Model Output Discussions 12z 03/05/2016

[cheese]

24 minutes ago, Polar Maritime said:

Netw-MR Model take on the Plume Wed/Thursday, Temps touching 31/32c in the South with some high cape levels which could lead to some of Steve's 'crackerjack' thunderstorms.. 

That is probably the biggest temperature contrast I've ever seen modeled. Looks like we'll miss out completely up here.

Edited August 20, 2016 by cheese

[stainesbloke]

6 minutes ago, Matthew Wilson said:

A pleasant fine settled bank holiday for England and Wales as settled conditions nudge in. Hopefully this holds and lots of sunshine is on the cards.

Agree, very pleasant if so, a nice end to a decent August. 

[stainesbloke]

7 minutes ago, cheese said:

That is probably the biggest temperature contrast I've ever seen modeled. Looks like we'll miss out completely up here.

Seen and experienced these sort of set-ups many times in the past, nothing overly unusual, though the differences in temps might not be so marked. Of course, I'd prefer to see corrections NW of the warmth rather than shifting everything SE. 

Edited August 20, 2016 by stainesbloke

[cheese]

6 minutes ago, stainesbloke said:

Seen and experienced these sort of set-ups many times in the past, nothing overly unusual, though the differences in temps might not be so marked. Of course, I'd prefer to see corrections NW of the warmth rather than shifting everything SE. 

Never seen a 10C difference between here and London before, except 10 August 2003 when it was 38C in London and 28C here. Definitely not common at all. Certainly, on all hot days in recent years there was never a big difference - London reached 33C in July this year, we reached 31C. London reached 37C in July last year, we reached 33C, London reached 34C on 1 August 2013, we reached 31C, etc etc.

I hope the heat is extended further N and W over the next few days but I suspect it's the nail in the coffin for most of us who don't live in the SE.

Edited August 20, 2016 by cheese

[Polar Maritime]

13 minutes ago, cheese said:

That is probably the biggest temperature contrast I've ever seen modeled. Looks like we'll miss out completely up here.

Yes 11c for parts North of the Midlands! Still plenty of time for fine adjustments over the next few days which would make all the difference.

[northwestsnow]

Some lovely summer weather on offer on the 0z runs, GFS looks mainly dry warm and sunny esp the further SE one goes,ecm also looks good with plenty of useable weather for outdoor lovers as the trough to  the west helps pump up some warm uppers towards the UK, all in all very happy - a nice end to the summer hols for many .:)

[bluearmy]

Beginning to see an ex TS or hurricane entering the n Atlantic basin within a fortnight on some high res modelling. been evident on the ens and distant GFS ops for a while now. 

[Sky Full]

9 hours ago, johnholmes said:

In terms of what the models 'do'. Beyond obvious differences in how different models are set up with the hugely complex formulae they use no model has predispositions to any outcome, be it extreme or average. They are all bound by the same thermodynamic equations with the initial data. That data can differ which may seem odd. However, before each run on each model the model itself has a programme that is devised to try and give the best possible initial set of data, if that makes sense. It might be an idea for all of us to either read or re-read Met Office information on how their model treats data and if it is available for the same thing with GFS and ECMWF. Highly complex but some folk might understand it, I did once but it is a bit beyond my old brain these days.

In terms of which model may be nearer the mark at time scales that fit the anomaly charts. Then whichever model fits the predicted upper air pattern on the anomaly charts nearest is most likely to have the nearest idea and thus to have the best chance of getting the bottom 18,000 ft correct! That is IF the 3 main anomaly charts are pretty much the same for the 6-10 day period AND the synoptic models cope correctly with the bottom 500 mb of the atmosphere. Not easy as the hugely difficult factor of moisture becomes more and more important in this bottom 500 mb.

Thanks for this explanation - very interesting and it reminded me just how difficult it must be to try and forecast the weather through 18,000ft of atmosphere 24 hours ahead, never mind 8-10 days ahead!  I do find it curious that that the formulae used by the model computers don't take historical averages into account though.  It's difficult to comprehend how complicated the formulae must be that calculate global atmospheric conditions days in advance using physical data and thermodynamics.

[knocker]

Hey ho said Rowley and enter the ecm which has a quite different evolution for the end of next week.

