Model Output Discussion 12z 18/10/2012

[Gavin Hannah]

Just out of curiosity, is that the Jet Stream in the Med??

[Radiating Dendrite]

That is the southern arm. The northern arm is to the NE of Scotland.

[peterf]

there ya go lol.

off to the tech thread meself,much less drama.

[chionomaniac]

I don't come on here to spend the evening deleting posts. Please be relevent to the topic or I will put you on OON's timeout list.

[SMU]

The track of the american shortwave at 108 is more of an 'inland runner' over canada- precipitating higher heights across greenland V the 12z,

as a result a better height profile to our NE as well-

Should be a better run...

S

[Gavin Hannah]

t.108

Reload!? Watching in anticipation.

Edited October 22, 2012 by IBringTheHammer

[Frosty.]

The FI cold snap/spell is now coming into the reliable timeframe and it is a bonus to get such an arctic blast towards the end of october, looking back 12 months and it was generally very mild with not a sniff of anything cold. There looks like being a fair scattering of wintry showers by friday, especially towards the far north and down the eastern side of the uk and some of these showers will turn to snow, especially in the heavier showers and on higher ground, let's not forget windchill, quite a brisk N'ly and possibly strong in the far northeast. Most areas will become a lot sunnier than recently but frosts look like becoming widespread. Coming back to the present, we got so close to an indian summer, just across the english channel they had a sunny 22c while we were stuck in mist/fog and drizzle but the mild murky weather will be swept away south by friday and may not return for a while.

[Zenarcher]

18z looking better around 120 hours high pressure over Greenland looks to be in a better place,

18z

12z

[Met4Cast]

18z is an improvement on the 12z thats for sure with re-load potential! I feel that the re-load is showing too soon though, after the initial blast of cold the Arctic has pretty much displaced all of its cold into Europe, it doesn't look like a re-load would be any colder than the initial shot, the cold pooling over the Arctic just isn't there at the moment.

[Gavin Hannah]

18z is an improvement on the 12z thats for sure with re-load potential! I feel that the re-load is showing too soon though, after the initial blast of cold the Arctic has pretty much displaced all of its cold into Europe, it doesn't look like a re-load would be any colder than the initial shot, the cold pooling over the Arctic just isn't there at the moment.

I get that impression too. The Really cold air doesn't get a chance to build, and it's looking at the moment like it would dwindle out. The good news is that the HP looks to be going nowhere fast.

18Z

12Z

Better reload on the 18Z. This is at t.141.

Edited October 22, 2012 by IBringTheHammer

[Met4Cast]

I get that impression too. The Really cold air doesn't get a chance to build, and it's looking at the moment like it would dwindle out.

We have -25 850hPa air at the moment, and thats forecast to only just make Southern England

The reload has significantly less "cold air" over the same place, going by the 18z

So definitely not any "colder" I wouldn't have thought, but I suppose it'll help keep temperatures below average with further widespread frosts! IF it comes off, of course

[Gavin Hannah]

We have -25 850hPa air at the moment, and thats forecast to only just make Southern England

The reload has significantly less "cold air" over the same place, going by the 18z

So definitely not any "colder" I wouldn't have thought, but I suppose it'll help keep temperatures below average with further widespread frosts! IF it comes off, of course

Do you mean -2.5?

[Met4Cast]

Do you mean -2.5?

Nope.. -25c over Greenland in the first chart, I think, it might be -20c - Sorry, I didn't mean -25c was forecast to reach Southern England, I meant after it had been displaced etc..

Edited October 22, 2012 by Daniel AKA WMD

[Gavin Hannah]

Ah lol. I notice that as the ruun goes deeper, the air over the Atlantic begins to cool down. Far more green tones than yellow. And Colder in southern europe.

Edited October 22, 2012 by IBringTheHammer

[chionomaniac]

A flatter pattern than modeled recently but still a NW/SE orientated jet stream in the offing. That will always keep the country in a coolish flow.

[Gavin Hannah]

Better for recycling cooler air rather than dragging warm air up from the south. Interesting run, has it's plus points and negative points. Few more runs required I think before it's safe to call exact duration and depth of the cold shot and any potential reload.

Edited October 22, 2012 by IBringTheHammer

[Met4Cast]

One thing to take from the 18z is that High Pressure remains over Greenland all the way out into deep FI and this really helps temperatures plummet across Greenland once again, we don't really see any form of PV either until deep FI so that's encouraging too.

Obviously all about trends at this stage, and the ECM & GFS are not wanting to develop a polar Vortex or particularly zonal pattern.

