Model Output Discussion 00z 19/07/13

[Average Joe]

This from Martin Gibbs....a less hysterical approach than some I've read elsewhere, as always!

 

In Summary though a basic slow trend towards something more thundery next week is emerging where it leaves the UK by the end of the week and next weekend is unclear. GFS has ditched it's deeply unsettled phase next weekend with a much more gentle approach this morning while the other output all show a zone of thundery weather moving slowly North later in the week. I am less then convinced that a major thundery outbreak is likely from these type of synoptics as the features moving up from the SW are shallow and ill defined. Yes, I'm sure there will be some nasty storms scattered about next week but 'scattered' is likely to be the key word as I think some places may miss them and stay largely dry and still very warm at least until the weekend when a gentle cooling trend might edge in from off the Atlantic

[Radiating Dendrite]

This matt Hugo character, has just shown that the 3 longer range ensemble models now have low pressure tracking near, on top of the UK for late July / early August.

https://mobile.twitter.com/MattHugo81/status/358145512848908288/photo/1

 

Take that with a large pinch of salt.

 

He just interprets what the models show, which is often more wrong than right. 

[Scorcher]

Yes he's been wrong quite a lot this month already, he expected a breakdown to cooler, unsettled conditions by the start of this week which just hasn't happened. The guy is no wiser than we are as to what will happen in 2 weeks time.

[Man With Beard]

I cannot find one single model, including navgem, gem and bom which shows the Azores high reinserting itself over the UK in FI. They all either have low pressure near us, or on top of the UK. So at this moment, the models all suggest a fresher begining to August and likely beyond (if you see their recent overnight outputs)

I do completely agree with the first sentence. It would take quite a big turn around in the models to push the Azores high back our way with the same vigour as recently. But I interpret the result slightly differently; most seem to take us into a bit of a "no man's land". It's not entirely clear to me just how settled/unsettled the week after next would be. It doesn't look like a typical Atlantic incursion, though - fresher yes, but low-mid 20s I imagine so still not cool

[Jezzer]

Doesn't look quite so bad as certain posts or the tweet from Mat Hugo make it sound assuming this is the same output, not sure if he does tweet positive posts or ones about settled/warmer weather, just only ever see ones like the last one posted in here..

I was thinking exactly the same thing earlier, I've only ever seen him tweet about potential low pressure moving into the UK. Does he have a preference?Anyway, it's fascinating model watching at the moment, twists and turns at every juncture.

[Frank Trough]

Well, as mentioned extensively on here already the "change" now looks inevitable for next week - it's just a matter or timing and also what the actual change will mean in terms of weather on the ground. I think the GFS is still probably touting the worst case scenario and there will be plenty of chopping and changing before the change fully kicks in. However, given the ridiculously great weather we've had for all of july so far it doesn't take much thought to work out that it's likely to be cooler and more unsettled!  

 

in the more reliable (and not that i doubt England's ability with the ball...) i'm wondering if there is any prospect of the final day of the test being disrupted on monday? a bit of rain might be handy.....

 

ECM and to a certain the GFS don't want to know....UKMO sticks out though:

 

 

I think the likelihood is another completely dry test match, isn't it?  

Edited July 19, 2013 by Pharaoh Clutchstraw

[Alexis]

The centre of any low sat to our SW wouldn't exactly usher in cool weather.

[storm1080]

I do completely agree with the first sentence. It would take quite a big turn around in the models to push the Azores high back our way with the same vigour as recently. But I interpret the result slightly differently; most seem to take us into a bit of a "no man's land". It's not entirely clear to me just how settled/unsettled the week after next would be. It doesn't look like a typical Atlantic incursion, though - fresher yes, but low-mid 20s I imagine so still not cool

 

I think I saw on the most recent ECM T96/144 a big ridge from the azores high extend northwards mid atlantic, could that help block/shut northwards the second low thats "due", after this iberian

Edited July 19, 2013 by storm1080

[forecaster]

Indeed. Though it makes it sound like a long period. It is in fact only 29th July - 3rd August.

 

Does anyone know the verification stats of the long range ensembles? What did they say about our current hot spell, for example?

 

The EC monthly forecast runs twice a week. I had a quick look at the 27th June run, which showed a good signal for anomalously high 500hPa heights over the UK for the 3 week period from Day 12 (8th July) onwards and corresponding low precip and high 2m temperature signals. 

[Frosty.]

