Storms and Convective Discussion - 20th April 2019 onwards

[Thunder and Lightning]

5 minutes ago, Harry said:

GFS really quite shabby for Tuesday/Wednesday (showing brief thundery potential for EA during the morning). However, WRF-NMM much more optimistic in terms of MUCAPE flooding in from the SE...largely limited to the SE quarter. Also keen to break out convective precipitation with it. Assuming this is what the MetO is favouring in terms of its warnings.

Yeah, the ECMWF shows thundery rain throughout Tuesday night and Wednesday early morning but not any signs of the afternoon thunderstorms that the UKMO are suggesting. Hoping that sufficient daytime surface heating could trigger some thunderstorms by afternoon/evening and if any storms persist they may have a chance of becoming severe as bulk shear looks to increase. Still hoping for a very unlikely scenario of extremely heavy rain due to an MCS Tuesday night with strong winds and then discrete severe thunderstorms later on Wednesday.

[Swansonson69]

It's gone very dark and menacing here but no real cells about. I can't help but notice all that heavy rain over Northern Ireland. Pretty intense. 

[Zak M]

Quick question: Does anyone know why the Met Office has issued the warning as far north as Hull when the overnight storms are most likely going to happen in the south-east?

Edited June 16, 2019 by zmstorm

[Swansonson69]

14 minutes ago, zmstorm said:

Quick question: Does anyone know why the Met Office has issued the warning as far north as Hull when the overnight storms are most likely going to happen in the south-east?

Dunno, maybe they see something we don't. 

[Marko1690]

1 hour ago, Swansonson69 said:

It's gone very dark and menacing here but no real cells about. I can't help but notice all that heavy rain over Northern Ireland. Pretty intense. 

Pretty insane in Belfast, but no thunder 

[Harry]

From an imby perspective, GFS seems to be more in agreement with the WRF-NMM in terms of imports across the SE Tuesday night (precip wise) but less keen in terms of instability...tend to prefer the latter model in any event 24-48 hours out. 

One thing GFS has done which is encouraging is boost the instability over N France (>3,000 with LIs of -9/-10). If it lifts the instability a bit further north then could very much be game on.

@zmstorm it could be more for heavy rain than the thunder element...but warnings may get refined between now and then. Obvs I hope the instability is more widespread than currently showing.

[Allseasons-Si]

Evening guys,by heck this fibre broadband is good and nice to be back on the pc after waiting over a week of no internet,now i have 40mb to the 4mb at the old house and settling in nicely,just uploading a couple of clips (and will be done very shortly) of rotating structure of a shower that past over this afternoon,ok they are done plus a few pics

sorry for my mate on phone lol

and from the other day of which i thought was a storm and did have one rumble of thunder from it.

Edited June 16, 2019 by Allseasons-si

[Swansonson69]

7 minutes ago, Harry said:

From an imby perspective, GFS seems to be more in agreement with the WRF-NMM in terms of imports across the SE Tuesday night (precip wise) but less keen in terms of instability...tend to prefer the latter model in any event 24-48 hours out. 

One thing GFS has done which is encouraging is boost the instability over N France (>3,000 with LIs of -9/-10). If it lifts the instability a bit further north then could very much be game on.

@zmstorm it could be more for heavy rain than the thunder element...but warnings may get refined between now and then. Obvs I hope the instability is more widespread than currently showing.

I noticed the boost in CAPE over France. I think I pointed it out yesterday. 

[Mapantz]

I am not authorised to post charts from a certain model, but I have created a highly complex graphic to illustrate what it shows around 03Z on Wednesday.

In that area, it shows some extremely intense rainfall rates. Don't take it as gospel, it's likely to change.

[Swansonson69]

2 minutes ago, Mapantz said:

I am not authorised to post charts from a certain model, but I have created a highly complex graphic to illustrate what it shows around 03Z on Wednesday.

In that area, it shows some extremely intense rainfall rates. Don't take it as gospel, it's likely to change.

How extreme are we talking?

[TJS1998Tom]

18 minutes ago, Mapantz said:

I am not authorised to post charts from a certain model, but I have created a highly complex graphic to illustrate what it shows around 03Z on Wednesday.

In that area, it shows some extremely intense rainfall rates. Don't take it as gospel, it's likely to change.

Hoping there's an upgrade for storms more North, would be good to have a storm here in Lincoln on Tuesday/Wednesday

[Josh Rubio]

I’m hoping the storms extend slightly Westwards, so more of the Midlands and the north can have a better chance of seeing some action. 

[Swansonson69]

It'd only need a slight adjustment west and I'd be in for a proper shot. It's not too far off looking at that diagram. 

[Gordon Webb]

A Update From Convective Weather

Day 2 Convective Outlook

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

ISSUED 21:43 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. Advection of a high Theta-W airmass will likely be occurring on Tuesday morning from France into southern England as a lead impulse drifts northeastwards in the southwesterly flow aloft. Elevated convection will likely occur as a result, initially over the Channel Islands before drifting towards southern England - however, this appears likely to turn increasingly frontal with time as baroclinicity increases on the western flank, with any scope for renewed elevated convection likely to be focussed towards SE England, and later East Anglia. Lightning activity with this first round of activity on Tuesday daytime is uncertain, given somewhat limited instability and subtle forcing.