It has the unstable area giving possibly some intense convective activity tracking north over the UK Thursday and early Friday and by 18z has it NE of Scotland. At the same time it has drifted and filled the Atlantic low to be 200-300 miles west of N. Ireland. It then develops a shortwave in the slack circulation in the south of said low which develops into quite an intense little feature and is N. Ireland by Sunday midnight bringing some wet weather to Ireland, Scotland and west Wales and England leaving a westerly showery regime in it's wake.

[knocker]

Looking at the GEFS anomalies for the BH I suspect the GFS det. may be pushing the optimistic button.

[knocker]

A skew-wiff Omega block BH not looking great unless you are in Whitstable.

 

Edited August 20, 2016 by knocker

[johnholmes]

2 hours ago, Sky Full said:

Thanks for this explanation - very interesting and it reminded me just how difficult it must be to try and forecast the weather through 18,000ft of atmosphere 24 hours ahead, never mind 8-10 days ahead!  I do find it curious that that the formulae used by the model computers don't take historical averages into account though.  It's difficult to comprehend how complicated the formulae must be that calculate global atmospheric conditions days in advance using physical data and thermodynamics.

without wanting to clutter up the model thread the link below gives you the Met O link to modelling and some of the research that goes into trying to improve things. Headache making very quickly!

http://www.metoffice.gov.uk/research/modelling-systems/numerical-models

No idea about ECMWF or GFS but I am sure if anyone wishes to delve then GFS at least will give similar information on how the US treat modelling.

[Captain Shortwave]

I guess this is a weird situation for heat lovers at the moment as we actually want the ridge in the Atlantic and the Greenland area to hold on for as long as possible.

This hinders the eastwards progression of that low and hence allows the heat to build northwards across Europe and parts of the UK. I must to feeling a little disappointed for those in the north where the warmer and drier weather never really makes it there compared to the output just 24 hours or so ago. Still the is good agreement from an area from the Bristol channel to the Humber and south and east of this point to see a very warm or even hot spell of weather before a breakdown Thursday night into Friday. We really need that low to stall and sink further south to firstly extend this spell and secondly bring more areas of the UK into play.

Some temperature predictions based of the models for midweek.

      

30C possibly on Tuesday, Wednesday and Thursday with 90F possible on the latter two days, but you can clearly see the dividing line where a cold front sits through the northern part of England and most of Wales, it is worth noting the risk of thunderstorms on both Wednesday and Thursday night.

The 06z is coming out now and it does look a little better so far in the early stages in terms of the upstream pattern. We await with interest.

Indeed the 06z extends the warmest conditions further north and west to cover most of England and the far south and east of Wales, it also stays hot in the south east on Friday as the cold front moves erratically eastwards during the day bringing the risk of thundery showers. 30C possible on Tuesday, Wednesday, Thursday and Friday on this run.

 

 

Edited August 20, 2016 by Captain Shortwave

[coldcomfort]

3 hours ago, Matthew Wilson said:

A pleasant fine settled bank holiday for England and Wales as settled conditions nudge in. Hopefully this holds and lots of sunshine is on the cards.

Absolutely no point whatsoever in looking that far ahead atm, especially with GFS, which time and time again recently has been proven reliable for only one thing post T+120hrs, i.e building hopes of heat/plumes, only to dash them 3-5 runs later.

[stainesbloke]

1 minute ago, coldcomfort said:

Absolutely no point whatsoever in looking that far ahead atm, especially with GFS, which time and time again recently has been proven reliable for only one thing post T+120hrs, i.e building hopes of heat/plumes, only to dash them 3-5 runs later.

Haha, that is true. Though the ECM has had some spectacular climb downs too. GFS run looks ok so far...

[Captain Shortwave]

In terms of the coming bank holiday weekend, well I suspect like many on here that the 00z GFS was being very optimistic, the 06z looks more in line with other models and ensemble suites. So going by the GFS 00z ens

      

Probably changeable with rain or showers for many areas but no washout at the moment, temperatures look to be on the warmer side of average, more so the further south and east you go. This pretty much sums up our summer to be honest, it's okay to good, not a stunning spell but not a disaster either. That said this is a long way off in terms of the model output and things could change, I wouldn't for example rule out another surge of warmth coming from the south if the amplified longwave pattern we will see this coming week could re-establish itself and hence hold low heights to our west. A low possibility at the moment though.

