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Storms and Convective Discussion - 20th April 2019 onwards

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Looks like a beautiful well structured storm towards the NE coast of Yorkshire. I am just looking at the lightning path and I think that may be the same storm I was under in Nottinghamshire, although it did not have such amazing structure at that point. If it is then it travelled some distance without dying.

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Day 2 Convective Outlook

VALID 06:00 UTC Sat 27 Apr 2019 - 05:59 UTC Sun 28 Apr 2019

ISSUED 18:56 UTC Fri 26 Apr 2019

ISSUED BY: Chris

A deep area of low pressure will continue to move eastwards across northern England and eventually into the North Sea later in the day. Strong gusts associated with the low will continue across Ireland, England and Wales, through the day before easing in the evening. 

There are two areas of interest with regards to convection and lightning risk. 

S Scot, NE/E Eng:  Weak instability (up to 200 J/kg) generated by a little surface insolation along with a zone of surface convergence will help to generate some heavier showers and perhaps a few thunderstorms during Saturday afternoon. Initiation should be around 11z across S Scotland and N England, with the risk area dimensioning and transferring southeastwards later in the afternoon and into the early evening

S Ireland, S Wales, SW/S Eng: South of the low, sunny spells and surface insolation in a strongly sheared environment will allow for some sharp showers to develop. Lightning is deemed to be less likely in this zone, but cannot be ruled out, mainly during the morning and through early afternoon. 

http://www.convectiveweather.co.uk/forecast.php?date=2019-04-27

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A couple of stills from my wife's video of last nights storm on the Yorkshire Coast. She didn't manage to capture any of the cloud formations probably because she was setting off to fetch me from the station.

VideoCapture_20190425-193902-a.jpg

20190425_194846-a.jpg

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Finished editing and uploading my video of Thursday's hailstorm near to Southwell. Uploaded to my YouTube channel.

 

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Day 2 Convective Outlook

VALID 06:00 UTC Sun 28 Apr 2019 - 05:59 UTC Mon 29 Apr 2019

ISSUED 18:57 UTC Sat 27 Apr 2019

ISSUED BY: Chris

The remnants of the low pressure that brought strong winds to parts of Ireland and SW Britain on Friday and Saturday will fill and move southwards from the southern North Sea into the Low Countries. This will still help to to generate a few showers across eastern/southeastern England during Sunday. 

Surface heating in the unstable air will generate about 100-200 J/kg of CAPE and a few heavier showers will develop during the middle part of the day on Sunday, and drift southwards into the afternoon before fading into the evening. Lightning is considered a very minimal risk, but cannot be ruled out. 

http://www.convectiveweather.co.uk/forecast.php?date=2019-04-28

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Day 2 Convective Outlook

VALID 06:00 UTC Mon 29 Apr 2019 - 05:59 UTC Tue 30 Apr 2019

ISSUED 19:00 UTC Sun 28 Apr 2019

ISSUED BY: Chris

A long-wave trough in the Atlantic to the west of Ireland will allow for some warm air advection across western Ireland. If any sunny spells develop this could help to produce 100-200 J/kg of CAPE by midday and early afternoon. A few heavy showers may develop, with a very low end risk of lightning, however extensive cloud cover and warm mid-level temperatures will likely limit the risk and depth of any convection that develops.  

http://www.convectiveweather.co.uk/forecast.php?date=2019-04-29

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Posted (edited)

Not uk based but head over here...

some good lightning

 

Edited by Allseasons-si

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Day 2 Convective Outlook

VALID 06:00 UTC Tue 30 Apr 2019 - 05:59 UTC Wed 01 May 2019

ISSUED 17:32 UTC Mon 29 Apr 2019

ISSUED BY: Chris

A cold front will move eastwards across Ireland during the morning, and behind it a post-frontal trough with some slight cold advection aloft will steepen lapse rates and help to generate a few heavy showers. This combined with a little sunshine through early afternoon will generate a small amount of CAPE (100-200 J/kg). Showers will likely develop, but as over the last few days lightning is considered only a small threat. 

http://www.convectiveweather.co.uk/forecast.php?date=2019-04-30

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If anything kicks off today, I would favour places around the Humber.

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Posted (edited)

It's gone from sunny to cloudy in the space of half an hour here but difficult to see if its convective as there's a lot of low level murk about.

Edited by reef

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Posted (edited)

Did much the same here but one could see the cloud here, a mix of CuSc with even a few spots of rain for about 5 minutes.

Perhaps the Extra 06Z predict skew-t helps explain this

Td=9 T=16 C about that time

https://www.netweather.tv/secure/cgi-bin/premium.pl?action=cskew;sess=aabbeb6454942c578269dae5ee5e18cf

Edited by johnholmes

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There looks to be a higher possibility of thundery showers tomorrow. 

