Storm risk - Monday 9th May onwards

[Hector the Convector]

I've never tried to upload any weather pics before (so hopefully this works) but here's a video screen shot of the Southampton storm at roughly 6.30pm. The view is from Eastleigh Swan Center car park and i believe the lightning is striking somewhere near to West Quay shopping center.

[TropicThunder]

38 minutes ago, Hector the Convector said:

I've never tried to upload any weather pics before (so hopefully this works) but here's a video screen shot of the Southampton storm at roughly 6.30pm. The view is from Eastleigh Swan Center car park and i believe the lightning is striking somewhere near to West Quay shopping center.

I live just a few minutes from West Quay and we didn't have any lightning overhead, it was all slightly to the west and south of here but still a good show. Nice pic btw!

[Costa Del Fal]

4 hours ago, Gordon Webb said:

technically that's after rain not specific to thunder only

petrichor

Pronunciation: /ˈpɛtrʌɪkɔː/

noun

A pleasant smell that frequently accompanies the first rain after a long period of warm, dry weather or other than the petrichor emanating from the rapidly drying grass, there was not a trace of evidence that it had rained at all

of course I'm just nitpicking so feel free to ignore

Absolutely correct Gordon. Sadly didn't have time to offer an explanation similar to yours earlier.

Think people often associate the smell with thunder as because often petrichor is smelt following warm dry, weather, those first rains can often be accompanied by thunder in the breakdown.

[Sparkiee storm]

I know its still quite a while away, but thought i'd post this potential for the bank holiday.

[Allseasons-Si]

4 hours ago, East_England_Stormchaser91 said:

Just caught this beauty!! 

Nice shots there EES,i bet you was buzzing when you saw that,i know i was when i spotted one a few weeks ago on the boarders of Scotland,altough yours is more defined than what i saw,but still a nice spectical to see

 

[East_England_Stormchaser91]

2 hours ago, Allseasons-si said:

Nice shots there EES,i bet you was buzzing when you saw that,i know i was when i spotted one a few weeks ago on the boarders of Scotland,altough yours is more defined than what i saw,but still a nice spectical to see

 

Was almost stunned to see it right there in front of me as soon as I got upstairs! Having been keeping my eye on dark clouds the other side of the house, it was kind of lucky that I went to look the other side! Sure is a brilliant sight to see, so long as it doesn't hit your house haha. 

They are more common in this part of the country than some might think however. Sleaford back in 2012, Peterborough on 28th July 2005 which also hit moulton in Lincolnshire 30 mins later, tearing the church roof off. Long Sutton, Lincolnshire on the 21st June 2012 too! Plus many more as well. Must be the flat topography round here that has a similar effect to the Midwest I assume. 

[William Grimsley]

Just wondering, when's the next plume coming? To me it looks like next week but can't see a massive amount of elevated thunderstorms with it.

[Harry]

With each GFS run, the glancing blow of a spanish plume for the far SE is looking more likely Saturday evening/overnight, the western extent of the plume readily de-stabilising across N/NW France and tracking NE. 

As ever with these setups it is very easy for it all to nudge east enough to miss our shores, or indeed 'clip Kent'. 

Interesting all the same and very much keeping an eye on it - noting that 00z yesterday kept all potential over the continent, while 00z today has nudged it westwards in line with other runs. Also, Tomasz Schafernaker's forecast last night had a line of deep blues and greens running towards London and the Home Counties, but (due to obvious uncertainty) he did not direct much attention to it at this stage.

Edited May 19, 2016 by Harry

[Bolt from the Blue]

19 minutes ago, William Grimsley said:

Just wondering, when's the next plume coming? To me it looks like next week but can't see a massive amount of elevated thunderstorms with it.

Bank Holiday weekend looks good with max temps in the 20s and a low positioned out in the Atlantic just to the SW of the British Isles. Still a fair way to go yet though

[weather09]

Yes, Harry, noticed GFS putting a more northerly steer on the advection of low-level moisture and instability toward far SE quarter ahead of the cold front.  ECM and UKM, however, keeping main region of instability and storms to the continent, however even they would suggest risk of torrential rain and potential for storms with passage of cold front.  

[NUT]

Looks like again it's sparking off in ireland

[Stuart]

Day 2 Convective Outlook

VALID 06:00 UTC Fri 20 May 2016 - 05:59 UTC Sat 21 May 2016

ISSUED 19:36 UTC Thu 19 May 2016

ISSUED BY: Chris

A post-cold frontal environment will provide modest cold air aloft and along with surface heating could generate a few isolated to scattered heavy showers during the afternoon on Friday. CAPE values are small and lapse rates are marginal so the risk of lightning remains in the 5-10% region across this area. 

