Convective Storm/Discussion thread - 11/06/16 onwards

[Candice]

1 hour ago, AIRMET said:

How it hasn't produced a single sferic yet is beyond me!

Well capped

[Harry]

31 minutes ago, William Grimsley said:

Hmm, that's strange, there should be more CAPE shown here as it's expected to be insane tomorrow. In other news, just had a massive black based Cumulus Congestus cloud go over, went very dark and calm and then suddenly very humid as the wind shifted from SE to SW but no rain!

Ah, looks like a shower developed just north of here, what a surprise!

Why do you believe more CAPE should be shown and what makes you think tomorrow will be insane? There's a risk of some heavy showers, perhaps few thundery, but not convinced about more than that!? 

[Harry]

Tower rocketing just south of here, getting very good height with pileus just visible (I would say 10-15 miles south). Could spark soon I would guess.

[Gordon Webb]

22 minutes ago, Harry said:

Why do you believe more CAPE should be shown and what makes you think tomorrow will be insane? There's a risk of some heavy showers, perhaps few thundery, but not convinced about more than that!? 

yep the forecast is for a lot of rain and showers tomorrow which may turn thundery into the afternoon if certain conditions allow and even the met office warnings indicate they don't know where worst of any potential weather will be and Devon and Cornwall will be one of first places to see weather improve anyhow , even me in the west midlands is only on the fringe of the warning zones with most of it further east anyway

Edited June 11, 2016 by Gordon Webb

[Windblade]

Did have hazy sunshine after those earlier rumbling cells cleard from mid afternoon and very warm and humid feeling, but its clouded over now. Nothing significant on the horizon that I can see. I think with the nature of the current setup, that could be it for these parts today. I'd love a nice relaxing night time storm as I'm going to bed this evening, but I doubt it's going to happen today. Tomorrow is looking ok, could be in with another chance of seeing something.

Edited June 11, 2016 by Windblade

[IanR]

i think someone mentioned  that today would be more about the rain than the amount of thunder and lightning,

 they were correct, apart  from some areas of the south east getting thunder again , its been dissapointing,  too overcast , with just heavy or moderate rain 

[Polar Maritime]

Heavy rain here now.

[alexisj9]

As I was walking home from town earlier, I noticed a cloud that had hit the cap with some flattening, then started over shooting, I'm guessing there was a storm to my north west.

[Milocation]

yep!

 

[The PIT]

First bit of real rain of the day now.

[Gord]

Just like this time yesterday, heavy rain is becoming a bit more widespread across the Midlands now.

Raining quite heavily here at the moment.

[toggerob]

Road Closures in Poynton (south Stockport) due to localized flooding.

[weather09]

Looks like it may be a bit of a late starter tomorrow as instability and drier air at mid-level comes in post-occlusion, with associated dynamic rain and cloud debris moving over country morning/early afternoon. Lapse rates a little steeper on 12z which has enhanced modeled CAPE.  Though if residual cloud sticks around for any length of time, CAPE not likely to be quite as high as is being modeled.  Might be an overlap of upper jet/modest shear and instability toward far south and west, perhaps something to work with.  Question mark over instability and coverage of storms though.  

[toggerob]

Just a few miles up the road, today's rain has led to some major flash-flooding in localized areas. The main A6 completely impassible now.

http://www.manchestereveningnews.co.uk/news/greater-manchester-news/watch-incredible-moment-torrential-rain-11459898

 

[Darren Bown]

Looking rather dark to my west at the moment.

[Gordon Webb]

just sawn the latest news 24 forecast and there emphasis for possible storms tomorrow is NW England is Lincolnshire and the wash and also some crossing from west to east in southern England to the London area of course all this depends on cloud breaks and sunny spells sparking them they have the midlands grey and murky with bits and pieces of rain all this taken with the usual caveats

[STORMGUY]

Can just about make out a cb through the low level cloud now. skys looking stormy.

[Gord]

3 minutes ago, STORMGUY said:

Can just about make out a cb through the low level cloud now. skys looking stormy.

Love to be proven wrong but I think just heavy rain will be our lot for this evening.

Have to admit, the sky does look very dark though.

Edited June 11, 2016 by Gord

[STORMGUY]

That cb as matured bigger now as it nears here very black now

[Summer Sun]

Day 2 Convective Outlook

VALID 06:00 UTC Sun 12 Jun 2016 - 05:59 UTC Mon 13 Jun 2016

ISSUED 19:13 UTC Sat 11 Jun 2016

ISSUED BY: Dan

Another messy day is expected on Sunday with a mix of dynamic and convective precipitation across the country. Various weak(ening) frontal boundaries will attempt to nudge NE-wards, but eventually decaying before becoming the required forcing for deep convection given some strong surface heating. In particular, wind convergence along a cold front will allow a line of scattered heavy showers and perhaps a few thunderstorms to form from Norfolk curving NW-wards to Cumbria - however, instability is marginal (couple hundred Jkg-1 CAPE) with hints in forecast soundings of slight capping in the mid-levels, which may limit overall convective depth.

