Model Output Discussions 12z 08/03/17

[damianslaw]

All thoughts on the weekend - indeed a bank holiday one, and the best of the bunch in my book. Last year we managed a wonderful May bank holiday weekend- whit, very warm on the Sunday here, one of the warmest days of last summer. I suspect if you look back at weather records, whit may bank holiday on average far more often settled and pleasant than the late August one..

There are lots of uncertainties what may happen over the weekend, where will the shallow low pressure forecast to move up from Iberia decide to position itself. How warm will it become? Speaking of temps, remember a maximum temp is a max, might only hit the figure for a few minutes, whilst significant part of the day is 2-4 degrees lower. Max of 30 degrees shown by BBC in a favoured localised spot only as well. 

[Man With Beard]

The ECM run has got me thinking about the all-time record of 32.8C. A 20% chance of going on Sunday or Monday if the ECM scenario sticks, imo.

[SizzlingHeat]

4 minutes ago, Man With Beard said:

The ECM run has got me thinking about the all-time record of 32.8C. A 20% chance of going on Sunday or Monday if the ECM scenario sticks, imo.

Doubt if 30 will be breached if I'm honest. 

[Singularity]

1 hour ago, Ross Andrew Hemphill said:

What is this caveat you speak of?  And if those charts came off, it wouldn't only be this forum in meltdown! Lots of positive signs for really great weather in the next few weeks, everything just has to fall into place for us for once. 

Standard for long range models e.g. still an experimental science, sometimes well wide of the mark, not to be taken too seriously therefore.

CFSv2 has historically been particularly unreliable, but it seems to have improved since the turn of the year.

[Man With Beard]

58 minutes ago, SizzlingHeat said:

Doubt if 30 will be breached if I'm honest. 

That's the other 80%

[Comandante]

1 hour ago, SizzlingHeat said:

Doubt if 30 will be breached if I'm honest. 

Any evidence or just a hunch? Even the BBC and Met Office forecasters are predicting the strong possibility of 30C anytime between Thurs and Sat.

[Kentspur]

1 hour ago, SizzlingHeat said:

Doubt if 30 will be breached if I'm honest. 

1 hour ago, SizzlingHeat said:

Doubt if 30 will be breached if I'm honest. 

Maybe not on a Dorset beach but my.location most probably will! Or Heathrow if SE flow

 

[Cheshire Freeze]

30C looks doubtful to me, very doubtful but if it's going to be achieved it'll be Thursday- why?- because Thursday sees the UK under the influence of HP with little wind to speak of

Just a light breeze for most- so with still air and strong insolation (and warm uppers) a hot day in built up areas especially.

Fast forward a day or two and the winds freshen from the SE

Still warm but gusty

Even more so on Saturday

Hence GFS has temperatures nowhere near 30C

Not even N France is shown to breach 30C. People can say the GFS undercooks temperatures but I doubt it's undercooking widely by 5-6C

[skifreak]

5 minutes ago, CreweCold said:

30C looks doubtful to me, very doubtful but if it's going to be achieved it'll be Thursday- why?- because Thursday sees the UK under the influence of HP with little wind to speak of

 

Not even N France is shown to breach 30C. People can say the GFS undercooks temperatures but I doubt it's undercooking widely by 5-6C

Is that a 28ºc just East of Loch Eriboll on the North Coast? Fohn effect of the SE wind in the NW Highlands could certainly help inflate the temperature there.

[Cheshire Freeze]

4 minutes ago, skifreak said:

Is that a 28ºc just East of Loch Eriboll on the North Coast? Fohn effect of the SE wind in the NW Highlands could certainly help inflate the temperature there.

Checking the hi-res it's a 23C. 

Obviously the ECM would be different but its evolution around the weekend looks iffy to me- nothing scientific but all looks too slack for Saturday. I would imagine its 0z run will look different.

Edited May 23, 2017 by CreweCold

[Captain Shortwave]

5 hours ago, CreweCold said:

30C looks doubtful to me, very doubtful but if it's going to be achieved it'll be Thursday- why?- because Thursday sees the UK under the influence of HP with little wind to speak of

Just a light breeze for most- so with still air and strong insolation (and warm uppers) a hot day in built up areas especially.