Nothing's really kicked off today.

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Day 2 Convective Outlook

VALID 06:00 UTC Thu 02 May 2019 - 05:59 UTC Fri 03 May 2019

ISSUED 18:35 UTC Wed 01 May 2019

ISSUED BY: Chris

Much of the British Isles will be in a northwesterly flow through Thursday as a ridge of high pressure to the southwest begins to be pushed away and cold front spreads southwards across Scotland during the day. 

Pre-frontal troughs and weak surface convergence will be the focal point for heavy showers that will develop in conjunction with day-time heating across much of central and southern Britain. CAPE values of 100-300 J/kg will develop by early afternoon with modest mid-level laps rate, however profiles are quite moist, and there is virtually no shear, so while heavy showers are likely, lightning potential is seen as a low-risk. 

http://www.convectiveweather.co.uk/forecast.php?date=2019-05-02

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 Winds from the north west are not often associated with thunderstorm or heavy shower potential and I pretty much agree with the forecast outlook. Having said that there are some interesting details we can explore which might prove interesting. As pointed out in the forecast wind convergence is key and without it convection potential is severely reduced. Compare the mid afternoon chart for rainfall and the chart for low level winds with convergence below and you should see a close match.
 Next up is the forecast SkewT charts which show cooler drier air moving in aloft which should act to increase the height of convection as the lifted tropopause moves south.  This shows up more clearly on the comparison between the mid day and late afternoon forecast SkewT's for the west midlands below. This can often result in increased lift through the freezing zone and could increase the risk of hail. Sometimes just looking out the window and observing can tell you a few things as well. I notice this morning that lower level cloud seems to be moving along quicker than upper level clouds. This can just be an early morning effect, but forecast SkewT's are hinting at the same thing. This can mean that updrafts and downdrafts are clearly separated leading to stronger longer lived convection , along with localized inflow winds. Combining with convergence very weak tornadoes should not be totally ruled out.
 This does not mean that we should expect significant thunderstorms today and there are clear hints that the most we should really expect is some heavy showers. Mid level lapse rates are not that strong, day time temperatures will not result in fast building convection and the Overnight Nottingham Sounding shows some notches which could inhibit convection at certain heights if the atmosphere does not change.My best guess is that lightning will be pretty isolated if there is any at all today, but I would have some concerns about hail.
 Its always interesting to me just to explore some of the detail even if it is not a classic thunderstorm day.

nmmuk3hrprecip.png

nmmukwind.png

sound-WestMidlands-12.png

sound-WestMidlands-18.png

2019050200.03354.skewt.parc.gif

gfs_pvort_eur15.png

gfs_pvort_eur18.png

gfs_el_eur18.png

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Posted (edited)
Quote

BrickFielder:

...even if it is not a classic thunderstorm day...

 

Meanwhile on the radar...

IMG_20190502_111952.png

Edited by Another Kent clipper
Technical error

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There's some power in those showers forming over Anglesey because they are reaching here on a WNW wind, a direction which normally kills them over North Wales and sends another load to the Pennines.  NW-NNW winds normally bring them down the Cheshire Gap to affect here instead.

The last one was pretty torrential.

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Torrential rain in these showers... just had a flash/power surge when voting... don’t know if it was lightening as no flash registered on lightening maps.... lots of house alarms gone off and power cut at home as electric digital clocks all blank... 

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Non-stop torrential rain for the past 2 hours here, was out shopping in Chapel-en-le-Frith and the electricity briefly went off followed by that familiar sound of thunder, in all about 4 strikes seen/heard and still raining here currently.

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Loving the detailed analysis by brickfielder. Something that I’ve always appreciated during big plume events and even the average storm day. 

A few strikes over N Lincs way, and convection bubbling up nicely over the vicinity of Cambs/Lincs. Could be a few flashes around during the next few hours. 

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Two Cracks of thunder overhead.

Fairly heavy rain (big juicy convective buggers)

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Potent little cell over the Black Country....plenty of low level sheer

789611194_Thur003.thumb.jpg.ad59b06c15f15e6113a0fccb936bc462.jpg

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Posted (edited)

Arnie, I see your potent cell and raise you a... another potent cell. Looking southish or westish from Croydon

 

 

IMG_20190502_171233.jpg

IMG_20190502_170840.jpg

IMG_20190502_170821.jpg

IMG_20190502_170803.jpg

Last shot: it was actually a western direction and it's building

 

IMG_20190502_171233.jpg

Edited by Another Kent clipper

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Bo diddly squat here apart from one 30 sec spell of rain at lunch which didn't even wet the ground.

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