Convective/Storm Discussion Thread - 1st June onwards

[Summer Sun]

Updated thunderstorm warning

Between 14:00 Fri 27th and 23:45 Fri 27th

Scattered thunderstorms are possible.

What to expect

• Flooding of homes and businesses could happen quickly, with damage to some buildings from floodwater, lightning strikes, hail or strong winds
• Where flooding or lightning strikes occur, there is a chance of delays and some cancellations to train and bus services
• Spray and sudden flooding could lead to difficult driving conditions and some road closures
• Power cuts might occur and other services to some homes and businesses could be lost

Reason for update

There is a slightly increased likelihood of thunderstorms affecting parts of England on Friday. The warning area has been extended further south and parts of northwest England have been removed.

Further details

Whilst many places are likely to remain dry, there is the potential for thunderstorms to develop during Friday afternoon, lasting well into the evening. Where these occur expect torrential downpours with as much as 30 mm of rainfall in 1 hour and 60 mm in 3 hours. Large hail and strong, gusty winds will be additional hazards.

https://www.metoffice.gov.uk/public/weather/warnings#?date=2018-07-27

 

[Another Kent clipper]

35 minutes ago, karyo said:

Manchester will be bone dry again by the look of things...

that's not a sentence I wanna read lol 

[karyo]

1 minute ago, Another Kent clipper said:

that's not a sentence I wanna read lol 

Sadly that's how it looks, also the update that Summer Sun just posted has removed northwest England from the warning area.

[Ben Sainsbury]

I'm still not sure if I agree with the Met Office for Thursday, I would've liked to have seen anywhere along and east of the M6 covered with the yellow warning along with much of East Anglia (though a lower risk here). I still feel there is the potential for many central areas. (Map Attached)

We are continuing to see a further westward correction, with support from the AROME model suggesting many central areas may see something too. EURO4 is many concentrated towards Yorkshire with relatively no action anywhere south of Lincolnshire. The Netweather NMM probably the most widespread with any storms hugging the coastline and hence the extension towards East Anglia in my opinion. However must be noted the NMM generally performs relatively bad in regards to location of storms but moreso with imports than home-grown.

I'll update on the Thurs night potential tomorrow.

[Weather-history]

1 hour ago, karyo said:

Manchester will be bone dry again by the look of things (tomorrow and Friday) with the activity east of the Pennines. At least, my places looks east so I will be able to see the CBs.

I hope no storms develop at all Friday evening and clear skies to east/southeast. Total lunar eclipse moonrise, Friday dusk.

[Mokidugway]

5 minutes ago, Weather-history said:

I hope no storms develop at all Friday evening and clear skies to east/southeast. Total lunar eclipse moonrise, Friday dusk.

Though your horizon might be blocked by distant CBs

[karyo]

6 minutes ago, Weather-history said:

I hope no storms develop at all Friday evening and clear skies to east/southeast. Total lunar eclipse moonrise, Friday dusk.

By Friday night I will be sleeping comfortably with the cooler Atlantic air.

[Weather-history]

5 minutes ago, karyo said:

By Friday night I will be sleeping comfortably with the cooler Atlantic air.

Going to bed early? Moonrise is about 9.10pm.

Edited July 25, 2018 by Weather-history

[karyo]

2 minutes ago, Weather-history said:

Going to bed early? Moonrise is about 9.10pm.

Yes, due to sleep deprivation caused by the horrid heat 

[TJS1998Tom]

Just hope us in Lincolnshire have a chance this time, not really had a good storm this year, looking promising. Just hope there isn't a sudden move to the West : P 

[sparky1972]

1 hour ago, TJS1998Tom said:

Just hope us in Lincolnshire have a chance this time, not really had a good storm this year, looking promising. Just hope there isn't a sudden move to the West : P 

fingers crossed mate

 

[Stephanie Starr]

Fingers crossed I'm a Lincolnshire lass as well

[Mokidugway]

Lol, Lincolnshire is at least five times more stormy than here ,hope it all shifts west hitting only cumbria

[sparky1972]

41 minutes ago, Stephanie Starr said:

Fingers crossed I'm a Lincolnshire lass as well

i have just seen the met office forecast online and it has us down for storms tomorrow afternoon and nothing for friday

[Cableguy]

Looks like things will be to the east and north of here, can't buy any rain in this area

 

[The PIT]

Got a feeling that I will be looking at Thunderstorms to the east of me Friday with another band to the west of me which will die a death before it reaches us.

