Convective/Storm Discussion Thread 25/5/16 onwards

[William Grimsley]

2 hours ago, weather09 said:

Bit of an odd outlook this weekend with wave frontal boundary currently over UK oscillating east and west, before warm front pushes back to the west of the UK Saturday, introducing moister air mass at the surface. At the moment, looks like an increasing possibility of heavy showers/thunderstorms for some parts during the period as winds become lighter and veer to E/SE, resulting in warmer temps and moisture building inland within warm sector which generates decent instability, as per recent model outputs. 

Stagnant flow aloft with weak ridge precludes organised/severe convective weather, however. Though moist air mass and slack profile, and therefore slow storm motion, would pose a risk of high spot rainfall rates.  Bit far out so considerable changes ahead, but something to look at I guess.

Sounds interesting, would you say it would (looking at current model outputs) be appropriate to thunderstorm chase this weekend? I'm going to try my best to get into some thunderstorms so I can get both my thunderstorm fix and everyone else finally get the relief that I'm not hoping for thunderstorms all the time! XD

[weather09]

Hard to say.  Instability is being modeled, given the expected warming and moistening of surface profile, but that and the coverage of storms is questionable at this stage.  Though I think the decision of whether to chase is probably best made the day before, or even on the day of interest, as you'll have a better idea of likelihood of storms occurring, and when and where they're likely to occur. Doesn't look overly inspiring, but if current outputs hold to weekend, would say it's worth getting out and trying to catch something. 

3 days out, though, which is a long time in convective outlook terms. 

 

[William Grimsley]

Yes, exactly. On current terms, if what the GFS shows now materialises then I'd be go go go! Oh, and this time I'd be staying out till the evening and not "throwing in the towel"!

[Flash bang flash bang etc]

The OHs off to Poland with work at the weekend so I'll be game for a chase on Sunday provided that the conditions are right.

I always leave the final decision down to the conditions that day - my van's good with fuel but if I don't get to see any storms it's still a waste of money.

Chasing is all about weighing up the benefits. Two weeks ago it was well worth the 4 hour round trip to Dover - but I did that prepared to sleep in the van - would never have considered it otherwise, too far for one day!

In the end well worth it to see a good MCS - just a shame my home town can't provide more light shows like that... :-/

[Hodgheg]

Looking good for next week, happens i'm going to be on a boat in Norfolk too. Hopefully something materialises and i can get some good photographs.

[Martin Auld]

I know this isn't storm related but could somebody tell me what type of cloud this is  I'm guessing it's Altocumulus Lenticularis because there are a few elsewhere in the sky just now but I'm not too sure about this one 

[stainesbloke]

14 hours ago, William Grimsley said:

Yes, exactly. On current terms, if what the GFS shows now materialises then I'd be go go go! Oh, and this time I'd be staying out till the evening and not "throwing in the towel"!

Just a reminder that GFS is notorious for over-egging dew points. High teens being shown for the weekend which I'd say will be exaggerated by a good 3-5C as usual, quite an effect on the actual weather we get. 

[William Grimsley]

2 hours ago, stainesbloke said:

Just a reminder that GFS is notorious for over-egging dew points. High teens being shown for the weekend which I'd say will be exaggerated by a good 3-5C as usual, quite an effect on the actual weather we get. 

Not looking at Dew Points! Looking at the amount of precipitation shown inland on those two days...

[weather09]

Not wise to look at precipitation charts on a global model, especially when we're discussing about potential mesoscale events (i.e thunderstorms). Even purpose-built mesoscale and hi-res. models can struggle to resolve thunderstorm development.  

Think the point Staines was making, though, was that if the GFS is overstating surface dewpoints (which it often does), and looking at the setup at first glance it likely is, this in turn affects how much instability there'll actually be- moisture being contributor to CAPE. Saying that, even if the DPs were a few degrees lower than is being modeled for the weekend, would still be a risk of storms.  Things as they stand, likely to be a build of substantial instability inland with light winds and strong insolation this weekend, though the detail always best left to a day ahead or day in question.  

Edited June 2, 2016 by weather09

[William Grimsley]

Sounds good to me, hopefully we'll have the same setup as recent times with more thunderstorms so I can at least get into one.

[Mapantz]

This would be nice, wouldn't it?

[William Grimsley]

11 minutes ago, Mapantz said:

This would be nice, wouldn't it?

To be quite honest, you've had your thunderstorms this year. LOL.

[matty40s]

6 hours ago, Martin Auld said:

I know this isn't storm related but could somebody tell me what type of cloud this is  I'm guessing it's Altocumulus Lenticularis because there are a few elsewhere in the sky just now but I'm not too sure about this one 

never mind the blimmin cloud, that's blue sky you got there, not seen any since Sunday here......my solar panels have gone on strike!!

[Martin Auld]

1 hour ago, matty40s said:

never mind the blimmin cloud, that's blue sky you got there, not seen any since Sunday here......my solar panels have gone on strike!!

We've barely had a cloud in the sky for three days now. Hope you get some sun soon, get those solar panels working again

[William Grimsley]

Prime locations on Sunday and Monday looking like Somerset eastward so may have to make sure I have some more fuel in the tank! Oh, and more time at that! Will probably be heading up the A303 again but possibly further into Somerset this time, again as weather09 has mentioned, details could change and it's too early to try and pin down where and when areas may be affected.

