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Convective / Storm Discussion - 22nd December 2013 - 2014 onwards


Jane Louise

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Posted
  • Location: Kings Norton, West Midlands
  • Weather Preferences: Thunderstorms, Cold & Snowy
  • Location: Kings Norton, West Midlands

Surely that graph would indicate the potential for severe storms? Of course though, TT is pretty rubbish when it comes to measuring thunderstorm activity because it doens't take into account that there could be capping, really depends on your geographical position & doesn't actually take into account CAPE. If, however there was high CAPE and no capping, that graph at 60tt (max) would indicate some pretty ferocious storms. 

Edited by PerfectStorm
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Posted
  • Location: Belper, Derbyshire
  • Weather Preferences: Thunderstorms
  • Location: Belper, Derbyshire

Normally the jet stream pushes north in the summer and south in the winter, passing over us in the seasons of Spring and Autumn. Previous years have seen the jet stream get stuck across us during the summer hence the run of bad summers between 2007 and 2012. This did not happen last summer. This year, the jet stream is running across us during the winter (although with a bit more venom) and is struggling to get south, and so I am expecting it to be to our north again come spring. That being said I think the warm summer of 2013 could be repeated in 2014, but it may not take as long as it did in 2013 to get going.

 

Along with warmer weather will be some decent Spanish plumes, but it won't be the relentless rain of 2007 or 2012.... just a prediction (hopecast) Posted Image

Edited by Supacell
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Posted
  • Location: Poole, Dorset 42m ASL
  • Location: Poole, Dorset 42m ASL

OK, so if you've got more to throw at us, get on with it, and do it in stylePosted Image

Perched up on top of one of the hills in Bournemouth might well pay off tomorrow, watching the progress of some storm action.

Edited by Dorsetbred
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Posted
  • Location: Dorset
  • Weather Preferences: warehamwx.co.uk
  • Location: Dorset

I missed out in the Summer (again) it seems to be Winter time now, 4 thunder showers this month, a cracker of one on December 31st, maybe a few tomorrow?! That's ruined it now. :lol:

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Posted
  • Location: Newbury
  • Weather Preferences: Sunshine and snow but not together
  • Location: Newbury

Did someone mention Summer?... Hang on a mo haven't we winter to still get through? ;) ... Although wouldn't it be great if we woke up next week and it has all fast forward to Summer... If only. Mind you we are almost there with these mild temps..

So not sure or fair that we should have any more rain. Please please let there be snow soon at the end of this tunnel... Please? We need cold! I read somewhere that with all this weather don't be surprised that there are a plethora of spiders... Gawd.

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

Nor the shear environment, therefore the TT index is made redundant.  I guess as long as the colours are eye-catching, though, they'll continue to be posted.  In this context, those values are high because of the steep contrast in temperature between 850 and 500mb (i.e. the vertical total). So, it would be a lot more informative to show the 500mb geopotential height and temperature profile since it's height falls and resulting cooling of the air aloft that is creating a steep environmental lapse rate, which increases instability.

 

CAPE, moisture and shear are the three main variables to be monitoring ahead of an expected period of significant convective weather. 

 

And shear is not that good tomorrow, so any cells that do form will likely pulse out very quickly. Still, with ELT's at around -30 to -40 there could be some decent hail showers and occasional lightning/thunder. I do not expect anything that exciting though and certainly no organised storm activity. CAPE nothing special either but I suppose for January one can't grumble.... unless you want snow of course then it's all pretty pants away from the mountain tops.

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Posted
  • Location: Stanwell(south side of Heathrow Ap)
  • Weather Preferences: Thunderstorms, squally fronts, snow, frost, very mild if no snow or frost
  • Location: Stanwell(south side of Heathrow Ap)

Normally the jet stream pushes north in the summer and south in the winter, passing over us in the seasons of Spring and Autumn. Previous years have seen the jet stream get stuck across us during the summer hence the run of bad summers between 2007 and 2012. This did not happen last summer. This year, the jet stream is running across us during the winter (although with a bit more venom) and is struggling to get south, and so I am expecting it to be to our north again come spring. That being said I think the warm summer of 2013 could be repeated in 2014, but it may not take as long as it did in 2013 to get going.

