SE, London & EA - Weather Discussion

[slater]

oh dear...latest charts this morning from next week temps back down as low as 9c for the South East  and next BH, absolutely shocking , Does anyone recall a year of below average temps that have lasted so long? also the lack of sun.

Since I joined here in 2010, I haven't known such a poor March and April...looks like May to follow suit...If I don't record a 20c next few days this will be the first time ever for me since i started taken weather info from 2010...

 

Edited April 29, 2023 by slater

[Freeze]

Sunny and 12c here, still quite a chilly breeze.

[Snowangel-MK]

Haven’t quite made the big 2 0 here but close to 18 so definitely a big improvement in temps and meant being able to stay outside most of the day without a coat on - currently enjoying a sit down with a cup of tea listening to bird song and looking at my colourful flowers  

Edited April 29, 2023 by Snowangel-MK
Typo

[alexisj9]

1 hour ago, Snowangel-MK said:

Haven’t quite made the big 2 0 here but close to 18 so definitely a big improvement in temps and meant being able to stay outside most of the day without a coat on - currently enjoying a sit down with a cup of tea listening to bird song and looking at my colourful flowers  

Nice. Had lots of bees in my garden today, do they swarm at this time of year, got that sort of vibe, just loads of them flying about not really feeding/drinking  much 

Edited April 29, 2023 by alexisj9

[moogyboobles]

It's that time of year for me when it feels colder indoors than it does outside! 

[MAF]

On 29/04/2023 at 15:20, Snowangel-MK said:

Haven’t quite made the big 2 0 here but close to 18 so definitely a big improvement in temps and meant being able to stay outside most of the day without a coat on - currently enjoying a sit down with a cup of tea listening to bird song and looking at my colourful flowers  

 

 

bird song or songbird?  

[Snowangel-MK]

3 minutes ago, MAF said:

bird song or songbird?  

For you, the sun will be shining… well it was here again today, walked my little legs off I have and got two very tired doggies

 

[alexisj9]

1 hour ago, Snowangel-MK said:

For you, the sun will be shining… well it was here again today, walked my little legs off I have and got two very tired doggies

 

Clouded over now here, I assume from the front.

[MAF]

3 hours ago, Snowangel-MK said:

For you, the sun will be shining… well it was here again today, walked my little legs off I have and got two very tired doggies

 

is that a euphemism 

[Kentspur]

10 hours ago, moogyboobles said:

It's that time of year for me when it feels colder indoors than it does outside! 

Depends on the type of property my new build flat with little ventilation is an absolute heat trap already its in the 20s inside! I hardly ever have to put the heating on even on cold winter days summer it's an absolute nightmare way too hot was mid 30s inside during the heatwave not much less than outside! Lost one of my pets due to overheating unfortunately in July

[Snowangel-MK]

1 hour ago, MAF said:

is that a euphemism 

Do euphemisms snore  

Looks like a dry bank holiday Monday, well this one anyway

[Sparky68]

Daylight on the commute this morning , finally! Summer just around the corner hopefully.

[Eagle Eye]

Lightning risk Outlook

Monday 1st May

Surface heating building up CAPE along a shortwave trough should provide for some fairly strong pulse showers and storms with a few longer lived cells plausible. Cold upper air in situ with low-level WAA alongside a theta-E plume.

A PV lobe (allowing wind convergence) will act as a trigger for convection along with the CAPE and surface heating factor and the longer lived convection will likely form in the shear-CAPE-PVmaxima. That'll likely occur in local gravity wave scales with large scale ascent and a bouyancy maxima for some rather deep convection but there are two problems with this. Firstly, forecasting gravity waves is extremely difficult. Secondly, one could simply not occur and therefore a larger storm within the pulse storms may not form.

Most storms should latch onto the low-level CAPE with cloud clearings and be surface based so the amount of 3CAPE is important. GFS soundings suggest 1/5 of total CAPE will be held in the averaged out portion of 3KM CAPE. So based off MUCAPE forecasts on the WRF NMM model with 800 J/KG of MUCAPE, 160 J/KG of mixed-layer CAPE in the 3KM area is possible which is fairly good averaged out CAPE. With surface based storms, torrential rain is possible. Given low-level lapse-rates very strong, hail up to 1.5 cm's appears plausible with the strongest of the storms.

Convection depth isn't that steep but with 40 knots of deep-layer shearing and favourable buoyancy they can be quite tall and produce quite frequent lightning. Mostly they may struggle to produce lightning because of quite shallow convection but sparodic lightning is possible from pretty much all cells that form tomorrow.

There is some streamwiseness of vorticity to the GFS soundings and with wind convergence, a few funnels and a very brief tornado can't be ruled out. So some hail, torrential rainfall and sparodic lightning occasionally frequent appear possible. However, drizzle and cloudiness in the morning weakens the amount of possible convection.

[Vortex3929]

12 hours ago, Kentspur said:

Depends on the type of property my new build flat with little ventilation is an absolute heat trap already its in the 20s inside! I hardly ever have to put the heating on even on cold winter days summer it's an absolute nightmare way too hot was mid 30s inside during the heatwave not much less than outside! Lost one of my pets due to overheating unfortunately in July

This is very true. I experience the polar opposite mostly due to an older build so it has a few draughts and also, I have a bare concrete floor so my flat is brutally cold all year round pretty much but a true blessing in summer when I keep the windows closed. It is a welcome ice box then.

