Massive bang of thunder here



This seems to have arrived.... Absolutely torrential rain now here in Dublin 12.

Road is completely flooded, that was intense rain....

MJohnston

Two big old rumbles just now in Dublin 7

IvySlayer

Saw 3 flashes of white lightning here in Lucan

Meteorite58

Mod Note: Made a blunder moving posts from the Summer to the Autumn thread, my apologies to those that posted, will try and rectify

Meteorite58

Today's detected sferics.

Makapakka

Any more due tonight?

Meteorite58

Makapakka wrote: »

Any more due tonight?

Maybe a few on Northern coasts.

Storm 10

Big storm in Rome now with sound non stop thunder enjoy click on pizza navona webcam on Skyline
Can't copy and paste for some reason

Meteorite58

Met Eireann : Wednesday: Cool, with a mix of sunny spells and showers, many of the showers will be heavy, some possibly of hail and there is a risk of scattered thunderstorms, especially in the north and west

IMO In a brisk NW'ly airflow over warm SST's with the passage of an upper trough and cold mid and very cold uppers producing big heavy showers, potential for enough forcing to give large high convection producing hail and scattered thunderstorms. Decent CAPE values and a fair amount of DLS with the Jet nearby. Very high lapse rates. Could be interesting .

Meteorite58

Should be plenty of convection tomorrow.

Oscar Bravo

Thunderstorm near Waterford now. Lots of strikes

Clonmel1000

Had thunder and lightning strikes here in the last hour. After hot and dry weather it's my favourite type. The weather really is broken though at the moment with the last 6 weeks being a disaster really.

Meteorite58

Not much widespread activity but a good few sferics detected between Clonmel and Waterford. Showers throughout the day here around Tralee and some very heavy ones in the afternoon with a trace of hail in them. Big fluctuations in temperatures during the showers.

Pangea

Thunder here in Donegal right now

MJohnston

HUGE downpour and heavy winds here in Dublin 7 at the minute, out of nowhere basically, but no sign of any rumbles!

M.T. Cranium

Hail quite likely from showers moving south through central Leinster, freezing level is down to 1800m or about 6,000 ft, cloud tops are probably well above that.

Meteorite58

Thurs looks like having some potential for convective shower activity possibly in the W and NW I would think as we will be under the influence of an upper trough and cool air aloft with SW'ly surface winds. Some showers perhaps weakly electrified.

Meteorite58

In the post frontal airmass tomorrow we should see convection bubbling up producing showers, not too sure if some of the showers could be weakly electrified.

Good CAPE values, and decent lapse rates with some DLS , no great temperatures but the SST's are still decent combined with the upper trough ( negatively tilted ? ) and cool air aloft might produce enough instability to produce a few sparks.

Meteorite58

( I swear I didn't read this first before making my post above )


http://www.convectiveweather.co.uk/forecast.php?date=2017-09-21





Day 2 Convective Outlook
VALID 06:00 UTC Thu 21 Sep 2017 - 05:59 UTC Fri 22 Sep 2017

ISSUED 20:09 UTC Wed 20 Sep 2017

ISSUED BY: Dan

Sharp upper trough pivoting NE-wards across Ireland and W Scotland on Thursday will provide the focus for deep convection as cold mid-levels overspread relatively warm SSTs and diurnal heating inland, steepening lapse rates and generating a few hundred Jkg-1 CAPE. A low-end SLGT has been issued where there is a better overlap of these variables, with scattered showers and a few thunderstorms likely on Thursday afternoon and early evening, the focus shifting mainly to coastal areas of western Scotland by Thursday night. One inhibiting factor will be quite dry profiles in the mid/upper levels, which may result in more isolated shower distribution - but given steering flow, an individual shower should cover some distance, and therefore increase the potential in lightning coverage. Hail to 1.5cm in diameter is possible from the strongest cells. Relatively high cloud bases (given 6-11C dewpoint depressions) should limit the funnel potential somewhat.

Meteorite58

Not many sferics after all. A small cluster detected in Donegal. What a day though, beautiful blue skies with some fine well scattered convective clouds, no rain here around Tralee.

I would think there wasn't enough moisture in the atmosphere for convective growth into electrified storm.

Netweather

Meteorite58

Met Eireann mention 'FRIDAY: Nice spells of autumn sunshine to begin, however it will become breezy with heavy possibly thundery showers moving in across the western half of the country'.

Upper vortex with very cold upper pool of air and looks like a lot of shear from the jet available. Cape and lapse rates should be reasonable.

highdef

Possible squall line developing in a line from Central Clare into North Kerry, heading east???

JCX BXC

highdef wrote: »

Possible squall line developing in a line from Central Clare into North Kerry, heading east???

There's been a flash out of it.

Storm 10

Thunder and Lightning in Oughterard Co Galway

Storm 10

Thunder and lightning west of Galway City now

ronnie3585

Huge clap of thunder in Galway city just there!

ronnie3585

Absolutely ferocious rain and hail in Galway city now. Unreal.

Storm 10

Hail thunder and lightning in Galway very active lightning

Hooter23

Huge hailstones in Galway:eek:

Lightening and hail the size of marbles here in Carnmore.

Storm 10

I have never seen hail like this in Galway on local radio they said the hail was ripping the leaves off trees on Lough Atalia, I drove under a bridge as I thought the car would be damaged by the hail along with other cars

Oneiric 3

Nice big clap of thunder here just now.

Edit: Thunder quite frequent now but core is off to SE.

Are some radio stations off the air?

km79

Oneiric 3 wrote: »

Nice big clap of thunder here just now.

Edit: Thunder quite frequent now but core is off to SE.

Gone to north of me thankfully

km79

Sky very dark looking north

Storm 10

More flashes East and West of Galway

km79

Storm 10 wrote: »

Anothe flash East of Galway

It's all missing me east of Galway
It has moved north east between us !

GIGANTIC boom of thunder to my north west
And another
Further away now

Oneiric 3

km79 wrote: »

Sky very dark looking north

Same sky here, except it is to my SE. Thunder seems to have eased up.

km79

Looking at radar I'd say it missed us by a km or so

Meteorite58

Some big Congestus producing a couple of localized showers and could see a few CB's in the distance but no sparks here in Tralee. Great cloudscapes nonetheless. Good few sferics detected around Galway, from accounts I would think there was more lightning then what is shown on the chart.

Netweather

Storm 10

Meteorite58 wrote: »

Some big Congestus producing a couple of localized showers and could see a few CB's in the distance but no sparks here in Tralee. Great cloudscapes nonetheless. Good few sferics detected around Galway, from accounts I would think there was more lightning then what is shown on the chart.

Netweather

Tell you it was a very exciting hour and half, some great flashes loud thunder and hail beautiful here now

robclay26

few nice flashes over Oldcastle area, Co. Meath, good view from Delvin

coconnellz

Very Heavy hail and rain shower just passed with lightening overhead around the cavan meath border area the ground is white with hail

Meteorite58

Updated chart of sferics detected today

lolie

That storm went almost directly overhead here, about a dozen big flashes before it moved on.
Missed the first few but a friend said one was the biggest flash he every saw overhead.
No hail here just very heavy rain.
Looking at the radar it's part of the same cell that passed over galway earlier.
Screenshot of a flash