[Isolated Frost]

Latest fax 12z and GFS 12z at +96 (Friday 12pm). Met going totally against the GFS, the HP cell is located much further NW and the 528 crosses Scotland and the top of England- instead of scaling the east coast. Obvious the Met see this spell differently and that would certainly give some snow shrs to northern areas, that's probably where the BBC optimism has came from. Completely different trough alignment and position as well with a little trough complex across the Kola Peninsula to Swedish Lapland, whilst the GFS goes from Svalbard to Moscow.

FAX says the initial cold snap ain't what the other NWP seem to want it to be...

[Met4Cast]

Latest fax 12z and GFS 12z at +96 (Friday 12pm). Met going totally against the GFS, the HP cell is located much further NW and the 528 crosses Scotland and the top of England- instead of scaling the east coast. Obvious the Met see this spell differently and that would certainly give some snow shrs to northern areas, that's probably where the BBC optimism has came from. Completely different trough alignment and position as well with a little trough complex across the Kola Peninsula to Swedish Lapland, whilst the GFS goes from Svalbard to Moscow.

FAX says the initial cold snap ain't what the other NWP seem to want it to be...

I'm guessing they're going with the MOGREPS then, they didn't come on board with this cold spell at all until that model came on board, I wonder whether its going to be slow again and eventually move over to what the other models are showing?

Is there a way for the public to view that model? Like, a pay to view?

[johnholmes]

I'm guessing they're going with the MOGREPS then, they didn't come on board with this cold spell at all until that model came on board, I wonder whether its going to be slow again and eventually move over to what the other models are showing?

Is there a way for the public to view that model? Like, a pay to view?

perhaps but the fee would make even well to do folk wince from what I've been told

your best info leak is Ian F

Latest fax 12z and GFS 12z at +96 (Friday 12pm). Met going totally against the GFS, the HP cell is located much further NW and the 528 crosses Scotland and the top of England- instead of scaling the east coast. Obvious the Met see this spell differently and that would certainly give some snow shrs to northern areas, that's probably where the BBC optimism has came from. Completely different trough alignment and position as well with a little trough complex across the Kola Peninsula to Swedish Lapland, whilst the GFS goes from Svalbard to Moscow.

FAX says the initial cold snap ain't what the other NWP seem to want it to be...

rare for the man/machine mix to be inferior to the model on its own-it will be interesting to see what does happen. Might be an idea to save GFS and Fax for same date/time and see which was nearest?

Edited October 22, 2012 by johnholmes

[Met4Cast]

perhaps but the fee would make evn well to do folk wince from what I've been told

your best info leak is Ian F

Thanks! I'll ask around, if its under £200 I might purchase it depending on how long the subscription would be for, could come in handy, the MO seem to put a lot of confidence into the model going from the latest FAX, if that is indeed what they're basing their forecasts on

[Isolated Frost]

I'm guessing they're going with the MOGREPS then, they didn't come on board with this cold spell at all until that model came on board, I wonder whether its going to be slow again and eventually move over to what the other models are showing?

Is there a way for the public to view that model? Like, a pay to view?

Well the BBC and MO seem quite adamant with their evolution and they are certainly publicising it- so I wouldn't be too sure whether we will see a notable shift. A shift may occur though and it probably will be for a more HP-induced scenario.

I'm not sure if the ECMWF site do them, they charge big big prices if so though. The whole ECMWF site do offer a lot at a huge price. People like Matt Hugo might be able to help you on that though. I'm sticking with the trusty hi-res NMM for now.

[johnholmes]

Thanks! I'll ask around, if its under £200 I might purchase it depending on how long the subscription would be for, could come in handy, the MO seem to put a lot of confidence into the model going from the latest FAX, if that is indeed what they're basing their forecasts on

add a 0 and you might be near 6 months!

[Isolated Frost]

rare for the man/machine mix to be inferior to the model on its own-it will be interesting to see what does happen. Might be an idea to save GFS and Fax for same date/time and see which was nearest?

Indeed John, I will be keeping a close eye on both. What appears to be the major difference at even just +72 is MOGREPS/FAX placing the HP cell o/Iceland, rather than just W of Ireland, which is the most common NWP solution. A lot of analysis will be going on I'm sure and it will be interesting to see how the NMM reacts to it, as a speciality mesoscale model.

Here is the latest NMM at 48hr (Wednesday 6pm)

Compared to the GFS at 48hr (Wednesday 6pm)

GFS looking a touch more progressive. Not much difference though. Though at +48, the HP cell is in a very similar position on the GFS and FAX. Tomorrow will be the crucial day, and Wednesday and Thursday will be the fine-tuning I'd say. This time tomorrow, we should be in a much better place, but we all know that's never as easy as that.

[Met4Cast]

add a 0 and you might be near 6 months!

Shhiiii.. Forget it then, that's ridiculously expensive if right! I think i'll stick with the NW NNM models too if that is the case, it's a shame they only go out to 48hrs, but I suppose any further would lead them to be a lot more inaccurate