[Flash bang flash bang etc]

55 minutes ago, William Grimsley said:

Prime locations on Sunday and Monday looking like Somerset eastward so may have to make sure I have some more fuel in the tank! Oh, and more time at that! Will probably be heading up the A303 again but possibly further into Somerset this time, again as weather09 has mentioned, details could change and it's too early to try and pin down where and when areas may be affected.

I think your putting your money on a horse that hasn't even arrived at the track yet... ;-)

[William Grimsley]

Fair play, the most recent GFS run does look good, Sunday sees surface based thunderstorms develop just inland but also widely across Devon and Somerset, but what has caught my attention is elevated thunderstorms developing in the morning on Monday before reaching the coast by late morning before expanding to cover a bigger area inland as surface based convection takes over, something to watch. Also, there's the potential of a severe thundery breakdown as we head through Friday as low pressure moves in from the west triggering off both elevated and surface based thunderstorms widely across western England.

Edited June 3, 2016 by William Grimsley

[A.J]

not seeing any elevated thunderstorms on Monday morning going by the overnight model runs...just surface based showers developing from late morning onwards for central southern England developing inland and along local areas of wind convergence

As an aside, FAX output doesn't show logical progression from T72-84....A messy 'dogs dinner' of weather fronts and troughs circulating around LP in the mid atlantic, a much cleaner pattern at T84 and then back to a complete mess again at T96.....Me thinks forecasting for next week is going to be a headache at this time, and won't become much clearer until T0

[William Grimsley]

3 minutes ago, ajpoolshark said:

not seeing any elevated thunderstorms on Monday morning going by the overnight model runs...

GFS shows them breaking out in the English Channel early on Monday morning.

[A.J]

3 minutes ago, William Grimsley said:

GFS shows them breaking out in the English Channel early on Monday morning.

no, it just shows some light showers developing near coastal areas, with heavier showers developing further inland...Having looked at the parameters, I think you're taking the ppn charts too literally.....From experience, I've learned that even taking the gfs ppn charts at T24 is to take them with a pinch of salt......at T72, a pointless exercise 

Edited June 3, 2016 by ajpoolshark

[William Grimsley]

Doesn't look very light to me, but fair play.

[NO LONGER POSTING]

6 minutes ago, ajpoolshark said:

no, it just shows some light showers developing near coastal areas, with heavier showers developing further inland...Having looked at the parameters, I think you're taking the ppn charts too literally.....From experience, I've learned that even taking the gfs ppn charts at T24 is to take them with a pinch of salt......at T72, a pointless exercise 

Agreed, GFS precipitation charts are useless to look at when wanting to get a clearer picture of what may happen.

Wait for the high res and wait again, even then 99% of the time when it comes to thunderstorms they are wrong.

Weekend and early next week looks okay for something certainly the further East you are tomorrow Sunday more western and central 

Before prehaps Monday and Tuesday bring something for southern areas 

Edited June 3, 2016 by Surrey

[William Grimsley]

1 minute ago, Surrey said:

Agreed, GFS precipitation charts are useless to look at when wanting to get a clearer picture of what may happen.

Wait for the high res and wait again, even then 99% of the time when it comes to thunderstorms they are wrong.

Weekend and early next week looks okay for something certainly the further East you are 

Partly agree, partly don't, especially your last comment. I would really not say potential is location dependant in the upcoming week, West looks as best as East. If all models were wrong, then what's the point of discussing it, there is point because they're not always wrong. Anyway, all the thunderstorms over the weekend look like being Central and SW areas not Eastern areas.

[NO LONGER POSTING]

Just now, William Grimsley said:

Partly agree, partly don't, especially your last comment. I would really not say potential is location dependant in the upcoming week, West looks as best as East. If all models were wrong, then what's the point of discussing it, there is point because they're not always wrong. Anyway, all the thunderstorms over the weekend look like being Central and SW areas not Eastern areas.

Oh okay, take the below with caution subject to change massively it has been over the last few runs 

Saturday: East 

Sunday: West 

Monday: central southern 

Tuesday: East 

 

Rember these charts don't mean storms will happen, just one of many ingredients required although one of the most important is getting the energy there. 

 

[Harry]

I think this is a classic case of seeing pretty colours and equating it with stormageddon. El Brumo was a classic example in 2012, where many will recall some areas experienced widespread severe thunderstorms, while others (such as my corner of the world) baked and sweated in 33C heat, high dew points, crystal clear skies and watched over 3000/-10 CAPE/LI pfffft into nothing. 

It should be noted that despite widespread instability next week, the continent appears to remain under fairly High pressure which will suppress the risk of imported thunderstorms. Our opportunities at this stage appear to be from occasional trough features, CZs and good old fashioned surface heating - the problem with this is storms could well be isolated and even less predictable than with classic plume breakdowns. Furthermore and has already been mentioned, fronts associated with the low in the Atlantic could throw a lot of cloud up, particularly across more SW/W portions which could further limit storm risk.

I'm excited for next week as it is always nice to have some heat, humidity and a risk of a storm popping up at any time - but it is equally likely to be one of those periods where for the majority, instability will remain unrealised and a failure to manage excitement/expectations resulting in disappointment. 

Edited June 3, 2016 by Harry