Convective / Storm Discussion - 8th September onwards 2013

[Guest William Grimsley]

Where's this pepping up of rain, then?

[Supacell]

Bbc are mentioning thundery rain for thursday but GFS doesn't agree on the thundery part, although it does show heavy rainfall. We will know more by this time tomorrow as it comes into range of the NMM and NAE hi-res models.

[Guest William Grimsley]

Bbc are mentioning thundery rain for thursday but GFS doesn't agree on the thundery part, although it does show heavy rainfall. We will know more by this time tomorrow as it comes into range of the NMM and NAE hi-res models.

Yeah, it's possible that there will be thundery rain over W England and E England. Whilst C England will be sandwiched in between with showers.

Edited September 30, 2013 by William Grimsley

[Mapantz]

Yeah, it's possible that there will be thundery rain over W England and E England. Whilst C England will be sandwiched in between with showers.

 

I'll take a wild stab in the dark that you're looking at the NAVGEM precip model by coming to that conclusion? About as useful as fart in a wind tunnel at this range!

 

Looking at the isobars from various models at this range would suggest quite a widespread area across England and Wales seeing some pretty heavy rainfall. Tuesday night in to Wednesday could prove to be very wet in the South East too! Something interesting to keep an eye on anyway, the last two days here have been horrendously dull, drizzly, manky, depressing .. you name it ..  :lol:

[Guest William Grimsley]

I'll take a wild stab in the dark that you're looking at the NAVGEM precip model by coming to that conclusion? About as useful as fart in a wind tunnel at this range!

 

Looking at the isobars from various models at this range would suggest quite a widespread area across England and Wales seeing some pretty heavy rainfall. Tuesday night in to Wednesday could prove to be very wet in the South East too! Something interesting to keep an eye on anyway, the last two days here have been horrendously dull, drizzly, manky, depressing .. you name it ..  

I'm looking at no model. I was just refrencing the BBC Weather forecast.

I hope there is some heavy rainfall for the UK and, here.

[Supacell]

I maybe should have indicated that my previous comments regarding GFS having none of the thundery element was in reference to here where I live and the rest of the Midlands.

 

In actual fact there does looks to be a slight risk of storms over the SW, especially so later tomorrow and overnight into and including Wednesday - on Wednesday the risk could move into South Wales too. The GFS charts look good for storms on Thursday along the south coast and across the far SE behind an area of heavy rainfall which appears to expand NW across the country - but will this expanse of rain bring the risk of a rumble to more of us?

[Mapantz]

The bulk of the rainfall does look to be largely dynamic, though GFS continues to hint at a risk of storms for the south coast and far SE quarter from afternoon into evening period, as fairly moisture-rich air mass surges north and east with the lifting of the warm front.

 

fax_103013_12utc.gif 850_theta_e_10031312z.png

 

Particular attention is drawn to the triple point region on latest fax output, where greatest ascent occurs as the front occludes, which is highlighted by GFS with steep velocities modeled:

 

vert_vel_700_03101312z.png

 

Not overly convincing tbh and a bit up in the air wrt latest synoptic outlook as to when the risk is greatest. Bit far out atm though, so, as you say, best to wait 'til within NAE range for a somewhat clearer picture.

 

Certainly some strong PVA and a vortmax lobe there! I can see the reds & pinks showing up on the radar around the IoW/Hampshire area if the output continues to model it like that.

[Nick F]

Not so sure about Thursday's convective potential yet, though it does look like it will turn wet from the south as the shallow low and triple point drift north with a surge of moisture.

 

Although GFS limits CAPE to the far SW of the UK tomorrow/ Tuesday night, there maybe potential for thundery rain/embedded isolated storms to affect southern England tomorrow night as hinted at in MetO forecasts too. 12z ECM hints at an area of heavy (perhaps thundery rain?) moving NE from NW France clearing SE England/E Anglia Weds morning:

 

http://en.vedur.is/weather/forecasts/atlantic/#type=prec

 

Maybe worth keeping an eye on radar and lightning dectecors tomorrow evening/night?

Edited September 30, 2013 by Nick F

[Convective]

I'll take a wild stab in the dark that you're looking at the NAVGEM precip model by coming to that conclusion? About as useful as fart in a wind tunnel at this range!