The Ecm 00z ensemble mean is absolutely superb in my opinion and shows what I consider to be the ultimate uk summer charts which rarely occur, the mean shows intensifying heat & humidity during the first half of next week and I think mid 90's F is likely, possibly high 90's in the south/southeast, with the super heat and rising humidity comes an increasingly thundery week with potent storms being triggered but also a lot of scorching sunshine.

[storm1080]

I think I saw on the most recent ECM T96/144 a big ridge from the azores high extend northwards mid atlantic, could that help block/shut northwards the second low thats "due", after this iberian

 

GFS 6z hits at this ridge T165

[TEITS]

Not sure we'll need to wait until after it, we'll know if and when we are in it, but I take your point.  Also agree there is much to enjoy ahead of any breakdown next week, so I am off to do precisely that....just in case!

Im actually looking forward to next week more than our current weather. The combination of heat and increasing instability is just as exciting to me as a bitter NE,ly in winter.

[Winter1981]

Hi

 

I have been a member for  while, but am a bit of a 'lurker'.

 

A general model related question:

 

When we get a set up like the one forecast for the end of the week i.e. a low moving up from Iberia, would we expect to get frontal rainfall or convective rainfall (or both)?

 

Most 'lows' I know of have a frontal rainfall band.  However, i notice that in summer particularly, pressure is often low often continental Europe and they get convective thunderstorms rather than bands of rain.

 

Clearly, if the low was to move in and there was showers/thunderstorms, some would get them some would not, which is very different from a band of cloud and rain moving in.

 

Can anyone help?

 

Thanks

[shaky]

If anyone thought the 00z gfs was bad breakdown wise then take a look at the 06z cos its ten times worse!!the ridiculous thing is the fact that the 00z was showing temps of 25-27 degrees widely across england and wales for tomorrow but the 06z shows typically 23-24 degrees and only the western areas will see close to 27 degrees!!how can it change that much for tomorrow!!should we bin this run??

[Mark Bayley]

If anyone thought the 00z gfs was bad breakdown wise then take a look at the 06z cos its ten times worse!!the ridiculous thing is the fact that the 00z was showing temps of 25-27 degrees widely across england and wales for tomorrow but the 06z shows typically 23-24 degrees and only the western areas will see close to 27 degrees!!how can it change that much for tomorrow!!should we bin this run??

You are better paying attention to the higher resolution models (e.g. NMM) at that short time-scale. Or better still, now casting. For interest the 6z NMM shows 25-27c quite widely across England and Wales

[shaky]

You are better paying attention to the higher resolution models (e.g. NMM) at that short time-scale. Or better still, now casting. For interest the 6z NMM shows 25-27c quite widely across England and Wales

Blimey thats a big difference then between gfs and nmm!!why does the gfs keep changing for tomorrow??if it cant get the temperatures right for tomorrow and its less than 24 hours away now how can we rely on this model!!

[Man With Beard]

Although there's wide agreement on low pressure parking itself on next week, it's worth mentioning that this is best case scenario for those wishing for a breakdown and small changes could throw this forecast out of the window. These cut-off lows rarely behave themselves - it all depends on how much they deepen - which is often unknown even until T48. By next Thursday, this low could end up anywhere within a few hundred miles of where it is currently forecast - it could yet be further west (allowing more heat to filtrate the UK), it could be further north (staying more settled in the south) or further south (more settled in the north).

 

In fact, judging by past behaviour of such cut-off lows, I think the "staying south" option is extremely viable - if this happened, it's possible that the heatwave could stick around in the north into the last weekend of July.

 

In short, still some way before we can accurately forecast the end of next week, let alone August...

[Mark Bayley]

Blimey thats a big difference then between gfs and nmm!!why does the gfs keep changing for tomorrow??if it cant get the temperatures right for tomorrow and its less than 24 hours away now how can we rely on this model!!

The GFS runs at a lower resolution than the NMM, hence at the short time-scales higher resolution models, often nested within the lower resolution global models, are of better use for forecasting temperatures, frontal band progression etc... 

[samadamsuk]

Hey all.

 

I think Cut Off lows are usualy badly modelled compared to other features. I remember reading about 'Henrys Law', used in the US, which is where if a strong short wave comes within 1000 miles of the low, it will open up and rejoin the higher lattitude flow ..

 

All to play for next week - Will atleast be able to start to see the rough Jet profile for storm ventilation, if they do spark off - 

 

Sam

[snowmadchrisuk]

Well the GFS 6z shows the Breakdown in the SW even earlier , now Wednesday , with heavy Thundery showers both Monday and Tuesday . Next week is now looking nowhere near as good as it was with temps back down to low 20's by Wednesday and even Mid Teens in places. Can't complain though as were now on the 14th day of the hot weather , In the SW we have not been effected by cloud at all since this all started on the 5th July. Hot with Blue skys everyday . 

