Convective/Storm Discussion Thread - 1st June onwards

[East_England_Stormchaser91]

Must say, next week with this prospected seering heat that’s forecast to arrive, the charts at the same time are showing some insane potential (about time). 35+ degrees and high humidity would provide some rocket fuel for some explosive activity. On the 12z GFS, precip charts show multiple MCS’s moving S to N over the course of a few days! Hoping it sticks with this idea as we move forward! 

[Mokidugway]

1 minute ago, East_England_Stormchaser91 said:

Must say, next week with this prospected seering heat that’s forecast to arrive, the charts at the same time are showing some insane potential (about time). 35+ degrees and high humidity would provide some rocket fuel for some explosive activity. On the 12z GFS, precip charts show multiple MCS’s moving S to N over the course of a few days! Hoping it sticks with this idea as we move forward! 

Indeed ,and there's some  serious  heat over ibera, I'm mildly  excited now ☺

[Nick F]

Lift by surface breeze convergence tomorrow afternoon combined with surface heating into the high 20s of moist airmass pooling towards convergence looks to be the trigger for some slow-moving heavy showers and thunderstorms across parts of SE England, E Midlands into western E Anglia tomorrow  - looking at GFS. Hence the Thunderstorm Warning issued by Met Office yesterday..Also may be some storms imported from France clipping Kent in the afternoon/evening.

Edited July 19, 2018 by Nick F

[alr1970]

Is that the biggest Level 1 area ever, over the Black Sea and beyond? Shame it's nowhere near us!

[Lauren]

Blimey, that's impressive!

[Polar Maritime]

Yellow warning out for storms from the Meto.

[80sWeather]

3 hours ago, Nick F said:

Lift by surface breeze convergence tomorrow afternoon combined with surface heating into the high 20s of moist airmass pooling towards convergence looks to be the trigger for some slow-moving heavy showers and thunderstorms across parts of SE England, E Midlands into western E Anglia tomorrow  - looking at GFS. Hence the Thunderstorm Warning issued by Met Office yesterday..Also may be some storms imported from France clipping Kent in the afternoon/evening.

Yes!  Could see my first storm of the year.

Edited July 19, 2018 by 80sWeather

[tomdewey]

Yellow warning i
Thunderstorm
Between Fri 14:00 and Fri 23:59Further details
High temperatures may set off some heavy showers and thunderstorms, which in some places could be slow-moving and persistent, bringing a risk of flooding. Should they develop, in the heaviest showers some places could see 30mm of rain in an hour, which would likely bring flooding impacts particularly should this fall on an urban area. There would also be a smaller chance of impacts from lightning strikes. As is the nature of showers, many places will miss them altogether, and it is not possible to say precisely where they will occur, but the warning area highlights the region at greatest risk. South West England
Bournemouth Dorset Poole Swindon Wiltshire and I know it is only Salisbury part of Wiltshire the yellow warning because Warminster is not in it at the moment it's a bit disappointed in that

[convector]

I don't see anything happening today, with the dew points so low. none of the models appear to support of the weather warning either

[Tim Bland]

6 minutes ago, convector said:

I don't see anything happening today, with the dew points so low. none of the models appear to support of the weather warning either

Warning is for tomorrow. No storms were ever forecast for today.

[convector]

25 minutes ago, Tim Bland said:

Warning is for tomorrow. No storms were ever forecast for today.

wow it's thursday? i've been thinking it was friday this whole time -_- 

[alexisj9]

8 minutes ago, convector said:

wow it's thursday? i've been thinking it was friday this whole time -_- 

Oops. Wishful thinking probably.

