Model Discussion - January 17th

[Frosty.]

I know the operational model runs don't look as good, for coldies as they should considering all the changes that GP and others have been talking about, but it's only tuesday and things might look a lot better tomorrow, as it is, there is plenty of cold zonal weather for scotland especially with snow at times for the scottish hills and mountains in gale force westerly (veering NW'ly) winds from tomorrow night and throughout thursday and friday, even the weekend could bring snow to some higher parts of scotland and maybe even for hills further south.

Edited January 17, 2012 by Frosty039

[chionomaniac]

These anomaly charts are slowly but surely edging in the right direction as well.

[nick sussex]

Yes Nick.

I have to say the one thing troubling me is a scenario like February 2009 developing but without the initial easterly. The background signals are not too dissimilar.

Yuk!!!

For newbies a western based negative NAO often comes about when you have higher latitude blocking but its core sets up too far west and you're on the mild side of any troughing, an eastern based often delivers cold east to ne flows as any troughing is often over Scandi or further east and you're on the cold side of the trough.

I have to talk about the UKMO further outlook here as its relevant to that so apologies mods but I can't explain it any other way!

I sense the reason for the uncertainty in that outlook is that theres a good signal for higher latitude blocking, the reason they're giving these two options with no real middle ground is that this is really the only type of set up where you can have such a marked difference in weather.

I suspect theres a big split in the ECM longer range ensembles and thats why they've given that type of outlook, blocking yes but where and that will probably decide the rest of the winter.

[West is Best]

Oh dear. Three Atlantic dominated 12z outputs. Snow for the Scottish ski resorts and occasionally on the hills and mountains of the north, but that's about it really. Some squally conditions coming up at times, which will make it feel colder than it actually is.

It's back to the west I'm afraid. Batten down the hatches. I'm off for another couple of weeks unless something dramatic changes. Just pointless for cold lovers to get het up in this zonal winter. We just have to dine off last year for now.

[phil nw.]

These anomaly charts are slowly but surely edging in the right direction as well.

Yuk!!!

For newbies a western based negative NAO often comes about when you have higher latitude blocking but its core sets up too far west and you're on the mild side of any troughing, an eastern based often delivers cold east to ne flows as any troughing is often over Scandi or further east and you're on the cold side of the trough.

I have to talk about the UKMO further outlook here as its relevant to that so apologies mods but I can't explain it any other way!

I sense the reason for the uncertainty in that outlook is that theres a good signal for higher latitude blocking, the reason they're giving these two options with no real middle ground is that this is really the only type of set up where you can have such a marked difference in weather.

I suspect theres a big split in the ECM longer range ensembles and thats why they've given that type of outlook, blocking yes but where and that will probably decide the rest of the winter.

Yes if the pattern develops as spoken about there guys it is roughly in line with those NOAA 500hPa forecasts from last night.

That 8-14 day chart does show our trough further west,which as you said Nick would put us on the "warm" side.

I much prefer that chart of yours C-if the low hts stay there.

It does suggest that at some point we could get a sniff of an easterly as the nw euro throughing becomes split from the main vortex and drops south towards us.

That is being modelled by the ECM by day10-i know it`s in FI-but a logical evolution after the vortex split you highlighted Chiono.

This would allow a chance of those heights from the east to extend west over the top but that is some time away-and i shouldn`t speculate.

[Cloud 10]

Certainly the best forecast so far this winter for a -AO/-NAO combo setting up as we head towards the end of

january.

High lattitude blocking looking much more likely,but where this sets up will obviously be crucial.

AO> NAO>

[SP1986]

isn't the AO/NAO a summarisation of what is already showing up on the models, rather than any signal which might cause, or pertain to any cold spell in future. Unless I've completely misunderstood it in the past.

[West is Best]

The 12z model outputs, yes the model outputs, from the GFS, UKMO and ECMWF appear to continue the theme which has emerged over recent days towards a more Atlantic dominated pattern. The consistent trend towards flattening has seen first a potential easterly and then a potent northerly quashed. We are now left with -5 850hPa reaching the M4 corridor according to the GFS but one suspects that even this will push further north. Potential blocking mid-Atlantic at T144 is smashed by the developing low off Newfoundland at T168:

Edited January 17, 2012 by Paul

[phil nw.]

isn't the AO/NAO a summarisation of what is already showing up on the models, rather than any signal which might cause, or pertain to any cold spell in future. Unless I've completely misunderstood it in the past.

