Storm & Convective Discussion - 02/07/15 Onward - Heat & Plumes

[thunderhead 2005]

latest Cape - LI charts show that cape will max between 9pm onwards, jersey/ N france getting storms early that move northwards and intensifying.

 

all eyes on jersey and n france around 6pm

Edited July 3, 2015 by thunderhead 2005

[Karl83]

I use a GoPro camera and although it can get some great video of lightning I have found that if the bolt is too close or bright then on occasion you don't actually get to see the shape of the bolt but rather a very bright flash. Unfortunately you can't adjust shutter speed or exposure. I am hoping that tonight I get plenty of bites at the cherry for good lightning footage.

Do you video the storms or take pics? What settings do you use?

[Supacell]

Do you video the storms or take pics? What settings do you use?

 

I video them and use 720p and 60fps. The reason I don't use 1080p is because my laptop cannot handle editing footage at that resolution. 60fps is better than 30fps for capturing lightning I would think.

 

Another option would be to set it up to take 10 photos every second. I haven't tried this method so don't know how good it would be. I prefer video though, then you get to hear the rain and the thunder.

[Harry]

latest Cape - LI charts show that cape will max between 9pm onwards, jersey/ N france getting storms early that move northwards and intensifying.

 

all eyes on jersey and n france around 6pm

 

Operative statement I think in the latter part of your first sentence...assuming the cap fails to break across the SE. There is a lot of doubt currently as to whether the cap will break in N France...despite obscene instability. A number of charts show almost nothing across N France and the SE, while GFS seems to want most of the action over N France and the SE....time will tell - fair to say the majority of models want to keep N France and the SE dry.

Edited July 3, 2015 by Harry

[Heisenberg]

ahh a mid afternoon Kip.....whats that then? Does no one work :-0

 

I dont think anyone really knows where this will end up. Radar watch from later this evening i think

[jamesbhx]

A really tricky one to call for this evenings potential. I'd say looking at available data and taking an average across various models and independent forecasts, you're more likely to see some activity the further west you are however the severity would appear to increase the further east you are.

So west - higher chance but less severe potential, East - less chance but higher severe potential for anything that develops. I'd probably draw an imaginary east/west line from the Isle of Wight - Oxford - York.

[I remember Atlantic 252]

ahh a mid afternoon Kip.....whats that then? Does no one work :-0

 

I dont think anyone really knows where this will end up. Radar watch from later this evening i think

 

this week off, wimbledon

[Paul Sherman]

Thanks great guide, im assuming you use one of those remote to take multiple shots?

 

however i can wire up my DSLR to my laptop which has the same remote setup.

 

Yh should have said, I use a Remote Release Shutter Cable which allows you to keep dry if in a car etc, also I used F13 in that picture as the street lighting was quite bright, obviously if you are in a field and its total blackness all around you need F6 TO F10 as a max.

[Heisenberg]

No I've had this week off, so no work will be missed.

Ah, would love a week off .......Some very whispy clouds starting to show around Heathrow......otherwise, its a clear, calm and blue sky out there at the moment....So need a storm Sick of being in the NSC for so long

[Nick F]

Only just got the chance to do a forecast for storms for later, but better late than never:

 

Storm & Convective Forecast

 

 

Issued 2015-07-03 09:47:04

Valid: 03/07/2015 0600z to 04/07/2015 0600z

 

CONVECTIVE/STORM OUTLOOK - ISSUED 3RD JULY 2015

 

Synopsis
 

Slow-moving upper trough over the mid-N Atlantic to the west of the British Isles will become increasingly negatively-tilted over the next 12-24 hrs. Nose of 100knt jet at 300mb rounding the base of the trough will push NE across the western UK this evening with corresponding increase in SWly flow generally aloft. A sharpening shortwave trough will eject NE towards the UK from the base of the upper trough. At the surface, hot and moist airmass characterised by high theta-w values (16-18C) currently over France will advect back NW across the UK this evening and overnight to the south of northward moving warm front. Surface cold front moves in from the SW tonight, which combined with shortwave trough moving in from the SW and general cooling aloft, will create large scale ascent and destabilisation of the of high theta-w plume.

 

… ENGLAND, WALES, IRELAND and N. IRELAND …

 

A shortwave trough is very evident on water vapour imagery this morning between the Azores and NW Iberia around 15W, this will continue NE today and will later engage high theta-w plume spread NW from France across southern/central Britain and Ireland this evening and overnight. Over-running of the shortwave and associated cooling aloft atop of warm moist plume will create steep lapse rates and strong instability in the warm sector between warm and cold fronts moving N tonight. GFS indicates up to 800-1200 j/kg MLCAPE towards Sern and Ern England in the warm sector spreading N across England and Wales , somewhat less further west towards Ireland. Large scale ascent created by approaching shortwave, cold front and falling heights will support storm development initially over SW approaches, The English western English Channel/N France before storms develop further east then spreading in a broad line N and NE across S England, Wales, Ireland, Midlands and eventually N England and N Ireland later in the evening and overnight.

