Storms and Convective discussion - 20th March 2023 onwards

[toggerob]

4 minutes ago, Rufus Butterfield said:

Passed it! It did chuck it down at one point, but it was brief.

Awesome  I passed 2 years ago after waiting a little later in life, but it's a game-changer once you get used to the solo-driving. It's a luxury being able to look at any summer storms forecast and having the ability to easily 'chase convection ' without relying on buses, trains, hotels, etc.

[Justin1705]

Some lovely shots of the small cell in NW London St Albans earlier today, but also just some genuinely lovely pictures of convective clouds in rich blue skys with a beaming sun!! More of this in the summer would be  

 

[Justin1705]

17 hours ago, Rufus Butterfield said:

Driving test tomorrow; hopefully won’t get caught in a downpour.

Good luck. Remember MSM mirror signal manoeuvre, also relax the examiner will never mark you down for being cautious/ safe. Best of luck! You can do it ! And if there is a downpour, slow to a safe speed and turn lights on !

[Metwatch]

Shot of cumulus mediocris from earlier today in the distance. 

A bit of a yellow hue on the second picture as I forgot to change the white balance when shooting the sunset the other day on the bridge camera. 

[Eagle Eye]

Convective Outlook ️

 

Fri 31st 0900 - Fri 31st 2200

 

A tight low is expected to pass through the channel hitting southern counties overnight  and is it ejects initially slightly Northeast overnight (with the strongest winds down forcing SE towards northern France as it turns towards straight east in the daytime), the tight forcing and wide vorticity lobe behind the main occluded front may allow for CAPE to build up to around 1000 J/KG in areas in the daytime.

 

Vorticity builds up slightly left of the geostrophic flow behind the low pressure due to surface friction and boundary-layer dynamics beyond the scope of this discussion as it's rather long and I don't understand it fully in this certain scenario. That increased forcing and the amount of latent heat releasing possible is the reason why given cloud breaks very good showers and thunderstorms are possible. The surface winds are very weak and up to the lower-Trop they increase fairly quickly. So low-level shear is fairly steep but the natural shearing beyond the strong surface drag across the risk area is quite weak and unidirectional supporting pulse-type storms.

 

The updrafts beyond the base are likely to be quite straight and therefore very little chance of tilt/veering and small Supercell formation is unlikely plus the low-level shearing doesn't support hail either apart from the northern half of the risk where the shearing is a lot weaker with much better vorticity and convergence with weaker lower-Trop winds. Once again supporting pulse-type storms but perhaps intense and quick and given they're fairly surface based they could be comparatively slow-moving compared to the southern half of the slight risk. Hence lightning may be fairly organised for about 15-30 minutes with hail and stronger downpours.  Hence the added AOI.

 

Given slight WAA of moist air up from the channel towards East Anglia and the southern area of the Midlands, there may also be an increase in activity in the evening with the low pushing southwards therefore allowing the general cell motion to change southerly with increasing shear parallel to slight cold pooling above surface heating.

 

However, MUCAPE is weakening with this southerly movement so we have decided to only keep it to a slight and no AOI for the more southerly area. Hefty downpours are still possible but low-level shearing doesn't support hail with them unless the upper cold pooling is more intense than expected and the low-level shearing doesn't weaken into the evening.

 

Most likely risks are hail in the AOI especially, hefty downpours, sporadic lightning potentially organising and convergence allowing for a funnel/tornado but unlikely given other parameters.

[Windblade]

Thought I heard a bit of distant thunder last night/this morning about 1am when we had some heavy rain that arrived just before midnight. A quick check on Blitzortung confirmed there was indeed some strikes just north of me.

Edited March 31, 2023 by Windblade

[minus10]

Well some pretty heavy rain just after a burst of sun...think some lively showers as the low crosses with the sun induced convection..

[Windblade]

Netweather have issued a storm watch for this afternoon...

 

THUNDERSTORM WATCH - FRI 31 MARCH 2023

Issued 2023-03-31 08:48:41
Valid: 31/03/2023 0600 - 01/04/2023 0600

 

 

Forecast Details

Storm Mathis, named by MeteoFrance, will track east across S England on Friday. Showery bands of rain circulating around the low will turn increasingly convective with heavier bursts at times as the low clears east towards the southern North Sea this afternoon. Convection will be strong enough to perhaps produce lightning in places across S England, Midlands and E Anglia this afternoon – though the risk will be fairly low. There is a risk of localised flooding where heavier convective bursts train in places.

Issued by: Nick Finnis

Issued by the Netweather forecast team whenever there is a risk of storms or severe convective weather, these discussion based and in depth forecasts will highlight the areas at risk and give an in depth description of the risk and the factors surrounding it.

 

 

You can actually see the curl on the radar image as the center moves past...

