Convective Storm/Discussion thread - 02/09/16 onwards

[Weather-history]

Showers today

 

[Summer Sun]

Day 2 Convective Outlook

VALID 06:00 UTC Mon 26 Sep 2016 - 05:59 UTC Tue 27 Sep 2016

ISSUED 19:45 UTC Sun 25 Sep 2016

ISSUED BY: Chris

An upper trough axis will move eastwards across northern Scotland helping to produce very modest lapse rates and around 200 j/kg of CAPE. This will be enough to generate some heavy showers, a few with a low end risk of thunder, mainly during the morning and early afternoon. 

Elsewhere, low pressure centred the southwest of Ireland will push an area of cloud and rain across Ireland and into southwestern parts of Britain during the day. Ahead of this scattered showers will be possible, but with slight height rises and the lack of instability, convective potential will be limited across southern and eastern England. There will also be the very small chance of embedded lightning within precipitation near the low (western England and Wales), but it is deemed too small of a risk to include in this forecast. 

http://www.convectiveweather.co.uk/forecast.php?date=2016-09-26

[East_England_Stormchaser91]

Yet again the Balearics are under a warning. There has not been one day where I haven't seen distant lightning at night or a decent storm overhead, and I've been here for 4 days now. Really is quite exceptional out here. 

The way the storms breed and form out here is so quick too. Think the lapse rates must have something to do with it, as it's almost been like watching a video sped up whilst a cell is forming in real time! 

Just got back in from having a beer and watching some cracking distant lightning from a cell south of menorca from Majorca. 

Can safely say I've seen more convective activity in this 4 days alone than I have in the UK all year! 

[Buzzard]

I was in Ibiza on a lads holiday in Sept 96, amazing storm which I have seen an article about somewhere.

Back here in London...what is this storm that has appeared from nowhere...didn't think this was forecast?

[Allseasons-Si]

Hi guys

i still haven't looked through the footage of my clips of the storms earlier this month,don't worry i have not forgotten about it,just not had the time,maybe the end of this week If i get the work done in the garden.

[Supacell]

I know it was almost 2 weeks ago but check out this little clip of the footage I took from just outside Winchester- turn the volume up as loud as you can! 

One of many, but this was probably the closest and certainly the best captured

 

Edited September 28, 2016 by Supacell

[Nick F]

More for northern Britain and EIRE really, but as well as winds gusting to 50-60mph over Scotland, perhaps 60-75mph far NW Thursday morning, some lively and perhaps thundery showers too:

Storm & Convective Forecast

Issued 2016-09-28 22:48:32

Valid: 29/09/2016 00z to 30/09/2016 00z

CONVECTIVE / STORM FORECAST - THURS 29TH-SEPT-2016

Synopsis

Long-wave upper trough to NW of UK edges SEward across the UK during Thursday. A deep area of low pressure passing close to northern Scotland overnight runs east and merges with low pressure complex over Norway. Cold front associated with this low will clear SE UK Thursday morning, with a cool Pm flow following which will become increasingly unstable across Scotland and N. Ireland.

... SCOTLAND, N. IRELAND, EIRE and NW ENGLAND ...

Cold front sliding SE across England and Wales is unlikely to produce any strong convection, due to poor lapse rates/ warm mid-upper temps above front. 

Forward side of large-scale upper trough pushing SE across the UK will introduce sufficiently cold and dry mid-level air atop of warm seas and modest land heating to create an increasingly unstable Polar maritme airmass across northern mainland UK and EIRE. So across the above areas expect scattered or numerous heavy showers, some of which will be accompanied by hail and thunder. Vertical deep layer shear will tend to become weak as the greater instability arrives from the NW in the morning and into the afternoon. Though one or two troughs and occluded fronts in the strong westerly flow could organise convection sufficiently to bring a risk of localised flooding. There is also a risk of strong and perhaps isolated damaging convective gusts associated with downdrafts bringing down strong upper winds within heaviest showers or storms across central Scotland in particular. Therefore have issued a MARGINAL risk of severe weather here.

[Chris.R]

 Lightning getting more frequent to the north. A recent strike north of Burnley.  :-) 

[Weather-history]

Quite a poky cell running along the north of Fylde. 

[Chris.R]

A sferic just  North of Kirkby but didn't hear anything from it. 

[Thunderstruck]

19 minutes ago, Chris.R said:

A sferic just  North of Kirkby but didn't hear anything from it. 