 

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 even warmer, moist low-level airmass into southern England. This will be accompanied by stronger forcing for ascent, on the forward-side of the approaching shortwave. It seems likely scattered elevated showers and thunderstorms may develop on Tuesday evening from the eastern English Channel and SE England, and then across parts of East Anglia overnight.

 

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, guidance has remained relatively consistent over the past few days and, should this continue, an upgrade to MDT may be possible.

The Low Risk Shifted West But Focus Still On SE England And East Anglia

Edited June 17, 2019 by Gordon Webb

[LightningLover]

Oooo, Convec. weather are considering putting forward a MDT risk zone! Now that's got me excited! Whenever there is A MDT risk zone is by them, It is usually very accurate, and a night-time channel light show nearly always unfolds...

[Flash bang flash bang etc]

Not getting excited but here are my thoughts on tomorrow’s action:

 

 

Green - slight

Yellow - moderate

Red - chaos and swearing

[Gordon Webb]

13 minutes ago, Flash bang flash bang etc said:

Not getting excited but here are my thoughts on tomorrow’s action:

 

 

Green - slight

Yellow - moderate

Red - chaos and swearing

Well there will be certainly swearing outside these areas

[Stuart]

ALID 06:00 UTC Mon 17 Jun 2019 - 05:59 UTC Tue 18 Jun 2019

ISSUED 06:13 UTC Mon 17 Jun 2019

ISSUED BY: Dan

UPDATE 06:13 UTC SLGT extended across other parts of Scotland, and into NW Republic of Ireland

 

Upper low will linger close to NW Scotland during Monday, placing the British Isles under a reasonably strong southwesterly flow aloft. A cold pool will swing northeast across Northern Ireland and Scotland, steepening mid-level lapse rates and coinciding with diurnal heating to yield 400-800 J/kg CAPE. 

 

Some longer spells of rain may affect the Northern Isles and northwest Scotland for a time, but elsewhere scattered showers and a few thunderstorms are likely to form in an environment with 30-40kts DLS. This should help tilt updrafts allowing cells to become fairly long-lasting, with some line segments at times. A low-topped supercell may also be possible, along with hail up to 1.5cm diameter and perhaps an isolated tornado. Shear is greatest towards the south and east, and so the Hebrides are more likely to have rather "pulse type" convection instead.

 

Some sporadic lightning will be possible almost anywhere across Scotland and Northern Ireland, so rather difficult to pin-point specific areas for a SLGT - but a blend of model guidance, coupled with a favourable ingredients-based overlap of convergence / instability / shear would suggest a slightly higher risk of lightning in N + E Scotland, and parts of Northern Ireland (though confidence in this aspect is somewhat limited). That said, there is the potential for a PVA lobe to drift towards western Scotland during the second half of the afternoon, which may provide sufficient forcing for increased lightning activity here also.

 

Elsewhere, the straddling cold front draped over Wales and northern England may produce some convective activity by the afternoon courtesy of surface heating near the frontal boundary - the main risk being over Yorkshire and/or Lincolnshire. However, convective depth will be fairly limited and lightning is considered rather unlikely. Some model guidance suggests a minor frontal wave could bring a zone of thicker cloud and increase in frontal rainfall at time of peak heating, which would minimise the risk of convection here.

 

Finally, late on Monday night advection of a high Theta-W airmass will likely occur over the Channel Islands and the English Channel. Subtle forcing aloft will encourage some elevated convection to occur towards Tuesday morning. However, the timing of this (whether it is largely after 06z Tuesday, beyond this forecast period) and the somewhat questionable magnitude of instability precludes an upgrade to SLGT over the Channel Islands for now.

 

http://www.convectiveweather.co.uk/forecast.php?date=2019-06-17&fbclid=IwAR3-ppEsBwsagXx3tK0gH2CrXSTtgMGRv-y0vItvOsXm39uMl5TtrSFjFo0

[Another Kent clipper]

Come on Harold!  You can come through for us this time

[Harry]

1 hour ago, Another Kent clipper said:

Come on Harold!  You can come through for us this time

What’s the Harold reference about? Lol

[Harry]

06z WRF-NMM makes for dismal reading for tomorrow night - booo! GFS even less keen.

Could be the first of many last minute eastward shifters, however I think I am right in thinking that the 06z over the past few days has been the most bullish at the plume shunting eastwards, compared to other runs of the same models. 

Not completely doomed just yet but the trend is not a great one this far out. 

Edited June 17, 2019 by Harry

[Another Kent clipper]

55 minutes ago, Harry said:

What’s the Harold reference about? Lol

Thunderstorm Harold was on flash bang etc's map.  I'm not sure if they originally coined it or not

[NO LONGER POSTING]

38 minutes ago, Harry said:

06z WRF-NMM makes for dismal reading for tomorrow night - booo! GFS even less keen.

Could be the first of many last minute eastward shifters, however I think I am right in thinking that the 06z over the past few days has been the most bullish at the plume shunting eastwards, compared to other runs of the same models. 

Not completely doomed just yet but the trend is not a great one this far out. 

Harry.. You of all people I would have thought know not to fall into the model trap when it comes to predicting thunderstorms.. Bit like snow 

 

Let's get something on radar first lol 

[Arnie Pie]

On 16/06/2019 at 12:27, Flash bang flash bang etc said:

#ThunderstormHarold

It’s happening folks

you could just be right there Flash

[Swansonson69]

1 minute ago, Arnie Pie said:

you could just be right there Flash

For Kent and the South East. Hope they get some decent storms.