Storms and Convective discussion - 1st August 2022 onwards

[TJS1998Tom]

Wishful thinking even though they wouldn't survive the journey lol

 

[SarahWxm]

I’m at my in-laws in Telford atm waiting to see if the storms on the Welsh border/Hereford move anywhere towards here, before going back home to Wrexham. My hubby is moaning at me because he wants to go home. Is it worth me hanging on or will those storms not make it here?  
 

I'm currently peed off as earlier today I was down Somerset way and missed those storms around Warminster by a couple of hours lol  

Edited August 15, 2022 by SarahWxm

[seb]

19 minutes ago, A Face like Thunder said:

Cornwall seems to have been badly affected according to Tomas S. According to the BBC News, you will be able to received text alerts for flooding from later in the year.

Yes it’s the mobile alert system. Like the emergency alerts in the US and many other countries. Was meant to launch in December, then in the Spring, then in the Summer.

Guess Priti is too busy….

/assets/images/govuk-opengraph-image.png

Emergency Alerts - GOV.UK

WWW.GOV.UK

---

Your mobile phone or tablet may get an emergency alert if there’s a danger to life nearby. Alerts tell you what to do to stay safe.

 

Edited August 15, 2022 by seb

[Andrew Hurcomb]

Come and gone over Hereford. Lots of lightening mostly in  cloud. Went west of hereford, then pepped up as it went up Lugg valley heading towards Bromyard. Not enough rain though.

[ChezWeather]

Keeping a watchful eye on the radar, anything gets within the vicinity after darkness & i'll head out

[ChannelThunder]

When you look at the satellite, the fax charts, where the low pressure is etc, it feels like there should at least be storms moving in from the channel tonight. Alas, it just never seems to happen like that, not any more anyway,

[BrickFielder]

Usual warnings on this information that I simplify things and don't exactly follow the rules so this will be a flavour of things rather than some of the very good technical explanations on the internet from professional meteorologists (My interpretation should be taken with a pinch of salt). Maybe somebody will do a proper pinned post of this but in the meantime check Nick's very good pinned guide to thunderstorms in the UK which covers many of the ideas which about SkewTs.

SkewT Diagrams are usually seen with respect to soundings. Here a weather balloon is released to rise through the atmosphere and the temperature, dewpoint, wind speed and wind direction are recorded at different levels as the balloon rises and then plotted on the SkewT diagram. From this information you get a snapshot of the air conditions and this is useful for predicting weather conditions downwind. For example the Nottingham soundings are sometimes useful for weather prediction later in the Netherlands or Germany. The only upstream sounding for the UK is Castor Bay in Ireland which tends to be useful for Scotland and Norway. UK weather models rely heavily on Satellite monitoring which give a good idea of the air conditions upwind but has some limitations. What I tend to have a quick look at is the forecast (predicted) SkewTs and because they are not based on real measured conditions I often take certain liberties just to get a rough feel of conditions. 
 The types of things I can see from the diagrams is how humid air (dewpoint too close to temperature at any height may mean messy convection), is convection possible, is there cooler air aloft making things more unstable, is there wind shear which could enhance storms or make them long lived, is there CIN or a CAP stopping convection and how low cloud bases are and how high cloud tops are. Looking at a forecast SkewT I have numbered some features and lines and will try to explain what they are and how I interpret things (shortcuts included) 