Yes it is Stephen.I must admit i wonder why these are used as a forecast.It is just another way at looking at all the ens. members wrt to the overall pressure measurements in the NH.

They change run to run.

Edited January 17, 2012 by phil n.warks.

[nick sussex]

I do hope we don't end up with a western based negative NAO, it would be frustrating for the strat warmings to do their job and evict the PV from Greenland only for high pressure to set up too far west.

This is why many of us have stressed that higher latitude blocking doesn't guarantee cold, you have to have some luck for this to set up in the right place. Of course though with this risk comes a much bigger pay off in terms of cold and snow for the UK, if you want a cold spell you need that blocking.

Of course we could still be lucky and get the block in the right place, we did last year in the early winter so lets be positive in that theres at least some signs that blocking may be appearing soon.

[cyclonic happiness]

The ECM is excellent in as much as how it's absolutely destroyed that bloomin polar vortex!

There has to be a really good chance with this that we can develope something interesting like a high pressure to the north ot the east in the time that it's still dissrupted?

[Glacier Point]

Looking at last nights NOAA 500hPa mean Hts forecast is quite interesting.I have found these to be quite good -,the times i have used them.

Here for example was their forecast on 9th Jan. for 6-10 days ahead--,so around today.

and todays GFS

not bad,maybe it overestimated the cross-polar heights but overall the modelling of the Azores High nearby and the placement of the main troughs and ridges are pretty close to where we are now.

This was last nights and the latest forecasts days 6-10 and 8-14.

actually Phil, the verification against anomaly looks like this...

>>

The GEFS AO and NAO runs have posted some impressive -ve values, and noteworthy on the NAO which might suggest depressions taking a more southerly track and keeping cold locked to the north. Expect the unexpected I suggest in the 5-10 day timeframe.

Given this and NWP output today, I suspect the CPC 8-14 dayer out in the next hour might show a positive anomaly over Greenland.

Edited January 17, 2012 by Glacier Point

[phil nw.]

actually Phil, the verification against anomaly looks like this...

The GEFS AO and NAO runs have posted some impressive -ve values, and noteworthy on the NAO which might suggest depressions taking a more southerly track and keeping cold locked to the north. Expect the unexpected I suggest in the 5-10 day timeframe.

Given this and NWP output today, I suspect the CPC 8-14 dayer out in the next hour might show a positive anomaly over Greenland.

Thaks GP-yes pretty good then.

Last nights output was promising for those +Ht anomols.to our north at the 10+day range so be it will be interesting to see if the new chart builds on that trend.

[stewfox]

The ECM is excellent in as much as how it's absolutely destroyed that bloomin polar vortex!

There has to be a really good chance with this that we can develope something interesting like a high pressure to the north ot the east in the time that it's still dissrupted?

There should be a ban on posting any chart post T144, the nerves won't take it.

Its like promising a 5yr old child on every single day that they will have a large ice cream next week ..then make them eat lettuce because thats all you can afford now in the reliable time frame. Its just cruel.

[nick sussex]

GP a quick question and not to put you on the spot but ECM 144hrs, your last line expect the unexpected!

I like the ECM 144hrs, my chart of the day, am I barking up the wrong tree?

Feel free not to answer this GP, I just realized the drama it might cause in here.

Edited January 17, 2012 by nick sussex

[stratty]

If you need a bit of eye candy, have a look at the CFS run throughout Feb

http://www.meteociel.fr/modeles/cfse_cartes.php?ech=894&code=0&carte=0&mode=2&run=10

[cold snap]

just as i was about to throw the towel in.cfs daily,goes hand and hand with the update from met office.i know a lot of you may not think its worth even looking at and clucthing at straws,see what you think,just thinking there i wonder if its like whats being seen in the ecm 32,febuary could be epic you know.just saying.

just as i was about to throw the towel in.cfs daily,goes hand and hand with the update from met office.i know a lot of you may not think its worth even looking at and clucthing at straws,see what you think,just thinking there i wonder if its like whats being seen in the ecm 32,febuary could be epic you know.just saying.

