Thunderstorms and Convective Potential

Snowbie

Post here of all things thunderstorm related,whether it be radar,maps,charts,forecasts or just simple discussions.
Over the months you will find some variables or terms describing suitability of storms which are:
CAPE - This is the amount of potential energy in the atmosphere. High CAPE will indicate a high chance of thunderstorms.
LI - Lifted Index (LI) displays the 'trigger' potential at the surface to initiate unstable conditions. A low or negative LI will indicate conditions for thunderstorms are favourable.
Cb-Cumulonimbus or thundercloud.
Anvil-Where the top of the Cb reaches the stratosphere and spreads out like a flat top.
Cell or Supercell-An individual storm or a violent storm.
Squall line-Multi cellular organised storms forming in a line usually ahead or parallel to cold fronts.
Embedded Storms-Storms that are contained in overcast conditions
Convection-Warm air rising,cools,condenses forming cumuli clouds.
Orographic lift-Low level winds are forced to rise against rising terrain ie:mountains.Prevailing wind on a hot summers day,this lift can produce rapid convection.
Convergence zone-usually refers to a region in the atmosphere where two prevailing winds meet and interact, usually resulting in turbulent weather.
Lapse rate steepeing-is another fancy term for instability.
Sferics-Sound of low-frequency radio signals that derive from lightning strikes.Common terms would be strikes or strokes.
Some useful links
http://www.irlweather.com
http://durrow.athost.net/lightning/
http://www.gyweather.com/
http://www.isleofwightweather.co.uk/live_storm_data_sound.htm
http://www.wetterzentrale.de/pics/Rsfloc.html
http://www.estofex.org
http://www.blitzortung.org/index.php?mode=0&map=5&lang=e
http://www.nowcast.co.uk/lightning/
http://meteocentre.com/lightning/map_sfuk.php?time=0&lang=en&map=Europe
http://www.estofex.org/guide/
http://www.strikestareu.com/
If anyone has any more feel free to post them.

Snowbie

Chances of storms has increased and look possible right across the country later today, tonight and into tomorrow Tuesday.

A renewed risk seems to run up the Irish sea for SE and E areas later.
Will post up charts later.

squonk

some widespread and extremely heavy rain pushing into Clare & Kerry now on ME's radar. Could be nasty up here later on if that stays as intense as it crosses the country.

nacho libre

On the gfs it was saying the heaviest rainfall will be in the West this time.

Storm 10

Very heavy rain here at present and looking at the latest Met Eireann radar worse to come.

http://www.met.ie/latest/rainfall_radar.asp

Snowbie what are the chances of Thunderstorms here today/tonight

DOCARCH

I see LI is forecast to be -4 for most of tommorow morning to mid-afternoon for the Dublin area with a CAPE of 823 j/kg around 3pm.

Can't remember the last time I saw LI below -3 for Dublin!

cian1500ww

What are the chances of thunder in Leitrim today or tonight ?

I love watching thunderstorms.

nacho libre

If anywhere in the West will get a thunderstorm out of this it will be Galway city. It seems to be most lightning-friendly place in the West of Ireland

cian1500ww

nacho libre wrote: »

If anywhere in the West will get a thunderstorm out of this it will be Galway city. It seems to be most lightning-friendly place in the West of Ireland

Off to galway with me then

Thunder down in the cork area now in that huge blob of rain.

Heaven preserve us if and when it starts moving up the country.
This is getting beyond ridiculous.

cian1500ww

Will that move towards the North West ?????

Wertz

Just got a phonecall from a mate asking me to look out in to the bay (Dundalk)...says the clouds were acting strangely...had a look; definitely a rotating updraft at the edge of a shower cloud (very heavy large drops of rain)....took some pics but no use without video. No thunder or much else...sky very very leaden grey though.

Damomanye

cian1500ww wrote: »

Will that move towards the North West ?????

at this stage looks like its moving generally in the North east direction

cian1500ww

Damomanye wrote: »

at this stage looks like its moving generally in the North east direction

Looks like I might get the tail end of it from the latest radar.

lucernarian

I've been unbelievably lucky so far this evening in avoiding the rain. It hasn't rained here since this morning.

Right now, I can see very heavy rain only a few miles from the southwest to the northwest of me but it's only edged a couple of miles closer for the last hour or so.

cian1500ww

To_be_confirmed wrote: »

I've been unbelievably lucky so far this evening in avoiding the rain. It hasn't rained here since this morning.

Right now, I can see very heavy rain only a few miles from the southwest to the northwest of me but it's only edged a couple of miles closer for the last hour or so.

