SE, London & EA - Weather Discussion

[Norfolk Sheep]

18 minutes ago, Ed Stone said:

A rather dull, grey and depressing 13C here just now. At least those knee-jerk charts showing 8C at midday came to nothing!

Yep, dull and damp, with slightly less wind than yesterday. Earlier it looked like the cloud would break but it's now just uniform yuk. 

On the plus side I found my Strike Alert which was in the caravan utensil drawer for some reason!

[Tn9]

7 hours ago, Hotspur62 said:

Yeah like others have said it looked a certainty that we would be hit by heavy rain thunder and lightning about 8.30 last night as radar was giving the kitchen sink in weather terms to those near the coast of Kent but it just all disintegrated and gave us some light rain in the early hours and then has re intensified north of London again!!You couldn’t make it up.Oh well good luck to all those who like a good storm in the north of our region

Spot on ,exactly what happened ,I found it unbelievable,we in a small corridor of nothing ,well 60 odd miles wide and about the same long 

[Polaris]

Dill, damp, miserable  day. 
Rotten - feels like a November day. 

Soaked ground from all the boring rain last night. 
 

Need a boiling hot dry spell = to weather gods. 

26 minutes ago, TN9 said:

Spot on ,exactly what happened ,I found it unbelievable,we in a small corridor of nothing ,well 60 odd miles wide and about the same long 

No storm here. 
Just boring soaking rain 

[Dami]

I must say it was disappointing to see the Thunderstorm warning go this morning.

boo.

[Tn9]

2 hours ago, Polaris said:

Dill, damp, miserable  day. 
Rotten - feels like a November day. 

Soaked ground from all the boring rain last night. 
 

Need a boiling hot dry spell = to weather gods. 

No storm here. 
Just boring soaking rain 

Well we missed that too  really,and watching  the forecast ..same again tonight ,the word he  said .. which is perfect .   Fizzling ..well thats no favourite word of mine  

[tomp456]

The sun does not set for another 50 minutes. 

Yet it is as dark as an autumn night. 

[Wimbledon88]

Turned out nice again.

Why don't the met office etc just get a rain app on a phone. Much more accurate. Met Office had it dry all evening here in SW London. Its now absolutely tipping it down. Well that's what a 1.4bn computer does I suppose.  

[lassie23]

What a load of pizzle

[alexisj9]

Woo hoo we have clear sky now, about twelve hours to late to do anything though.

[Wivenswold]

Looks like we're in the sweet spot as far as the models are shaping up, milder for a start. 

A lot of unhappy northern types in the Model Discussion thread, I got my head bitten off for challenging the popular theory on there that it will feel like October for the rest of June. I guess we're lucky to live in the driest part of the UK and do better than most while the Atlantic fires-up and pressure rises from the Azores.

[Eagle Eye]

We've talked about the past a lot recently but let's talk about the future now and as @Wivenswoldsays, it's looking quite good for our neck of the woods, with some decent temperatures and Storm chances possible. Thats what happens when the Atlantic fires up, a lit of people get low pressure whilst we bask in the sun and get the Storms as well. Maybe it isn't fair on them but it's how the atmosphere works and they get a lot more snow than we usually do in Winter.

For the time being, a low pressure system caused by that La Nina drive swings by and cools down temperatures slightly for us, bringing a lot of cloud and maybe some drizzle as well. Although there may also be a drive for some showers and the occasional area of Thunderstorms when small areas of ridging at different levels occur and lapse-rates kick into effect bringing some light instability.

However what you can see on that last model attached is that high pressure is building up from Frqnce and what that does is advect warm air with it. A typical troughing plume only with June warmth means that theta-E is shared quite far West rather than being restricted to the far East Coast and the North Sea.

The areas that will be affected by this are still to be determined and I would expect more of a spread to the East with this so dont worry about specifics just yet. All you really need to know is that the potential is there for now. I would think London could do quite well from this with its extra heating. There is expected to be a capping in place and so some surface heating would be required to break the cap but I would think it would be enough by early afternoon unless there is a lot of cloud around.

Furthermore there is evidence that ridging may build over us later on.

That is backed by the MJO which looks like it should be re entering the Western Pacific within the next couple weeks and slowly backing will build for this ridging to push upwards.

All in all I wouldn't think that it'll be too bad anytime soon after the next couple days have gone by.

Temperature wise and as long as there is little to no cloud GFS tends to underdo temperatures and so it showing 25°C later this week is a good sign, I would say widely 23°C with Heathrow being the hottest area once again.

[Freeze]

It's turned Into a nice day here, 18c and blue skies, still a bit breezy though.

[Eagle Eye]

Here goes then, more short term heavy shower/Storm potential.

