Convective / Storm Discussion - 28th July onwards 2013

[J10]

 

Apologies JL, just wanted to clarify a few things from yesterday as I didn't get the opportunity to last night...

 

 

I agree with those posters that say certain organisations were ramping up the thunderstorm potential in terms of it's coverage - it never (to me at least) looked like it would be a widespread affair, only isolated embedded cells with any significant thunderstorm potential being in the far southeast. That seemed to be the case back on Thursday, and remained so right up to the point. So I can understand that frustration to a certain point, but I did try and state many times in the past couple of days that some folk were going to be disappointed if they kept ramping this event up! 

 

In discussion with fellow colleague Ian Fergusson, it was clear that although the Met Office expected locally large rainfall totals, some of the high-res modelling actually left parts of the country very dry with little rainfall forecast for Saturday. This was most notably north of London in their modelling at the time, although given the complexity of the situation it was virtually impossible in advance to say 'yes these areas will hardly see any rain', but to that degree it's not surprising to see some places see very little in the way of rainfall. I sat at Dungeness for about 8 hours yesterday afternoon waiting for the storms to cross the Channel, and we had some pretty heavy rain for a time there with a lot of surface water collecting on roads etc.

 

With regards to the temperature forecasting for yesterday, naturally the NAE (which drives the BBC/Met Office graphics) had a lot of cloud and mid-level showers throughout much of the day for yesterday, before the heavier rain arrived during the afternoon. The combination of a general lack of these earlier showers and the later arrival of the rain meant much more sunshine across southern Britain than was forecast for the previous days, so it's only natural the temperatures were much higher than expected. Not necessarily an error with modelling the temperature, just the general local weather which in turn has an impact on how high the temperatures can go.

 

In terms of modelling, I feel a combination of UK4 and GFS did reasonably well, although the GFS is limited by it's horizontal resolution somewhat. In particular the CMC (Canadian Global Model) did best overall with consistency and placement in the days running up to this event. 

 

 

Quote from Thursday:

 

 

 

 

 

Next couple of days has always had the better potential for more widespread scattered t-storms.

 

 

Do people use the temp range feature on some days

 

 

As this can show when big temp outcoems are possible.

[Cloud 10]

The NAE got the position of the LP pretty much spot on,just a fraction to deep.

 

 

 

 

Wind gusting over 50 mph on the NE coast at the moment.

[Supacell]

So.... Are you saying Wrexham may actually have a chance of a storm today?? Lol

 

It's always difficult to pick out a specific town but Wrexham certainly within the high risk area. Wrexham would have a better chance today than yesterday or from the plume event early last week

[Chris.R]

Well the met office text forecast for NW england doesn't meantion thunder today and it is confusing, where as the liverpool airport TAF is bullish for thunderstorm rain with a 40% prob untill 06Z tomorrow, starting now. Interesting.

[ZONE 51]

My subscription for NW Extra ran out yesterday and I'm too disillusioned to renew it. So of course we will have storms today!

 

Seriously though, can't see much happening round here today. Started off with the usual Cheshire mid-level white/grey murk that we've come to know and hate. Feeling cool too, much cooler than yesterday.

Have you seen the next 5-7 days potential!

 

Lots of thundery showers/storms even could have evening thunderstorms for many areas today and Monday.

 

Thursday heat plume could return with some home-grown and imported thunderstorms/MCS.

Edited July 28, 2013 by ElectricSnowStorm

[IanR]

I think it would be so ironic if today I am too far EAST  

would not surprise me

[Summer Sun]

The rain is now leaving Darlo brighter sky is on the horizon no thunder here in Darlo overnight the wind picked up whilst it was moving through but thats died down now

[SarahWxm]

It's always difficult to pick out a specific town but Wrexham certainly within the high risk area. Wrexham would have a better chance today than yesterday or from the plume event early last week

I suppose that's something then lol. I'm gonna hope for the best, expect the worst as every time I've been confident something will happen, nothing has (well unless you class 1 bang of thunder as something happening lol)

[Summer Sun]

Amber warnings are still in force for

 

East Midlands, North East England, North West England, West Midlands, Yorkshire & Humber

 

Until 12:00pm

Edited July 28, 2013 by Summer Sun

[Methuselah]

I suppose that's something then lol. I'm gonna hope for the best, expect the worst as every time I've been confident something will happen, nothing has (well unless you class 1 bang of thunder as something happening lol)

Well Sarah, that's one more than we had over here...

[Backtrack]

Looking good for some electrical showers kicking off today

[staplehurst]

Fair enough, can we all agree and say that the NAE has had a complete shocker this week. If weather and temperature graphics are worked out by this model then its issues extend beyond yesterdays stormgate, for example predicted maximum temperatures for large areas of England were as much as 5-6 degrees lower than what those areas actually got.

