SE, London & EA - Weather Discussion

[Eagle Eye]

16 hours ago, classylady said:

Hi everyone, not been on here for a little while as my dear dad passed away at the end of February……

So sorry for your loss 

[Eagle Eye]

So here's a load of stuff from yesterday.

Timelapses stuff as well.

 

   

 

[classylady]

Many thanks to everyone for all the kind messages. X

[alexisj9]

Been a nice warm day today, finally jumper was enough no jacket, need a jacket now though.

Edited April 7, 2023 by alexisj9

[Snowangel-MK]

On 05/04/2023 at 16:30, MAF said:

and on that note ^ what's everyone's favourite easter egg? 

This one…. I won it for first prize in our parish Easter window decoration competition

[Snowangel-MK]

Happy Easter to you all, I’ve spent the day gardening and enjoying the warm sunshine and spring flowers

[Vortex3929]

On 05/04/2023 at 16:30, MAF said:

and on that note ^ what's everyone's favourite easter egg? 

One that is all chocolate (not hollow) would be lovely. Wouldn't be as satisfying to punch into pieces to eat though. And probably really expensive 

Happy Easter all

Edited April 7, 2023 by UKSnakey

[lottiekent]

Morning, unexpectedly chilly again last night (if you’d believed the MO that is) with a low of 1.5c.

Currently 7c and cloudy. Annoying as I can see the cloud line on the radar is just to the west. Hopefully it’ll burn off but I don’t think I’m going to be lucky sadly.

[Summer tyre]

We're supposedly under the cloud too, but it's bright and sunny with no cloud visible and 12.1 deg C. It went down to 3.6 lowest at 5am. Hopefully you'll get that come across.

[Neilsouth]

Lots of cloud here, right down to Folkestone . As if we haven't seen enough cloud!! f f s

Edited April 8, 2023 by Neilsouth

[Neilsouth]

When is this cloud going to **** :(

[Snowangel-MK]

Went out early this morning and it was very frosty but what a gorgeous day, so nice to sit in the garden and feel warm sunshine  

[Summer tyre]

6 hours ago, Neilsouth said:

Lots of cloud here, right down to Folkestone . As if we haven't seen enough cloud!! f f s

Oh no! Sunny here with a high of 12.8 - mind you, there has been a slightly chill easterly gentle breeze. I hope it perks up there tomorrow as I'm coming to Folkestone for lunch.

Edited April 8, 2023 by Snow tyre

[MAF]

2 hours ago, Snowangel-MK said:

Went out early this morning and it was very frosty but what a gorgeous day, so nice to sit in the garden and feel warm sunshine  

I'd be happy to feel just a little warmth  

glorious day here... while i was left alone  

[alexisj9]

6 hours ago, Neilsouth said:

When is this cloud going to ****

It hasn't at all today unfortunately.

[andymcpool]

Definitely T-shirt weather on Clapham Common 

[Summer tyre]

I could see the sea frit rolling in over the hotel from the seafront. Coming back home we had lovely weather inland and I could see the low mist as we came back to the coast.  It has really depressed temperatures; it's 14.5 inland and yet only 8 back home!

[Eagle Eye]

A cold front clears to the east with a double edged shortwave trough behind it providing the lift needed for strong buoyancy and under general surface heating with the general synoptic scale features looking fairly conductive for pulse thunderstorms however as usual defining a single area is difficult.

Gravity wave features that make local environments 'the most' conductive for thunderstorm development should theoretically be handled best by models such as the UKV and AROME so we have mainly based our forecasts in terms of coverage in terms of those models. I find that they tend to forecast saturation and sometimes storm mode quire different to other models and sometimes reality.

Cloud clearings on a surface heating day is a very important factor in heat buildup and the release of heat properly into a conductive environment. Given the timing of the clearing front still being handled badly by the models it is difficult to tell what will happen in the eastern part of England.