[Norfolk Sheep]

28 minutes ago, Cableguy said:

Looks like things will be to the east and north of here, can't buy any rain in this area

 

And west and north for me. Looks like several more days without rain at least to the following weekend. Almost the end of July and not a single storm? Ridiculous. 

[Flash bang flash bang etc]

Google Weather (please don’t laugh) has had us down for thundery showers Thursday late and these turning into full-fledged storms through the early morning on Friday.

Its been on there for a while, too.

So why is nobody mentioning the risk of potential storms on Thursday in central southern areas? Or is it okay if we all get washed away in the floods...

[Cableguy]

16 minutes ago, Flash bang flash bang etc said:

Google Weather (please don’t laugh) has had us down for thundery showers Thursday late and these turning into full-fledged storms through the early morning on Friday.

Its been on there for a while, too.

So why is nobody mentioning the risk of potential storms on Thursday in central southern areas? Or is it okay if we all get washed away in the floods...

Euro 4 model(normally pretty reliable) showing nothing down here, storms further north later on in Linc's etc

 

[Stuart]

Day 2 Convective Outlook

VALID 06:00 UTC Thu 26 Jul 2018 - 05:59 UTC Fri 27 Jul 2018

ISSUED 19:55 UTC Wed 25 Jul 2018

ISSUED BY: Dan

Large upper trough centred to the west of the British Isles will encourage northward advection of a very warm, moist airmass across Britain on its forward flank. Subtle forcing aloft may allow one or two elevated showers to occur on Thursday morning over parts of southern and eastern England, the depth of convection a little questionable as to how much lightning (if any) may occur. 

 

... E MIDLANDS / N ENGLAND THURS LATE AFTERNOON / EVENING ...

However, by the afternoon strong surface heating with dewpoints of 15-17C should yield 1,300-1,800 J/kg CAPE, which combined with low-level convergence and orographic influence may allow a few scattered thunderstorms to develop over eastern England late afternoon and more especially into the evening hours. North Lincolnshire into Yorkshire is the most favoured area for a couple of isolated evening thunderstorms, drifting to the north, highlighted by the northern portion of the MDT. Forecast profiles exhibit reasonable speed and directional shear, with backed low-level winds, which combined with significant instability suggests the potential for a supercell or two capable of large hail up to 2.0cm in diameter and frequent lightning - as such, a SVR has been introduced. However, dry mid-levels and a warm nose at 700mb may inhibit deep convection somewhat.

 

... ENGLAND / N + E SCOTLAND OVERNIGHT ...

Overnight, increased forcing aloft will further destabilise the airmass across portions of England, with an increase in coverage of elevated thunderstorms (cloud bases probably 8,000 - 10,000ft) expected along the plume axis from Cen S England northwards to the east coast of Scotland - hence a rather large SLGT area, with a southwards extension of the MDT to highlight the corridor with best multi-model consensus (though this may need nudging eastwards if guidance trends that way).

 

... IRELAND / W SCOTLAND ...

Over Ireland, elements of embedded mid-level instability release may occur within the frontal zone slowly tracking eastwards during Thursday daytime. A few isolated lightning strikes will be possible, before the potential shifts northwards to the Hebrides overnight.

 

http://www.convectiveweather.co.uk/forecast.php?date=2018-07-26

[Summer Sun]

Day 2 Convective Outlook

VALID 06:00 UTC Thu 26 Jul 2018 - 05:59 UTC Fri 27 Jul 2018

ISSUED 19:55 UTC Wed 25 Jul 2018

ISSUED BY: Dan

Large upper trough centred to the west of the British Isles will encourage northward advection of a very warm, moist airmass across Britain on its forward flank. Subtle forcing aloft may allow one or two elevated showers to occur on Thursday morning over parts of southern and eastern England, the depth of convection a little questionable as to how much lightning (if any) may occur. 

 

... E MIDLANDS / N ENGLAND THURS LATE AFTERNOON / EVENING ...

