Storm Discussion

[VillagePlank]

Rightyo chaps, and chapesses ... here's the take for the S/E for Monday

First of all the skew-t :

I can't get hold of the 18x skew-t for tomorrow, so this one is the 12z (are the forecast skew-t available on Nw Extra for every four hours?) This, unfortunately, is the start of the period, but it still look as if it's building well. Max temperatures are up, and very nice Tdd sits about the mid level, there is some directional shear near the surface with some speed shear high up to keep things going. Not bad at all, in my opinion, particularly as the target period is about rush hour tomorrow evening. Clouds heights are reasonably high, CAPE is starting to build, LI, and K, are in the ball park, though not great, unfortuately, and TT looks very promising.

Here's your normal CAPE and LI charts for 18z tomorrow ...

It seems clear that the potential seems to be moving (I don't like the word advecting!) S/E with, now, perhaps, the S/E seeing it's far share of the indices at 18z. LI is still on the edge, not great, but enough to not stop the good stuff happening. The LI, of course is a measure of atmospheric instability, and it does look like the atmosphere is more stable ...

The big uplift of E Anglia has now gone (perhaps back on GFS 6z) with the best area probably, now around E Anglia, E Essex and Kent - looks to me for some sferics perhaps after dark? Talking of after dark .... here's the 'steering' winds for around midnight tomorrow ...

It has to be said that most of the time the winds are heading N/E, but much later in the day, they switch to an E, SE direction.

It still seems to me that the action will be based North of a Cardiff-London line, but, however, showers, now, should be expected to break out almost anywhere ...

Overall opinion is that someone somewhere in the UK is going to see a monster, tomorrow; I think it will be in the E of the country, and possibly in Essex based on the above forecast. Certainly need surface temperatures to hit around 20C for the GFS forecast to come true.

Here's hoping that GFS put it far to far northwards .... Happy hunting

Edited June 14, 2009 by VillagePlank

[Coast]

here's the take for the S/E

Neat summary VP. I can only add to that:

Moving Eastwards

[maidstone weather]

Met Office is going for 24C in the S/E so that should really help things kick off if it all pans out Thanks for the analysis VP

[Neilsouth]

Thanks Plank

We weren't far off storms last night

[Phil UK]

Thanks for that, VP. I think that in mainland UK from 2pm and 20ºc+ onwards will see something major kick off then move east or north east. I haven't seen so much atmospheric instablility in quite a while.

Phil.

[Costa Del Fal]

Neat summary VP. I can only add to that:

Hi, could i have the link to the site where the thunderstorm chance maps are please.

Thanks.

Edited June 14, 2009 by Blizzards

[Phil UK]

Thanks Plank

We weren't far off storms last night

Not far off?? Did you see that development over the English Channel? How the heck did that come about? Considering that the Channel usually kills off storms as opposed to developing them, as has been the case so far this year.

Phil.

[Coast]

I think this could be quite widespread on Monday:

Not far off?? Did you see that development over the English Channel? How the heck did that come about? Considering that the Channel usually kills off storms as opposed to developing them, as has been the case so far this year.

Well I heard and saw it rattling around in the early hours!

[Nick F]

Funny how everyone's talking about tomorrow, when there's storms likely today over Ireland and the north. I guess if it's not 'in my back yard' (IMBY) you're not interested

.. and what's with all these weatheronline charts, N-W ones are far superior!

Does look interesting tomorrow, gotta go out for the day so will have a closer look this evening.

[maidstone weather]

Hi, could i have the link to the site where the thunderstorm chance maps are please.

Thanks.

http://ows.public.sembach.af.mil/index.cfm?section=Hazards

[frostyjoe]

yes same thing i was thinking if it aint in the south then knw one cares. lol

[maidstone weather]

yes same thing i was thinking if it aint in the south then knw one cares. lol

er no not really, i'm always interested in storms, but prefer them over my house

Tbh parts of Ireland/Scotland are having two consecutive days with thunderstorms possible - i've had none this year!

[frostyjoe]

yea lol , i cant wait to see if i can see the storms today as i was in the cinema when the storms were over my area , so missed them but could hear them over the cinema. lol

[Neilsouth]

Funny how everyone's talking about tomorrow, when there's storms likely today over Ireland and the north. I guess if it's not 'in my back yard' (IMBY) you're not interested

True lol , why should i care about storms hundreds of miles away unless i see good after footage i suppose

[Phil UK]

Coast, then why do people in the SE keep moaning about lack of storms?