 

http://www.convective.weatherquest.co.uk/forecast.php?date=2016-05-20

[knocker]

I digress with a touch of whimsy

 

[Greeny]

Chris and EES can I post the pics to share in my FB group please?

William, shame the action was further east to your location yesterday. The potential was there but throughout the day the instability was shifting eastwards and by the time the diurnal heating had built up enough energy it had passed your area. Shame about that buddy. The best part was pretty isolated anyway. A lot of people would have missed out.

Chris, when you take an interest in storms and go chase or watch out for certain features you tend to see more than just watching storms as they pass by. I have found this to be true since I started chasing.

Edit if you are very lucky you get those rareties surprise you at your doorstep. Dont count on it though

Edited May 19, 2016 by Greenday

[Chris.R]

 Torrential rain. Nice. 

[Supacell]

BBC mentioning the possibility of some thundery showers breaking out late on in the south east tomorrow evening. This would tie in with the NMM charts from the Netweather Extra suite which appears to indicate an area of CAPE moving from France into the SE of England. However, the GFS which was showing this same set up earlier in the week has appeared to move away from this scenario, instead showing a narrow miss as storms remain over the other side of the Channel. NMM on the left and GFS on the right, both showing MLCAPE for 9pm tomorrow evening:

    

The Euro4, which I have found to be quite accurate so far this year, shows what looks like a Kent clipper. So, for those who live in the SE, possibly another one of those watching the radar and willing the storms across from France scenarios. Clearly a few more runs between now and then so plenty of opportunity for the models to fall into line and sing from the same hymn sheet (hopefully the NMM hymn sheet).

For the greater proportion of the population (and myself) I am currently looking at Sunday with quite widespread CAPE being shown by the GFS. With a forecast of sunshine and showers I would expect some of these showers to grow into thunderstorms, but with the current uncertainties I wouldn't be placing my bets quite yet.

 

[Harry]

Indeed, GFS steering away and in my experience GFS tends to have a fair to decent handle on these setups. NMM 5 this morning, which I also consider a fairly accurate model, also on an eastward shunt.

Therefore I'm reducing any expectations to negligible, based on previous experience.

What has happened on many occasions previously however is that cold fronts progress more slowly than expected. What we appear to be talking about is down to mere hours; if the CF stalls, it will enable greater instability to advect northwards, however if it passes as currently modelled, I think its a no go. 

On the plus side, GFS (at least) is continuing to favour some thunderstorm potential as we head through next week and near the bank holiday weekend. While I usually wouldn't entertain something so far out (on any level), I am surprised by the consistency in the model projections even at this range...7-10 days out is not unusual to flitter between 3000 CAPE/-9 LI to 0 CAPE/+14 LI from run to run. 

Will be interesting to see how it plays out.

Edited May 20, 2016 by Harry

[IMP757]

Based on the charts I might just be in the sweet spot on Sunday, won't hold my breath though, a lot can happen between now and then!

[East_England_Stormchaser91]

20 hours ago, Greenday said:

Chris and EES can I post the pics to share in my FB group please?

William, shame the action was further east to your location yesterday. The potential was there but throughout the day the instability was shifting eastwards and by the time the diurnal heating had built up enough energy it had passed your area. Shame about that buddy. The best part was pretty isolated anyway. A lot of people would have missed out.

Chris, when you take an interest in storms and go chase or watch out for certain features you tend to see more than just watching storms as they pass by. I have found this to be true since I started chasing.

Edit if you are very lucky you get those rareties surprise you at your doorstep. Dont count on it though

Yes mate feel free to  

sunday looking quite interesting to me at the moment. Will be keeping an eye on the runs as we get nearer. 

[weather09]

Yes, Sunday looking decent for showers and general thunderstorms in post-cold front environment .  Likely some good hailers given steep mid-levels (cold air at 500mb) and strong heating of a reasonably moist boundary layer, which looks to generate several 100J/kg CAPE (per recent outputs) during afternoon. Nothing significant anticipated as winds fall light throughout much of the profile, so weak shear overall, though winds do increase somewhat past 500mb and left-exit jet streak at 300mb still residing over eastern parts, so better forcing aloft over here, with perhaps potential for modest winds at that level to take advantage of more potent updrafts.  Shortwaves in cold air aloft likely focus for showers and storms.  