However, by the afternoon strong surface heating with dewpoints of 15-17C should yield 1,300-1,800 J/kg CAPE, which combined with low-level convergence and orographic influence may allow a few scattered thunderstorms to develop over eastern England late afternoon and more especially into the evening hours. North Lincolnshire into Yorkshire is the most favoured area for a couple of isolated evening thunderstorms, drifting to the north, highlighted by the northern portion of the MDT. Forecast profiles exhibit reasonable speed and directional shear, with backed low-level winds, which combined with significant instability suggests the potential for a supercell or two capable of large hail up to 2.0cm in diameter and frequent lightning - as such, a SVR has been introduced. However, dry mid-levels and a warm nose at 700mb may inhibit deep convection somewhat.

 

... ENGLAND / N + E SCOTLAND OVERNIGHT ...

Overnight, increased forcing aloft will further destabilise the airmass across portions of England, with an increase in coverage of elevated thunderstorms (cloud bases probably 8,000 - 10,000ft) expected along the plume axis from Cen S England northwards to the east coast of Scotland - hence a rather large SLGT area, with a southwards extension of the MDT to highlight the corridor with best multi-model consensus (though this may need nudging eastwards if guidance trends that way).

 

... IRELAND / W SCOTLAND ...

Over Ireland, elements of embedded mid-level instability release may occur within the frontal zone slowly tracking eastwards during Thursday daytime. A few isolated lightning strikes will be possible, before the potential shifts northwards to the Hebrides overnight.

http://www.convectiveweather.co.uk/forecast.php?date=2018-07-26

[Summer Sun]

Day 3 Convective Outlook

VALID 06:00 UTC Fri 27 Jul 2018 - 05:59 UTC Sat 28 Jul 2018

ISSUED 20:12 UTC Wed 25 Jul 2018

ISSUED BY: Dan

 

... FRIDAY MORNING ...

Elevated thunderstorms will likely be ongoing on Friday morning along the ThetaE plume from Cen S England, through eastern England to perhaps the Northern Isles. These should continue to drift north along the same corridor through the day, but probably with some reasonable gaps developing as forcing aloft and instability weakens temporarily in the wake of each thunderstorm cluster.

 

... FRIDAY AFTERNOON / EVENING ...

Strong surface heating with temperatures in the mid 30s Celsius and dewpoints of 18-20C will create a very unstable environment by the afternoon, with CAPE values in excess of 1,500 J/kg possible. This combined with elements of low-level convergence and stronger upper forcing arriving, as a shortwave drifts northwards on the forward side of an approaching upper trough, should provide the trigger for scattered surface-based thunderstorms to develop, particularly during the late afternoon and into the evening hours.

Given the magnitude of instability, strongly-sheared profiles and dry intrusion in the mid levels, large hail over 3cm in diameter will be possible along with damaging outflow winds and very frequent lightning. Some surface water flooding could occur in a few places. A MDT has been issued where surface-based thunderstorms are most likely to develop, and it is likely upgrades will be required in future outlooks.

 

... FRIDAY NIGHT ...

On Friday evening and night, increased forcing aloft will destabilise the instability plume more widely, with an increasing coverage of elevated thunderstorms likely to erupt over eastern England, gradually clearing to the east - perhaps bending back westwards over parts of northern Scotland and the Northern Isles. Frequent lightning is expected with this activity. A broad SLGT has been issued for now (which includes the pulses of elevated convection during Friday daytime), but some areas may be upgraded to MDT.

 

... AREAS TO THE WEST ...

Farther west over Ireland, Wales and SW England, both the initial cold front and the following occlusion/cold front could provide some convective potential during Friday and/or Friday night, but confidence in location and evolution is not particularly high to warrant an upgrade to SLGT for now.

 

http://www.convectiveweather.co.uk/forecast.php?date=2018-07-27

[Biggin]

Does that mean nothing all day for the South East corner ? Cant quite make out if all is North of London and East ?

[Flash bang flash bang etc]

I’m sorry but these forecasts seem to be entirely ignoring the likelihood of some thunderstorms over areas further south. I might be wrong but it seems strange everyone is going for everything happening up north...

Edit: okay so CW upgraded us to a slight, I’ll give them some kudos for that

Edited July 25, 2018 by Flash bang flash bang etc

[Flash bang flash bang etc]

More detail here: https://www.metcheck.com/SEASONAL/weekly_storm_discussion.asp