Storms and Convective Discussion - 20th April 2019 onwards

[Mapantz]

2 minutes ago, Paul said:

Here's a sneaky screenshot from the UKV for first thing tomorrow morning. 

Oh you scallywag! 

[tomdewey]

This is the Cape model for next Tuesday and Wednesday next week 

[Stormyking]

An interesting Morning this Morning, some real heavy showery rain at times. A few Lightning strikes and some rumbles, I did miss the majority of it as slept through my alarm  though it wasn't very frequent at all.

Will be keeping an eye on this Evening and Tonight for sure

[StormLoser]

I'm struggling with the difference in the Models. Estofex is my usual port of call and they've stuck with their model as of yesterday. But this morning's weather is pretty much as expected and the radar trend looks like the Met Office is right.

I shall watch with interest. If only I could feel the more dramatic models for this evening are correct; but I've seen so many busts I tend to remain rather cynical. Like a few other folks on this forum, I have a weird storm-free zone around me.

I consoled myself with Pecos Hank videos on YouTube last night...       Lucky man. Unlucky residents.

[Hodgheg]

7 minutes ago, tomdewey said:

This is the Cape model for next Tuesday and Wednesday next week 

Ah I'll be flying back from tolouse that evening. Hoping this comes off 

[Tom Jarvis]

1 hour ago, Ben Sainsbury said:

I don't know the area well whatsoever so I'm heading there and just seeing what works out haha.

Go to one of the beacons on the South Downs has great views south and north. There is an car park at ditchling and at Firle. 

[Harry]

5 minutes ago, John90 said:

Ah I'll be flying back from tolouse that evening. Hoping this comes off 

You a fan of violent turbulence @John90??

[Flash bang flash bang etc]

2 minutes ago, Tom Jarvis said:

Go to one of the beacons on the South Downs has great views south and north. There is an car park at ditchling and at Firle. 

It’ll be full of millennial stoners who’ve seen the distant lightning and decided to pop out for a puff and to play their migraine-inducing nu-skool traphop rubbish on their naff Halfords stereo system.

Happens a lot these days so I tend to avoid hill-top car parks and prefer to find isolated laybys on quiet back roads ... if I can

[StormChaseUK]

I have overlayed place names for the Weds am model

[Paul]

2 minutes ago, StormChaseUK said:

I have overlayed place names for the Weds am model

That's a bit further north than the screenshot I shared of it  

[Harry]

NMM 2KM is quite a pleasant improvement in the instability! However, it breaks precip much further north (north of the M4 corridor up towards the NE). This precip however does not overlay the greatest instability. 

[Hodgheg]

18 minutes ago, Harry said:

You a fan of violent turbulence @John90??

I do enjoy a bumpy flight. 

[StormChaseUK]

12 minutes ago, Paul said:

That's a bit further north than the screenshot I shared of it  

Yes just noticed the model is not mapped horizontal,  matching the isle of wight it shows the echoes south of London, up to Oxford.   M4 really.

[MP-R]

A lot of the rain on the radar isn’t actually falling here but the sky looks ripe!

[dave reid]

Tonight I'm carp fishing at a lake near Harlow.....could be a fun night ahead

[Harry]

What an upgrade this is - this is the 06z run of the WRF-NMM 0.5 (the one I rely on most at short range for CAPE business). The earlier run I posted was from the 2KM equivalent which in my experience historically is nowhere near as accurate. Over the past few days the 06z has been the most pessimistic run also.

Indicating a much more extensive area of instability as well as much higher instability - upwards of 2,000 across a big swathe of SE counties with in excess of 1,000 for the whole SE quarter (this is just a grab for 03:00). Also, it does not clear until late morning. 

If this is accurate then we could (after all) be looking at something much different from a glancing blow.

 

 

Edited June 18, 2019 by Harry

[Flash bang flash bang etc]

15 minutes ago, MP-R said:

A lot of the rain on the radar isn’t actually falling here but the sky looks ripe!

Your area is quite far from the main risk zone. Not sure if there’s enough instability or forcing to make much of it.

Lovely undulating clouds tho

[Flash bang flash bang etc]

5 minutes ago, dave reid said:

Tonight I'm carp fishing at a lake near Harlow.....could be a fun night ahead

Carp and CAPE

[MP-R]

4 minutes ago, Flash bang flash bang etc said:

Your area is quite far from the main risk zone. Not sure if there’s enough instability or forcing to make much of it.

Lovely undulating clouds tho

Fine by me lol. Outside all afternoon so don’t want rain.

[Frosty hollows]

1 hour ago, John90 said:

Ah I'll be flying back from tolouse that evening. Hoping this comes off 

Yikes! No thanks!

[dave reid]

11 minutes ago, Flash bang flash bang etc said:

Carp and CAPE

Carp, CAPE & Catfish!!

