Uk Convective General Discussion & Forecasts - May 2012 Part 2

[NL]

Perhaps one day we might see this in the reliable time-frame..!! ..

[Coast]

Perhaps one day we might see this in the reliable time-frame..!! ..

Holy swear filter!!!!! I'l be keeping an eye on that as we get nearer the time.

Perhaps the GFS boys set the needle way up too high, or maybe on May 24th someone is going to get the biggest bang of their lives!!!

[Cakie]

Yikes, if that came off that would be amazing

[Guest QuantumSnow]

Perhaps one day we might see this in the reliable time-frame..!! ..

Whoa!! Steady on there..! Big bangs in the south east? Never!!

[Harry]

GFS always over-eggs CAPE/LI in that time frame.

The only time in 7 years of looking at charts and using this forum, were CAPE/LI values like that actually experienced was late June last year, during one of the most humid spells in my living memory in the UK!

Dew points were around the 20C mark with temperatures peaking at 31-32C....on that basis, I think we can safely say those current charts for the 24th May are somewhat over-egged, lol

[A.J]

The GFS CAPE FI eye-candy charts are a sight for sore eyes, they always downgrade, but after all the cruddy weather we've endured it gives that nice 'summer is around the corner and spanish plumes are here again' sort of feeling, even if reality says "it isn't, and they're not!"...lol

[Alex95]

Torrential downpours in Newcastle this afternoon. Even had hail at one point, yet the forecast was overcast and drizzly!

[Supacell]

GFS always over-eggs CAPE/LI in that time frame.

The only time in 7 years of looking at charts and using this forum, were CAPE/LI values like that actually experienced was late June last year, during one of the most humid spells in my living memory in the UK!

Dew points were around the 20C mark with temperatures peaking at 31-32C....on that basis, I think we can safely say those current charts for the 24th May are somewhat over-egged, lol

Would that be the "El Gordo" event? If so then even with those CAPE/LI nothing actually happened on the day, it was the following day under much less CAPE that big thunderstorms fired up.

[Robbie Garrett]

Something does tell me we are way overdue a 'major' Spanish plume event, 90s esque sort of storms. I'll say one thing, if the trough stays nearby and displaces to the south west.... and high presssure can build to our east.......game on.

[Convective]

Monday evening looks good? Medium CAPE and LI values and some good temperatures across much of the country plus by the time the afternoon comes round, the sun should be out in a few places to do its job in aiding convection!

Edited May 12, 2012 by Convective

[Convective]

I was really bored this morning so why not make a storm forecast? Here's mine, bearing in mind its rather amateur Anyway thought I would give it a shot based on the charts available on here. Lets see how it pans out and how mine compares to the professional forecast that should be issued later today or tomorrow. Here you go!

A SLIGHT RISK was issued for Northern Ireland, Isle of Man, Southern Scotland, North West England and North East England mainly for convection that will initiate throughout the late morning/ early afternoon hours sparking heavy showers and isolated thunderstorms which may be accompanied by small hail and thunder and lightning. Some of these showers will continue accross the northern Irish Sea, allowing them to survive into where they may also be accompanied by small hail and thunder and lightning although due to lower lapse rates convection is likely to be more messy here.

A LOW-SEVERE RISK was issued for parts of County Antrim, County Armagh and County Down where CAPE values are expected to exceed 600 - 700J/kg and LI expected to reach -3 in parts. During the end of the afternoon, the wind should of moderated and the air temperature should rise to 14°c or 15°c meaning any initiation of convection will be slow moving posing the risk of lying precipitation/ flash flooding. Showers here are expected to consist of small hail, heavy rain and thunder and lightning.

Through both of these areas, overall shear will be low meaning any developments will be confined to single celluar structure rather than MCS.