1. Winds going up through the atmosphere giving direction and strength (number of barbs). The more winds turn with height and more speed difference there is between the surface and upper levels (Wind shear) the more severe a storm might be.
2. Isotherm lines (blue) and saturation mixing ratio lines (yellow dotted) are used to calculate the lcl and ccl(cloud base). Everywhere along an isotherm has the same temperature.
3. Saturated adiabatics (green dashed lines) (dry adiabatics are the red lines but I don't really use them but should). As moist air rises it condenses out into cloud and becomes cooler. If the air is still warmer than the surrounding air after the cooling it will continue to rise. So this line is the rate at which air cools as it goes up and produces cloud.
4. The actual or forecast temperature of air at a particular height above the ground. If the temperature drops rapidly (lapse rate) between the surface and high up at the tropopause due to cooler air aloft and drops quicker than the saturated adiabatic rate then air will rise and produce cloud (convection) up to a point where warmer air is encountered. There other mechanisms for example fronts that produce cloud so it is not the complete story.
5. Dewpoint temperature which is a measure of humidity of the air. If the dewpoint and temperature are very close together then humidity is likely close to 100% and cloud will form at that level which might affect temperatures at the surface and lapse rates. Humidity at the surface will tend to dictate cloud base levels and whether any moisture is available to form clouds.
6. This is a line I add myself to guess at the cloud base level. It should be parallel to the saturation mixing ratio but I tend to use the isotherm line. To do this properly you should draw a line from the surface temperature parallel to the dry adiabatic (red lines) and draw a line from the surface dew point parallel to the saturated adiabatic (yellow dashed lines). This is the place where a surface parcel of air will begin condense out into cloud provided the meeting point of the two lines is above the temperature line.(This is where I take a bit of a rough shortcut)
7. This a line also added by myself which estimates the level of free convection (cloud top height). This should be a curved line from the intersection point determined by 6 (cloud base level) following the saturated adiabatic until it intersects with the temperature line. The larger the area between this line and the temperature line the more unstable the atmosphere is.
8. Things like elevated convection (The lines I have drawn don't work) and other scenarios may show up here. The higher the cape number the more unstable and stronger storms will happen. Li represents the lapse rate and the higher it is the stronger storms will be. CIN is a rating of prevention of convection and the higher the number the less likely storms will occur. Pressure 1000mb tells you convection should be from the surface and not elevated.

Strictly speaking the forecast SkewT shown may not lead to a storm due to the CIN level, but considering it is estimated from satellite images certain liberties when taken in conjunction with precipitation charts don't seem unreasonable.

OK lets test out the theory on a forecast SkewT from tomorrow. (I will try do it properly for once - if I am interpreting the lines correctly)

I can see the dewpoint line close to the temperature line at higher levels. This suggests convection might be embedded or very messy. There are very strong winds up near the tropopause which would suggest a jet stream (high fast winds) and cloud tops being spread quickly at higher levels. Wind speed and direction differences are not in the key areas to affect storm development much (lower and mid levels are more important). CIN of zero shows no prevention of convection and the 200 of Cape suggest weak instability and hence weak storms. 

Looking at precipitation charts I would take that SkewT with a pinch of salt. Forecast SkewTs can be useful but need to be looked at in conjunction with other charts and the latest satellite imagery. Looks like multiple low level convergence zones occurring  which will tend to cause moisture pooling. Moisture pooling will increase the surface dewpoint and alter any forecast SkewT which does not take that into account. Wales looks like a good spot for storms again tomorrow but any cloud clearance may spark storms so keep an eye on the radar.

 

Hopefully this might start to clear a little fog around SkewT's but it is not easy to explain and after a while it becomes instinctive for some storm enthusiasts and you begin to take liberties.

 

[Peachy]

15 minutes ago, SarahWxm said:

I’m at my in-laws in Telford atm waiting to see if the storms on the Welsh border/Hereford move anywhere towards here, before going back home to Wrexham. My hubby is moaning at me because he wants to go home. Is it worth me hanging on or will those storms not make it here?  
 

I'm currently peed off as earlier today I was down Somerset way and missed those storms around Warminster by a couple of hours lol  

Unfortunately it looks to be heading in the direction of Kidderminster. Wolverhampton and on to cannock.

