Storms and Convective Discussion - 20th April 2019 onwards

[Swansonson69]

4 minutes ago, Harry said:

Let’s see what the 18z brings...but GFS in the past two runs (compared with 24 hours ago) most definitely showing an eastward shunt.

I have seen in the past few years westward trends as models evolve...given the slack flow overall anything’s possible.

What charts are you looking at @Swansonson69?

Mind you I was looking at the pressure charts and not the CAPE charts until after. I don't know anymore because some essambles where going crazy because the upgrade. One was going down to below 25°c for the upper Air. Then the precip chart yesterday was completely Dark Blue, like the whole thing. Today pressure wasn't showing up correctly. So I dunno. Just gonna wait for the day to arrive. 

[Flash bang flash bang etc]

5 minutes ago, Harry said:

Let’s see what the 18z brings...but GFS in the past two runs (compared with 24 hours ago) most definitely showing an eastward shunt.

I have seen in the past few years westward trends as models evolve...given the slack flow overall anything’s possible.

What charts are you looking at @Swansonson69?

With the meandering flow we are presently dealing with I think it’s already gonna be a case of nowcasting on the day.

Even if charts were suggesting it nailed for the south it could all change quite significantly at the last moment.

That’s the deal with the UK

Personally even thundery rain is better than anything we’ve had this year so far, I’m not going to waste too much time letting my hopes get built up and dashed repeatedly over the next 72 hours - I’m no glutton for punishment!

On the day the UK will do what it does best. We won’t see a humdinger I’m pretty sure of it, more likely cloud cover will scupper the majority of the heating necessary to get the best CAPE values and we’ll get something akin to what Germany or Benelux regards as ‘the usual midweek thundery shower’.

[Zak M]

Current view to my East

 

Edited June 15, 2019 by zmstorm

[East_England_Stormchaser91]

Just had a little beauty pass here! Few rumbles heard. Get in. 

[Zak M]

Lightning detected 15 miles away and I think I heard the thunder although I can't be too sure.

[Zak M]

Anyone know what this is in the distance?

 

[Mapantz]

Taking Kent as an example, the GEFS show the OP run to be at the extreme end of the scale for CAPE Weds/Thurs. It's not an outlier, but it certainly doesn't have much support for the levels of CAPE it is showing.The GEFS mean is showing between 600 and 800 J/Kg.

[Zak M]

@East_England_Stormchaser91   Guessing you just heard something? 

[James1979]

On the way back from Peterborough to St Neots just now.  Lovely cloudscapes today.

[Flash bang flash bang etc]

24 minutes ago, Mapantz said:

Taking Kent as an example, the GEFS show the OP run to be at the extreme end of the scale for CAPE Weds/Thurs. It's not an outlier, but it certainly doesn't have much support for the levels of CAPE it is showing.The GEFS mean is showing between 600 and 800 J/Kg.

Tuesday night is looking very warm. There’s a small window from 7am weds which from what I can see at moment will be critical to get the Sun going and push temps up to levels where we can see something significant kicking off.

Obvs things can and will change but I’m expecting storms to get going around 11am  to midday and then move off NEward at a reasonable pace.

Its early days yet and obviously I’m not interested in the slightest which is why I’m definately not checking the charts/apps etc every couple of hours...  

[AnvilCrawlers]

These where taken around 17:15 at pitsford reservoir in northamptonshire.gave a couple of rumbles of thunder but did not see the lightning.

[Chris.R]

 Slight chance today imby around midday but not much CAPE or instability shown by WRF. Think it may be underestimating though as it has the initial surface temperature 4°C too low. 

Shows a risk window of only a few hours which makes sense as the win veers partially on-shore. If this doesn’t happen then I have a better chance.

Liverpool TAF just showing PROB30 of +SHRA. 

Edited June 16, 2019 by Chris.R

[Gordon Webb]

11 hours ago, Flash bang flash bang etc said:

Tuesday night is looking very warm. There’s a small window from 7am weds which from what I can see at moment will be critical to get the Sun going and push temps up to levels where we can see something significant kicking off.

Obvs things can and will change but I’m expecting storms to get going around 11am  to midday and then move off NEward at a reasonable pace.