 

Storms will likely organise quickly, given 40-50 knts of 0-6km deep layer shear indicated with winds veering and strengthening sharply with height. This will support bowing line segments or even a few supercells, capable of producing large hail given fairly high CAPE values and also a damaging wind threat – so have issued a general SLIGHT risk across central, S and E England and Wales – where CAPE is highest. Winds backed easterly to the SWly flow aloft will also generate large Storm-Relative Helicity (SREH) values across S England later this evening, which suggests a tornado or two is not out the question if mesocyclones form – particularly before midnight when there maybe still sufficient diurnal warmth. Have included a hatched area rather than a higher risk here for the tornado threat, for now, as well as the risk of large hail and wind damage … given uncertainties over exactly where and when storms will form before moving NE across England and Wales later in the evening and overnight – the greatest uncertainty lies with eastward extent of storms given less forcing for ascent and more capping of the atmosphere towards SE England, despite more favourable severe parameters.

 

Issued by: Nick Finnis

Edited July 3, 2015 by Nick F

[thunderhead 2005]

Operative statement I think in the latter part of your first sentence...assuming the cap fails to break across the SE. There is a lot of doubt currently as to whether the cap will break in N France...despite obscene instability. A number of charts show almost nothing across N France and the SE, while GFS seems to want most of the action over N France and the SE....time will tell - fair to say the majority of models want to keep N France and the SE dry.

there are low amounts of CIN in N France, so there is potential http://www.infoclimat.fr/modeles-meteorologiques.html?model=wrf/france&param=cin&term=11#forceTerm=7

[Harry]

there are low amounts of CIN in N France, so there is potential http://www.infoclimat.fr/modeles-meteorologiques.html?model=wrf/france&param=cin&term=11#forceTerm=7

 

That's a downgrade then...charts I observed yesterday showed fairly considerable CIN here, hence the doubt set out in the Estofex analysis.

[thunderhead 2005]

There's also Storm Relative Helicity which peaks around 23hrs

 

With the most instable cape around the same time

Edited July 3, 2015 by thunderhead 2005

[Supacell]

No I've had this week off, so no work will be missed.

 

Me too. I took last week and this week. What a great week to be off

[Mapantz]

The tropospheric ducting forecasts suggests the inversion for the Southeast, disappears from anywhere between 12:00 and 18:00. A good positive, I would say?!

[ChezWeather]

Im certainly staying up all night! Looks like the midlands is a good place to be for this one, as supacell mentioned lets just hope it doesnt turn into the dreaded thundery rain!!

 

 

Edited July 3, 2015 by ChezWeather

[Paul Sherman]

That WRF Model is Insane for this evening, takes a Nocturnal Supercell from Hampshire to just south of Lincs in a 4 hour period from 10pm until 02z dumping around 3" of rain in its path.

 

I will be very surprised if that happens!

[thunderhead 2005]

 

 

 

 

This chart shows the increase threat of supercells possibly tornado's

[Neilsouth]

Lots of thick altocumulus here, so much so the sun has gone in

 

Good sign perhaps !

[Snowshine]

Latest convection updates:

NETWEATHER - 2015-07-03 09:47:04
A shortwave trough is very evident on water vapour imagery this morning between the Azores and NW Iberia around 15W, this will continue NE today and will later engage high theta-w plume spread NW from France across southern/central Britain and Ireland this evening and overnight. Over-running of the shortwave and associated cooling aloft atop of warm moist plume will create steep lapse rates and strong instability in the warm sector between warm and cold fronts moving N tonight. GFS indicates up to 800-1200 j/kg MLCAPE towards Sern and Ern England in the warm sector spreading N across England and Wales, somewhat less further west towards Ireland. Large scale ascent created by approaching shortwave, cold front and falling heights will support storm development initially over SW approaches, The English western English Channel/N France before storms develop further east then spreading in a broad line N and NE across S England, Wales, Ireland, Midlands and eventually N England and N Ireland later in the evening and overnight.
Storms will likely organise quickly, given 40-50 knts of 0-6km deep layer shear indicated with winds veering and strengthening sharply with height. This will support bowing line segments or even a few supercells, capable of producing large hail given fairly high CAPE values and also a damaging wind threat – so have issued a general SLIGHT risk across central, S and E England and Wales – where CAPE is highest. Winds backed easterly to the SWly flow aloft will also generate large Storm-Relative Helicity (SREH) values across S England later this evening, which suggests a tornado or two is not out the question if mesocyclones form – particularly before midnight when there maybe still sufficient diurnal warmth. Have included a hatched area rather than a higher risk here for the tornado threat, for now, as well as the risk of large hail and wind damage … given uncertainties over exactly where and when storms will form before moving NE across England and Wales later in the evening and overnight – the greatest uncertainty lies with eastward extent of storms given less forcing for ascent and more capping of the atmosphere towards SE England, despite more favourable severe parameters.