[phil nw.]

Yes CS the 006 z GFS run seems more in line with the 00z ens with the main surge of warmth for the south east quarter but all areas seeing a better few days next week.

The Exeter T84 fax for Tues shows the ridge building in with resultant southerly drift bringing the warmth into the UK by mid-week.

It does look like that towards the BH weekend something more changeable is on the cards-ECM mean T96 and then T168hrs

 Comparing the day 4 chart with day 7 the upstream jet flattens out pushing our ridge of warmth away as the westerlies move-the south east hanging on to the best weather perhaps a day or so longer.

 

[PersianPaladin]

The orientation of the upper flow has clearly not developed as expected by the models earlier on, and of particular note is the development of short-wave features just to the exit of the jet-streak north of the UK. These spoiler shortwaves can make a big difference, and very much are an inevitable part of the jet-evolution - thus preventing the development of heights to the west of Scandinavia. Still, their emergence can be entirely unexpected thus demonstrating the chaotic and contingent complexity separating conditions at 300hpa down to 500hpa and below. We've seen these sort of shortwaves ruin set-ups in winter, albeit they usually prop-up in different locations such as south of Sweden; thus cutting off the cold air advection to the UK. I remember one such feature, was a particular heart-breaker for us all.

Edited August 20, 2016 by PersianPaladin

[Polar Maritime]

The heat filling the Southern half of the UK by Wednesday on this evenings GFS.. I would expect more macro adjustments over the next day or two.

Edited August 20, 2016 by Polar Maritime

[knocker]

Max temp 12C on Thursday.................for NW Scotland and not to smoky in NW England either

Edited August 20, 2016 by knocker

[Man With Beard]

Small differences between ECM/UKMO and GFS at T96 results in up to a 4C temperature difference:

        

An even bigger difference between the GEFS tonight and the ECM from this morning:

http://modeles.meteociel.fr/modeles/gens/ecmwf/graphe_ens3.php?mode=0&x=306&y=141&run=0&ville=Londres&runpara=0

I can't imagine either one is going to move a whole 5C at just T96/T108. I imagine they'll meet somewhere in the middle?

[knocker]

I think it safe to say the BH weekend is a long way from being nailed down but the ecm's latest take on it.

Thursday 12z sees the Main low way west of Ireland with band of convective activity tracking north trough central England with the usual NW/SE split temp wise.

This activity clears away by 12z Saturday and in the interim the Atlantic low has tracked east over Scotland and dissipated leaving the UK in a very slack pressure area with new low approaching from the south west and temps nearer average, albeit it should  be dry.

Sunday should be pretty dry in most places although again the temps no great shakes with the proviso that the new low is steadily approaching from the SW and the fronts reach the SW during Sunday afternoon. This movement of low NE ceases and it becomes stationary in the South Irish Sea area.

 

[blizzard81]

Another back track from the models with regards to some extreme temps - just like winter. Other forces are in play here

[Captain Shortwave]

The pub run is a little slower with the breakdown though not as slow as the 06z this morning. 

It does look like Tuesday, Wednesday and Thursday will be hot for the south east, the length and potency of the heat away from here is more uncertain with small discepencies between the models offering large differences in terms of temperatures.

The 18z maxima for Tuesday, Wednesday and Thursday

      

30C possible potentially on all three days, 90F possible on Wednesday in my opinion, Thursday is uncertain, if we could hold the hottest air over the UK long enough then the maximum on Wednesday could be surpassed, potentially getting close to the mid-thirties, especially with an 850 temperature profile shown on the GFS (18-20C across the south east for a good 24 hours leading to Thursday afternoon). The evolution of the breakdown is very delicate and hence could drastically alter the temperatures predicted on Thursday in particular.

The bank holiday weekend still looks likely to be mixed, but if we can get a ridge through the UK then it would likely bring some very warm conditions albeit not at the same range of temperatures seen during the middle of this week.

Edited August 20, 2016 by Captain Shortwave

[Man With Beard]

A backtrack on the backtrack??

GFS keeps churning out hot temperatures for Wednesday in the S and E - rather cooler in the N and W