[Scorcher]

All I will say is the 06Z runs have been pretty poor recently in terms of accuracy, I prefer to wait for the evening runs, particularly the ECM 12Z. Not ruling out the 06Z but it's so far away from the ECM 00Z that something has to give, and the ECM certainly hasn't backed down so far.

[legritter]

Afternoon all ,Todays charts and data certainly paints a very interesting period ahead .as i said recently temp next week could hit 34c somewhere ,although i did mention 34/36c was on the cards my gut feeling now is more like 34c max ,but it wouldnt take much to be higher given right synoptics and of course areas of clear sky in the right places .there is still a big question mark on location of any trough of low pressure BUT i think at this stage fun and games in the skys of UK looks very likely as we approach mid week if not before .so alot of interesting weather to get through quite possibly before the end of July ,as far as august outlook [very dodgy ground in my opinion ]for new posters and learners keep an eye on regular posters visit the learning area and remember get off computer and look at the weather in the sky .upper air conditions in our atmosphere that you see on upper air charts can be seen looking at cloud types ,and as i have mentioned look at the Science of contrails which you can find on internet ,as the moisture builds next week you will see some interesting signs above our heads .so as usual tonights main runs will firm up more on next week , and Met Office Fax will become a thing of beauty with all those interesting fronts etc .so as for the driest july possible on record as some media reports said recently we enter a period next week when a months rain could fall in a day ,thats the weather gang a quick change artist but of course not guaranteed .

[JRMcLeod]

I'm not an expert, and i tend to follow a few regular posters comments on here but given the recent warm spell, and based on the uncertainty in the models, even at the short range, i am more inclined to lean towards this warm spell re-asserting itself after a mid week blip.  I cant help but think the models want the "default" weather back to our shores...but i just can't see that happening yet. I would love to think we will have UK wide storms and potential but i cant see it.  Maybe the South West and South Wales but other than that i dont see widespread storms.

 

I cant seem to shake the feeling that this warm spell of calm weather will be with us until at least August, even (dare i say it) beyond that.  The Atlantic is so quite i just cant see anything changing it.  Until i see something "striking" i dont think HP will be far from UK shores at all.

 

Maybe i'm wrong and clutching at straws but thats how i see it playing out!  Fingers Crossed!

[Weather Boy]

If anyone thought the 00z gfs was bad breakdown wise then take a look at the 06z cos its ten times worse!!the ridiculous thing is the fact that the 00z was showing temps of 25-27 degrees widely across england and wales for tomorrow but the 06z shows typically 23-24 degrees and only the western areas will see close to 27 degrees!!how can it change that much for tomorrow!!should we bin this run??

 

Yes, people will correct me if I'm wrong, but I don't think I've seen any model until the 6z give us a deep low parked right over southern England like this before:

 

 

Inclined at this point to think that this is a rogue run, but lets see how well it's supported by its ensembles.

 

Based on recent form (i.e. last six months), one would have to favour the ECM evolution which has seemed rock solid, which would see a breakdown in terms of totally settled weather but no breakdown when looking at heat.  I will be really interested to see which model has called it correctly.  If it's the GFS (although I think that the 6z is edging towards the bin, subject to any future support) then it can restore some credibility.  If the solution is nearer the ECM, then in my book it's another nail in the GFS's coffin.

 

My other reason for supporting the ECM is that I think that the models tend to be somewhat over-progressive with breakdowns in these situations, for reasons I posted yesterday.

[Eskimo]

Yes, people will correct me if I'm wrong, but I don't think I've seen any model until the 6z give us a deep low parked right over southern England like this before:

 

 

Inclined at this point to think that this is a rogue run, but lets see how well it's supported by its ensembles.

 

Based on recent form (i.e. last six months), one would have to favour the ECM evolution which has seemed rock solid, which would see a breakdown in terms of totally settled weather but no breakdown when looking at heat.  I will be really interested to see which model has called it correctly.  If it's the GFS (although I think that the 6z is edging towards the bin, subject to any future support) then it can restore some credibility.  If the solution is nearer the ECM, then in my book it's another nail in the GFS's coffin.

 

My other reason for supporting the ECM is that I think that the models tend to be somewhat over-progressive with breakdowns in these situations, for reasons I posted yesterday.

Would I be right in thinking that could bring endless chances of thunderstorms during diurnal heating?