Winter Model Discussion - Cold Hunting 08/01/13 00z Onwards

[bluearmy]

lets not get the ens out of perpective. we are looking at a varied model output at the moment and are merely wanting to see some support for the operational solution of greenland/iceland/scandi blocking. its not there on the 12z in abundance and the trend is to increase the number of mobile runs wrt previous ens suites. as one would say if it were colder solutions showing up, it s all about trends. lets hope this trend reduces on the next few ens suites. the next operational is usually visible in one of the previous runs ens members. a cluster of mobile runs just increases the chances that the next operational will be mobile. nothing more nothing less. no histrionics. just maths and experience.

EDIT: and a scan through the NH profiles makes it clear that on those runs which are mobile - we are in the wrong place hemispherically. i think there is only one or two members that diont have a distorted/displaced/shattered vortex

Edited January 8, 2013 by bluearmy

[mulzy]

Don't bother posting anything positive mate, everyone is freaking out saying the run is terrible because of the control. You would think that the run was predicting 20 degree temps. Jeso...

A little unfair - most people called the operational as they saw it and now we're calling the ensembles as we see it. The GFS, UKMO and GEM operationals are excellent/good. The ensembles are good in the short term, but a lot poorer than recent runs in the medium term (and yes I know things can flip again). That I think is a fair reflection of current NWP output.

[tight isobar]

Lets be clear here...if ecm follows suite its still not a done deal......or is it!!!!....

[Met4Cast]

I look at this and wonder why anyone is interested in making sweeping statements about FYI with respect to output and the good and the bad of it - and more-so the control because it is about diametrically opposed to the op - so if you dont like one you should not even be considering the other. Overall 850 and 500 mean is actually improved from a cold perspective on the 12z run overall

Reading this thread you'd think the cold spell was over listening to some of the negative comments.

Scatter continues into the medium term which was expected of course, the warmer ensembles skew the mean. I don't think anyone can realistically say whats going to happen beyond the weekend, my best guess is that we'll see the mean lower as the time approaches, that's often the case.

I'd dismiss both the Control and Operational to be honest, they're both on the opposite ends of the ensembles.

[Cheshire Freeze]

We've seen it time and time again where the ensembles trend against the stunning output with future op runs following suit accordingly. Hope it's not the case this time or the laptop will definitely get it

[nick sussex]

The GFS is a really wonderful run, the UKMO looks to be trending in similar fashion.

We await the ECM now but I would be surprised to see that continue with its trend of recent runs. You would expect to see some form of backtrack from it.

Perhaps not completely following the GFS/UKMO but some trend back towards them.

I see alot of talk re the ensembles but you have to weigh the operationals much higher within 144hrs because of their higher resolution.

Edited January 8, 2013 by nick sussex

[Stuie]

If Carlsberg did weather forecasts. Considering this is T90 and was not showing any signs of a snow risk until Sunday, this to me, being 4 days away is closer than we were in Dec (albeit the GFS). It does get better over the weekend if it does pan out.

[Tim Bland]

In low res are the ensemble perturbations exactly as reliable as the operational? Are they all at the same resolution? I always thought operational was second best to the op then the rest were allot less reliable?? Thanks in advance for anyone who knows?

[Captain Shortwave]

Very significant upgrades in the short term with a pretty sharp cold spell for the weekend into the beginning of next week. This is pretty well supported with the mean for london around -8/9. If this verifies that cold will be more problematic to shift even if the Atlantic does force a successful attack. Whilst there is a lift in atmospheric temperatures, the ground level temps are less responsive suggesting perhaps a settled spell under the azores high. Well that's my call on it at worst.

[Buzzit]

Last post from me for now as I dont want to get involved when the ECM starts rolling - I know this a bit IMBY but I think its very important to see just how much of a change has gone on in the FGS in the last 24 hours both in terms of the depth of cold this weekend and the pattern ongoing - I personally would be very suprised if the ECM is not onboard with this weekend when we see the 12z - peace folks...

[MR EXTREMES]

And the control isn't interested. I feared this, as we needed this and the Exeter run at 1800 to support the earlier frames.

Uncertainty remains I'm afraid. As always!

so why is the ukmo similar then?

[Met4Cast]

We've seen it time and time again where the ensembles trend against the stunning output with future op runs following suit accordingly. Hope it's not the case this time or the laptop will definitely get it

We've also seen time and time again where the ensembles play catch up and join the Op.

The fact the UKMO has trended the same way gives me a little more hope, the ensembles are excellent in the short term but then scatter into the medium term, as you'd generally expect.

[Cheshire Freeze]

I see alot of talk re the ensembles but you have to weigh the operationals much higher within 144hrs because of their higher resolution.