If you need a bit of eye candy, have a look at the CFS run throughout Feb

http://www.meteociel.fr/modeles/cfse_cartes.php?ech=894&code=0&carte=0&mode=2&run=10

stratty you beat me to it,mods feel free to delete my previous post

[cold snap]

If you need a bit of eye candy, have a look at the CFS run throughout Feb

http://www.meteociel.fr/modeles/cfse_cartes.php?ech=894&code=0&carte=0&mode=2&run=10

stratty you beat me to it,mods feel free to delete my previous post

[Frosty.]

The 12z model outputs, yes the model outputs, from the GFS, UKMO and ECMWF appear to continue the theme which has emerged over recent days towards a more Atlantic dominated pattern. The consistent trend towards flattening has seen first a potential easterly and then a potent northerly quashed. We are now left with -5 850hPa reaching the M4 corridor according to the GFS but one suspects that even this will push further north. Potential blocking mid-Atlantic at T144 is smashed by the developing low off Newfoundland at T168:

It really isn't as bad as you suggest, the models are at least looking similar to the first half of december with a good chance of cool/cold zoneality and a big improvement from the very mild spell we had at christmas. Having just read GP's latest post, i'm sure the models are going to be producing some much colder/snowier looking FI charts in the next 8-14 days, just need a bit more patience. After tomorrows mild interlude, the models show a colder spell, especially further north with snow risk increasing for northern hills.

[BLAST FROM THE PAST]

actually Phil, the verification against anomaly looks like this...

>>

The GEFS AO and NAO runs have posted some impressive -ve values, and noteworthy on the NAO which might suggest depressions taking a more southerly track and keeping cold locked to the north. Expect the unexpected I suggest in the 5-10 day timeframe.

Given this and NWP output today, I suspect the CPC 8-14 dayer out in the next hour might show a positive anomaly over Greenland.

Can you or someone post a link to the 8-14 cpc?

BFTP

[phil nw.]

Can you or someone post a link to the 8-14 cpc?

BFTP

Here you are

http://www.cpc.ncep.noaa.gov/products/predictions/610day/fxus06.html

Look on the left hand side at the search menu and click on the 500hPa links Fred.

[Cloud 10]

Can you or someone post a link to the 8-14 cpc?

BFTP

Climate Prediction Center - 8-14 Day 500mb Outlook

[TEITS]

The 12z model outputs, yes the model outputs, from the GFS, UKMO and ECMWF appear to continue the theme which has emerged over recent days towards a more Atlantic dominated pattern. The consistent trend towards flattening has seen first a potential easterly and then a potent northerly quashed. We are now left with -5 850hPa reaching the M4 corridor according to the GFS but one suspects that even this will push further north. Potential blocking mid-Atlantic at T144 is smashed by the developing low off Newfoundland at T168:

Good evening mate hope you are well.

The recent model output has been disappointing with regards to the trend of LP moving E instead of SE. Still the ECM ensembles are out and I think the mean in the extended range has dropped slightly compared to the 0Z.

http://www.knmi.nl/exp/pluim/vijftiendaagse/Data/15DAAGSE_06260_NWT.png

Still onwards and upwards with plenty of more fasinating model output likely to occur. I still don't think we have seen the end of the changes either!

[Tim Bland]

If you need a bit of eye candy, have a look at the CFS run throughout Feb

http://www.meteociel.fr/modeles/cfse_cartes.php?ech=894&code=0&carte=0&mode=2&run=10

If you look at that CFS run, even at 180hrs it is out of kilter with the likes of GFS / ECM. How can +800jrs have any accuracy if it is wrong in the short term - unless the other models are going to do a massive U turn which I doubt.

[Daniel Miller]

If you need a bit of eye candy, have a look at the CFS run throughout Feb

http://www.meteociel...0&mode=2&run=10

Hmm.. I wonder what the probability of the 1074hr chart verifying is? haaa...

Could someone tell me, what is the actual point to that? It seems like a waste of electricity to produce, even if it does look pretty..