 

Edited March 31, 2023 by Windblade

[Arnie Pie]

Not expecting much today but cells are beginning to pep up

 edit; Plenty of direction fluctuation to the low level winds, an eye out for some funnels

Just in case

https://www.youtube.com/watch?v=WWf69M1sTfg

 

Edited March 31, 2023 by Arnie Pie

[Windblade]

Well, had a lot of heavy showery stuff mixed in with longer spells of rain this afternoon. About 20 minutes ago it came over very dark and the rain got VERY heavy. I'm actually quite surprised there hasn't been a few flashes/rumbles mixed in with it. Still raining here, heavy on and off...

[ChannelThunder]

Just a handful of lightning strikes over the pond in yesterday's outbreak then...

[LightningLover]

13 minutes ago, ResonantChannelThunder said:

Just a handful of lightning strikes over the pond in yesterday's outbreak then...

Yeah, we can do better than that!! Unbelievable day for them, two tornado driven HIGH risks! First time since April 2012. Looks like another outbreak is possible in a few days time, active start to the season.

[harrywhiterowoutdoors]

2 hours ago, LightningLover said:

Yeah, we can do better than that!! Unbelievable day for them, two tornado driven HIGH risks! First time since April 2012. Looks like another outbreak is possible in a few days time, active start to the season.

Yep Tuesday looking interesting 30% for severe thunderstorms it might give yesterday's outbreak a run for its money

[A Face like Thunder]

I went from Cheshire to Suffolk and back yesterday and can confirm that it was very wet. Rainfall was continuous in the morning and then after a brief interlude, the showers came packing in, making the return journey on the A14 in particular a bit of a 'mare. No thunder and lightning seen where I was, but reports of flooding on the M25 north of London and on the M4 near Newbury, and I have to say I was not surprised.

[Iceman2606]

Thundery Showers After Storm Mathis - 31 March 2023 Time-Lapse

 

[Rufus Butterfield]

Looking like a very quiet couple weeks ahead, storm wise.

[minus10]

Although not strictly the topic of this thread we have another severe weather situation imminent in the USA..

...where the weather is concerned the US doesnt do it by halves...

...lets hope there are no more fatalities...

 

 

[Jamie M]

Trough moving through tomorrow, suspect it'll be a case of if the sun plays ball or not. 

[Eagle Eye]

Tomorrow's forecast 

Convective Outlook ️

 

Diurnal heating behind an occluded front with a helpful shortwave trough in the vicinity allowing for 300-400 J/KG of SBCAPE to potentially build up in the afternoon hours fairly widespread across England and Wales capable of a few lightning strikes but fairly pulse storms.

 

Shallow convection along a weakly sheared zone between the moderately sheared occluded front and the colder sector shear in Ireland means that kinematics do not favour anything other than sparodic lightning therefore we have kept it to a low risk.

 

Strongly saturated air around London area in the afternoon may mean that most convection is initially north of there with convection inhibited by low-level cloud. Clearings are expected initially in the NW slowly also clearing SE towards London into the evening so best chance for the showers are from mid-day till evening before diurnal heating weakens.

 

Weak low-level shearing given very strong 0-0.6 mile (-8°C+ widespread) lapse-rates could allow for hail with the strongest convection areas but storms may not last long enough to get a strong enough updraft for anything other than small hail.

 

Given the weak deep-layer shearing (though I haven't looked specifically at soundings) rain shafts are unlikely to be separated from updrafts so low-precipitation type storm photos are unlikely for any photographers suggesting more distant structure photographs or closer angry cloud photographs may be the best you can get with any stronger Storms though good luck forecasting pulse storms to a specific area.

 

These will come with the risk of sparodic lightning, small hail (1-2cm's) and heavy rainfall if they can organise well enough.

 

[The Tall Weatherman]

Convective Weather

WWW.CONVECTIVEWEATHER.CO.UK

---

Forecasting thunderstorms and severe convective weather across the British Isles and Ireland for up to the next 5 days.

Might have a few Rumbles Today.

[A Face like Thunder]

N & E Yorkshire coast seem to be favourites for some beefy showers this afternoon. 

[ANYWEATHER]

Looks threatening around the Sham at the moment

[Thunders]

1 hour ago, The Tall Weatherman said:

Convective Weather

WWW.CONVECTIVEWEATHER.CO.UK

---

Forecasting thunderstorms and severe convective weather across the British Isles and Ireland for up to the next 5 days.

Might have a few Rumbles Today.

yeah me too

[CoventryWeather]

Currently in Skegness until tomorrow, so not in my usual place as stated. 

Not expecting much thunder here, might be a chance late afternoon and evening, but looking forward to see some decent cloudscapes later. Enjoy your day all. 

[ANYWEATHER]

Potential. Al we want is a Funnel