The issue here isn't within 144 hours Nick it's the 7-10 day period where a lot of the perturbations have backed off the Greenland high idea, instead opting to place more energy around this area and an attendent Atlantic incursion into the UK. In my mind, potential heights around Greenland are the difference between a cold snap this weekend followed by status quo and something rather more sustained.

[weather eater]

We've seen it time and time again where the ensembles trend against the stunning output with future op runs following suit accordingly. Hope it's not the case this time or the laptop will definitely get it

And we have seen it the other way round, which leaves us non the wiser

[Cheshire Freeze]

We've also seen time and time again where the ensembles play catch up and join the Op.

The fact the UKMO has trended the same way gives me a little more hope, the ensembles are excellent in the short term but then scatter into the medium term, as you'd generally expect.

The ensembles were already on board though, there was no catching up to do. Ahhh well we'll just have to wait and see! (as ever)

Edited January 8, 2013 by CreweCold

[Chris K]

Just got home from work and that sure is one cold run for the 12z GFS. Exciting times model watching no matter what the outcome. (Crosses fingers for at least one spell of snow)

Who has got a beer and palpatations waiting for the ECM...go on be honest

[garbagebags]

Forgive my ignorance but could the big ensemble scatter fairly early on be down to possible effects or "unknown effects" of the SSW? might the models be struggling with it?

[Dampdorset82]

We've also seen time and time again where the ensembles play catch up and join the Op.

The fact the UKMO has trended the same way gives me a little more hope, the ensembles are excellent in the short term but then scatter into the medium term, as you'd generally expect.

Exactly, the UKMO is coming on board the GEM is looking positive. With the differences in the ensembles suite it would be near impossible to produce a scenario so looking across the models and seeing agreement is where I would pick up a trend. The ensembles of course will be all over the place depending on how it places the PV and with the displaced PV at the moment the output of blocking and colder condtions is where we will be heading in the med term..

[ChartViewer]

BOM at 144 looking ok

T168 Very nice

Edited January 8, 2013 by ChartViewer

[Met4Cast]

The ensembles were already on board though, there was no catching up to do. Ahhh well we'll just have to wait and see! (as ever)

Not really - There was always a lot of scatter beyond the weekend and the 12z shows nothing different about that. It's a big upgrade in the shorter term with the ensemble mean dropping further still.

The ECM 00z ensembles were brilliant with London temperature mean not getting above 4c throughout the entire run. I don't think we have too much to worry about, until we start seeing a big shift in all models, I think we're okay.

[Rocheydub]

so why is the ukmo similar then?

very broad question that I haven't got the time to answer.

A few people jumping down my throat for stating facts. Yes the GFS op was superb for most, but there was less support than I anticipated, and the control goes off on one completely different. Hence my lack of faith. I isn't say it wasn't going to happen, just that uncertainty reigned still!

Anyway, back on topic, ECM rolling out. Time will tell.

I certainly don't want to get into a he said-she said childish debate. You'd swear MY lack of current positivity would cause this cold spell to fail!

Think ill skip posting here for a while if that's what to expect.

[Iceberg]

Re ECM coming out now, what is shows beyond t120 isnt really important. its model agreement out to T120 we need today and tomorrow, anything beyond this time will certainly change anyway. Just saying this to preempt any posts saying that the ECM is terrible at T168 so its all over.....

[MR EXTREMES]

ecm t48 clearly shows a cooldown but is it the deep cold will skirt by the east coast....in future frames

Edited January 8, 2013 by model rollercoaster

[Southender]

So it seems the forum has gone from chasing the cold to chasing the mild?

Massive upgrades in the reliable/semi reliable and lots of you are now concerning yourselves with outcomes over a week away.

Come on people lets get a sense of perspective here. The cold is showing its hand from this weekend. Lets see if it arrives first before worrying about it leaving.

[Cheshire Freeze]

Not really - There was always a lot of scatter beyond the weekend and the 12z shows nothing different about that. It's a big upgrade in the shorter term with the ensemble mean dropping further still.

The ECM 00z ensembles were brilliant with London temperature mean not getting above 4c throughout the entire run. I don't think we have too much to worry about, until we start seeing a big shift in all models, I think we're okay.

If you look at the ensembles for the 500hpa level you can clearly see the large mild 'hump' which hasn't been so pronounced on other suites. This suggests that the appetite for deep cold amongst the ensemble members has diminished on this run. There is actually quite good agreement on this, despite the 'scatter'. It suggests either HP over the UK as a mid latitude feature or Atlantic incursions over the HP.

I'm in no way suggesting this will be the outcome as it may reverse on the 18z but it's food for thought if nothing else.

Edited January 8, 2013 by CreweCold