If the cold front can clear early such as the UKV and Swiss models suggest then we may see the surface forcing and shearing parallel to the cold sector allow for a cluster or even a small squall if the cloud can clear.  According to the Swiss 4x4 model, while the clouds may not clear fully, the significant shearing along the channel and south and then the parallel DLS at 50-70 knots along the London to east area in the early afternoon and the strong forcing likely given the PV lobe along the western side of moisture tongue then a squall line or cluster could easily form there. The UKV has a similar idea but with a couple clusters and visibily weaker clearings and therefore CAPE buildup. 

Very few of the models support this though given the cold front timing to be later. There still could be some clustering up in the east into the evening with cloud clearings but perhaps weaker and with a lot less CAPE build up. 

In the daytime across the 'slight risk' and 'area of interest' areas and SBCAPE is likely to buildup above 300 J/KG widespread and locally around 800 J/KG and given fairly strong lift with the subtle shortwave forcing and convergence supported by a couple of small-scale PV lobes: pulse thunderstorms and perhaps some clustering in the more sheared zones appears likely. Saturation is unlikely to be a major problem and therefore cloud clearings should be fairly widespread and good enough for the low-level lift needed.  Though the northern half of the slight risk appears more saturated and may struggle a little bit for clear cloud clearings for storms to form.

So this supports moderately tall pulse thunderstorms quite widespread across the UK and Ireland.  Low-level lapse-rates are very strong and given weak low-level shearing hail is supported fairly well but deep-layer shearing being weak should limit that to 1-2 cm's max unless the southern side of the slight can get tall storms then that may support bigger hail perhaps up to 3-4cm but only for a short time if the shearing increase times well.

Supercells are not supported much by the synoptic scale pattern except a small chance in the southern mode. Soundings and hodos tend to favour more single cell or multicellular storm modes with most of the little shearing going speed rather than directional.

The further south you go and the more directional it gets with the vorticity being more streamwise than crosswise also supporting tornado's. There is also less amount of CAPE which is storm energy and less support there is for storms overall.

The best chance for a Supercell may be in the Cornwall region but there is very low support for a storm and I suspect will rely on gravity wave forcing that doesn't appear to be there that much.

Perhaps the best region for tornadic development is on the southern portion of the slight risk. With vorticity becoming increasingly streamwise and low-level shearing becoming more directional and actual storms likely to form in that area then a tornado may be possible in that area.

So general support is for sparodic lightning which may organise for a time and small hail. An isolated tornado or two may be possible. Perhaps some torrential rainfall and strong winds as well at 60+ km/h in some areas.

[alexisj9]

Been a nice day here, but could hear the port beacon and fog horns most of the day.

Edited April 9, 2023 by alexisj9

[lottiekent]

Thick fog to start Sunday morning, cleared quickly to a lovely day. However, right on the seafront where my daughter was working in an ice cream shop, it was thick fog all day with the foghorn sounding from first light until almost sunset. 
Apparently there were lots of visitors who came down for a day at the seaside, presumably who set off in the sunshine, picnicking on the beach anyway in their coats! 

[alexisj9]

17 minutes ago, lottiekent said:

Thick fog to start Sunday morning, cleared quickly to a lovely day. However, right on the seafront where my daughter was working in an ice cream shop, it was thick fog all day with the foghorn sounding from first light until almost sunset. 
Apparently there were lots of visitors who came down for a day at the seaside, presumably who set off in the sunshine, picnicking on the beach anyway in their coats! 

I've done that before but during the summer holidays lol, still cold in the fog on the beach . Lived in London then.

[Vortex3929]

13 hours ago, Eagle Eye said:

A cold front clears to the east with a double edged shortwave trough behind it providing the lift needed for strong buoyancy and under general surface heating with the general synoptic scale features looking fairly conductive for pulse thunderstorms however as usual defining a single area is difficult.

Gravity wave features that make local environments 'the most' conductive for thunderstorm development should theoretically be handled best by models such as the UKV and AROME so we have mainly based our forecasts in terms of coverage in terms of those models. I find that they tend to forecast saturation and sometimes storm mode quire different to other models and sometimes reality.

Cloud clearings on a surface heating day is a very important factor in heat buildup and the release of heat properly into a conductive environment. Given the timing of the clearing front still being handled badly by the models it is difficult to tell what will happen in the eastern part of England.

