Convective/Storm Discussion Thread - 1st August onwards

[Summer Sun]

Day 2 Convective Outlook

VALID 06:00 UTC Sun 24 Sep 2017 - 05:59 UTC Mon 25 Sep 2017

ISSUED 17:47 UTC Sat 23 Sep 2017

ISSUED BY: Dan

Blocking pattern persists across much of Europe, with a largescale trough over the North Atlantic. On the forward-side, a slow-moving frontal zone straddling the Irish Sea will become subject to wave development as a series of shortwaves drift northwards in the mean upper flow. This will result in renewed pulses of heavy rain running along the front, with potential for some embedded convection elements - though with rather meagre instability, confidence is not particularly high on the lightning aspect and hence a broad LOW threat level has been issued.

One area of interest involves W Cornwall / W Devon into S + W Wales during the late afternoon but more especially evening hours as a pronounce zone of wind convergence is simulated by successive EURO4 runs behind the main frontal precipitation. Given very moist low-level air with dewpoints of 14-16C, and PWAT in the mid 20s mm there is scope for a line of heavy showers to develop and propagate NE-wards with time. Marginal mid-level lapse rates suggests such convection may be restricted somewhat in depth (and hence limiting the lightning potential), but a secondary LOW threat level has been issued to be considered as "MARGINAL" (15-30% chance of lightning within a 25 mile radius) which may be upgraded to a SLGT if confidence improves.

 

Elsewhere, in the post-frontal environment a few isolated to well-scattered showers are likely over western Ireland given closer proximity to upper trough and associated deeper instability.

 

http://www.convectiveweather.co.uk/forecast.php?date=2017-09-24

[Windblade]

No storms forecasted today but spotted two huge well defined cb's with a clearly defined anvil on the left one an hour ago over north east london. Can just see them through the smog...

Edited September 26, 2017 by Windblade

[Summer Sun]

Yellow warnings issued for the west on Sunday and Monday

Between 00:05 Sun 1st and 18:00 Mon 2nd

Spells of heavy and persistent rain are expected over some areas of western and northern Britain accompanied by strong winds at times. There is a small chance that homes and businesses could be flooded, causing damage to some buildings and that some communities could become cut off by flooded roads. Where flooding occurs there is a slight chance of delays to train and bus services whilst spray and flooding could lead to difficult driving conditions and some road closures. There is a small chance of fast flowing water or deep floodwater causing danger to life. In addition, strong winds may be an additional hazard at times with a slight chance of trees falling, power cuts and loss of other services to homes and businesses.

Spells of heavy rain are likely to reach western Britain later on Saturday and may become prolonged by the early hours of Sunday, only clearing southeastwards later on Sunday. Many places, particularly high ground will see 25-50 mm of rain, but where the rain becomes prolonged as much as 100 mm could fall over upland areas. The exact location of where the largest rainfall totals will occur is currently uncertain. Although it looks as if the more persistent rain should clear away southeastwards later on Sunday, further heavy persistent rain is possible in places on Monday; this appears more likely across the more southwestern parts of Britain. Strong winds are likely at times, with gusts of 50-60 mph possible in some exposed coastal areas.

https://www.metoffice.gov.uk/public/weather/warnings#?date=2017-10-02

Edited September 28, 2017 by Summer Sun

[alexisj9]

6 hours ago, Summer Sun said:

Yellow warnings issued for the west on Sunday and Monday

Between 00:05 Sun 1st and 18:00 Mon 2nd

Spells of heavy and persistent rain are expected over some areas of western and northern Britain accompanied by strong winds at times. There is a small chance that homes and businesses could be flooded, causing damage to some buildings and that some communities could become cut off by flooded roads. Where flooding occurs there is a slight chance of delays to train and bus services whilst spray and flooding could lead to difficult driving conditions and some road closures. There is a small chance of fast flowing water or deep floodwater causing danger to life. In addition, strong winds may be an additional hazard at times with a slight chance of trees falling, power cuts and loss of other services to homes and businesses.