My god that tickled me.As instability gets a grasp of the majority of the country over the next few days, we should see things pick up on the convective front. Although the ejection of moisture only just tickles the south, any instability is good around costal areas at this time of year!

[Supacell]

The latest GFS models indicate a slight chance of something thundery across SW England and S Wales later on today and overnight as part of a band of rain that moves towards the east. However, by the time the rain band edges towards the Midlands it will likely lose any electrical activity. Best chances look to be close to the south coast of Dorset, Devon and Cornwall. Tomorrow, there could be some thundery showers across more of Wales. 

 

As for Thursday's rain. GFS and lightning wizard show some heavy rain for a time, but it is dynamic with very little if any convective activity as part of the band. Detail is sketchy at this time but there is still a probability of thunderstorms running into the south coast and affecting the far SE during Thursday night.

[Dorsetbred]

The latest GFS models indicate a slight chance of something thundery across SW England and S Wales later on today and overnight as part of a band of rain that moves towards the east. However, by the time the rain band edges towards the Midlands it will likely lose any electrical activity. Best chances look to be close to the south coast of Dorset, Devon and Cornwall. Tomorrow, there could be some thundery showers across more of Wales. 

 

As for Thursday's rain. GFS and lightning wizard show some heavy rain for a time, but it is dynamic with very little if any convective activity as part of the band. Detail is sketchy at this time but there is still a probability of thunderstorms running into the south coast and affecting the far SE during Thursday night.

I'll take that.....

[Coast]

The latest GFS models indicate a slight chance of something thundery across SW England and S Wales later on today and overnight as part of a band of rain that moves towards the east. However, by the time the rain band edges towards the Midlands it will likely lose any electrical activity. Best chances look to be close to the south coast of Dorset, Devon and Cornwall. Tomorrow, there could be some thundery showers across more of Wales. 

 

Today does look a long shot:

 

 

 

 

I think anything that is there is out to sea?

 

 

 

 

Edited October 1, 2013 by Coast

[Coast]

Nothing from ESTOFEX, but this from Dan at UKASF:

 

 

 

Synopsis

 

An upper trough/low over the Atlantic will continue to swing northeastwards towards the British Isles, while an upper omega block, with axis down the spine of the North Sea, will reside to the east of Britain. At the surface, a couple of weakening occlusions will bring some occasional showery rain to western parts of Britain, but with particular attention focussed on a shortwave trough approaching during the afternoon and evening hours.

 

Discussion

 

... SW ENGLAND ...

 

With the approach of a shortwave trough, there is a signal for a cluster of high-based showers and a few thunderstorms to develop during the afternoon and evening hours, lightning primarily over the Brest peninsula and nearby English Channel, which may retain some sporadic lightning activity (perhaps) as it nears southern and eastern parts of Cornwall and Devon (hence the inclusion of a low-end SLGT here). This area of showers/rain will continue to drift and expand northwards through the evening towards Dorset, Hampshire and IoW, although it is questionable as to how electrically active this will be by this stage. Stronger cells may produce some small hail and locally heavy rainfall given PWAT values of 30+mm.

 

 

... IRELAND ...

 

Convection is possible in the post-frontal airmass as the arrival of a shortwave trough enhances forced uplift. Scattered showers and a few thunderstorms are possible, with CAPE values of 400-600 J/kg forecast. Excessive cloud is likely to be the main inhibiting factor. Given rather moist surface airmass, low LCLs and 15-20kts LLS, an isolated funnel or tornado cannot be ruled out, perhaps also with some small hail in any stronger cells.

 

 

[Nick F]

Wouldn't rule out a risk of embedded thunder away from the southwest in the outbreaks of rain spreading northeast overnight too across southern and later central parts of England. Although the GFS CAPE charts are a reasonably good broadscale guide, wouldn't take the highest values as gospel to likelihood. Axis of warm moist air pushing north out of France tonight ahead of shortwave moving NE, so wouldn't be surprised of the odd flash and rumble anywhere for S England early hours/Weds morning.

 

As always, watch developments on radar and lightning detectors!