[Nick F]

Storm & Convective Forecast

Issued 2018-07-19 15:21:22
Valid: 20/07/2018 00z - 21/07/2018 00z

THUNDERSTORM OUTLOOK - FRIDAY 20TH JULY 2018

Synopsis

A weakening diffuse upper-level trough will edge east across the British Isles, towards the surface an occuluding frontal system will move slowly SEwards across northern and western areas, weakening as it does so, before stalling across northern and western England into Saturday morning. A warm and humid airmass will be in place ahead of this frontal system on Friday across SE England and E Anglia, unstable towards a likely breeze convergence zone - which will support heavy showers/thunderstorms. In addition, a shortwave moving NE over northern France, bringing a potential area of thunderstorms N/NE, may glance Kent during early morning then again afternoon/evening.

... SE ENGLAND, E MIDLANDS, E ANGLIA ...

A shortwave trough accompanied by thunderstorms moving NE out of the Bay of Biscay across W and eventually N France may push isolated elevated thunderstorms on towards eastern English Channel tonight / Friday morning, perhaps clipping Kent, though weaker instability here may struggle to support anything more than a few elevated thundery showers with isolated lightning. Isolated flooding may occur if these pass through.

Attention then turns to rising temperatures inland under sunny skies across above areas, temps reaching high 20s Celsius combined with breeze convergence inland and associated moisture pooling (Precipitable Water / PWAT on forecast soundings reaching 33mm) forecast to increase CAPE modestly to around 200-500 j/kg during peak heating towards the convergence. Rising temperatures and lift along the convergence may trigger heavy showers and some thunderstorms. 

Some model uncertainty, even at this short range over position of likely convergence zone, but most likely a zone broadly setting up between Hampshire and Lincs/North Cambs early afternoon before shifting slowly SE across SE England into the evening. Although vertical shear will be very weak, back building from cold pool generation of cells developing along convergence and slow-movement of cells will present the risk of localised flooding issues given hard and dry ground - with rainfall rates in excess of 30mm/per hour locally possible. Hail, perhaps isolated large along with frequent cloud-to-ground lightning may also accompany any storms.

Thunderstorm re-developing over northern France during Friday may again clip Kent in the afternoon and evening, as they will be elevated, locally heavy rainfall leading localised flooding and frequent cloud-to-ground lightning will be the main risk, also small hail and gusty winds may accompany these storms.

Issued by: Nick Finnis here: https://www.netweather.tv/weather-forecasts/uk/convective

[Cambridgeshire Weather]

Hopefully Cambridgeshire are finally going to get the action it deserves! Home grown storms are well known here so hopes up for a big bang

[Summer Sun]

Day 2 Convective Outlook

VALID 06:00 UTC Fri 20 Jul 2018 - 05:59 UTC Sat 21 Jul 2018

ISSUED 20:01 UTC Thu 19 Jul 2018

ISSUED BY: Dan

Upper trough over the British Isles and Western Europe will gradually dig southwards, while slowly nudging southeastwards. On the forward side, a plume of high ThetaW air (and associated mid-level instability) will attempt to drift northwards from France towards SE England - but probably struggling to make much progress across the English Channel. As such, a few residual showers from mid-level origin are possible over SE England and perhaps East Anglia on Friday morning (but little, if any lightning) - though some model guidance (i.e. 12z EURO4) suggesting this may form into a more organised area of dynamic rain, which may have implications for potential convective developments later in the day.

 

Meanwhile, a slack pressure pattern over southern and eastern England will promote convergence zone development. In the absence of any significant upper forcing, this CZ may provide enough of a trigger for a few isolated to well-scattered heavy showers to form, particularly so during the late afternoon and into the evening hours in a zone from Dorset/Hampshire NE-wards towards Cambs/Lincs (including W London). PWAT 25-30mm and slow storm-motion will bring the risk of locally high rainfall totals and the threat of surface water flooding, especially (a) if one occurs over an urban area, and (b) considering very dry ground and high surface runoff following prolonged dry spell.