Given PWAT in the order of 26-28mm, scope exists (like Saturday) for slow-moving heavy showers capable of local flooding, but perhaps with limited amounts of lightning. Have issued a SLGT for now to highlight main zone at risk, but may require a downgrade if lightning potential continues to look marginal.

Farther south, heating of the shallow moist zone (SMZ) with surface dewpoints of 13-15C coupled with falling heights and the approach of a dry intrusion will yield an environment with 700-1,000 Jkg-1 MLCAPE. Provided there are sufficient cloud breaks to allow some insolation to develop, then a few isolated to well-scattered thunderstorms may form during the afternoon/evening hours, capable of producing hail locally over 1.0cm in diameter and quite frequent lightning. DLS begins to increase from the SW towards evening, and so this may enable storms to become better organised later in the day with perhaps late initiation in some areas.

Low LCLs, wind convergence (especially close to the south coast from sea breeze, and perhaps also in a separate zone across the south Midlands / Home Counties towards evening as a small surface low forms) and modest CAPE may produce one or two funnels or weak tornadoes. Cells that develop earlier on in the afternoon will pose the greatest threat of excessive rainfall / minor flash flooding given reducing PWAT values as the afternoon/evening progresses. This zone will need monitoring for perhaps either an expansion of the SLGT farther north into the central Midlands and/or the introduction of a MDT.

http://www.convectiveweather.co.uk/

[Gordon Webb]

1 hour ago, Summer Sun said:

Day 2 Convective Outlook

VALID 06:00 UTC Sun 12 Jun 2016 - 05:59 UTC Mon 13 Jun 2016

ISSUED 19:13 UTC Sat 11 Jun 2016

ISSUED BY: Dan

Another messy day is expected on Sunday with a mix of dynamic and convective precipitation across the country. Various weak(ening) frontal boundaries will attempt to nudge NE-wards, but eventually decaying before becoming the required forcing for deep convection given some strong surface heating. In particular, wind convergence along a cold front will allow a line of scattered heavy showers and perhaps a few thunderstorms to form from Norfolk curving NW-wards to Cumbria - however, instability is marginal (couple hundred Jkg-1 CAPE) with hints in forecast soundings of slight capping in the mid-levels, which may limit overall convective depth.

Given PWAT in the order of 26-28mm, scope exists (like Saturday) for slow-moving heavy showers capable of local flooding, but perhaps with limited amounts of lightning. Have issued a SLGT for now to highlight main zone at risk, but may require a downgrade if lightning potential continues to look marginal.

Farther south, heating of the shallow moist zone (SMZ) with surface dewpoints of 13-15C coupled with falling heights and the approach of a dry intrusion will yield an environment with 700-1,000 Jkg-1 MLCAPE. Provided there are sufficient cloud breaks to allow some insolation to develop, then a few isolated to well-scattered thunderstorms may form during the afternoon/evening hours, capable of producing hail locally over 1.0cm in diameter and quite frequent lightning. DLS begins to increase from the SW towards evening, and so this may enable storms to become better organised later in the day with perhaps late initiation in some areas.

Low LCLs, wind convergence (especially close to the south coast from sea breeze, and perhaps also in a separate zone across the south Midlands / Home Counties towards evening as a small surface low forms) and modest CAPE may produce one or two funnels or weak tornadoes. Cells that develop earlier on in the afternoon will pose the greatest threat of excessive rainfall / minor flash flooding given reducing PWAT values as the afternoon/evening progresses. This zone will need monitoring for perhaps either an expansion of the SLGT farther north into the central Midlands and/or the introduction of a MDT.

http://www.convectiveweather.co.uk/

those forecast slight areas ties in exactly with what the Beeb showed earlier but again all comes down to cloud breaks but even if that happens widespread activity looks unlikely , it seems to be down to timing as pwat values decrease through the afternoon and evening so early afternoon showers will probably be heaviest and if cloud breaks allow and convergence along south coast or south midlands and home counties there could be late afternoon / early evening showers . storms

in a few ways this forecast is a carbon copy of today heavy showers in northern England north midlands lincs and also in the south with a not so bad bit in the middle not good but probably not as bad

Edited June 11, 2016 by Gordon Webb

[Norfolk Sheep]

Had about an hour of semi-convective drizzle, so should be grateful for this meagre crumb.....

[Weather-history]

Odd swirling or rotary motion in the clouds around 1.17 on time-lapse

 

[IanR]

the bbc has lightning graphics over the north west of england for 23.00 tonight.   ok then  

[STORMGUY]