Tomorrow will be exactly 2 months since my last one, but would be ironic to see a storm when I'm trying to celebrate my 2nd month in the NSC, and I only signed up for lifetime membership oh so recently too.

You know, I remember not all that long ago (1995 maybe? which theoretically was all that long ago!) when Kent and surrounding regions were seeing storms every other day. Birmingham/Solihull got diddley squat. Same as when you lot moaned about that you never get snow. February 2009, oh yes! Makes a change from Scotland nicking it all.

Phil.

[Tony Gilbert]

Moderate Risk of Scattered Thundery Showers Ireland, Scotland, Central and northern UK. 09Z-21Z Sun 14th June 09

Once again a rather low risk outlook with a good probability of widespread thundery showers. Filling quasi stationary low just west of Ireland continues to push further surface fronts across the UK & Ireland during Sunday. Upper cold pool remains in place and sustains a moderate lapse rate as surface heating once again gets under way. A weak shear profile all but precludes any suggestion of severe weather. Though some reference is given to the risk of some late troughing N.Wales. Where a mid level dry incursion runs through on 30kt winds at 500 mb.

Central Scotland should develop a strong convergence zone establishing a breeding ground for the odd funnel report.

[peterf]

huge towers forming to the east of me.wait and see

[Phil UK]

Thank you, Mr Gilbert. But convection is already beginning here in the Midlands. Could be an interesting 48 hours.

Phil.

[03jtrickey]

It seems clear that the potential seems to be moving (I don't like the word advecting!) S/E with, now, perhaps, the S/E seeing it's far share of the indices at 18z. LI is still on the edge, not great, but enough to not stop the good stuff happening. The LI, of course is a measure of atmospheric instability, and it does look like the atmosphere is more stable ...

The big uplift of E Anglia has now gone (perhaps back on GFS 6z) with the best area probably, now around E Anglia, E Essex and Kent - looks to me for some sferics perhaps after dark? Talking of after dark .... here's the 'steering' winds for around midnight tomorrow ...

Hi,

Would you or someone possibly be able to explain the Vertical Velocity charts, and their significance? I am assuming the lower the number, the greater the instability. Is this correct? Can storms still develop where VV is positive? I'm wondering because there is a circle of positive VV over the Severn Vale and Cheltenham, and I am hoping this won't mean our chance of storms is reduced on Monday.

Thanks,

James.

[Nick F]

N-W forecast issued for today, storms likely again in pretty similar areas as yesterday:

http://www.netweather.tv/index.cgi?action=...d728f287426868f

[maidstone weather]

latest run is a very slight downgrade, but hey it's expected

[VillagePlank]

Would you or someone possibly be able to explain the Vertical Velocity charts, and their significance? I am assuming the lower the number, the greater the instability. Is this correct? Can storms still develop where VV is positive? I'm wondering because there is a circle of positive VV over the Severn Vale and Cheltenham, and I am hoping this won't mean our chance of storms is reduced on Monday.

Literally, it's the forecast of the vertical motion of air.

For clouds to form air needs to rise, the lower the figure, the faster (or more vigorous) it rises. These charts show what the expected motion of air is in hPa (or air pressure) So a -15, say, means that a packet of air will move up in the atmosphere by 15hPa, so if you're at 850hPa, in an hour you'd be at 835hPa. It's worth noting that it is cumulative statistic deriving from vorticity and temperature movement.

It is unlikely that storms will form in positive VV conditions. But, beware of seeing this as a key statistic - it is not a complete profile of the potential for storms - local surface heating can change the profile in minutes. In my opinion it should be seen as expected 'average' conditions with, of course, local variation appearing both above and below the average line. It's just part of the puzzle that one likes to see when looking for storms.

Edited June 14, 2009 by VillagePlank

[azores92]

judging by the latest gfs, the place to be tomorrow looks somewhere in laois or offaly, where CAPE values are forecast to be consistently high through the mid/late afternoon period. in the uk, the east of wales/west midlands could well go bang by mid afternoon tomorrow.

[Supacell]

Regarding tomorrows potential. Are we looking at a rash of thunderstorms breaking out randomly across the country or is there likely to be a defined area of storms breaking out and then moving across the country as an MCS?

I am kind of hoping its the latter as these scenarios tend to favour evening storms for me, and I dont want to miss everything by being at work, as normally happens when its thundery showers.

[Gordon]

Hi Nick

can you or somebody else just clear something up for me

on your thunderstorm map you have four colours to denote severity

black yellow red and pink

can I assume the colour of the risk areas as in todays map ireland and scotland is black refers to the lowest level of severity and so on and so forth

Edited June 14, 2009 by Gordon