 

It is worth noting that there is still some considerable uncertainty over whether any showers will develop - forecast soundings exhibit a slight warm nose at 700mb which may limit the depth of convective cloud, though this may cool slightly during the evening hours as the upper trough approaches from the NW. Even if air parcels are able to pass this layer, CAPE profiles look rather skinny and given a distinct lack of shear, such convection will tend to be rather pulse-type in nature and may not produce much lightning at all. Risk of lightning considered 20% for now (and therefore below SLGT threshold) - there could be some scope for an upgrade to SLGT for parts of Berks / Bucks / Northants and perhaps W London if confidence improves a little.

 

Farther north, any isolated lightning from medium-level instability release over Ireland will likely ease fairly quickly on Friday morning as instability weakens - as such, no threat levels have been issued (see forecast for Thursday for more information). A LOW threat level also issued for SW England for Friday night / early hours of Saturday with some subtle hints of marginal mid-level instability release with an area of showery rain sinking S/SE-wards.

http://www.convectiveweather.co.uk/forecast.php?date=2018-07-20

[Allseasons-Si]

I might go on a storm chase tomorrow for the first time in what seems like an eternity,with slow moving cells it could be worth it,i am going to travel towards Lincolnshire after 2pm when i finish work and stay put then make decision's while i am there.

[sparky1972]

Just now, Allseasons-si said:

I might go on a storm chase tomorrow for the first time in what seems like an eternity,with slow moving cells it could be worth it,i am going to travel towards Lincolnshire after 2pm when i finish work and stay put then make decision's while i am there.

i must admit i have been surprised not to have read so far the Lincs is in prime position again, lol, normally happens and we get nothing, lol

[Allseasons-Si]

@Nick F

you posted the 10m wind chart earlier,is there a Cz down the eastern side of england too aswell as from the wash to central southern england on the latest?

or am i reading that wrong.

[DAVID SNOW]

3 minutes ago, Allseasons-si said:

@Nick F

you posted the 10m wind chart earlier,is there a Cz down the eastern side of england too aswell as from the wash to central southern england on the latest?

or am i reading that wrong.

Waiting around Peterborough would be my place to be tomorrow.

[shaky]

11 minutes ago, Allseasons-si said:

@Nick F

you posted the 10m wind chart earlier,is there a Cz down the eastern side of england too aswell as from the wash to central southern england on the latest?

or am i reading that wrong.

Yup and another thing ive noticed today is that line of thunderstorms seems to be pushing slightly further west with each run to the point where much of the east midlands could see some thunderstorms!!wouldnt be surprised if the cz is further west tomorrow as a result!!

[Allseasons-Si]

9 minutes ago, DAVID SNOW said:

Waiting around Peterborough would be my place to be tomorrow.

Yes,i was just about to comment on the dewpoints,cape,convective clouds and ppn,but slight adjustments could mean me chasing further SE,i would not want to do that but if the storms are good enough i might push the extra mile or two

charts all for 3pm tomorrow.

i am hoping the adjustments are a little further NW,then it would be a hop,skip and jump for me.

Edited July 19, 2018 by Allseasons-si

[Mapantz]

EWN's WRF take on it:

 

A lot of inter-model variation on tomorrow. A case of watching the skies and glancing at the radar.

[Allseasons-Si]

2 minutes ago, Mapantz said:

EWN's WRF take on it:

 

A lot of inter-model variation on tomorrow. A case of watching the skies and glancing at the radar.

Not saying that them charts are wrong but i hope they are,it would be a longer travel if so

radar watching would get some hammer tomorrow,lets not hope it's my pc that gets it lol

[Cambridgeshire Weather]

16 minutes ago, Allseasons-si said:

Not saying that them charts are wrong but i hope they are,it would be a longer travel if so

radar watching would get some hammer tomorrow,lets not hope it's my pc that gets it lol

I think these will be more localised western rather than eastern

[Norfolk Sheep]

Oh dear, off to Kent tomorrow - talk about rocks and hard places! I think Norwich may be too far north and east so would have to take a drive, likewise north Kent may be badly placed as well! Can't chase unfortunately so probably a missed opportunity back home....grrr....