Storm & Convective Discussion - 02/07/15 Onward - Heat & Plumes

[ChezWeather]

Convective Weather seem to have hit the nail on the head in my opinion.

 

"... ENGLAND AND WALES ...

 

Rapid warm air advection will develop across southern Britain through the evening hours, causing surface dewpoints to increase as a warm front lifts northwards. Meanwhile, the Atlantic upper trough will pivot NEwards, overlapping with the arrival of this plume during the evening, and providing sufficient lift. Consequently, expect thunderstorms to develop through the evening hours, initially fairly well-scattered across SW England, with activity expanding farther N and E as the evening progresses.

 

With the approaching trough, DLS will strengthen with favourably-backed surface winds. This combined with 800-1,200 Jkg^-1 MLCAPE suggests the potential for storms to become organised, perhaps into supercells capable of producing large hail. Forecast profiles suggest most storms will be elevated above 700mb, thus limiting the tornado risk, but if any storms do become rooted within the boundary layer, then there would be the risk of a tornado developing.

 

There exists some uncertainty with developments farther east, namely across SE England and the Channel Isles. Capping may be too strong or upper forcing not strong enough to generate storms here (as per consistent signals in EURO4/UKV/ECMWF) while GFS is more keen to develop storms over northern France and run them northwards into CS/SE England. Given these uncertainties have opted to go for the general consensus for now (hence reducing probabilities towards the SE, the MDT placed where best agreement exists amongst most models) but cater for the risk of large hail and heavy rain (given PWAT 35-40mm) as the primary threats with any strong storms that may develop in central and southern Britain. In either case, mass ascent will see storms become more numerous as instability axis moves north, merging into an area of thundery rain and eventually losing most lightning activity during the early hours of Saturday as instability weakens and clears eastwards to the North Sea."

 

http://www.convectiveweather.co.uk/forecast.php?date=2015-07-03

[William Grimsley]

Has anybody seen what looks like long lines of Ac Cas going from N to S as far SW as the Scilly Isles? It could be more unstable to the west looking at this picture.

 

[Methuselah]

So when is it expected to kick off, guys? Around 9-10pm? 

 

Nyet...Around Lincolnshire!

[Nouska]

Chances for IOW anyone?

 

According tothe12Z HiRLAM, you would be the first port of call.

 

 

http://www.weeronline.nl/vakman-index/130/0

[Petorious]

Clouds appearing now, going very hazy and the humidity has shot up. Today feels so much more ripe than Wednesday for storms here. and I think Northamptonshire could be a prime location as well, fingers crossed minus the large hail (love my car, dont want dents!!!)

[Snowshine]

This is the latest UKMO projects...first snapshot, 2200, second short, 0100.....LOL!!!! 

 

Untitled.png

 

That's explosive development

That sure would be good if it were to be the outcome.

 

This warning seems pretty accurate - although I would extend the severe risk (within the black line) further North.

[Paul]

For those who maybe didn't see it earlier, Nick has issued a convective forecast:

 

http://www.netweather.tv/index.cgi?action=convective;sess=

 

[Methuselah]

For those who maybe didn't see it earlier, Nick has issued a convective forecast:

 

http://www.netweather.tv/index.cgi?action=convective;sess=

 

convmap0307.png

I like that!           

[Supacell]

Has anybody seen the latest BBC forecast with Nick Miller - it looks rather tasty around Lincolnshire. New BBC graphics in line with Euro4.

[Chris.R]

Not sure how long it been available for iOS but quite recently I downloaded the app called Blitzortunglive onto my iPhone and that does use live data, you can set a radius around a point by pressing and holding the map for a second, and it sends push notifications/alerts when lightning occurs. It also has a countdown till the next thunder, but don't have experience with it yet

thank you so much :-) don't know why I couldn't find it before, sounds just what I was looking for. Might keep the first one as well to see which is more accurate, though if they are using the same data then obviously you would think they would be the same.

[AWD]

It looks to me more and more that various model data is coming together to suggest Hampshire could kick start things tonight.

Whether they are correct or not is another matter but until developments hit the radar, this is all we have to go with.

Well that, barking dogs and cows lying down in fields!!

[gottolovethisweather]

For those who maybe didn't see it earlier, Nick has issued a convective forecast:

 

http://www.netweather.tv/index.cgi?action=convective;sess=

 

convmap0307.png

 

What do the hashed lines in the black area represent, Paul?

[Gordon Webb]

Convective Weather seem to have hit the nail on the head in my opinion.

 

"... ENGLAND AND WALES ...

 

Rapid warm air advection will develop across southern Britain through the evening hours, causing surface dewpoints to increase as a warm front lifts northwards. Meanwhile, the Atlantic upper trough will pivot NEwards, overlapping with the arrival of this plume during the evening, and providing sufficient lift. Consequently, expect thunderstorms to develop through the evening hours, initially fairly well-scattered across SW England, with activity expanding farther N and E as the evening progresses.

 

With the approaching trough, DLS will strengthen with favourably-backed surface winds. This combined with 800-1,200 Jkg^-1 MLCAPE suggests the potential for storms to become organised, perhaps into supercells capable of producing large hail. Forecast profiles suggest most storms will be elevated above 700mb, thus limiting the tornado risk, but if any storms do become rooted within the boundary layer, then there would be the risk of a tornado developing.