 

Along with warmer weather will be some decent Spanish plumes, but it won't be the relentless rain of 2007 or 2012.... just a prediction (hopecast) Posted Image

Exactly my thoughts. Expecting a return to the thundery summers of the 90s. My theory(I had said this 1-2 years ago) is that increase in snowfall especially the southeast during winter+very cold, decrease in thundery plumes from south, a connection is there I think. (look at the 90s with mild winters and thundery summers (winters more out of the 10 were mild than cold)) This winter and summer might just confirm my thoughts (not good for snow fans) 

 

Affected mainly the north we didn't have to many of those bad summers here, especially 2010

Edited by ElectricSnowStorm
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Posted
  • Location: Stanwell(south side of Heathrow Ap)
  • Weather Preferences: Thunderstorms, squally fronts, snow, frost, very mild if no snow or frost
  • Location: Stanwell(south side of Heathrow Ap)

Just read what weather said. So going to post some charts up for readers on this. some charts here compare for Thursday and today (so you can see the bigger difference in upper temperatures to today)

NAE

chart 1=Height 500hpa

         2=Height 850hpa

1-

Posted Image

Posted Image

2-

Posted Image

Posted Image

 

 

Troughs showery but thundery and can see the unstable airflow on the GFS LI here:

Posted Image

This is early but moves north and east.

 

Edited by ElectricSnowStorm
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Posted
  • Location: King’s Lynn, Norfolk.
  • Weather Preferences: Hot and Thundery, Cold and Snowy
  • Location: King’s Lynn, Norfolk.

I feel this year could be the year of the monster thunderstorms come summer time with Spanish plumes ETC..

 

SSTs are going to be very high this summer I feel so the channel wont be the killer this time Posted Image

Im with you on that mate! I do think we could see some much better activity this year than the last half a decade. There has definitely been a turning point I feel of late.

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Posted
  • Location: South Shields Tyne & Wear half mile from the coast.
  • Location: South Shields Tyne & Wear half mile from the coast.

ESTOFEX's take on developments today.

post-5386-0-14158800-1389856313_thumb.pn

 

DISCUSSIONSouthern British Isles to western FranceThe west-European mid-level trough expands east during the day. Cold air advection is expected especially at mid-levels, while low-level maritime air masses are advected into the forecast region. Due to strong DCVA, QG lift is expected, and differential cold air advection results in steepening lapse rates from the west. At low levels, a moist south-westerly flow will persist, and weak CAPE will be possible during the day.Due to the large-scale favourable forcing, showers and thunderstorms forming in the maritime air mass are expected. Especially over the land, strong 0-3 km vertical wind shear will allow for multicells and mesocyclones (favourably low-level veering and 0-3 km SRH around 150 m²/s²). Given a large overlap of strong low-level vertical wind shear (0-1 km bulk shear 12 m/s), mesocyclones and tornadoes are not ruled out. Limiting factors are the rather weak low-level buoyancy and the lack of pronounced low-level warm air advection. Additionally, persistent multicells with bowing segments will be capable of producing severe wind gusts at the leading edge of fast moving cold pools (850 hPa winds around 20 m/s).Convective activity will likely spread east but is expected to weaken given limited low-level moisture. Additionally, advection of drier low-level air will reduce the instability in the evening hours across most of France. Convective activity is therefore forecast to weaken.

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

LEVEL ONE BABY!

 

This has been on the cards for a few days and I'd almost pre-empted the level ! this morning as I was driving into work! I'm surprised none of the other dedicated storm sites have issued a forecast, I guess they figure there is less likelihood of thunderstorms at this time of year generally and get on with their real lives.

 

So lets start with some GFS type stuff:

 

Posted Image

 

Posted Image

 

and selfishly, for me:

 

Posted Image

 

Posted Image

Some CAPE all around our shores to the South West and Southern coasts:

 

Posted Image

 

Dorset and Devon in the firing line as the day goes on and things move East:

 

Posted Image

 

Big areas of shear and convergence all over the SW spreading East:

 

Posted Image

 

Posted Image

 

Plenty of convective rain with it:

 

Posted Image

 

Fingers of SBCAPE creeping up through The Channel:

 

Posted Image

 

Higher level lapse rates good:

 

Posted Image

 

Possible helical activity, but that may be limited to the other side of The Channel:

 

Posted Image

 

Camborne Skew-T already looking encouraging:

 

Posted Image

 

Let me dig out some more stuff so we can have a see what others are projecting.

