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Convective / Storm Discussion - 23rd August onwards 2013


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Posted
  • Location: Barry, South Wales (40M/131ft asl)
  • Weather Preferences: Cold snowy Winters, warm stormy spring & sumemr, cool frosty Autumn!
  • Location: Barry, South Wales (40M/131ft asl)

Regular flashes in the very distant far south west, will go west of here though!

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Posted
  • Location: South Gloucestershire BS35
  • Weather Preferences: Severe weather enthusiast
  • Location: South Gloucestershire BS35

Distant lightning to my north,sky looks clear but can clearly see the cloud producing it with each flash

 

Confirmed - I live about 10 miles North of Bristol and i'm seeing lightning flashes in the sky to the NW. I'm hearing no thunder at all so it must be far way.

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Posted
  • Location: Truro, Cornwall
  • Weather Preferences: Winter - Heavy Snow Summer - Hot with Night time Thunderstorms
  • Location: Truro, Cornwall

Nowhere in the UK can beat the downpour we endured here in Falmouth today. 45 minutes of non stop torrential rainfall, the odd flash and rumble and hail. I didnt see the worst of the hail though the video and photos are only from a mile or 2 away from us.

 

Best of all, those pictures are more wintry looking than the 12 hours of snow could deliver us in January this year! Posted Image

 

Would Land/Sea convergence have played any role in sustaining the cell for so long. I know steering winds in the upper levels were light today over Cornwall so showers were already slow moving but generally light winds promote convergence dont they?

Edited by Blizzards
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Guest William Grimsley

Nowhere in the UK can beat the downpour we endured here in Falmouth today. 45 minutes of non stop torrential rainfall, the odd flash and rumble and hail. I didnt see the worst of the hail though the video and photos are only from a mile or 2 away from us.

 

Best of all, those pictures are more wintry looking than the 12 hours of snow could deliver us in January this year! Posted Image

 

Would Land/Sea convergence have played any role in sustaining the cell for so long. I know steering winds in the upper levels were light today over Cornwall so showers were already slow moving but generally light winds promote convergence dont they?

Yeah, I think that shower was helped by convergence as it developed a few miles in from the S Cornwall coast. Also, light upper level winds and light lower level winds help to make convergence happen.

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Posted
  • Location: Barry, South Wales (40M/131ft asl)
  • Weather Preferences: Cold snowy Winters, warm stormy spring & sumemr, cool frosty Autumn!
  • Location: Barry, South Wales (40M/131ft asl)

Had some distant thunder and lightning here last night from over the Bristol channel, was nice to see though wish it was overhead!

Managed to catch this though it is blurry :(

post-10181-0-32333000-1378537856_thumb.p

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Guest William Grimsley

Had some distant thunder and lightning here last night from over the Bristol channel, was nice to see though wish it was overhead!

Managed to catch this though it is blurry Posted Image

Posted Imagelightning13.png

I think that's a great catch, DeepSnow! Well done! :D

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Posted
  • Location: Eastbourne, East Sussex (work in Mid Sussex)
  • Location: Eastbourne, East Sussex (work in Mid Sussex)

Nothing this morning from ESTOFEX or UKASF, Netweather forecast in place from Nick and SkyWarn have:

 

 

SKYWARN UK SEVERE WEATHER WARNING #031
ISSUED: 1000UTC FRIDAY 6TH SEPTEMBER 2013 (GJ/GS)
 
SKYWARN UK HAS ISSUED A WARNING FOR SEVERE WEATHER AS FOLLOWS:
 
HEAVY RAIN LEADING TO A RISK OF LOCALISED FLOODING - NORTHERN ENGLAND, SOUTHERN SCOTLAND, NORTH WALES, ISLE OF MAN AND NORTHERN IRELAND
 
IN EFFECT UNTIL 0600UTC SUNDAY 8TH SEPTEMBER 2013
 
DEVELOPING NEAR-STATIONARY LOW PRESSURE OVER THE IRISH SEA
 
DISCUSSION:
 
THERE IS INCREASING MODEL AND PARTNER AGENCY CONFIDENCE IN THE POSSIBILITY OF SEVERE WEATHER RISKS THROUGH THE WEEKEND. THE DEVELOPING SURFACE LOW PRESSURE SYSTEM IS EXPECTED TO REMAIN NEARLY STATIONARY AS THE UPPER TROUGH CUTS OFF, GENERATING PERSISTENT AND HEAVY RAIN IN THE WARNING AREAS. THROUGH FRIDAY AND OVERNIGHT INTO SATURDAY, AREAS OF NORTHERN ENGLAND MAY SEE ACCUMULATIONS OF 40MM WIDELY WITH PERHAPS AS MUCH AS 70MM OVER HIGHER GROUND. INTO SATURDAY, AREAS OF NORTH WALES, SOUTHERN SCOTLAND AND NORTHERN IRELAND MAY SEE ACCUMULATIONS OF 40-50MM WIDELY, ESPECIALLY NEARER IRISH SEA COASTS OWING TO EMBEDDED CONVECTION. LOCALLY, SOME PLACES MAY SEE 30MM WITHIN A SHORT SPACE OF TIME, LEADING TO A RISK OF RAPID SURFACE RUN-OFF AND FLASH FLOODING, WITH POSSIBLE RIVER CATCHMENT FLOODING GOING INTO SATURDAY. THIS WARNING MAY BE UPDATED. PLEASE MONITOR WEATHER AND TRAVEL INFO AS NECESSARY.

 

 

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Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

Synopsis

 

Deep cut-off low continues to sit above the British Isles through Saturday, with strong jet streaks on both western and eastern flanks. Trough axis lies roughly down the Irish Sea. Cooling mid-levels combined with warm SSTs will allow for some convection.