Fast forward a day or two and the winds freshen from the SE

Still warm but gusty

Even more so on Saturday

Hence GFS has temperatures nowhere near 30C

Not even N France is shown to breach 30C. People can say the GFS undercooks temperatures but I doubt it's undercooking widely by 5-6C

The GFS actually doesn't show a single day where we get into the mid-twenties, let alone closing in on the 30C, for example Thursday

      

GFS just 21-23C with just NW Wales getting to 25C. Arpege calling for 25-27C widely 

Friday similar

   

To me the GFS does look to be undercooking the temperatures by a good few degrees, add to that it is really washing out the warmer 850s which may or may not be correct, arpege last summer was a lot closer to the general temperature range.

Still no real agreement on the evolution over the weekend, complicated by an area of low pressure running along the jetstream towards Iberia and how this interacts with the ridge over Europe. As such no agreement on timing of any breakdown and hence when cooler air from the west makes it across the whole of the UK.

 

Just as an aside, can we try to keep things on topic in here, I know that might be difficult due to the horrific events of last night, but there is a thread open to collect our thoughts and emotions on the event. Thank you.

 

Edited May 23, 2017 by Captain Shortwave

[SizzlingHeat]

Latest runs water down the weekends warmth yet again. Saturday showing maxes of between 23-25c with increasing cloud, a freshening breeze and a chance of some showers. Sunday shows the majority of the plume has been pushed east of the UK, leaving a legacy of high cloud and temps between 21-23c whilst Monday between 19-21c with sun and clouds. 

 

It is such a shame but the ukmo is showing similar and ecm really on its own for prolonging or intensifying the warmth. BBC certainly going to re think the 30c for Saturday because they are going to be significantly off the mark imo.

 

Still.... Time for changes being 3 days away but the general evolution is there now. Still warm overall but the phrase 'hot' will be used less frequently by meto by end of today.

 

The weekend looks to be warm/very warm to begin with and becoming increasingly unsettled with showers, but some sun will remain, especially in the south East.

 

Regards

[Matthew.]

Monday sees the Azores high pushing north-east. Hopefully a pattern to keep for the season ahead with low heights over Greenland

[Polar Maritime]

Some post have had to go as off topic. Please continue discussions on the Model Output.

Thanks.

[Frosty.]

The Ecm 00z is fantastic if you love heat..no downgrade..it shows a very summery spell which continues well into next week.

Edited May 23, 2017 by Knockers

[Captain Shortwave]

The ECM continues to model the weekend differently with it again rebuilding the Euro ridge with very warm to hot conditions persisting until the middle of next week when we finally see fresher conditions push east. 

     

An increasing risk of thunderstorms breaking out and heights lower but again temperatures close to 30C again.

It will be interesting to see whether the ECM has got the handle of that southerly tracking low correct and hence is right about extending the warmth through into the following week.

[Frosty.]

I think we are still on for 30-32c during the weekend as our high drifts east into the north sea and we import increasingly hot and humid continental air up and across the uk with scorching sunshine and a growing risk of T-Storms breaking out..and it's not even summer yet!

[Summer Sun]

Friday looks very warm inland even northern parts of Scotland could be in the upper 20s

[SizzlingHeat]

27 minutes ago, Knockers said:

I think we are still on for 30-32c during the weekend as our high drifts east into the north sea and we import increasingly hot and humid continental air up and across the uk with scorching sunshine and a growing risk of T-Storms breaking out..and it's not even summer yet!

I think you will find it's unlikely the temps will get much past 27 perhaps 28c. Likely for Saturday only as growing agreement for Sunday to be cooler and cloudier. It's nice to try and hold out hope from the ecm but even if the uppers are correct, I feel too much cloud with scattered showers will reduce the chance of 30 degrees even more. Ukmo and gfs say no after Saturday even then only up to 25 or 26. I think Thursday and Friday will be the best days of the week. It's down hill from then

[knocker]

A breakdown of ecm temps which illustrates once again a large geographical variation

Friday - generally quite warm over the whole of Britain with temps generally around 24C, perhaps 26C in places.