There's proably a whole lot heading your way by the looks of the radar.

lucernarian

By the looks of that radar, it's been heading right past me for the last 4 hours:D

It was threatening to drizzle when I wrote my last post, but the heavy rain near to the west of me continued on and it's brightening up again. Also, the Dunleer and Drogheda NRA weather stations both had the lowest relative humidity in the country as at 7pm.

But we could be punished for our dry afternoon later tonight!

cian1500ww

There seems to be a very wide band to that system thats over Cork at the moment, I wonder will that mean it will affect Leitrim ?

JanuarySnowstor

Just clearing Cork now.
Being honest it wasn't that heavy and for some reason looked much worse on radar

DOCARCH

cian1500ww wrote: »

There seems to be a very wide band to that system thats over Cork at the moment, I wonder will that mean it will affect Leitrim ?

You seem to very anxious for Leitrim to get rain? Are you running short of rain up there?:D

If it's thunderstorms you're after I suspect what comes after the main rain band may produce the thunderstorms.

LI for Dublin area at midday tomorrow now forecast at -5 and CAPE at 975 j/kg.

cian1500ww

DOCARCH wrote: »

You seem to very anxious for Leitrim to get rain? Are you running short of rain up there?:D

If it's thunderstorms you're after I suspect what comes after the main rain band may produce the thunderstorms.

Its the thunder I'm anticipating. And no we're surely not short of rain, unfortunately.

lucernarian

It rained there for 2 minutes, not heavy at all but the drops were big.

Btw, I've a wee suspicion the met radar underestimates rainfall closer to it and overestimates further away.

Docarch, what are your sources for your lifted index forecast of -5? The GFS run at 12z this afternoon forecasted -3, and CAPE of about 600 Joules/Kg

DOCARCH

@ cian1500ww Unfortunately conditions will be a little less favourable for thunderstoms for you. Note that I am not saying you will not get storms just that conditions will be better for south and east for storms to develop.

Deep Easterly

cian1500ww wrote: »

There seems to be a very wide band to that system thats over Cork at the moment, I wonder will that mean it will affect Leitrim ?

Most rainfall models seem to be struggling with this current band of rain at the moment. UKMO seem to have the heaviest stuff running up through the centre of the country as well as the east tonight.



Forecast for 4.00am above. Not sure about thunder Cian, but if there is any going, you seem to have equal chance of getting some.

I already know there will be none here though.

Snowbie

Storm 10 wrote: »

Very heavy rain here at present and looking at the latest Met Eireann radar worse to come.

http://www.met.ie/latest/rainfall_radar.asp

Snowbie what are the chances of Thunderstorms here today/tonight

The chances of storms tonight is low according to the latest 12Z GFS but there is a couple of hundred j/kg of Cape around, so the odd rumble of thunder be possible with nothing organised.

Later tonight a low risk again moves into the SE and runs up the east coast, SW and west.

Tomorrow the GFS atm is overplaying the potential of storms across the whole country with very high Cape values as there be very little insolation(lack of sun getting to the surface) due to the front returning across the area. The greatest risk imo is the south midlands and SE due to longer exposure to surface warming which should be enough to spark heavy showers/storms? maybe early on.

Will compare the 12z and 18z runs later to see if there is any difference and post up charts if any risk remains.

DOCARCH

To_be_confirmed wrote: »

Docarch, what are your sources for your lifted index forecast of -5? The GFS run at 12z this afternoon forecasted -3, and CAPE of about 600 Joules/Kg

Lazy route : Metcheck (http://www.metcheck.com/V40/UK/FREE/stormwatch.asp)

cian1500ww

Thanks for that guys, I'll keep an ear out. Just light rain here at the moment.

Snowbie

The 18Z has rolled out and GFS has come onboard now. It shows that some possible Ts development mainly in the Leinster area and more into the SE. With surface warming (if sun makes an appearance) and with winds from the WNW the Wicklow mountains will aid in lift.

Lapse rates(instability) is favourable over the SE. Anything over 26C fall rate is good.
However there is no shear at low and mid levels so Ts if any be short pulse type storm's.
No wind convergence but MTS should aid in lift aswell as surface warming.
Most important there is no convective inhibition or Cap/lid on convection.
There are signs that an upper trough develops and moves through over Ireland ahead of the returning front with cold air aloft so which favours the steepening of lapse rates but later runs should confirm that.

All depends on how conditions at the surface aid in developing. No sun, no fun.

All attach below are from 18Z for 1500.

Snowbie

Torro have released a Tornado Watch for mainly the SE.

http://www.torro.org.uk/torro/forecast/index.php

Hmmm maybe?

Added more atmospheic winds for earlier in the day Tuesday.