Its early days yet and obviously I’m not interested in the slightest which is why I’m definately not checking the charts/apps etc every couple of hours...  

bbc breakfast forcast suggesting this taking a more easterly track for overnight tuesday into wednesday , wouldn't take much notice of this at this range but any warm weather seems to be firmly in SE only but of course that might change too and GFS cape/LI charts for overnight tuesday/wednesday are almost devoid of anything but then again I'm no expert as I'm sure other factors will be involved

Edited June 16, 2019 by Gordon Webb

[The PIT]

17 hours ago, zmstorm said:

@The PIT  Looks like a storm is heading your way, your first for the year 

Nope no storm here just rain so we remain the general theme of not having storms or what do survive here are so weak if you fell asleep you miss them.

[Mr Frost]

First thunderstorm of the day has arrived here in Gourock, Scotland.

Couple of flashes/rumbles directly to my North. 

[The PIT]

Chances today are better according to Convective weather however as with predicting storms it's highly difficult unless you live in Sheffield when the answer is generally no storms these days.

[todd1970]

Really fancy our chances today , cells already firing up to my south and west , suns out here and the clouds are building.

[matty40s]

I was resealing boat windows yesterday afternoon on the River Soar...managee to get the last one in just as this struck me.

 

Edited June 16, 2019 by matty40s

[matty40s]

T'other half has just gone down to Basildon, says she's been through some torrential showers already, windscreen wipers hardly coped (it is a French car though).

I have re commended she takes her brolly with her looking at what's headed her way!!

[BrickFielder]

Moderate chance of thunderstorms today depending on cloud cover with a low possibility of a more severe storm. I am particularly looking at parts of the midlands across to Humberside. A low level convergence zone from the south west through to east Anglia should also produce some convective activity. 

I did think that the trigger for convective activity in the north midlands was low level trough, but having had a closer look it might be a mid level dry slot, which shows up on the forecast skewT. Satellite imagery confirms there is a drier slot but it might move through a bit quicker than forecast. With a jetstreak overhead updraft and downdraft separation will likely lead to longer lived storms and with slight wind veer at low levels and speed wind shear through the upper levels then storms could become quite tilted. This means localized flooding is a real possibility.  Worth keeping a close eye on especially for low topped supercells towards the north east.

 

[Summer Sun]

Day 3 Convective Outlook

VALID 06:00 UTC Tue 18 Jun 2019 - 05:59 UTC Wed 19 Jun 2019

ISSUED 09:00 UTC Sun 16 Jun 2019

ISSUED BY: Dan

Broad upper troughing will reside over the Atlantic on Tuesday, placing the British Isles under reasonably strong southwesterly flow aloft. Later in the day, backing flow as a weakening shortwave over Biscay approaches (originally a potent upper low over the Azores on Sunday night) will tend to advect an increasingly warm, moist low-level airmass (dewpoints 14-16C) into southern England. 

Increasing baroclinicity will encourage the development of a surface low and frontal rain, sliding northeastwards across parts of England and Wales on Tuesday night. However, within the warm sector profiles will become increasingly unstable, and it seems likely scattered elevated thunderstorms may develop on Tuesday evening / night in a zone from the eastern English Channel and across parts of SE England and East Anglia.

There is inevitably some level of uncertainty in these complex setups, with the exact timing and location of thunderstorm potential subject to change (or even shift too far east to affect the British Isles). However, provided guidance remains relatively consistent, upgrades are likely in later forecast updates.

http://www.convectiveweather.co.uk/forecast.php?date=2019-06-18

[Flash bang flash bang etc]

Regarding the Tuesday/Wednesday potential for the south (which I am going to call Thunderstorm Harold) Metcheck are still seeing favourable potential:

https://www.metcheck.com/SEASONAL/weekly_storm_discussion.asp

 

Edit: Touché Dan

Edited June 16, 2019 by Flash bang flash bang etc

[Summer Sun]

Day 1 Convective Outlook

VALID 06:00 UTC Sun 16 Jun 2019 - 05:59 UTC Mon 17 Jun 2019

ISSUED 23:37 UTC Sat 15 Jun 2019

ISSUED BY: Dan

An increasingly elongated upper low will reside to the west of Ireland, creating strong southwest flow aloft over the British Isles. Cool air aloft combined with diurnal heating of a reasonably moist low-level airmass (dewpoints 10-13C) will yield 300-700 J/kg CAPE. Scattered showers and a few thunderstorms are expected to develop by midday and through the afternoon / early evening, particularly across N / NE Scotland, the Midlands into northern / eastern England, and across the Republic of Ireland and into Northern Ireland. 