Edited October 1, 2013 by Nick F

[ardsar]

There has been quite a lot of lightning activity already off the SW coast. Its making slow progress N / NE. Had some lively bursts on the detector. Plymouth is currently 16.5 Degrees and 98% humidity. Had a hefty shower around 8am. 

[Coast]

Interestingly, this smattering of NMM charts for 20.00hrs tonight has Wales highlighted along with the SW as an area we might want to keep an eye on:

 

 

 

 

 

Animation of the fronts moving through during this period:

 

Edited October 1, 2013 by Coast

[A.J]

nice little cluster of thunderstorms pushing northwards from Brest towards the south cornish coast.....could be quite lively in Penzance and Falmouth in the next couple of hours

 

[Guest William Grimsley]

The latest GFS models indicate a slight chance of something thundery across SW England and S Wales later on today and overnight as part of a band of rain that moves towards the east. However, by the time the rain band edges towards the Midlands it will likely lose any electrical activity. Best chances look to be close to the south coast of Dorset, Devon and Cornwall. Tomorrow, there could be some thundery showers across more of Wales. 

 

As for Thursday's rain. GFS and lightning wizard show some heavy rain for a time, but it is dynamic with very little if any convective activity as part of the band. Detail is sketchy at this time but there is still a probability of thunderstorms running into the south coast and affecting the far SE during Thursday night.

Yes, there is a good chance of some thundery weather later on today for SW England, especially. There is lovely thunderstorm to the S of Cornwall, pushing towards W Devon, now. Even so, there is a lot of thundery weather pushing in behind this thunderstorm. So, fingers crossed.

[ardsar]

Very distant rumbles of thunder hear in Plymouth....

 

But the sferic activity has died down for a bit. Hopefully he is just resting lol

Edited October 1, 2013 by ardsar

[Guest William Grimsley]

A lovely thunderstorm is about to hit the S coast of Devon. If this gets a move on and keep its intensity, there could be in for a late afternoon thunderstorm, here.

Edited October 1, 2013 by William Grimsley

[poseidon]

Met office now have a weather warning out for heavy thundery rain over South/Central England and Wales for Thursday with a "likely" rating.

[NO LONGER POSTING]

A lovely thunderstorm is about to hit the S coast of Devon. If this gets a move on and keep its intensity, there could be in for a late afternoon thunderstorm, here.

 

Dead now

 

http://www.blitzortung.org/Webpages/index.php

[Coast]

Here's that next front coming in from the West for later:

 

[Nick F]

Storm & Convective Forecast

Issued 2013-10-01 14:35:04

Valid: 01/10/13 1400 to 02/10/13 0600z

 

  THERE IS A RISK OF THUNDERSTORMS FORECAST

Synopsis
Slow-moving upper and collocated surface low will be situated to the SW of Ireland during this forecast period, with a slow-moving occluded front moving in across western Britain. A belt of strong upper level flow will remain just south of the UK over Nern  France while a shortwave-trough moves northeast across Sern Britain ahead of this stronger flow - which will serve to increase convective potential over the next 12-24 hours.

SW ENGLAND, WALES, IRELAND, S ENGLAND and THE MIDLANDS.

Height falls/forcing for ascent ahead of aforementioned short-wave trough moving northeast across Sern Britain/Ireland will create increased forced ascent of warm/moist low to mid level flow also spreading north across Sern England, Wales and Ireland over the next 12-24 hours - with heavy rain and isolated embbeded elevated thunderstorms likely to spread north across SW England, Wales, Ireland this afternoon and evening and perhaps further north and east across The Midlands and other parts of southern England into the overnight period. Convective activity will be generaly rooted above the boundary layer - so no severe weather is anticipated ... though high PWAT (Precipitable Water) values of 30mm+ suggests high rainfall totals in a short space of time are possible, leading to localised flooding. Also there is a risk of hail and gusty winds.

 

Also can be found here: http://www.netweather.tv/index.cgi?action=convective;sess=d5bcf18ce9cbd3f3eb81bc6a35ceb028

Edited October 1, 2013 by Nick F

[Guest William Grimsley]

Dead now

 

http://www.blitzortung.org/Webpages/index.php

Not anymore.

Here comes the thunderstorm!