Looking at the radar that might possibly be a false return

[I remember Atlantic 252]

24 minutes ago, Weather-history said:

Quite a poky cell running along the north of Fylde. 

can see possibly that to my extreme north

[Chris.R]

8 minutes ago, Jcweather said:

Looking at the radar that might possibly be a false return

  I was thinking that as I don't remember hearing anything close at that time on the radio. 

Edited September 29, 2016 by Chris.R

[carl1980]

Just heard thunder 

[Chris.R]

Sferic West of Liverpool airport, not audible from here. 

[carl1980]

6 minutes ago, Chris.R said:

Sferic West of Liverpool airport, not audible from here. 

Didn't see the lightning but heard a rumble, nothing since

[cheshire snow]

40 minutes ago, carl1980 said:

Didn't see the lightning but heard a rumble, nothing since

Heavy rain Thunder Lightning at Manchester Airport

 

C.S

[toggerob]

Thunder here in the Peaks, quite unexpected.

[toggerob]

Interesting TAF report for Manchester Airport this evening and overnight..

TAF: EGCC 292023Z 2920/3024 20008KT 9999 FEW040 PROB40 TEMPO 2920/2921 6000 +TSRAGS BKN014CB PROB30 TEMPO 2921/3018 8000 SHRA

thunderstorm, heavy rain, small hail or snow pellets

[alr1970]

Nice anvil development on the shower north of Warrington now:

[Weather-history]

The Ribble express was in force this morning

 

[Frosty hollows]

l word being used in tonight's met office warnings:

http://www.metoffice.gov.uk/public/weather/warnings/#?tab=warnings&map=Warnings&zoom=5&lon=-3.50&lat=55.50&fcTime=1475276400&regionName=uk

[Nick F]

Storm & Convective Forecast

Issued 2016-09-30 22:09:05

Valid: 01/10/2016 0000 TO 02/10/2016 0000

CONVECTIVE / STORM FORECAST - SAT 1ST-OCT-2016

Synopsis

A well-defined upper-level low/trough in the strong belt of upper westerlies covering northern Europe will shift east across the UK during Saturday. At the surface, a shallow area of low pressure will cross S Ireland Friday night, then S Wales and S England on Saturday, slightly deepening to around 1003mb as it does so. Wrap around occlusion moving east with the low will bring outbreaks of heavy rain and also airmass will become sufficiently unstable for some thunderstorms.

... IRELAND, ENGLAND and WALES, S SCOTLAND ...

Water Vapour imagery Friday evening shows a well-defined dry air vortex of upper low/trough crossing S Ireland, with associated lift and increasingly colder mid-level temperatures atop of relatively warm SSTs increasing low-level lapse rates/CAPE and enhancing convection over western areas. Heavy showers and a few isolated thunderstorms will drift east in across Ireland, S England, Wales, Midlands and NW England Friday night. Then thundery downpours could occur across  much of England and Wales and perhaps S Scotland during Saturday wherever lift is enahnced and/or pockets of instability occur where the sun comes out / or over warm SSTs beneath cold air aloft spreading east.

These heavy showers and perhaps storms will organise into bands locally due to combination of large scale ascent aloft with passage of upper low, local surface wind convergence near slack low pressure centre moving east and lift along wrap around occlusion. And with low-to-mid-level winds becoming light as upper/surface low passes through, showers/storms will become slow-moving bringing a risk of localised flooding where cells train over one area. Storms may also be accompanied by hail and gusty winds too.

Although deep layer shear will become weak under upper low passing through, low-level shear will be enhanced by backing of winds with passage of low ... particularly near coastal areas  ... and also enahnced by wind convergence. This increase in LL shear locally may allow more stronger/bouyant updrafts over warm SSTs to rotate and tighten to form isolated tornadoes or waterspouts.

Other than the potential for some very localised areas of flooding, the risk of severe weather looks minimal due to cloud cover and extensive non-convective rainfall limiting potential instability to give a signal for a low/isolated storm coverage - so a general thunderstorm risk will suffice for now.

Issued by: Nick Finnis

[Convective]

On 14/09/2016 at 12:26, Mapantz said:

@Convective would be in a nice place if it does work out.

Sorry! Only just seen this now. I was in a storm-starved Skiathos on this day, getting envious of the potential back home! Everything seemed to miss here on that day though, despite the odds.

 

There have been a few flashes of lightning and rumbles of thunder here over this evening. Some fairly decent, but activity seems to have died off now. We've also had heavy rain, hail and even graupel and sleet! 

[Bolt from the Blue]

Just had a crack of thunder here