Storm & Convective Discussion - 01/03/15 onwards

[BrickFielder]

Certainly a suggestion of instabillity perhaps post frontal during the early to mid evening today.

Lapse rates through the middle layers look steep enough for a storm.

The trouble is that it is not exactly surface based (sbcape is weak) and the forecast SkewT does not look that good.

 

I am not totally convinced and model agreement is not particularly good, but certainly some potential for rotating cloud. Updrafts are probably not strong enough to lift low level vorticity though. Worth keeping an eye on.

Edited May 8, 2015 by BrickFielder

[Eugene]

Next tuesday looks a non event i'm afraid.

[Greeny]

there has been some altocumulus and some weak mammatus above at the moment.

[NO LONGER POSTING]

Next tuesday looks a non event i'm afraid.

 

got charts..

[Captain Shortwave]

got charts..

Some of the models in particular are tending to trap the potential storm bringing low over the Azores, as such we never get the blast of very warm air and instead we see a weak cold front push south east Monday night bringing cooler and drier air in from the Atlantic again.

We certainly need this to change, ridiculous to think last nights BBC forecast was going for 26C on Tuesday which is only 4 days away only for most of the models to now say that we will reach the high teens at best.

[Mokidugway]

Possible Supercell storms over Southern France at the moment ..

[Harry]

There's definately an increasing sign of a possible Spanish plume development on Tuesday. We have an area of low pressure in the Atlantic pumping up warm air and moisture from Southern Europe.

 

850Temps.png

 

Because of this, the CAPE rises and the air becomes increasingly unstable. The warm 850s also cause the lapse rates to rise, which is the perfect recipe for thunderstorms.

 

CAPE.png Lapse.png Risk.png

Well...this is certainly no longer on the cards

Tbh, if like last year I get naff all until July and then get successions of awesome storms, I'll be elated...though to have not heard a roll of thunder or seen lightning in 2015 is pretty bad form by any standards

[Thunderbolt_]

Netweather is giving me a 57% risk of thunder between 20:00 and 22:00, and it actually might not be as far fetched as it seems at first. The sky is looking more fierce than it did before and there is almost a very constant low, deep rumble in the air.

[Mokidugway]

Some deep cloud moving into the North west ...

[Greeny]

I'm currently trying to work out where this has come from.

 

http://www.estofex.org/

[Mokidugway]

Insolation from the clearance perhaps , although Sky here not showing any tower development yet ..

[Greeny]

Insolation from the clearance perhaps , although Sky here not showing any tower development yet ..

 

There's some wind convergences only within the forecast area, perhaps being reasonably strong and pushing the air further up than the forecast EL (Equilibrium).

[Eye to the sky]

Heading home from Norfolk today and have just hit a downpour near Nottingham,though the radar doesn't show anything too exciting.Some impressive clouds aound at the moment all heading east as well.So could catch something later Greenday?.

[NUT]

Just had a short shower here. Must have lasted about 2 minutes but had a bit of hail thrown in with it

[Greeny]

Heading home from Norfolk today and have just hit a downpour near Nottingham,though the radar doesn't show anything too exciting.Some impressive clouds aound at the moment all heading east as well.So could catch something later Greenday?.

 

The metoffice forecast did mention showers in our area this afternoon. Will keep a north eye out whilst going about my business

[Mokidugway]

Some cumulus about ,nothing very exciting though ..

[Harry]

The GFS 12z caught my attention earlier...I didn't post as the general Synoptics aren't great. But it shows an impressive pulse of very high instability right up to the French north coast for the briefest of periods...the storm risk to boot shows it detonating quite rapidly.

As I emphasise it does not quite reach our shores and it is just the 12z showing it. The ECM chart shows slightly more preferable setup where as GFS more keen to cut off that plume over N France...some slight realignments might however bring it ashore, so perhaps one to keep a cheeky glance on.

Edited May 9, 2015 by Harry

[Greeny]

The GFS 12z caught my attention earlier...I didn't post as the general Synoptics aren't great. But it shows an impressive pulse of very high instability right up to the French north coast for the briefest of periods...the storm risk to boot shows it detonating quite rapidly.

As I emphasise it does not quite reach our shores and it is just the 12z showing it. The ECM chart shows slightly more preferable setup where as GFS more keen to cut off that plume over N France...some slight realignments might however bring it ashore, so perhaps one to keep a cheeky glance on.

Are you talking about Monday's potential?

Edit: or could be Wednesday as its even closer according to GFS then.

Edited May 9, 2015 by Greenday

[Harry]

Are you talking about Monday's potential?

Edit: or could be Wednesday as its even closer according to GFS then.

Sorry...I didn't specify did I I was referring to Wednesday

Curious to see what 18z suggests

Edited May 9, 2015 by Harry

[Dale Hay]

Estofex currently have this...

(Text snipped from Estofex)

Storm Forecast

Valid: Sun 10 May 2015 06:00 to Mon 11 May 2015 06:00 UTC

Issued: Sat 09 May 2015 20:49

Forecaster: TASZAREK

A level 1 was issued for N United Kingdom and Ireland mainly for severe wind gust and tornadoes.

Discussion

...N United Kingdom and Ireland...

Within trough approaching into Scotland and advection of cold air of polar origin in its rear flank, thermodynamic instability resulting from steep lapse rates (> 7C/km) and humid boundary layer (average mixing ratios ~ 7 g/kg) will reach 100-200 J/kg. Although free convective layer will be shallow (3-4 km), impressive mid and low level airflow will pose high threat for severe wind gusts of convective origin. Linearly organized convection within such environment cannot be also ruled out. High values of LLS (~ 10-15 m/s) overlapping with SRH 0-1 km ~ 150 m2/s2 will also pose a risk for tornado occurrence. Convection in this region is expected during the night and in the end of the forecast period. The highest threat for severe weather phenomena will fall on the passage of the cold atmospheric front (0300-0600 UTC). Due to relatively low and uncertain thermodynamic instability, the confidence of the forecast seems to be low.

[Harry]

Agreed...storm drought continues.

Slim chance across C/S England Thursday, but then naff all. Thursday 21st (which is hardly worthy of much consideration at this stage) hints at brief plume but again barely making inroads.

Roll on June

Edited May 10, 2015 by Harry

[Nick F]

Might be of interest if you're in Scotland ... shortwave trough moving E and NE bringing storms across waters of NW Britain and western Isles this morning which could spread across the mainland later. Netweather stormforecast:

 

http://www.netweather.tv/index.cgi?action=convective;sess=

 

[NUT]

Quite a barrage of storms up here but to the north west. Still though showers down here. Who knows might get a grumbly surprise

[NUT]

All clearing away to the east now so any chance of a grumble for today probably gone

[Harry]

Indeed on both counts - for us it looks pretty dire for the rest of May at this stage.

Really starting to crave a good plume (except for the stage beetles and pterodactyl like moths that flourish on the first decent plume *shudders*)...or even a decent post frontal maritime swathe of convection)

Across the pond, Fri/Sat looking good for the chase crews...perfect territory too