 

There exists some uncertainty with developments farther east, namely across SE England and the Channel Isles. Capping may be too strong or upper forcing not strong enough to generate storms here (as per consistent signals in EURO4/UKV/ECMWF) while GFS is more keen to develop storms over northern France and run them northwards into CS/SE England. Given these uncertainties have opted to go for the general consensus for now (hence reducing probabilities towards the SE, the MDT placed where best agreement exists amongst most models) but cater for the risk of large hail and heavy rain (given PWAT 35-40mm) as the primary threats with any strong storms that may develop in central and southern Britain. In either case, mass ascent will see storms become more numerous as instability axis moves north, merging into an area of thundery rain and eventually losing most lightning activity during the early hours of Saturday as instability weakens and clears eastwards to the North Sea."

 

http://www.convectiveweather.co.uk/forecast.php?date=2015-07-03

 

is that an upgrade or downgrade of the potential weather

 

edit - i mean the thunder activity

Edited July 3, 2015 by Gordon Webb

[Paul]

What do the hashed lines in the black area represent, Paul?

 

Have a read of the forecast Tony, it's all in there

[Snowshine]

What do the hashed lines in the black area represent, Paul?

I'm pretty sure that signifies a marginal tornado risk.

[Jan]

Need a catch up, I am down in Shrewsbury for a few days, am I right in thinking the storm potential

is greater here than in Liverpool

[elfinpunk]

Just had to grab my DSLR for this as I needed the zoom, some very odd lines in the clouds as they pass, never seen this before. Any ideas? (Undulatus cloud still passing).

Edited July 3, 2015 by elfinpunk

[mhielte]

My current plan is to stay put as I look to be well placed for the main band moving from the southwest later. However, because anything that breaks out further east will likely have a higher chance of being severe I am all set to drive east using the A52 from Derby should this happen. I am aware of the potential for something to develop around Hampshire and move NE towards Lincolnshire.... this would have to cross the A52 to make this track.

 

That is my plan for now, could be different by 6pm

Yes, I'm broadly looking at the situation the same as you I'm staying put now in Sheffield this evening, but I have somewhere around Grantham in mind should the severe stuff kick off further east. I'm looking at quiet b-roads near Grantham to put in my satnav just n case!

[gottolovethisweather]

Have a read of the forecast Tony, it's all in there

 

I have now but still unclear about it, I guess it represents the highest are of storm risk, if not, I'm blaming the heat in this room I'm sat in. 

 

That aside, Thanks to Nick F for producing the goods for all us storm nuts once again. Top man! 

Edited July 3, 2015 by gottolovethisweather

[A.J]

It looks to me more and more that various model data is coming together to suggest Hampshire could kick start things tonight.

Whether they are correct or not is another matter but until developments hit the radar, this is all we have to go with.

Well that, barking dogs and cows lying down in fields!!

not forgetting seaweed     .......

 

for me personally, the models are pretty much out of the window now, just a rough guide.....radar/sky watching is the key

 

current conditions here in Lyneham are 25C, a moderate SW breeze, a slow increase in humidity, with patchy Ac & Ac Cas streaming up from the south/south west

Edited July 3, 2015 by ajpoolshark

[Chris.R]

Need a catch up, I am down in Shrewsbury for a few days, am I right in thinking the storm potential

is greater here than in Liverpool

Think you will do really well down there but think I'm going to do well here as well. No local reports from around here now Edited July 3, 2015 by Chris R

[Nick L]

I have now but still unclear about it, I guess it represents the highest are of storm risk, if not, I'm blaming the heat in this room I'm sat in. 

 

That aside, Thanks to Nick F for producing the goods for all us storm nuts once again. Top man! 

 

It's hidden deep in the text, but it highlights the higher tornado threat.

 

I think this should be added to the key in future, Paul/Nick?

[Wet'n'Dry]

is that an upgrade or downgrade of the potential weather

 

edit - i mean the thunder activity

 

It's a bit of both Gordon, at this moment it's unsure what will happen. Thunder/Lightning potential and energy is strong to the East but the trigger is lacking at the moment. Further to the West and stretching up through the midlands it's a good mixture of ingredients but any storms are likely to not be severe and fairly scattered but frequent.

[gottolovethisweather]

not forgetting seaweed     .......

 

for me personally, the models are pretty much out of the window now, just a rough guide.....radar/sky watching is the key

 

current conditions here in Lyneham are 25C, a moderate SW breeze, a slow increase in humidity, with patchy Ac & Ac Cas streaming up from the south/south west

 

And a bit of this for the poolsharks/storm lovers in here I reckon.

 

 

*Who is Lady Luck going to deliver the goods to tonight, I wonder*

Edited July 3, 2015 by gottolovethisweather

[Paul]

It's hidden deep in the text, but it highlights the higher tornado threat.

 

I think this should be added to the key in future, Paul/Nick?

 

I think it's just something Nick's done today as a sort of one-off, as with the uncertainty he didn't want to put a mod risk in there. If he keeps using it though we can definitely add it to the key.