Model Output Discussion 12z 18/10/2012

[Frosty.]

06z is loooking much better than the 00z for cold and possible snow however as said above we've been told to "bin" the 06z run in the past which I fail to see why as its another run with more possibilities

Yes it's a very good run for cold prospects and is more like some of yesterdays output from ukmo plus fax charts, ecm, gem, jma etc. I just take the view that it's the most recent data available and therefore has to be the best, lack of weather balloons and all.

[Liam J]

Cold and wet GFS 6z run into FI - Only good news will be for the Scottish Ski resorts. Certainly not a stonker imo - but that is entirely based on your expectations & preferences.....

[MKN]

Have to agree with Liam regarding the 6z. Uppers just aren't cold enough for all but the scottish highlands.

[Frosty.]

Cold and wet GFS 6z run into FI - Only good news will be for the Scottish Ski resorts. Certainly not a stonker imo - but that is entirely based on your expectations & preferences.....

By october standards it's a stonker, still nearly 6 weeks until official winter starts and the outlook is wintry showers and widespread frosts, not bad eh.

[gottolovethisweather]

Cold and wet GFS 6z run into FI - Only good news will be for the Scottish Ski resorts. Certainly not a stonker imo - but that is entirely based on your expectations & preferences.....

I rarely post within this thread but I agree with Liam in that it is a perfect run for those with a liking for cold and wet synoptics. The wet part especially hinting at snowier interludes for the lucky few. Snow is impossible to predict at this stage and not even really worth talking about until nearer the time. I like the latest GFS run as I am a coldie at heart and when compared to yesterday's 06z I think it is probably even an upgrade, with wintry type synoptics showing throughout. Having said all this, one must also keep your eyes peeled on what the stratosphere is up to.

I look forward to this afternoon's and evening's runs with bated breathe.

Edited October 22, 2012 by gottolovethisweather

[Scorcher]

I have never seen such an accurate run........its beautifully spot on

BFTP

Is this tongue-in-cheek? Would like to know how you know this. I'm sure the run would be very inaccurate if it was showing mild temperatures!

[Adam lufc]

Liam that 6z will produce wet weather but not only snow on Scottish mountains. So likewise depends what your expecting? Low level metre deep snow?

[Summer Sun]

The Met Office are going for the following after this weekend

Relatively cold and unsettled conditions will return thereafter with sometimes prolonged wintry showers interspersed with drier and brighter periods

[Met4Cast]

06z Run shows mild zonal - "Ahh bin it, its rubbish anyway, doesn't have enough data"

06z Run shows cold Northerly air - "Ah, maybe it isn't so bad, I don't know why everyone says bin it"

Brilliant. Talk about double standards

[SteveB]

I think by the lack of comments regarding a good 06z run indicates most have taken to the idea of binning it regardless

[latitude]

I rarely post within this thread but I agree with Liam in that it is a perfect run for those with a liking for cold and wet synoptics. The wet part especially hinting at snowier interludes for the lucky few. Snow is impossible to predict at this stage and not even really worth talking about until nearer the time. I like the latest GFS run as I am a coldie at heart and when compared to yesterday's 06z I think it is probably even an upgrade, with wintry type synoptics showing throughout. Having said all this, one must also keep your eyes peeled on what the stratosphere is up to.

I look forward to this afternoon's and evening's runs with bated breathe.

Im not sure that anyone here even two days ago was expected low lying snow from this cold outbreak. Everyone I think was impressed by the level of cold reaching our shores this time of year. Scottish mountins etc yes, but appart from that quite limited.

[Gavin Hannah]

Anytime the -5 Isotherm passess overhead is a chance for low level snowfall. That said, the chances are probably lower during Autumn than in winter. The Weather from thur/fri onwards is as already mentioned, looking very good for the ski resorts, which is, if Im being honest, at this early stage, all I'm concerned with.

The output looks good. If it continues into winter, then we may well get a good start to winter this year. I'm still favouring an overall blocked winter over the Atlantic/Greenland.

[BLAST FROM THE PAST]

Is this tongue-in-cheek? Would like to know how you know this. I'm sure the run would be very inaccurate if it was showing mild temperatures!

Yes it was....buT also yes it would be wrong if it showed very mild

BFTP

Edited October 22, 2012 by BLAST FROM THE PAST

[Liam J]

By october standards it's a stonker, still nearly 6 weeks until official winter starts and the outlook is wintry showers and widespread frosts, not bad eh.

Yes I must remember to add - For the time of year then we can't really complain on what we're seeing within the model outputs, whether this bodes well for the coming winter well, I don't think anyone can comment with any significant degree of confidence.

Unfortunately quite a few people have inflated and unreal expectations about what to expect towards the end of this week, take it for what it is - Much more pleasant if you don't allow your expectations to be built up like a sky scraper only for them to come crashing down when the reality hits.

Without being overly fussy and nit picky - it's not often we have such synoptics so early in the season (and indeed at all in some of the past winters) So I'm deffo looking forward to the first autumn chill & some crystal clear skies above the frosty landscapes, and I'll just happen to be in Aviemore as the cold air penetrates southwards, hoping to see some of the white stuff

Edited October 22, 2012 by Liam J

[Mark Neal.]