Sorry to hear for the loss during summer. That is awful

[Tn9]

There is a few hefty showers even as far out west  as Swindon ..I here have some gorgeous hot sunny spells at moment so hope all overlaps sits in place at the right time  ..not to much  this or too  much that ..the front I think was a non active ...but its like throwing all the ingredients for  storm in the kitchen and saying get on with that ..let's see what our smidging of atmosphere cooks up

[Kentspur]

2 hours ago, UKSnakey said:

This is very true. I experience the polar opposite mostly due to an older build so it has a few draughts and also, I have a bare concrete floor so my flat is brutally cold all year round pretty much but a true blessing in summer when I keep the windows closed. It is a welcome ice box then.

Sorry to hear for the loss during summer. That is awful

Thank you wouldn't it be lovely to be able to afford two homes one for summer one for winter my place would be a winter snow lovers dream if only we had snow!

[Methuselah]

It's better today: 16C, sunny spells, and some big shower clouds building.

[Blessed Weather]

6 hours ago, Methuselah said:

It's better today: 16C, sunny spells, and some big shower clouds building.

Yes, much better Pete. Got to 16C here too at 16.00. The showers peaked early afternoon and became less widespread later (so more sunshine to bump the temp up). Still some sharp ones about tho. Shame to see the cold air digging south again tomorrow with -1C air temp at approx 1,500m. Don't want it this time of year.

Radar 13.25 

Cooler 850s tomorrow

[alexisj9]

Another nice warm day, love winds from the north down here, apart from in winter lol, sheltered, so just a small breeze, showers stayed away, though we did get some cloud, old showers perhaps, or showers trying to develop but didn't get any umph. 

[Snowangel-MK]

Oh dear looks like it will be “Reign” showers on King Charles coronation parade Saturday …hopefully it will be dry Sunday afternoon I’ve been looking forward to this .. 

 

[MAF]

2 hours ago, Snowangel-MK said:

Oh dear looks like it will be “Reign” showers on King Charles coronation parade Saturday …hopefully it will be dry Sunday afternoon I’ve been looking forward to this .. 

things ramping up here in Westminster, lots of BBC outside broadcast lorries parked up around the abbey and houses of parliament and parliament green has been re-turfed and looks splendid again, unlike the patch of mud it looked like a week ago.

[lassie23]

The chances of seeing some sleet before spring is over looks remote.

[Eagle Eye]

Convective Outlook ️

 

Thu 04 2200 May - Fri 05 2300 May

 

A small plume of moist Theta-E air along with surface heating and the most bouyant surface-boundary layer air parcels of the year so far will provide ample 3CAPE for strong convection. Though shear is fairly unfavourable (weak), the EL is quite deep and so tall convection is still possible.

 

Convergence with strong PV lobes will provide that strong bouyancy and that appears to run quite deep into the atmosphere and so could counteract the amount of shear and aid storm height. With storm height, the potential for lightning tends to increase and so we have issue a low-end moderate.

 

Generally this favours quite a high amount of entrainment CAPE. With moderately favourable kinematics and quite high CAPE. 1000 J/KG of CAPE appears likely in areas quite wide and the strongest we've seen so far this year which is a huge favour towards why we introduced the moderate risk.

 

Despite the moderately saturated profiles, those shouldn't be too much of a worry for lightning potential though very organised potential is low. Some weak clusters may form given forcing but the main problem is lack of deep-layer shearing so mostly pulse thunderstorms appear to be the main mode.

 

Just north of London there are some very bouyant air parcels mid-aftenrnoon which would suggest very deep convection relative to the time of year is possible but highly saturated profiles have kept us from extending the moderate down towards there. Instead, in the moderate area, there is a lot less over saturation and the soundings run quite typical to a high-end setup in England. If it weren't for the weak shearing, I suspect it would be a high end moderate but the weak shear keeps organisation from happening so we are likely to keep at sparodic lightning, frequent for a time.

 

The max height of storms won't be realised if air parcels can't stay in the bouyant and less than over saturated areas for long enough given the weak shearing in place. However, I suspect that even if this were the case some quite strong storms may still occur in the moderate area just not as frequent lightning as was possible. There's no real way to tell at the moment.

 

In high end American setups, the more parallel an air parcel stays to the moist air mass, the better chance of breaking a CAP there is. There is no real CAP in place here but the air parcel movement should be fairly parallel to the mid-level flow aiding storm height plausible and the length the pulse storm can occur in. However, this is very experimental of me.

 

Given strong lapse-rates, surface based storms and moderate PWAT, small (<2cm) hail is quite plausible and heavy rainfall likely if hit by a storm. Along with frequent lightning for a time in the strongest areas of CAPE.

[Eastips85]

Hard to see anything but a half decent day today and this weekend. Normally thundery showers equals get the BBQ out as those showers never appear or appear in the form of light drizzle. We shall see

[andymcpool]

Nice cheeky Rumble just now in Balham!