Spells of heavy rain are likely to reach western Britain later on Saturday and may become prolonged by the early hours of Sunday, only clearing southeastwards later on Sunday. Many places, particularly high ground will see 25-50 mm of rain, but where the rain becomes prolonged as much as 100 mm could fall over upland areas. The exact location of where the largest rainfall totals will occur is currently uncertain. Although it looks as if the more persistent rain should clear away southeastwards later on Sunday, further heavy persistent rain is possible in places on Monday; this appears more likely across the more southwestern parts of Britain. Strong winds are likely at times, with gusts of 50-60 mph possible in some exposed coastal areas.

https://www.metoffice.gov.uk/public/weather/warnings#?date=2017-10-02

By the read up, that will probably go up to amber with more confidence

[Summer Sun]

24 minutes ago, alexisj9 said:

By the read up, that will probably go up to amber with more confidence

If they do they will trigger storm Brian the first named storm didn't really do any damage that I recall and probably didn't warrant the name

Edited September 28, 2017 by Summer Sun

[alexisj9]

24 minutes ago, Summer Sun said:

If they do they will trigger storm Brian the first named storm didn't really do any damage that I recall and probably didn't warrant the name

Yep sound similar to a few years ago when that flooding in cumbria happened. Also the west coutry stuff, fingers crossed not as bad.

[Mokidugway]

2 minutes ago, alexisj9 said:

Yep sound similar to a few years ago when that flooding in cumbria happened. Also the west coutry stuff, fingers crossed not as bad.

Flooding was terrible around here not helped by the authorities jaffa cakes poor response either .

[Despicable Weather]

8 hours ago, Summer Sun said:

If they do they will trigger storm Brian the first named storm didn't really do any damage that I recall and probably didn't warrant the name

Err you mean Storm Aileen, the one that caused power loss to thousands of homes, brought down trees because they were in full leaf?

http://news.sky.com/story/uk-surveys-damage-after-storm-aileen-cuts-power-to-50000-11033703

https://www.theguardian.com/uk-news/2017/sep/13/storm-aileen-batters-britain-with-high-winds-and-power-cuts

To be fair up where you are escaped being struck but the stronger winds etc which even seemed to bamboozle the Met. Off predictions/warnings DID strike down here during the night when thankfully most were snoozing in bed and out of harms way 

It wasn't the strongest of storms and had it swept through in late Autumn once trees had dropped then it may not have been named. As it was, it was very early and I do think it warranted the name due to the damage caused and thus was a fair call by Met.Off in that regard.

[Summer Sun]

Updated warning now expires at 18:00 Sunday instead of 18:00 Monday and it also removes the south west but adds a bit more of Scotland

Between 00:05 Sun 1st and 18:00 Sun 1st

Spells of heavy and persistent rain are expected over some areas of western and northern Britain accompanied by strong winds at times. Flooding of a few homes and businesses is possible. Spray and flooding on roads could make journey times longer and could affect some bus and train services. In addition, strong winds may be an additional hazard at times, perhaps with falling trees causing some interruptions to power supplies. This warning has been updated and is now a dual warning for rain and wind. The area has now changed to remove southwest England from the warning but to extend it across more of Scotland. The impact assessment has been reduced to low.

Spells of heavy rain are likely to reach western Britain later on Saturday and may become persistent over high ground by the early hours of Sunday, clearing southeastwards later on Sunday. Some 15-25 mm of rain is likely in places, particularly high ground where locally 50 mm is likely, perhaps with as much as 80 mm falling over mountains of Scotland and Cumbria. Strong winds are likely at times, with gusts of 40-50 mph in places, particularly coasts and high ground where 60 mph gusts are possible.

https://www.metoffice.gov.uk/public/weather/warnings#?date=2017-10-01

 

[Another Kent clipper]

Just had what felt like a convective shower, about 30 minutes ago in ardwick.  Its nice now

 

Edited September 29, 2017 by Another Kent clipper
Second pic cumulus congestious presumably

[Mokidugway]

Some heavy convective showers around aviemore 

[Summer Sun]

Wind warnings issued for Monday in the north

Between 00:05 Mon 2nd and 23:55 Mon 2nd

Strong west or northwest winds are likely to affect northern areas of the UK on Monday. Some delays to road, rail, air and ferry transport are likely. Some bus and train journeys may be affected with some journeys taking longer. Delays for high-sided vehicles on exposed routes and bridges are likely. Some short term interruptions to power supplies are possible.