If the cold front can clear early such as the UKV and Swiss models suggest then we may see the surface forcing and shearing parallel to the cold sector allow for a cluster or even a small squall if the cloud can clear.  According to the Swiss 4x4 model, while the clouds may not clear fully, the significant shearing along the channel and south and then the parallel DLS at 50-70 knots along the London to east area in the early afternoon and the strong forcing likely given the PV lobe along the western side of moisture tongue then a squall line or cluster could easily form there. The UKV has a similar idea but with a couple clusters and visibily weaker clearings and therefore CAPE buildup. 

Very few of the models support this though given the cold front timing to be later. There still could be some clustering up in the east into the evening with cloud clearings but perhaps weaker and with a lot less CAPE build up. 

In the daytime across the 'slight risk' and 'area of interest' areas and SBCAPE is likely to buildup above 300 J/KG widespread and locally around 800 J/KG and given fairly strong lift with the subtle shortwave forcing and convergence supported by a couple of small-scale PV lobes: pulse thunderstorms and perhaps some clustering in the more sheared zones appears likely. Saturation is unlikely to be a major problem and therefore cloud clearings should be fairly widespread and good enough for the low-level lift needed.  Though the northern half of the slight risk appears more saturated and may struggle a little bit for clear cloud clearings for storms to form.

So this supports moderately tall pulse thunderstorms quite widespread across the UK and Ireland.  Low-level lapse-rates are very strong and given weak low-level shearing hail is supported fairly well but deep-layer shearing being weak should limit that to 1-2 cm's max unless the southern side of the slight can get tall storms then that may support bigger hail perhaps up to 3-4cm but only for a short time if the shearing increase times well.

Supercells are not supported much by the synoptic scale pattern except a small chance in the southern mode. Soundings and hodos tend to favour more single cell or multicellular storm modes with most of the little shearing going speed rather than directional.

The further south you go and the more directional it gets with the vorticity being more streamwise than crosswise also supporting tornado's. There is also less amount of CAPE which is storm energy and less support there is for storms overall.

The best chance for a Supercell may be in the Cornwall region but there is very low support for a storm and I suspect will rely on gravity wave forcing that doesn't appear to be there that much.

Perhaps the best region for tornadic development is on the southern portion of the slight risk. With vorticity becoming increasingly streamwise and low-level shearing becoming more directional and actual storms likely to form in that area then a tornado may be possible in that area.

So general support is for sparodic lightning which may organise for a time and small hail. An isolated tornado or two may be possible. Perhaps some torrential rainfall and strong winds as well at 60+ km/h in some areas.

An interesting read! Thank you for taking the time to write up such detail. I read the netwx storm forecast this morning and saw the tornado symbol and wondered what your take would be - and you've already posted very similar. Personally I'd love to see a tornado but, living in a built up area would mean potential damage to buildings and that wouldn't be nice.  Will settle for storms... I need my fix

[Eagle Eye]

1 hour ago, UKSnakey said:

An interesting read! Thank you for taking the time to write up such detail. I read the netwx storm forecast this morning and saw the tornado symbol and wondered what your take would be - and you've already posted very similar. Personally I'd love to see a tornado but, living in a built up area would mean potential damage to buildings and that wouldn't be nice.  Will settle for storms... I need my fix

Unfortunately, even if a tornado did form and it wasn't a UK esque quick spin up you'd be unlikely to see it given that most Storms are likely to be high precipitation mode anyway.

[Tn9]

5 hours ago, UKSnakey said:

An interesting read! Thank you for taking the time to write up such detail. I read the netwx storm forecast this morning and saw the tornado symbol and wondered what your take would be - and you've already posted very similar. Personally I'd love to see a tornado but, living in a built up area would mean potential damage to buildings and that wouldn't be nice.  Will settle for storms... I need my fix

A tornado will end up doing what it wants ..built up or in a field ..like or loathe it ..be quick on your toes is my advice ..been not nice this morning not really heavy rain but a bit monotonous..but sun popped out gruesome looking clouds but all gorgeous but no bite 

Edited April 10, 2023 by TN9

[Lauren]

A distance flash and rumble coming from over Isle of Grain way from here.