I'm looking forward to the drop in temperatures. From mild start to the week to a plunge to end the week. Also with the models showing a much better weekend, might be a raw wind but also sunshine looks like being a common feature. Overnight frosts the potential also. Wintry showers for northern areas is a added bonus and looks like the ski resorts will get a decent amount of snow. For a late October situation this is a great start and we should all enjoy what the weather is going to throw at us

[gottolovethisweather]

Im not sure that anyone here even two days ago was expected low lying snow from this cold outbreak. Everyone I think was impressed by the level of cold reaching our shores this time of year. Scottish mountins etc yes, but appart from that quite limited.

Perhaps not and besides that is precisely what I'm stating in my previous post. Talk of snow sends this forum into a frenzy at the best of times but an actual reality check of one's hopes need to be addressed too. Quite simply put, October snow for a greater part of the UK is not beyond the realms of possibility a la October 2008 even at this early stage. I am not forecasting snow but wintry type synoptics are as good as nailed.

*best get back to discussing the output proper from here on in*

Edited October 22, 2012 by gottolovethisweather

[shedhead]

Clearly a quick transition to significantly colder weather is on the cards during Friday/ Saturday, but even so any wintry ppt does look to be in rather short supply. We then have to look for a reload to deliver the kind of cold synoptics touted by GFS for next week and at this stage that still looks a little too far off to assume it's anything like guaranteed. More runs needed... as is often the case.

Edited October 22, 2012 by shedhead

[Timmytour]

I have never seen such an accurate run........its beautifully spot on

BFTP

That was superb! For those who didn't get it....you had to have been here! :-)

[Rocheydub]

That was superb! For those who didn't get it....you had to have been here! :-)

BFTP at his best. I know this is off topic, but I spat coffee all over the laptop when I read that comment.

Mind you don't bite that tongue off in your cheek!!!

[phil nw.]

More recent output suggest that those Greenland heights will ease further west next week towards the Canadian Maritimes

Meanwhile that Scandiavian upper trough looks like disrupting across the UK with time which will mix out the coldest Arctic air.

This is what some observers refer to as a west based -NAO.

Here`s the 00z NAEF`s and the ECM00Z ens mean to illustrate the easing of the pattern further west.

The London Ens graphs for 2m temps and percipitation pretty much underline where we look like heading after the introduction of the colder air on Friday.

This slight pattern shift will result in general conditions becoming more cyclonic and unsettled as the trough extends low pressure across the uk into next week with more rain about.It does however look like remaining on the cold side with single figure max`s for many.

This adjustment to the pattern is a fairly recent outcome and we will need some more runs to be certain that`s the way foward but if the MJO continues in phase 1 as we go into November then that would seem a logical development.

[Zenarcher]

Here's a 24 hour comparison between some of the models,

Yesterdays 00z run for 2am on the 27th,

Today's for the exact same time,

Pressure over Greenland is pushed more South on today's run.

When comparing yesterdays 06z GFS run with today's it does seem similar to today's 00z run but notice the improvements for the 29th,

Yesterday the high was much further South,

Today's run for the same time and day the high pressure looks better and the temperatures for the UK are colder,

Onto the ECM comparing its 00z runs nothing much to note just today it slides over to the GFS.

For the 31st the ECM has pushed things a lot further West,

And Today's,

For the UKMO when comparing the 27th of October not much had changed at all so I decided to look at the Northern Hemisphere charts for more,

Yesterday's

Today's,

On Today's run the low pressure over Sweden, Finland and Russia is placed more South. The high pressure in the Atlantic is pushed further North. Also the low pressure systems over Northern Canada and the west coast of America are placed slightly more further West.

Edited October 22, 2012 by weathermaster

[shedhead]

Agreed Phil, the pattern you describe in your closing sentance may well be something of a recent development, but nonetheless the background signal do lend pretty decent support to it, with NW'erly rather than N or NE'erly winds predominating around the turn of the month. So never mild after the middle of this week, but not the depth of cold touted by some fairly recent runs either.

Edit: Matt's latest post in the Strat thread also lends weight to the idea of flatter pattern as we go into Nov.

Edited October 22, 2012 by shedhead

[BLAST FROM THE PAST]

Rochey and Timmy

cheers guys an opportunity I could not miss :-).

Weathermaster, a really good post

BFTP

[nick sussex]

I think an easy assessment of todays output is unsettled in the outlook, colder showers some wintry, any snow accumulations mainly reserved for higher ground in the north.

In the extended outlook if you want cold to remain then the neg NAO must not become west based. This is often a problem in these types of set ups.

There has been some moderation in terms of the cold in relation to the initial colder shot, both the ECM and UKMO originally wanted to hold onto the straight northerly for longer,as we can see now another low pressure looks to track se'wards because of the timeframes what happens after this is uncertain.

If you look at the ECM ensemble maps.

http://www.ecmwf.int...t!2009112700!!/

It's easy to spot the members trending to a more west based negative NAO, once you get low pressure stuck over the UK the cold gets mixed out and you enter a more average showery type set up.

We often see the cold pushed too far east with northerly topplers, the reverse problem often occurs with the trend in the later outputs, the cold funnels south to the west of the UK.

So in a nutshell

Negative NAO centrally based to the south of Greenland with Scandi trough= cold showery conditions

West based negative NAO, core of heights near the Canadian Maritimes= average conditions with showers.

Eastern based negative NAO= drier conditions for most of the UK, generally colder to the east with any showers more east and se as the flow often gets directed from a more ne quadrant.

So thats what I'd concentrate on in future outputs, look out for events in the eastern USA and eastern Canada, low pressure track there does effect high pressure near Greenland.

Edited October 22, 2012 by nick sussex

[snow drift]

I think this run from GFS is further west. Or are my eyes just going funny due to stareing at so much output?