Edited May 13, 2012 by Convective

[Supacell]

Nice one convective, although I'd be tempted to include NE England & SE Scotland in the green area for tomorrow. I would expect places such as Northumberland/Borders to be in with a good chance. There looks to be some convergence of the winds along with around 400-500 J/KG of SBCAPE (on the GFS) which should allow storms to develop in an unstable environment. Will be interesting to see what the experts make of it

[Convective]

Nice one convective, although I'd be tempted to include NE England & SE Scotland in the green area for tomorrow. I would expect places such as Northumberland/Borders to be in with a good chance. There looks to be some convergence of the winds along with around 400-500 J/KG of SBCAPE (on the GFS) which should allow storms to develop in an unstable environment. Will be interesting to see what the experts make of it

Great input! Thanks alot! Has now been updated!

[Nick F]

Risk of a few storms popping up over northern and central UK and Eire in the cool but unstable polar flow tomorrow:

http://www.netweather.tv/index.cgi?action=convective;sess=e0d4c8ce06fe1489f8b01032a6a43ddf

[Convective]

Does anyone have any precipitation maps or lightning maps for Monday 11th May last year at about 1pm? Just looking at photos from a school event that was then and there are some amazing cloud structures in the background! CB's with great anvils! It was a really warm day too.

[Coast]

Here we go then, what has the atmosphere got in prospect for us storm fans today?

Netweather:

http://www.netweather.tv/index.cgi?action=convective;sess=

ESTOFEX reckon pretty well anyone might have a chance:

Storm

Valid: Mon 14 May 2012 06:00 to Tue 15 May 2012 06:00 UTC

Issued: Mon 14 May 2012 04:29

Forecaster: PUCIK

SYNOPSIS

Two major synoptic scale features will dominate the mid and upper levels of troposphere over the forecast area - the first one being a deep cyclonic vortex over the Norwegian Sea with an attendant trough crossing British Isles during the afternoon hours and amplifying towards southeast. The second one will be a rapidly translating trough moving from Italy towards Greece and then Turkey. Strong 30 m/s flow is forecast at the base of the trough. An ill defined ridge will develop between these two features while a de-amplification of ridge over Iberia is forecast.

Closer to the surface, two low pressure centers are simulated - one centered over the Norwegian Sea with very little movement during the day and central pressure close to 970 hPa, another one associated with the trough over the Mediterrranean, forecast to slightly deepen over the Aegean Sea in the night hours. A ridge over Central Europe will connect a large high over the Atlantic with high pressure system over northern half of Eastern Europe. Main frontal boundary will run from Northern Iberia to Southern Italy, Balkans, curving towards Eastern Ukraine and Russia.

SkyWarn concentrating on northern parts of the UK:

SKYWARN UK SEVERE WEATHER WATCH #021

ISSUED: 0900UTC SUNDAY 13TH MAY 2012 (GS/SM/GJ)

SKYWARN UK HAS ISSUED A SEVERE WEATHER WATCH FOR THE FOLLOWING REGIONS:

SCOTLAND NORTHERN IRELAND NORTHERN ENGLAND

IN EFFECT FROM 0900UTC SUNDAY 13TH UNTIL 2100UTC SUNDAY 13TH MAY 2012.

LOW PRESSURE TO THE NORTH OF SCOTLAND TO BRING HEAVY PRECIP AND STRONG GUSTS ACROSS THE INDICATED AREAS.

THERE IS A POSSIBILITY OF SEVERE WEATHER AFFECTING THE INDICATED REGIONS IN THE TIME PERIOD SPECIFIED. THREATS WITHIN THIS WATCH INCLUDE, BUT ARE NOT LIMITED TO:

HEAVY RAIN...FLOODING...STRONG GUSTS

DISCUSSION:

AN AREA OF LOW PRESSURE SITUATED NORTH OF SCOTLAND WITH TIGHTENING ISOBARS WILL BE BRINGING STRONG WINDS WITH HIGHER GUSTS ACROSS SCOTLAND, NORTHERN IRELAND AND NORTHERN ENGLAND. GUSTS OF BETWEEN 40-50MPH CAN BE EXPECTED IN THESE REGIONS BUT EXPOSED, WINDWARD FACING AREAS ARE LIKELY TO SEE GUSTS OF 60MPH.