... SCOTLAND ...

For Scotland, shear will tend to weaken by the time the majority of deep convection occurs, and so a more "pulse type" mode is expected - though any showers/storms that can develop early, primarily over Highland, may benefit from reasonable shear to become somewhat-organised. Nonetheless, given cold air aloft and the depth of convection likely to be deepest here than elsewhere in the British Isles, some small hail will be possible from the most intense cells, and perhaps a couple of funnel clouds where showers/storms develop over zones of low-level wind convergence which will likely develop during the afternoon hours around the Moray Firth coastline. Slower storm motion here may result in some localised surface water issues.

... ENGLAND ...

Elsewhere, a strongly-sheared environment is expected allowing updrafts to become longer-lived and cells somewhat organised as they track generally to the northeast. A couple rounds of showers/thunderstorms will be possible across England, associated with a pre-frontal trough early afternoon, and then perhaps the approaching warm front late afternoon / early evening. The most intense cells, including the potential for a supercell, may produce hail close to 2cm in diameter. Low-level winds will be a little more backed as storms approach the east coast, and so here would be the best potential for an isolated tornado.

... REPUBLIC OF IRELAND / NORTHERN IRELAND ...

Perhaps the best overlap of favourable conditions for organised thunderstorms (in the British Isles) will exist over Ireland, although the forecast evolution here is less-clear due to a potentially messy precipitation mode as a new Atlantic frontal system approaches. Assuming sufficient cloud breaks and surface heating can occur, then scattered showers and a few thunderstorms may affect parts of N / NW Republic of Ireland initially - early afternoon - spreading northeastwards across Northern Ireland with time, with perhaps a second round developing near Limerick and environs later in the afternoon / early evening as the left exit of the approaching mid-level jet streak overspreads the area - these then migrating northeast across the northern half of Leinster during the evening hours.

A couple of supercells will be possible, with the potential for hail up to 2cm in diameter, and perhaps a tornado where low-level winds become locally backed, enhancing the low-level shear and SREH. Due to limited confidence in forecast evolution, have refrained from issuing a SVR for now.

http://www.convectiveweather.co.uk/forecast.php?date=2019-06-16

[Gordon Webb]

3 minutes ago, Summer Sun said:

Day 3 Convective Outlook

VALID 06:00 UTC Tue 18 Jun 2019 - 05:59 UTC Wed 19 Jun 2019

ISSUED 09:00 UTC Sun 16 Jun 2019

ISSUED BY: Dan

Broad upper troughing will reside over the Atlantic on Tuesday, placing the British Isles under reasonably strong southwesterly flow aloft. Later in the day, backing flow as a weakening shortwave over Biscay approaches (originally a potent upper low over the Azores on Sunday night) will tend to advect an increasingly warm, moist low-level airmass (dewpoints 14-16C) into southern England. 

Increasing baroclinicity will encourage the development of a surface low and frontal rain, sliding northeastwards across parts of England and Wales on Tuesday night. However, within the warm sector profiles will become increasingly unstable, and it seems likely scattered elevated thunderstorms may develop on Tuesday evening / night in a zone from the eastern English Channel and across parts of SE England and East Anglia.

There is inevitably some level of uncertainty in these complex setups, with the exact timing and location of thunderstorm potential subject to change (or even shift too far east to affect the British Isles). However, provided guidance remains relatively consistent, upgrades are likely in later forecast updates.

http://www.convectiveweather.co.uk/forecast.php?date=2019-06-18

All those saying Kent Clipper are getting ready to say Told Ya

[Gordon Webb]

5 minutes ago, Flash bang flash bang etc said:

Regarding the Tuesday/Wednesday potential for the south (which I am going to call Thunderstorm Harold) Metcheck are still seeing favourable potential:

https://www.metcheck.com/SEASONAL/weekly_storm_discussion.asp

true but this paragrahps sums it up i think

There's still some uncertainty over the exact track of this feature, but thunderstorms could break out in the south and southeast during Tuesday night before merging into a spell of more persistent thundery rain. We will update this nearer the time as developments become clearer and confidence increases.