 

Discussion

 

... SW ENGLAND, W COUNTRY, S MIDLANDS ...

Showers are already ongoing offshore due to warm SSTs and cool mid-levels. Steering winds will continue to back from the west to the southwest, pushing further showers inland. As surface temperatures rise due to diurnal heating, showers will become more sustained as they move inland, with further showers developing elsewhere. A few hundred J/kg and ELTs down to -30C suggests some sporadic lightning is possible, particularly over Devon and Dorset where greatest proximity to the English Channel and best instability is likely to be present. Despite weak DLS (increasing significantly in the eastern section of the ISOL), some low-level convergence may allow showers to form a distinct NE-SW aligned line by this afternoon. Given cool air aloft, some hail up to 1.5cm in diameter is possible in any stronger cores. 

... SCOTLAND, NORTHERN IRELAND ...

As the main frontal rain continues to clear northwestwards, scattered showers and a few thunderstorms will form in the post-frontal airmass, as several hundred J/kg CAPE is generated. Best overlap of instability and DLS will be over W and SW Scotland, and given 30-50kts DLS and the left exit of the jeat streak, cells should become fairly well-organised. Given backed surface winds, there may be the potential for a funnel or weak tornado/waterspout, while such cool air aloft suggests hail perhaps greater than 2.0cm in diameter is possible in any stronger cores. Offshore convection is likely to increase over the North Sea through the evening hours, which given the steering flow may then push into parts of Aberdeenshire etc.

 

http://ukasf.co.uk/storm-forecasts/277

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Guest William Grimsley

A few hundred J/kg and ELTs down to -30C suggests some sporadic lightning is possible, particularly over Devon and Dorset where greatest proximity to the English Channel and best instability is likely to be present. Despite weak DLS (increasing significantly in the eastern section of the ISOL), some low-level convergence may allow showers to form a distinct NE-SW aligned line by this afternoon. Given cool air aloft, some hail up to 1.5cm in diameter is possible in any stronger cores. 

Bring it on! I'm in Devon and near the English Channel so this should be great here! :D

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Posted
  • Location: Dunmow, Essex (72m asl)
  • Weather Preferences: Anything apart from grey days
  • Location: Dunmow, Essex (72m asl)

Couple of sferics near poole.

Nice line of cells forming on radar.

Edited by poseidon
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Posted
  • Location: Cleeve, North Somerset
  • Weather Preferences: Continental winters & summers.
  • Location: Cleeve, North Somerset

Rumble of thunder to the southwestish of here.

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Guest William Grimsley

So far today, there has been had 1 torrential rain shower with pea size hail and 1 light rain shower, here. Rainfall Today: 3.4 mm Rainfall Last Hour: 0.4 mm High Rainfall Rate Today: 33.8 mm/hr 12:52. Posted Image

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Posted
  • Location: Belper, Derbyshire
  • Weather Preferences: Thunderstorms
  • Location: Belper, Derbyshire

Thunderstorm south of Salisbury towards the New Forest is putting out a few strikes and has some intense precipitation in it on the radar.

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Posted
  • Location: Brongest,Wales
  • Weather Preferences: Stormy autumn, hot and sunny summer and thunderstorms all year round.
  • Location: Brongest,Wales

Just recently heard about two rumbles of thunder from a dark cloud to my southeast.

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Posted
  • Location: Bedford Bedfordshire
  • Weather Preferences: Fire tornado
  • Location: Bedford Bedfordshire

The sky is looking more showery by the hour, still not convinced it will even rain here though. The garden needs it!

Edit: lots of showers popping up around me on the radar! Fingers crossed for some hail...

Edited by TheToastPeople
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Posted
  • Location: Winchester, Hampshire ~ Southern Central!
  • Location: Winchester, Hampshire ~ Southern Central!

I jsut battered by one coming in from the west. Was emptying the car and got a massive strike and crack all in one. Nearly peed myself! WAs small but very intense. Marble sized hail.

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Posted
  • Location: Dunmow, Essex (72m asl)
  • Weather Preferences: Anything apart from grey days
  • Location: Dunmow, Essex (72m asl)

Couple of sferics round Milton Keynes now - line of showers joining to the salisbury cell. Not much else happening though.

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Guest William Grimsley

So far today, there has been had 1 torrential rain shower with pea size hail, 1 light rain shower and 1 moderate shower, here. Rainfall Today: 4.4 mm Rainfall Last Hour: 1.0 mm. :D

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Posted
  • Location: Milton Keynes, Buckinghamshire, England. 108.7m ASL
  • Location: Milton Keynes, Buckinghamshire, England. 108.7m ASL

Couple of sferics round Milton Keynes now - line of showers joining to the salisbury cell. Not much else happening though.

 

Aye, small cell sitting to the south of MK, heard three loud booms and witnessed a very bright flash of lightning which was viewable even though there was full sunshine at the time.

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Posted
  • Location: Dunmow, Essex (72m asl)
  • Weather Preferences: Anything apart from grey days
  • Location: Dunmow, Essex (72m asl)

Aye, small cell sitting to the south of MK, heard three loud booms and witnessed a very bright flash of lightning which was viewable even though there was full sunshine at the time.

While walking the mutt I could see some towering clouds in the distance in that direction - looked quite impressive, but didn't have my camera handy.

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Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)

Some quite lively storms to the W and NW London currently, can see the line of CBs and even the bases between rain/hail cores clearly to the west from my office in west London.

 

post-1052-0-67595100-1378571650_thumb.jppost-1052-0-83633500-1378571663_thumb.jp 

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