Likely pulse Storms with very little shear backing forming in areas of convergence with decent Surface Based CAPE, easily able to form with little to no cloud, especially in the afternoon after a front clears overnight.
Areas where convergence typically forms such as south Kent and between Kent and East Anglia will likely get multiple rounds of these pulse Thunderstorms, areas near Lincolnshire may get longer lasting Storms with CAPE possibly in excess of 1,000 J/KG and enhanced convergence for a time with some slight shear backing. Any Storms that do form in that area may have relatively frequent lightning because of that shear backing however I think most lightning activity will be limited to times when convergence is enhanced and shearing  may occasionally increase.

It may be quite windy, so some Winter like sea breeze convergence may take place, enhancing Storm strength on the coast and may increase ability for lightning nearer to the coast. 

[danm]

A north/south London split today, which is unusual. Some rain and cloud for south London and the southern home counties. Beautiful, warm, sunny day here in north London and the northern home counties.

[AltonMatthew]

Coming to Great Yarmouth from Saturday for 7 days. Any idea what weather to expect so far on the current runs?  

[Harry's House]

43 minutes ago, danm said:

A north/south London split today, which is unusual. Some rain and cloud for south London and the southern home counties. Beautiful, warm, sunny day here in north London and the northern home counties.

A very disappointing day here with some rain earlier, still cloudy.

[Tn9]

4 hours ago, Harry's House said:

A very disappointing day here with some rain earlier, still cloudy.

Belted down in gravesend...after gorgeous start   .cloud increased..light drizzle,but warm none the least,15 .30 belted down for  half hour...thats what happened here today

 

 

 

Edited June 7, 2022 by TN9

[Norfolk Sheep]

Morning all 

More unrelenting drizzle for Norfolk this morning, my barn is full of Khyams and awnings still drying out from Monday (one of which dried nicely yesterday but is now wet again owing to aforementioned drizzle blowing in. Arrgh!)

God bless June, eh?

[Eagle Eye]

Today's update.

I have decided to do my own forecast for today since it has more than a slight risk of Convection.

An increased risk for Storms has been issued, with the potential for flooding, hail and strong wind gusts from Storms with high cloud bases. Areas of strong convergence may counteract the lack of shear to create tall Storms with the potential for moderate to frequent lightning for a time but this will only last for a time as the lack of shear will be an issue with long-lived Storms. Areas near Lincolnshire may get longer lived Storms with at least some shear there and I considered putting a moderate anywhere within the increased area in case of shear strengthening enough as it typically does later in the day because the risk of lightning is quite high it's just how long Storms can live for that's the problem.

Frequency of lightning as mentioned could be quite frequent for a time but mostly I think it will be relatively weak especially across the slight risk area with only 300J/KG CAPE values but in some areas, 800 J/KG looks likely with very localised >1,000 J/KG of CAPE meaning that some areas may get relatively frequent lightning without the shear especially across areas of East Anglia and so for some, they may get a tall Storm counteracting the lack of shear on a convergence boundary that stays relatively slow moving for a time with localised upwards vorticity within the air meaning that despite the lack of an updraft, hail is possible and frequent lightning is a possibility.

The air is relatively dry so the risk for flooding remains on the basis that Storms can take in most of the moisture available within the levels of the atmosphere. The amount of water vapor saturation in a column as a percentage looks to be pretty high locally, especially across the Midlands and the risk of flooding there is likely to be highest.  Across the South East and it is also pretty high suggesting a risk of flash flooding there as well but the amount of water that can be taken from is likely to be slightly less in that area.

Fluctuations of heat suggest the best convergence line will form across the south and so the slight risk has been extended as lightning is unlikely to be at an increased risk it hasn't become an increased risk, yet. Just North of London is likely to be the next area of convergence and that is shown on the increased risk, it may become part of a moderate extending to Lincolnshire though, as this is where CAPE values are widely at 500J/KG and locally above the 1,000 J/KG threshold. The final convergence line looks possible in the North or in Scotland and heavy Storms are possible, perhaps the occasional risk of lightning but CAPE values are likely to be pretty low there.

I've also included a 'discussion' for flooding, hail and stronger wind gusts risk.

[Sparky68]

I think we might get some rain

[Iceman2606]

7 June 2022 Time-Lapse

 

[Eagle Eye]

11 hours ago, Eagle Eye said:

Today's update.

I have decided to do my own forecast for today since it has more than a slight risk of Convection.

An increased risk for Storms has been issued, with the potential for flooding, hail and strong wind gusts from Storms with high cloud bases. Areas of strong convergence may counteract the lack of shear to create tall Storms with the potential for moderate to frequent lightning for a time but this will only last for a time as the lack of shear will be an issue with long-lived Storms. Areas near Lincolnshire may get longer lived Storms with at least some shear there and I considered putting a moderate anywhere within the increased area in case of shear strengthening enough as it typically does later in the day because the risk of lightning is quite high it's just how long Storms can live for that's the problem.