METCHECK - Fri 3 Jul 2015: 10:00 BST (UPDATED)
Another hot and increasingly humid airmass is expected to spread up from western Europe across England and Wales during Friday night and early on Saturday. With this airmass will come an increasing risk of thunderstorms developing during Friday night which could turn severe in places bringing torrential rainfall, large hail, gusty winds and a small chance of an isolated tornado but it is important to stress that many places will miss the storms altogether. 
There is higher confidence that an area of heavy and thundery rain will push north/north-eastwards across Wales and northern England during Friday night with some locally torrential downpours likely bringing an inch or more of rainfall in a short time which could lead to some localised flash flooding with the potential for over two inches of rain to fall from this event. Therefore these areas are now at high risk of seeing some potentially disruptive weather. 
For the Midlands, southern and eastern parts of England there remains some uncertainty over developments with the potential for intense thunderstorms to break out later this evening and into the night, but the location and intensity of any storms remains open to debate. Therefore it is likely that Flash Warnings will be issued here if needed and once developments become clear with the risk level remaining at moderate for now. 

This Weather Watch is likely to be updated again later today.

----------

 

TORRO

"ESTOFEX forecast for Friday and Friday night. We'll be keeping an eye on things and will issue watches or discussions if/when storm development occurs and if conditions still look favourable for severe weather."

[NUT]

Going to be a bit of a close call tonight (for us here) radar watching needed me thinks

[radiohead]

06Z HIRLAM shows a probable supercell south of The Wash at 3am.

Edited July 3, 2015 by radiohead

[alibabba]

Well that supercell can just move up a bit over the wash to me :-)

[Robbie Garrett]

I seem to remember that after a late evening and long hot day - London provides a heat island affect that nowhere else can match in the UK,  7 times out of 10 it's exploded storms normally drifting over from the South,  the south downs also gets things going.   You just have to fly along the South Downs in an airplane or depart London Gatwick and you'll realise how turbulent that area is.   I guess it's not exact science but theoretically it's plausible that some sort of acts are at work there that help break the CAP on a regular basis. 

 

Looking at the TAF's I'd hazard a guess anything east of Heathrow is where the CAP will be broken tonight.  The storms being more severe the further east you go.

 

The AIRMET also says quite a sea-breeze going on in the SE.

 

0000085600 628 FAUK34 EGRR 030430 AIRMET AREA FORECAST, SOUTHEAST ENGLAND, VALID JUL 03/0600Z TO 03/1500Z. MET-SITUATION: AT 06Z, A LIGHT TO MOD STABLE ENE FLOW AFFECTS THE REGION. STRONG WIND WRNG: ISOL SEA COT, MAINLY FM 12Z, 20-25KT GUSTS.

 

 

 

Heathrow 30% chance -

 

EGLL 030453Z 0306/0412 VRB04KT CAVOK BECMG 0311/0314 09010KT PROB30 TEMPO 0321/0401 09015G25KT 5000 +SHRA TSRA BECMG 0403/0406 24010KT PROB30 TEMPO 0404/0406 9000 BKN012

 

Temporary
from 03 at 21 UTC to 04 at 01 UTC Wind 15 kt from the East with gusts up to 25 kt Visibility: 5000 m heavy rain showers, thunderstorm, rain

 

Gatwick 40% chance - 

 

EGKK 030503Z 0306/0412 VRB04KT 9999 FEW030 BECMG 0312/0315 09010KT PROB40 TEMPO 0320/0324 08015G25KT 3000 +SHRA TSRA BECMG 0403/0406 23010KT PROB30 TEMPO 0405/0408 8000 BKN010

 

 

Temporary
from 03 at 20 UTC to 03 at 24 UTC Wind 15 kt from the East with gusts up to 25 kt Visibility: 3000 m heavy rain showers, thunderstorm, rain

Edited July 3, 2015 by Robbie Garrett

[Nouska]

06Z HIRLAM shows a probable supercell south of The Wash at 3am.

 

DWD ICON would concur with that ..... a nice run for all you storm hunters but is it correct?

 

 

http://www.meteociel.fr/modeles/icone_cartes.php?ech=6&code=0&mode=10&map=1&archive=0