Storm & Convective Discussion - 1 September 2015 onwards

[Dorsetbred]

48 minutes ago, Mapantz said:

I'm right on the edge of those thundery showers affecting Dorset. You can see the edge of them on my webcam.   

I'm fortunate and under them, sleet and hail a plenty, now waiting for the next one to cruise by.....

[Evening thunder]

On the way home I noticed some convection on the northern horizon but the radar/satellite doesn't show anything between us and South Wales.. could this be the South Wales showers viewed from all the way down here near Sidmouth?!
 

[William Grimsley]

As Evening thunder has pointed out, the air is incredibly clear today and the visibility is at least 50 miles in all directions. I can see the Cumulonimbus cloud from the shower near Dorchester from here!

Edited March 30, 2016 by William Grimsley

[Stuart]

Day 2 Convective Outlook

VALID 06:00 UTC Thu 31 Mar 2016 - 05:59 UTC Fri 01 Apr 2016

ISSUED 16:25 UTC Wed 30 Mar 2016

ISSUED BY: Dan

Sharp upper trough will migrate eastwards across the British Isles on Thursday, accompanied by cold mid-levels. This, combined with diurnal heating, will generate a couple hundred Jkg-1 CAPE, with orographic forcing / low-level convergence playing a key role in developing a few scattered showers and/or isolated thunderstorms, primarily through the afternoon and into the early evening.

 

Isolated heavy showers could develop almost anywhere, but the main focus being highlighted by the ISOL areas, but even here the chance of lightning is still considered quite low. Slow storm-motion and/or back-building will result in some locally prolonged heavy downpours, perhaps causing some localised surface water flooding - especially across parts of NE England and S/SE Scotland. A highly-sheared environment across these areas as a northerly jet encroaches from the Atlantic suggests that environmental conditions will be more favourable for lightning across N + E England and S Scotland. Small hail may accompany any stronger cells.

 

http://www.convectiveweather.co.uk/forecast.php?date=2016-03-31

[Greeny]

not to make too much of a big deal about it just yet but I'm just keeping an eye on the end of the weekend and the start of next week. GFS currently showing the winds direction coming from the South. Its 5 days away yet but worth keeping an eye on. Nothing mindblowing in potential though. Now that I've seen it I just have to mention it

 

Edit: This is my first post in a while and I tend to kick back into life once our storm potential begins to rise. I would like to wish you all the best for 2016 and hope that everyone gets a piece of the action! Please all remember to take care and be safe!

Edited March 30, 2016 by Greenday

[Weather-history]

My favourite type of time-lapse, cumuli waxing and waning

 

[Allseasons-Si]

Caught this cb going up to my NE 10 minutes  ago

Edit:turned into a mothership,this is 15 minutes later

this developing to my east

and this to my south

all very slow moving,so catch one and you will know about it

also,some heavy showers are now developing north of the humber,shouldn't be long before some sferics kick off there.

 

 

Edited March 31, 2016 by Allseasons-si
spell check

[Mokidugway]

Yep ,convection very evident today ,some nice cloudscapes about

 

[poseidon]

Just a had a nice little cell pass close by. Unfortunately it had finished producing sferics but still photogenic with lots of mammatus cloud...

[chapmanslade]

Just returned from the Charente region of France and was surprised by an MCS on Wednesday night. Wednesday was very warm (22C) with strong advection N from Spain. had no internet there but my son and I agreed the sky looked like a warm plume with mid level instability and Alt Cas as the sun went down. At 04.00 woken up by constant flashing (every 2 or 3 seconds) as an MCS moved up to the west of us. It lasted for a couple of hours. Drove up through France today in torrential rain for most of the journey slap under the wiggling Occlusion.

[William Grimsley]

I had the same thoughts as Greenday, looks like there could be some thundery outbreaks of rain over the weekend, it would be an ideal set up if we were in mid-Summer. Again, nothing to write home as of yet but things may change.

[Summer Sun]

Day 2 Convective Outlook

VALID 06:00 UTC Sat 02 Apr 2016 - 05:59 UTC Sun 03 Apr 2016

ISSUED 13:43 UTC Fri 01 Apr 2016

ISSUED BY: Dan

As a frontal wave develops and spreads rain northwards across England on Saturday evening, there is a very low chance (near 5-10%) of sporadic lightning on its eastern flank should enough (marginal) instability develop in the warm plume exiting France/the Low Countries. Chances are even if any lightning does occur, it will probably either remain over the near Continent, or out over open water of the southern North Sea.

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

[Methuselah]

21 minutes ago, Summer Sun said:

Day 2 Convective Outlook

VALID 06:00 UTC Sat 02 Apr 2016 - 05:59 UTC Sun 03 Apr 2016

ISSUED 13:43 UTC Fri 01 Apr 2016

ISSUED BY: Dan

As a frontal wave develops and spreads rain northwards across England on Saturday evening, there is a very low chance (near 5-10%) of sporadic lightning on its eastern flank should enough (marginal) instability develop in the warm plume exiting France/the Low Countries. Chances are even if any lightning does occur, it will probably either remain over the near Continent, or out over open water of the southern North Sea.

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

Who'da thunk it!

[Flash bang flash bang etc]

Can see some high level instability (I think) in bands right across the sky. This bodes well for tomorrow I hope. I'm free for chasin' all day and all of the night!