Frequency of lightning as mentioned could be quite frequent for a time but mostly I think it will be relatively weak especially across the slight risk area with only 300J/KG CAPE values but in some areas, 800 J/KG looks likely with very localised >1,000 J/KG of CAPE meaning that some areas may get relatively frequent lightning without the shear especially across areas of East Anglia and so for some, they may get a tall Storm counteracting the lack of shear on a convergence boundary that stays relatively slow moving for a time with localised upwards vorticity within the air meaning that despite the lack of an updraft, hail is possible and frequent lightning is a possibility.

The air is relatively dry so the risk for flooding remains on the basis that Storms can take in most of the moisture available within the levels of the atmosphere. The amount of water vapor saturation in a column as a percentage looks to be pretty high locally, especially across the Midlands and the risk of flooding there is likely to be highest.  Across the South East and it is also pretty high suggesting a risk of flash flooding there as well but the amount of water that can be taken from is likely to be slightly less in that area.

Fluctuations of heat suggest the best convergence line will form across the south and so the slight risk has been extended as lightning is unlikely to be at an increased risk it hasn't become an increased risk, yet. Just North of London is likely to be the next area of convergence and that is shown on the increased risk, it may become part of a moderate extending to Lincolnshire though, as this is where CAPE values are widely at 500J/KG and locally above the 1,000 J/KG threshold. The final convergence line looks possible in the North or in Scotland and heavy Storms are possible, perhaps the occasional risk of lightning but CAPE values are likely to be pretty low there.

I've also included a 'discussion' for flooding, hail and stronger wind gusts risk.

Whilst some places did get Thunderstorms, a lot more places than I expected didn't. The capping held in place for longer than I was expecting but that wasn't the main issue here as all it did was delay proceedings. What I think happened, was that the mid-levels were a lot dryer than I expected, perhaps influenced by the frontal rain that we had before and so clouds couldn't reach their potential height, instead, most of them capped off at quite low levels, cloud bases might have been slightly lower though, thanks to the low-level moisture content that the frontal rain left behind, that would have risen quite slowly under Surface Based capping once the temperature increased and with the relatively weak cap easily being eroded away, lower cloud bases were likely what happened in areas with highest rainfall. Some areas did get lightning relatively frequently and that's where I expect that the mid-level air parcels were displaced by an oncoming pressure line ( I don't know what to call them), especially later on in the day and so that Storm near Luton can be seen to have formed around the time when that rushed on and replaced the air parcels but with CAPE still lingering and the low-level jet increasing a Storm managed to develop relatively tall and bring heavy rainfall and some more organised lightning.

That Storm near Watton in East Anglia has also developed quite quickly, likely by an oncoming replacement of the mid-levels taking place in the last half an hour, although it'll likely weaken quickly as CAPE weakens, although they were replaced earlier as shown by some more organised Storms near it, this second replacement would have fully replaced the dry atmosphere around it at the mid-levels and the enhanced low-level jet would have meant that this Storm will likely have reached its full potential height with very little potential to become higher as eventually, the energy weakens higher up into the air and if loses its ability to go up further into the atmosphere.

Even without as much lightning as I expected, a lot of flooding from these Storms taking in around 90% of water from the surrounding atmosphere is liekly to have happened and there were some quite strong wind gusts with it as well.

All in all, I'm pretty happy with my forecast.

[NO LONGER POSTING]

GFS has a tendency to over egg temperatures a bit but the 06z running out now has 27c at midnight next Friday..  Fans at the ready!

All courtesy of the 15c isotherm line making inroads which doesn't actually happen that often.. Text book summer pattern setup with low pressure running North through the Atlantic and dragging very warm air up from Africa. If the Azores high gets displaced and moves over us you could really build in some heat unless it gets put under pressure from the west. 

Subject to change and these patterns will move East - West all the time as the models work it out. To far East and we miss the high temperatures and end up with more of an Atlantic westerly.. 

40c+ for many parts of France on this run... 

Serious summer heat.. 

 

[Eagle Eye]

2 hours ago, Surrey said:

GFS has a tendency to over egg temperatures a bit but the 06z running out now has 27c at midnight next Friday..  Fans at the ready!

All courtesy of the 15c isotherm line making inroads which doesn't actually happen that often.. Text book summer pattern setup with low pressure running North through the Atlantic and dragging very warm air up from Africa. If the Azores high gets displaced and moves over us you could really build in some heat unless it gets put under pressure from the west. 

Subject to change and these patterns will move East - West all the time as the models work it out. To far East and we miss the high temperatures and end up with more of an Atlantic westerly.. 

40c+ for many parts of France on this run... 

Serious summer heat.. 

 

Better tell my ginger friends before they melt then

[lassie23]

I wish it could be sunny 23c throughout the summer and a nice cool 9c every night.