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

NMM charts on NW Extra would have the potential for the day more confined to the SW, Wales and English Channel coasts. I'm marking out the Isle of Wight for special mention for later this afternoon, I think you guys could do well:

 

post-6667-0-44210200-1389858694_thumb.pn post-6667-0-42878100-1389858692_thumb.pn

 

post-6667-0-53961900-1389858699_thumb.pn  post-6667-0-06975600-1389858697_thumb.pn

 

I'm hoping it might stretch as far as Sussex by early evening, but may die out before it gets here.

 

post-6667-0-49428000-1389858812_thumb.pn

 

If you don't do Skew-T's, here's a simple explanation of some of the indices:

 

http://www.skystef.be/storm-indices.htm

 

 

 

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

Aviation weather forecast for today has things neatly covered, CB's at 27,000ft:

 

Posted Image

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

Something already kicking off in Somerset?

 

Posted Image

 

post-6667-0-12385300-1389859945_thumb.pn

 

Nothing on NW radar yet, but some showers on their way:

 

post-6667-0-39605300-1389859834_thumb.jp

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Posted
  • Location: South Shields Tyne & Wear half mile from the coast.
  • Location: South Shields Tyne & Wear half mile from the coast.

Aviation weather forecast for today has things neatly covered, CB's at 27,000ft:

 

Posted Image

 

Occasional Cb's flirting pretty close to the North East coast although I think they'll stay off-shore.  Hope the ESTOFEX forecast comes off for you southerners, it could turn out quite lively.

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

Starting to get going over France:

 

Posted Image

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Posted
  • Location: Dorset
  • Weather Preferences: warehamwx.co.uk
  • Location: Dorset

Continual showers here, some lovely clouds though, and hopefully some flashes and rumbles later. Nothing doing today, so it's a completely lazy day, watching the weather. :D

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Posted
  • Location: Dorset
  • Weather Preferences: warehamwx.co.uk
  • Location: Dorset

Tap on.. Tap off.. Tap on.. Etc

Huge drops of rain with some hail mixed in, 11mm already, 34mm/hr rate just a moment ago. I'm a little surprised the MO haven't issued a warning?!

Edited by Mapantz
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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)

Storm & Convective Forecast

Issued 2014-01-16 11:04:31

Valid: 16/01/2014 1000z to 17/01/2014 0600z

 

post-1052-0-50091100-1389870493_thumb.pn

 

 

THERE IS A RISK OF SEVERE WEATHER FORECAST
Synopsis

Upper level trough covers much of western Europe and an upper level blocking high sits over Nern Scandinavia during the forecast period. A deeply cyclonic and unstable S to SW flow covers the UK ahead of slow-moving low centred over western Ireland.

... SOUTHERN and WESTERN BRITAIN ...

Increasingly cold mid-levels overspreading from the west, as the upper trough slowly advances east, will steepen lapse rates across the UK. Mild/moist south to southwesterly low-level flow will create a few 100 j/kg CAPE towards southern and western areas of Britain as a result of the the increasingly cold air aloft, the greatest instability towards S and W coasts. Numerous bands of heavy showers will spread northeast through the day across many areas and with increasingly cold air aloft, there is a risk of some thunderstorms too - more particularly towards southern and western coasts. A marked short-wave trough is indicated to move east across southern Britain this evening, which will further enhance convective activity. Low-level veering near the passage of this trough is likely to create sufficient wind shear for multicells with bowing-line segments capable of strong wind gusts (50-55mph). Also, the frequency or training over one area of showers/storms over southern Britain will pose a risk of flooding, given already saturated ground. Also, given strong forcing and low-level veering near trough, a tornado can't be ruled out. Therefore have issued a slight risk for Sern and Wern areas.

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Posted
  • Location: Dorset
  • Weather Preferences: warehamwx.co.uk
  • Location: Dorset

It's relentless here, reports of bad flooding on the roads all around the area, from Wareham to Poole, Swanage to Wareham etc ..

Just had another torrential downpour within 10 minutes of the last one, very gusty winds too. 15mm and counting, I expect to exceed an inch before the day is out.

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

It's relentless here, reports of bad flooding on the roads all around the area, from Wareham to Poole, Swanage

 

I hope The Fish Plaice and The Ship Inn aren't affected - I might starve!

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