[RebsAbbo]

Well I’ve just driven through North East Lincs through thunderstorm. Apparently it had been thundering in Louth from about 4pm. As I left the area at 5pm to travel back to Yorkshire I followed the storm (thunder, lightning & heavy persistent rain) towards the Humber Bridge. Even very nearly got taken out by a strike as driving along there was a very bright white flash in front of my windscreen!! Of course the dash cam only records for so long & Sod’s Law dictates that by the time I got home, it was overwritten from the minute after that strike! Pulled over at Humberside Airport to watch the storm for about 10mins. Not good footage though as too much background traffic noise

Edited August 15, 2022 by RebsAbbo

[Harry]

6 hours ago, Thunderstruck said:

Looks like things are getting going around here too, and the radar supports that, with small cells to the North and South

I had a good view of that developing line across E/S London driving back from a class and to my eye there’s not enough oomph or height in the developing cells to generate much if any lightning. Yes there’s enough moisture to drop a good localised downpour but I’m not convinced there’ll be much sparks…would love to be wrong though

[SarahWxm]

22 minutes ago, Peachy said:

Unfortunately it looks to be heading in the direction of Kidderminster. Wolverhampton and on to cannock.

Typical of my luck today  

[snow raven]

Just seen fork lightning across the sky, followed by a very distant rumble of thunder  

[minus10]

1 hour ago, ThundersnowDays said:

 

Have walked down those very steps when on hols a number of years ago...lovely village...incredible to see that waterfall though whilst still sitting hear in the arid drylands..

1 hour ago, FBR said:

Looking west from Gloucester towards Hereford... lucky gits. Still bone dry here

Beautifull !!

[Norfolk Sheep]

If anyone's desperate...

https://www.webcamtaxi.com/en/italy/tuscany/florence-centre.html

[minus10]

If this lot hold out may see some flashes fron the furthest west storm as they move ne..

[Harry]

9 minutes ago, snow raven said:

Just seen fork lightning across the sky, followed by a very distant rumble of thunder  

Was eating dinner - bugger!

[Sam jackson88]

something growing north of Guernsey fingers crossed it grows

 

[minus10]

9 minutes ago, Norfolk Sheep said:

If anyone's desperate...

https://www.webcamtaxi.com/en/italy/tuscany/florence-centre.html

Yes...the storms over Italy presently are much more like it!! If we could just get some on that level !!

[ChannelThunder]

7 minutes ago, Sam jackson88 said:

something growing north of Guernsey fingers crossed it grows

 

Had a nice elevated sunset ruined by a load of low cloud that's come in off the channel. Certainly doesn't feel thundery anymore, but the cool breeze is amazing after the last week. Let's hope there's enough energy in the mid-levels to make something out of those Guernsey radar returns.

[Mapantz]

Parts of Cornwall and Devon could see another deluge during the early hours.

I'm liking the FAX chart for Wednesday - marked the area of interest:

Edited August 15, 2022 by Mapantz

[camturbo]

18 minutes ago, ResonantChannelThunder said:

Had a nice elevated sunset ruined by a load of low cloud that's come in off the channel. Certainly doesn't feel thundery anymore, but the cool breeze is amazing after the last week. Let's hope there's enough energy in the mid-levels to make something out of those Guernsey radar returns.

Cant figure out which way they are heading? Wonder if they will grow

[ChannelThunder]

8 minutes ago, camturbo said:

Cant figure out which way they are heading? Wonder if they will grow

Pretty much directly northeast. They're not showing any signs of growing at all so far, unfortunately. 

[I remember Atlantic 252]

1 hour ago, Peachy said:

Unfortunately it looks to be heading in the direction of Kidderminster. Wolverhampton and on to cannock.

Maybe Stafford too, but not expecting anything here, thunderless area this year

[camturbo]

4 minutes ago, ResonantChannelThunder said:

Pretty much directly northeast. They're not showing any signs of growing at all so far, unfortunately. 

Sounds about right!!! Fingers crossed they do

[Turquoise]

still absolutely nothing in my area. It really is quite incredible to go more than 2 years without thunder. Even on a day like today where most of the country have had some thunder or rain.