Tomorrow late afternoon and into evening sees severe convective risk for northern and western half of France where height falls with approaching upper trough, pre-front shortwave and cold front destabilise a potentially moderate CAPE environment (MLCAPE 1000-1500J/kg, per GFS)- sfc dewpoints mid-upper teens. Strong SW'erly mid-level winds with mid-upper level jet resulting in deep layer shear (albeit rather unidirectional) on the order of 50kts suggest initial discrete supercell storm mode after 17z, quickly becoming MCS as you head deeper into evening hours with passage of cold front.

Meso. models generally breaking out storms around 17/18z as forcing aloft arrives, with a short window for those severe sfc based storms, before becoming MCS dominant. Sfc parameters don't appear to overly favour tornado potential- modest 0-3km SRH up to 150m/s, flow not increasing too much at low level, and sfc winds could be a little more backed. Main risks would therefore appear to be large hail and severe convective winds.  

Edited May 20, 2016 by weather09

[Harry]

Let's hope Weather09 the CF decides to slow itself allowing some albeit brief advection across this part of the world...look extremely unlikely though sadly. Roll on Sunday albeit Midlands/EA/Lincs probably favoured spots, with reasonable risk across many other areas.

[Supacell]

I predict an eastern Kent clipper tomorrow evening/night. We will know better in the morning when we can compare the position of the cold front to forecasts and ascertain if it is moving slower, faster or the same as predicted. If it can slow down it may allow for some quite potent storms or an MCS to move north from France and affect more of the SE. 

For my part of the country, and for the vast majority, it is Sunday which is the day of interest this weekend. However, our local forecaster says it will be mostly dry bar an odd heavy shower. BBC graphics do show it being mostly dry over the central slice of the country, but the GFS does not agree with this as it shows numerous showers developing and lasting well into the evening too. I will await the Euro4 in the morning as currently can only see to 12z on Sunday.

[Mapantz]

1 hour ago, Supacell said:

I predict an eastern Kent clipper tomorrow evening/night. We will know better in the morning when we can compare the position of the cold front to forecasts and ascertain if it is moving slower, faster or the same as predicted. If it can slow down it may allow for some quite potent storms or an MCS to move north from France and affect more of the SE. 

For my part of the country, and for the vast majority, it is Sunday which is the day of interest this weekend. However, our local forecaster says it will be mostly dry bar an odd heavy shower. BBC graphics do show it being mostly dry over the central slice of the country, but the GFS does not agree with this as it shows numerous showers developing and lasting well into the evening too. I will await the Euro4 in the morning as currently can only see to 12z on Sunday.

Interesting that.. I was looking at that a few days ago, although it was further East in to the near continent. I've been busy lately, so I haven't checked (until tonight) and it has certainly shifted West since then. Those dewpoints look quite good!

 

[Supacell]

Day 1 Convective Outlook

VALID 06:00 UTC Sat 21 May 2016 - 05:59 UTC Sun 22 May 2016

ISSUED 09:28 UTC Sat 21 May 2016

ISSUED BY: Chris

Scattered showers are likely to turn heavy and thundery across Ireland and into parts of Britain during the afternoon on Saturday. Cold air aloft and afternoon surface heating will allow Surface to 500mph lapse rates to reaching into the lower 40s across Ireland, where the most frequent and widespread lightning is likely to occur during the afternoon. Lapse rates are less across Britain, but CAPE values of 300-500j/kg could allow for a few showers to turn thundery there in the afternoon. 

Saturday evening and overnight a plume of unstable air will move out of France pushing an area of showers and thunderstorms northeastwards. There is still a lot of uncertainty about the track of these storms, and it appears most of them will stay offshore, however it is close enough to include a risk. It should be noted that if these storms do move across Kent and up the east coast of East Anglia they would likely require an upgrade to SLGT as they could be quite electrically active. The situation will be monitored later this afternoon and through the early evening. 

http://www.convectiveweather.co.uk/

----------------------------------

A very close call this evening and into the night across the far SE and the east coast of EA, as per the forecast from Chris at Convective Weather above. As is usual in these situations it is going to come right down to the wire with the radar probably coming in very useful as we go into the evening. It is worth noting that most forecasts I have seen show this as being a close but no cigar situation but the very slightest westward shift from what is forecast would put the very southeast of the UK into the game. If it does miss then those on the SE coast of Kent and the east coast of EA could well still see the distant flashes. 

[William Grimsley]

Not sure if I'm being optimistic here, but Sunday looks pretty decent for my area due to widespread torrential downpours and thunderstorms breaking out especially inland. Does anyone follow?