THROUGH SUNDAY ASSOCIATED OCCULDED FRONTS AND TROUGHS WILL BE BRINGING A PERIOD OF HEAVY AND SUSTAINED RAINFALL, PRIMARILY ACROSS THE HILLS OF WESTERN SCOTLAND IN PARTICULAR WHICH ACCOMPANIED BY STRONG WINDS IS PROVIDING THE THREAT OF 40-50MM ACCUMULATED RAINFALL WITHIN A 12 HOUR PERIOD.

UKASF have N Ireland and a huge chunk of the North and Scotland under a watch:

Forecaster: Chris

Last Updated: 2012-05-13 18:41:00

Valid: 2012-05-14 00:00:00 - 2012-05-14 23:59:00

Areas Affected:

S Scotland, N England, N Wales, N Eire

Synopsis:

A deep area of low pressure will be centred over the Norwegian Sea and this will push a cold/occluded front southwards across Britain during the day. Behind the front an unsettled airmass will spread over northern Britain and Ireland with some particularly cold air aloft possible. Several troughs will move southward in a brisk NNW'ly flow.

Discussion:

Destabilisation of the atmosphere will occur during the day as cold air aloft is advected across N Britain and Ireland. Relatively low surface temperatures will limit surface based CAPE, however CAPE will increase from about 200j/kg in the morning over northern Eire to around 500j/kg during the afternoon, and 200-400j/kg will spread into northern England and southern Scotland during the afternoon as well. This will allow for quite a few showers to develop and few may be heavy with a few rumbles of thunder. The best of any shear values will be carried away to the south along the frontal boundary mentioned in the synopsis, however showers that develop early across Ireland could still tap into 30kt at of DLS at first, allowing for some more organised convection around midday. 500mb temperatures will cool to around -32C during the afternoon thus making it sufficiently cold that any showers that do develop will likely contain small hail, but with lack of shear it should not grow to severe levels. Showers will be much more isolated in N / Cen England during the afternoon than across northern Eire and the Borders.

Main risks: heavy downpours and small hail.

Nothing from TORRO, I'll go and find some pictures to add to the considerations for today!

[Chris.R]

Do you mean monday 9th may? I had a storm that day and AJ had his great supercell. Great day and was just after a spanish ploom.

[Coast]

21st OWS have any action down for later in the day:

If you take the lightning probabilities at face value, the action seems to be centred in the Irish Sea:

Or just in Northern Ireland???

CAPE again slap bang over the IOM:

Interesting lapse rates:

Pretty good agreement from all sources today on where anything might occur. As usual, down to some radar and lightning detector watching later today. Good luck!

[Coast]

So this one's for the fellas mostly; how much do you like thunder and lightning???

A Madrid man survived an unusual lightning strike recently.

http://digitaljourna...0#ixzz1upeP5r3E

Let me just say, please be very, very careful out there.......

[NL]

http://digitaljourna...0#ixzz1upeP5r3E

Let me just say, please be very, very careful out there.......

Probably that rare phenomenon known as 'Ball lightning'..!!

[Coast]

Probably that rare phenomenon known as 'Ball lightning'..!!

[A.J]

So this one's for the fellas mostly; how much do you like thunder and lightning???

http://digitaljourna...0#ixzz1upeP5r3E

Let me just say, please be very, very careful out there.......

Sometimes the medium of song sums up a news story.....all together now......"Goodness gracious, great balls of fire!".....lol

[Sprites]

line of showers over south lincs now, bit of convergence settiing them off, could turn heavy soon not really expecting thunder though, tomorrow looking better for East anglia and the midlands.

[Aaron]

Lightning in Northern Ireland now.. first of the day

[Sprites]

Some strikes showing up for cambridgshire/norfork area from the line that was over Lincs earlier, may head to my area 5pm ish.