Chief Forecaster's assessment

Winds are expected to strengthen across northwestern areas on Sunday evening with a swathe of gale force winds expected to cross many northern parts of the UK during Monday. Gusts of 50-60 mph are likely to develop quite widely, with gusts of 70 mph developing over parts of northern and western Scotland and more locally over high ground elsewhere. Winds are expected to peak across western Scotland in the early hours of Monday and through the Central Belt of Scotland during Monday morning's busy travel period. The strongest of the winds should gradually become confined to northeast Scotland by late evening. In addition, frequent heavy showers are likely to affect parts of western and northern Scotland. This warning has been updated to include more of Northern Ireland in the warning area as well as additional detail on the possible timings of the peak winds.

https://www.metoffice.gov.uk/public/weather/warnings#?region=ne&date=2017-10-02&regionType=area

[Summer Sun]

No warnings at all for tomorrow now the only warning in place is the wind one as posted above

[Andy Bown]

Why on earth were the warnings issued so early!

We either get them issued like this, or they're left too late, there is no common sense middle ground which means initial warnings are not issued until the more likely track/conditions are known! 

[matty40s]

I think Sundays warnings are being rehashed.  Usually take the old one down and put a new one out between 11 and 12

[Summer Sun]

1 minute ago, matty40s said:

I think Sundays warnings are being rehashed.  Usually take the old one down and put a new one out between 11 and 12

Whilst possible I doubt it tbh looking at the latest totals forecast for tomorrow

[alexisj9]

3 hours ago, Andy Bown said:

Why on earth were the warnings issued so early!

We either get them issued like this, or they're left too late, there is no common sense middle ground which means initial warnings are not issued until the more likely track/conditions are known! 

Its good that the rain amounts in the system seem to be revising downwards. Let's hope it doesn't change its mind.

[Mapantz]

I'm not sure why the warnings for wind and rain were posted in here? I don't have any time to read stuff or look at the charts much, so when I saw that there was activity in this thread, I thought there was a possibility of some convective weather, but none of which is related. 

[Summer Sun]

Some flooding in parts of the Lakes today which has caused some temporary flooding to roads and rail

[alexisj9]

2 hours ago, Summer Sun said:

Some flooding in parts of the Lakes today which has caused some temporary flooding to roads and rail

Already, may be the warnings will be back tomorrow.

[Tom Lynch]

Quite a few problems today from Millom right through Bowness , Wndermere and Stavelys new bridge has been tested 

Tom

[Mokidugway]

3 minutes ago, Tom Lynch said:

Quite a few problems today from Millom right through Bowness , Wndermere and Stavelys new bridge has been tested 

Tom

Fair few houses flooded in millom according to local news .

[pip22]

BBC Weather‏Verified account @bbcweather

 

 

 

 

A heads up for tomorrow night ... potentially wet & windy for some. Alina

[Chris.R]

40 minutes ago, pip22 said:

BBC Weather‏Verified account @bbcweather

 

 

 

 

A heads up for tomorrow night ... potentially wet & windy for some. Alina

What’s Alina? If they’re going to start using another list of names then that’s going to get rather confusing. Should just stick with Brian if there’s an amber warning.  Or is that are presenters name? 

Edited October 3, 2017 by Chris.R

[pip22]

Matt Hugo‏ @MattHugo81 34s35 seconds ago

 

 

Further addition - UKMO modified charts highlights a scenario to what the APREGE is indicating. Warnings a possibility for this feature...