An appropriate week to come out of the winter sky-bernation methinks :-)

[weather09]

Not convinced re. tomorrow evening/early hours Sunday, and so in agreement with Dan on very low risk. Moisture/warmth over far E/SE during the period looking too weak to suggest likelihood of deep convection/lightning, with mid-level lapse rates looking unimpressive.  Sure enough low-level moisture increases (indicated by relevant charts below), so perhaps possibility of shallow convection among largely dynamic rainfall where cold front(s) pushing up from the south engage this modestly moist air mass, so risk of locally high RF rates. But again, lack of deep moisture/warmth and instability, and lack of height falls/forcing aloft, inhibits more significant activity.  

  

Sunday evening and early hours Monday looking somewhat more favourable, where we see another push of modest low-level moisture ahead of another frontal system out to the west, but with better height falls and colder air aloft which steepens lapse rates/increases instability and risk of storms. 

[Summer Sun]

Day 3 Convective Outlook: Sun 03 Apr 2016

Day 3 Convective Outlook

VALID 06:00 UTC Sun 03 Apr 2016 - 05:59 UTC Mon 04 Apr 2016

ISSUED 20:45 UTC Fri 01 Apr 2016

ISSUED BY: Dan

Moisture plume will begin to advect north once again on Sunday afternoon/evening across southern and eastern Britain. At the same time, upper flow will continue to back as upper trough migrates NEwards, steepening mid-level lapse rates and increasing instability. It seems likely, given the passage of a shortwave trough, that at least some elevated convection will occur but in an environment with rather meagre CAPE (100-200 Jkg-1) and hence even if this does develop, it is still rather questionable as to how much lightning activity there will.

Overall, environmental conditions are slightly more favourable for at least some sporadic lightning on Sunday evening over highlighted areas compared with the setup on Saturday evening, but with a lot of uncertainty as to the general evolution at this stage.

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

[Nick F]

Low risk Sunday evening into night of strong enough convection within showery rain spreading north producing lightning across SE/E Anglia, as a shortwave mid-upper trough swings in form the SW and engages a plume of moisture feeding up via a backed SEly flow from France ahead of it.

GFS 500mb vorticity charts show trough moving in from the SW

... engaging moisture 'plume' ahead of it feeding in from the SE

ECM does show a narrow area of SBCAPE pushing up across the SE Sunday evening.

Monday shows better potential for thunder though, as upper low and its associated cold air (-25 to -30C at 500mb) moves in from the SW, creates steep lapse rates and CAPE with surface heating - GFS indicates Wales, N and W England with most instability for now, ECM more widely across central and eastern England.

GFS on Monday's 500mb heights and temps + 850-500mb lapse rates

GFS SBCAPE on Monday

Edited April 2, 2016 by Nick F

[William Grimsley]

10 minutes ago, Nick F said:

Monday shows better potential for thunder though, as upper low and its associated cold air (-25 to -30C at 500mb) moves in from the SW, creates steep lapse rates and CAPE with surface heating - GFS indicates Wales, N and W England with most instability for now, ECM more widely across central and eastern England.

GFS on Monday's 500mb heights and temps + 850-500mb lapse rates

GFS SBCAPE on Monday

Monday looks really good for us! Fingers crossed!

[William Grimsley]

19 hours ago, Summer Sun said:

Day 2 Convective Outlook

VALID 06:00 UTC Sat 02 Apr 2016 - 05:59 UTC Sun 03 Apr 2016

ISSUED 13:43 UTC Fri 01 Apr 2016

ISSUED BY: Dan

As a frontal wave develops and spreads rain northwards across England on Saturday evening, there is a very low chance (near 5-10%) of sporadic lightning on its eastern flank should enough (marginal) instability develop in the warm plume exiting France/the Low Countries. Chances are even if any lightning does occur, it will probably either remain over the near Continent, or out over open water of the southern North Sea.

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

That risk area is starting to move ever further west, I'm only just west of the edge of that risk area. Lets hope some upgrades start to happen and push the risk further westward, otherwise I think Monday is my best bet at the moment.

[A.J]

having perused the overnight NMM output, then I fully concur with the above posts....the potential is there sunday night through monday afternoon for some thundery activity

[William Grimsley]

2 minutes ago, ajpoolshark said:

having perused the overnight NMM output, then I fully concur with the above posts....the potential is there sunday night through monday afternoon for some thundery activity

I'm not sure if you mean here, but the only negative feeling I have about this is that I'm too far south?

[William Grimsley]

Just incase anything happens here, I have setup a Nest live stream facing south! https://video.nest.com/live/Atmiip

[A.J]

19 minutes ago, William Grimsley said:

I'm not sure if you mean here, but the only negative feeling I have about this is that I'm too far south?

inferring from Nick F's and w09 excellent posts, and my own thoughts, there is interest tomorrow night for the potential of some elevated convection more so south/south east counties (with an emphasis to the south east) and a more general risk on monday 

[Summer Sun]

Day 1 Convective Outlook

VALID 06:00 UTC Sat 02 Apr 2016 - 05:59 UTC Sun 03 Apr 2016

ISSUED 13:53 UTC Sat 02 Apr 2016

ISSUED BY: Dan

UPDATE 13:53 UTC Little change to expectations as highlighted below with a very low chance of lightning near North Sea coasts this evening/tonight, most likely over Belgium/the Netherlands (if any at all). Added LOW area over S Ireland for the potential for some convective elements that may arrive at the very end of tonight (near 07:00 BST)

As a frontal wave develops and spreads rain northwards across England on Saturday evening, there is a very low chance (near 5-10%) of sporadic lightning on its eastern flank should enough (marginal) instability develop in the warm plume exiting France/the Low Countries. Chances are even if any lightning does occur, it will probably either remain over the near Continent, or out over open water of the southern North Sea.

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

[William Grimsley]

*deleted*

Edited April 2, 2016 by William Grimsley