Saturday - the main heat area SE of a line Humber to Dorset where temps are around 26C, perhaps the odd 28C. North west of that line progressively cooler and only 12C in NW Scotland.

Sunday - Generally the hottest day but again the highest temps south east of a line Bristol to the Wash with temps in some places 28C, perhaps 30C in some places. In the north a marked contrast with temps 12C -20C.

Monday - the SE hanging on to some high temps 26C, possible 28C with the rest of the country slipping back to 22C - 12C

 

[knocker]

Further to the above the main convective outbreak crosses the north of England and Scotland late Sunday early Monday and during Monday further smaller outbreaks filter north from Iberia and by Tuesday these outbreaks are pretty general over England  This channel north for the instability is encouraged further by the HP building to the W/SW blocking inroads from the Atlantic trough. This is very much at odds with the previous run so the jury is still out on developments next week.

The EPS mean is more in favour of the previous run.

Edited May 23, 2017 by knocker

[I remember Atlantic 252]

1 hour ago, Frosty. said:

I think we are still on for 30-32c during the weekend as our high drifts east into the north sea and we import increasingly hot and humid continental air up and across the uk with scorching sunshine and a growing risk of T-Storms breaking out..and it's not even summer yet!

better name! still feel though it's too early in year for 30°, 25° will do though, decent warm temps, Thurs/Fri look warmest here 24°, Sat at 23°

[mb018538]

I think its still far too early to say exactly how warm/hot and how long it will last. The MetO forecast this morning still saying highly uncertain to exact details on this weekend - if the GFS/UKMO/ECM runs are all showing slightly different outcomes, then that seems fair to me. Either way it's going to be warm! ECM is a belter today, but perhaps a slightly warmer solution.



In the short to mid term the GFS 00z op was a bit of a colder outlier, there are plenty there supporting ECMs take on things. Just wait and hold tight folks!

[Tamara]

4 minutes ago, SizzlingHeat said:

I think you will find it's unlikely the temps will get much past 27 perhaps 28c. Likely for Saturday only as growing agreement for Sunday to be cooler and cloudier. It's nice to try and hold out hope from the ecm but even if the uppers are correct, I feel too much cloud with scattered showers will reduce the chance of 30 degrees even more. Ukmo and gfs say no after Saturday even then only up to 25 or 26. I think Thursday and Friday will be the best days of the week. It's down hill from then

Yes indeed, temperatures in the mid and high twenties are a tad underwhelming aren't they - especially when a UK settled warm/hot spell is restricted to a mere week and perhaps a day or two longer 

A relocation to the tropics solves disappointment in such a way as its possible to bask at a less tepid and sustained 30c + all year around 

Speaking of the tropics, the opening week or so of June sees easterly trade winds strengthen

http://www.bom.gov.au/climate/enso/#tabs=Trade-winds

This the result of a convection signal furthest away from us in the Indian Ocean, which will act to dampen atmospheric angular momentum tendency

The upshot of this is that rossby wave alignment will re-configure from upstream with emphasis likely to switch from the continent (notwithstanding the on-going uncertainty of timing of eventual breakdown of current increasingly very warm/hot spell) towards the Atlantic with some interplay between the Azores ridge and the Atlantic trough. This implies a somewhat flatter pattern over UK and NW Europe and temperatures closer to normal to a little above at times the further south and east one heads. No wash-out by any means and still some usable summer weather to be had.

However, once the tropical signal migrates eastwards and atmospheric angular momentum tendency re-boots , the pattern will re-amplify in our mid latitude sector and more widespread settled summer service should be resumed with the prominent Euro ridge returning and the trough banished away well to the NW.

Its then most likely a case of something of a replay of what we have with heat returning north from southern Europe.

Enjoy the lovely weather

 

[mb018538]

I don't get why the GFS is so massively underplaying the temps on Saturday:



21-23c in the SE with 850s at 13c, no cloud and no rain? Erm, yeah ok then....even parts of france under 16c 850s are shown as 25c. So, so wrong it's unreal.