[Flash bang flash bang etc]

To anyone umming or erring over whether it’s worth the chase please read this post by PJB at UKWW (can’t post link directly to the specific text)

Convective Outlook - Update 
Issued 10:30 Tuesday 18th June 2019
Issue 3 

Changes in Overall Risk

UPGRADE - Increase risk to 90% across the SE of England, East Anglia, London, extend to 06:00 Wednesday 


Detail 

This outlook upgrades the outlook to 90% Risk of Severe weather across the SE of England as far west as Dorset, Wiltshire, and especially across London, the SE of England and East Anglia. There is considerable model uncertainty with regards to the developments, however the Severe Weather and the Thunderstorms are very finely generated by a very small differences in the structure of the Elevated Moist Layer as it moves NE across Northern France and into the English Channel and then across the SE of England. Such subtleties in the EML are not going to be modelled except by the highest resolution models. Examination of the Forecast Soundings mean the only models which are going to depict the atmosphere over the English Channel are going to be the 2KM and below models. The Euro4KM is not likely to have sufficient resolution in order to pick it up, and the UK 2KM Inner domain will get its boundary conditions from the Euro4. Therefore the AROME 1.3KM has the highest resolution of models in exactly the right location to model the plume moving NNE and the very interesting structure of the lowest 1.0 KM of the atmosphere as we go through today and tonight.  

Sferics have already been seen over the English Channel in the EML, and the radar and satellite are a fairly good match to model Pseudo IR imagery at 09Z. The EML is marked by the >16C WBPT marker and this increases as the day and evening progresses and a closed >18C WBPT 850mb wet bulb isotherm is shown by later today. From study of the atmospheric soundings it appears there is some 900mb, 850mb, 950mb confluence and convergence in the area of the English Channel from the NW, NE, E and then from the SSE. This elevated confluence and convergence at around 0.9KM up in the atmosphere is enough to focus moisture, increase the wet bulb temperature and as a result the respective humidity. The elevated confluence will trigger cloud growth which will receive an injection of air from the South (Via the SE) and this zone appears to be the main development zone. From 15:00 BST through the evening and tonight, there is marked cooling above this level and continued warm inflow of air into the area of confluence in the EML. At the same time to the SE of the shortwave there is an increase of 700mb, 600mb and 500mb wind from the SSW, there is also a Jet Streak at 500mbs / 300mbs which will vent the storms outflow into an area of upper level divergence over the East Midlands and the Wash. This outflow is then picked up by the right entrance of the SW Jet over the North Sea. Therefore over the SE of England, there is a fairly slow moving almost back building zone of elevated confluence over the English Channel and a near ideal venting mechanism for the storms to develop and grow once the upper level cooling takes place and we are then able to create a larger amount of available potential energy above 750mbs right up to the top of the tropopause. Cloud top temps are likely to reach colder than -50C and be nearing -60C over the SE of England later this evening and overnight. Storms will also form over N France, these have the potential to produce even stronger wind gusts as they will have the stronger upper level kinematics and will be surface based storms formed by insolation, rather than EML convergence over the English Channel . The net effect is the same to the observer on the ground in anycase, though technically the storms are formed in different ways./.  

Primary Focus is the development which occurs from 15Z Onwards across the SE of England, upwards of 50,000 strikes possible through the evening and tonight (that may be an understatement) and considerable C/G action and within the cloud as well. Gloud Growth all the way up to 40,000 ft once we get the shortwave and cooling aloft above 500mbs (there is quite intense differential thermal advection occuring later today and it makes the profile of the atmosphere highly unstable) Risk of Torrential rain rates (in excess of 150mm/h and surface accumulations of 50mm in places. Small Hail and Straightline gusts exceeding 50 knts esp across the BLACK BOX AREA THIS EVENING and at FIRST TONIGHT . 

Travel Disruption, Flooding, Power Issues and the knock on effects to infrastructure across the SE as well as because of the already saturated ground damage to trees and even fallen trees is possible.  
Because of this I am UPGRADING THIS OUTLOOK TO 90% RISK OF SEVERE WEATHER 
 

[StormLoser]

37 minutes ago, John90 said:

I do enjoy a bumpy flight. 

Reminds me of leaving St Louis airport in 1995, straight into a squall line that was progressing up the runway very slowly. That was a roller-coaster of a climb out! Wings flexing, plane rolling, up, down with the passengers cheering every drop and bounce. It was the side-slides that were the most uncomfortable, where we were pushed against the cabin wall as the aircraft dropped sideways! Every so often a purple flash for lightning.  I never worried about bad weather and aircraft after that, having seen those wings warp around like they did.

Yep - enjoy!

[StormChaseUK]

Some decent heat packing in behind that rain , france shooting up 

[Freeman]

Afternoon All,

I don't often post on the forum but I would welcome some advice  From looking at the forecasts, it looks as though I have a low risk of witnessing anything severe in the next 24 hours, is my interpretation correct? I live just north of Peterborough!

The reason why I ask is because my location always seem to get hit or clipped by severe storms even when they are forecast to be further east / west. Not sure why...!