Planet X

Snowbie........you have it all, as in details / intelligence /dedication.


Superb.


John Cash would be still a hero though.

Snowbie

Snowbie wrote: »

Torro have released a Tornado Watch for mainly the SE.

http://www.torro.org.uk/torro/forecast/index.php

Hmmm maybe?

<Hold me> [I'm scared now...]

Snowbie

Look on the bright side, it might just suck up all the water off the fields for you now.:p

Lol
A water spout on land

Entirely possible anywhere in the East at the moment I think :D:o

DOCARCH

Looks like thunderstorm threat has been downgraded somewhat. Current forecast LI (-2) and CAPE (350 j/kg) well down on what was forecast yesterday.

Estofex revised foreact showing threat just clipping east coast. http://www.estofex.org/

What we need now is some nice sun/surface heating!

Some sferics showing up just off the Cork coast atm.

CrowdedHouse

Snowbie wrote: »

Torro have released a Tornado Watch for mainly the SE.

http://www.torro.org.uk/torro/forecast/index.php

Someone should tell them that the name of our country in the English language is Ireland

cian1500ww

Wasn't there a tornado not so long ago down the south of the country ? Are conditions today similiar to then ?

Oh and anoyone know why the radar at Shannon airport doens't appear to be functioning:

Major convection going on here.You can literally see the towers building as you look up at them bubbling like mad.
CB's everywhere in a very thundery looking sky with that tell tale sharp edge to them and the dark grey bordering the brilliant white.

Today is starting off interesting.

I'm expecting a fire cracker of an afternoon!

maquiladora

Deleted User wrote: »

Major convection going on here.You can literally see the towers building as you look up at them bubbling like mad.
CB's everywhere in a very thundery looking sky with that tell tale sharp edge to them and the dark grey bordering the brilliant white.

Today is starting off interesting.

I'm expecting a fire cracker of an afternoon!

There's a similar skyscape around Waterford now too.

cian1500ww

maquiladora wrote: »

There's a similar skyscape around Waterford now too.

Deleted User wrote: »

Major convection going on here.You can literally see the towers building as you look up at them bubbling like mad.
CB's everywhere in a very thundery looking sky with that tell tale sharp edge to them and the dark grey bordering the brilliant white.

Today is starting off interesting.

I'm expecting a fire cracker of an afternoon!

Any chance of some pics for those of us who don't get to admire these ???

M.T. Cranium

Would be expecting some very large falls of hail in some places, the upper atmosphere looks like November rather than August, so anything that reaches 25,000 ft will easily start to drop hail. I suspect the risk of a tornado is going to be greater over in southern England, although I would not totally rule it out in southeast Ireland later on. But hail, you might see more snow than in the whole of last winter, if it turns to slush.

DOCARCH

M.T. Cranium wrote: »

.....the upper atmosphere looks like November rather than August

The lower atmosphere isn't much better I can tell you - a very chilly 15.4c

Can see some convection starting http://www.sat24.com/frame.php?html=view&country=gb

Everything appears to be rotating around Kilkenny.

DOCARCH

DOCARCH wrote: »

The lower atmosphere isn't much better I can tell you - a very chilly 15.4c

Can see some convection starting http://www.sat24.com/frame.php?html=view&country=gb

Everything appears to be rotating around Kilkenny.

Interesting that.
You can see the convection I posted about build up and then spread out in a small area.
The best way I can describe the sky now is that it looks almost like what I saw at the Kennedy space centre last june (07)...

Except it's not 33c

That day there was tremendous thunder and lightning and intense rain all day

Snowbie

Some clear rotation around the upper low system from higher and lower clouds moving in opposite directions from the sat.
Looks to be an interesting afternoon in the SE.

darkman2

Some colourful echos starting to appear on radar just west of Dublin. Might yet get a thunderstorm. Very slow moving aswell.

mike65

Thunder and Lightening! :eek: First time I've seen a flash in two years.

edit -make that two flashes and its heading my way!!!!!!!!!!!!!!

Mike.

kensutz

More thunder

CIDK

Almost a perfect circle forming in the cloud around Wexford. Mental!:D

cian1500ww

Pictures please !!!!!

CIDK

cian1500ww wrote: »

Pictures please !!!!!

Just looking at the Sat. Clearly visible
http://www.sat24.com/frame.php?html=view&country=gb

rc28

Very heavy rain, occasionally torrential here. No thunder yet but the ground really doesn't need any more downpours.

DOCARCH

rc28 wrote: »

Very heavy rain, occasionally torrential here. No thunder yet but the ground really doesn't need any more downpours.

From the way things are moving it looks like if you get stuck under that you are going to get really wet!