Agreed, it hasn't done that well in recent weeks sadly. The BBC use what is called 'Best Data', which can differ from the NAE quite considerably on some days strangely. Overall the NAE did reasonably well for highlighting where and how high the extreme temperatures would be during the sunny, hot spells (ie consistently getting the highest possible temperature correct and in roughly the right areas Heathrow/Bournemouth etc). It just struggles quite a bit in plume events.

[ItIsGee]

Looking good for some electrical showers kicking off today

 

hopefully!

 

did  a little chase as the storm looked close! peak district killed it!

[Cyclonic]

Just took a walk along seafront from Sandown to Shanklin, lots of nice clouds around, much cooler today then of late with a fresh sea breeze. I shall live in hope of some storms today, even a flash of lightning will do 

Oh!!  Good Morning All

Coffee any1

[Summer Sun]

Its a wet old morning for Scotland this morning the rain is now starting to clear the southern half of NE England

 

The red dot is Darlington

[Moisty]

_{Some people should be thankful for what they had last Tuesday night, those storms completely passed Hampshire by and yesterday amounted to about 3 hours of drizzle, I'm not knocking the MO as I think they generally do a great job but when at 9am on Saturday they forecast rain on the south coast by 11am but it doesn't arrive until 4pm then that's not good, especially when you have events arranged.}

 

_{We cancelled a walk in the New Forest because of the forecast but actually would have been slapping on the sun cream!}

[wimblettben]

Can allready see some clouds building with some dark bases to the southeast of me.

[NUT]

Was having a look at the 8 hour animation on NW extra for my location. Not seen that much green/yellow which we have had for such a long time!

[Darren Bown]

Main difference today is the air is moving around a lot more today compared to the last few days. Feels like a proper British summer low today.

[Jane Louise]

And here's one from UKWW. Again, you'll have to pop along to the site to see the map lol. My comp just won't upload maps.

 

Slight to Moderate Risk of Thundery Showers Ireland and UK 12z-21z

 

Risk of Funnel/ Low Level Mesocyclones at Cloud Base Central South England

 

Stationary low remains west of Ireland maintaining unstable polar maritime flow across UK and Ireland through today. Moderate upper trough continues to increase upper lift and lapse rates for the whole region. Mid to low level jet axis expected to develop central south England later in the day where some isolated thunderstorms could well develop.

 

Today in general will see a much more solid risk of storms based within the boundary layer as better surface moisture is advected north from Biscay. Both GFS and WRF are pushing for high CAPE values over Ireland and Wales/ Midlands for around 1200 j/kg. We can therefore expect to see some very lively sferic activity for a time today. Though for most parts within a weakly sheared, saturated upper environment and only weak convergence we might expect some limit to organisation. Ironically my focus today looks to be much further south where the CAPE's are transient and much less than the aforesaid regions. It is expected that Dorset and Hampshire could well develop one or two isolated storm cells today with the added risk of a brief funnel or two but most certainly some visible rotation within the updraft region. This calculation for possible events is bought about by a combination of potential conditions;

Relatively weak northery flow at surface is turned 45deg and increased to around 27 kts at 900mb. So when I say 900mb the attention is on how abrupt this low level shear component is developed. In fact the region shows a good surface moist flow from the English Channel and strong potential instability from 600mb upwards. Vertical velocities reach 300mb where a further upper jet is showing around 60kts. In short if updrafts are sustain through a continual feed of moisture then tall updraft columns might be achieved with a risk of isolated hail. The only caution withis this region is the level and strength of the cap!

 

Personal note; If the 12z update remains conducive are there any members willing to chase Hants Dorset later this afternoon. Prob start a separate thread to discuss this. Please do not post back here!

 

http://www.ukweatherworld.co.uk/forum/index.php?%2Ftopic%2F98887-convective-outlook-sunday-28th-july-2013%2Fpage__pid__867161#entry867161

Edited July 28, 2013 by Jane Louise
Half the post missing lol

[carl1980]

Are the storms over north west France turning north? Are these the showers forecast here for later or will they be home grown ?

[Nick L]

Haven't really looked at much for today, but I have noticed that TORRO have gone into overhype mode as usual...

[Jane Louise]

Good convection here. Just waiting for forecasts from Estofex, Nick F and others to tie in with todays potential .

[poseidon]

In the end the met office forecast for my area was fairy accurate apart from getting the timing out by 2 hours. They said thundery rain and we had that [just]. Once we had the miniscule thunder though it seems that they decided it was necessary to change the forecast to thunder, even though by that time the rain had near enough stopped.

 

Looks like there's already a cell trying to cross the channel towards the SW nr the channel islands.

Edited July 28, 2013 by poseidon

[Jane Louise]

From Ian Fergusson:

 

Impressive convection near S Bristol: showers and storms today for many areas

 

pic.twitter.com/RRM7m2p37t

 

 

https://twitter.com/fergieweather/status/361422821928353794