Model Output Discussion - 26th December - 1st January

[bluearmy]

Well the latest GFS is an outlier but can anyone explain why GFS continue to use their mildest run please? The ensembles are trending down in temperature so not all bad and if the outlook was a jigsaw puzzle, we would have the corners sorted; still some work to be done but the pieces should start showing the picture soon; a seasonal offering I proffer.

"When I no longer thrill to the first snow of the season, I'll know I'm growing old."

They don't ' choose it'. It's the operational run. It's at a higher resolution than the ens throughout so it should be more accurate (but if it generally isn't, expecially when it disagrees with it's ens and other nap)

[Beasterly]

ECM 00Z continues to show the PV split under an influence of an Arctic high.

Please correct me if i am wrong

[Terminal Moraine]

GFS 00Z looks a major outlier. It is the mildest of the runs. Take a look at the GFS mean dropping to -5 at the end of the run with most trending downwards towards the end of the run. So a pattern change looking more confident this morning.

I wouldn't go so far as to say the operational is a major outlier, not until the final day at least, though admittedly it is among the milder members from the 5th onward, but then so is the control run for much of the time.

A straw to clutch at is the fact that the operational becomes one of the mildest members at about the time scale where lower resolution takes over from high. I suspect that future runs from the GFS will lean more towards the 00z ECM which shows at least polar maritime air across the country ( which would take us back to the conditions of early/ mid December) if not an attempt at a mid-Atlantic ridge reaching out towards Greenland.

In the meantime the low on Wednesday should provide some interesting weather for northern areas and as it moves away there's a good chance of hail, rain and sleet showers ( snow above about 350mts ) over north western areas, feeding into the Midlands on a strong north westerly.

[Frosty.]

The Ecm 00z shows a good blast of cold zoneality next week with the jet tilted nw/se and that would mean wintry showers spreading to most of the uk with widespread frosts and a lot of snow in the north, especially for northern hills, the gfs ensembles are trending colder so don't anyone be mislead by the op run as it's a mild outlier. Hopefully in the meto update today it will have more mention of snow and frost than previously. As for this week, it looks stormy in the north tomorrow and then colder with wintry showers.

Edited December 27, 2011 by Polar_ Low

[bluearmy]

The Ecm 00z shows a good blast of cold zoneality next week with the jet tilted nw/se and that would mean wintry showers spreading to most of the uk with widespread frosts and a lot of snow in the north, especially for northern hills, the gfs ensembles are trending colder so don't anyone be mislead by the op run as it's a mild outlier. Hopefully in the meto update today it will have more mention of snow and frost than previously. As for this week, it looks stormy in the north tomorrow and then colder with wintry showers.

Today's meto 30 Dayer will be the first one since the ECM op decided to go more amplified early jan. I doubt that exeter will change their outlook too much but will be interesting to see if the nuances move colder. I think they would wait for two con sec cold 32 day runs before shifting their stance.

[The PIT]

ECM lurches back to GFS version of events with a strong mobile Atlantic with mild windy weather dominating. Stormy at times in the north while the south east probably has a lot of dry settled weather which won't be good for the water shortage.

[bluearmy]

ECM lurches back to GFS version of events with a strong mobile Atlantic with mild windy weather dominating. Stormy at times in the north while the south east probably has a lot of dry settled weather which won't be good for the water shortage.

Hello, is anyone there? I suggest you have a good look at the models before posting. None of the the majors are lurching anywhere. gfs op remains many mild. ECM op remains many cool. That would seem to promise generally average if you weight each model the same.

[Cloud 10]

ECM lurches back to GFS version of events with a strong mobile Atlantic with mild windy weather dominating. Stormy at times in the north while the south east probably has a lot of dry settled weather which won't be good for the water shortage.

I must be viewing a different ECM!

Also the CFS should come with a health warning!

Meteociel - Modèle Numérique américain CFS

[Cecil Hogmanay Melchett]

ECM op looks promising.

Although the ens mean is not as promising and loooks flatter.

GFS continues to churn out mild outlier after mild outlier,why dont they just turn the lights out at HQ GFS?

[Uncle_Barty]

ECM 00Z continues to show the PV split under an influence of an Arctic high.

Please correct me if i am wrong

The chart you show does not and will not show that.

This is the chart you need - and it certainly shows the vortex far less organised and some amplification taking place. Still early days yet and remember that even this is 10 days away.

Edited December 27, 2011 by Jim_AFCB

[bluearmy]

ECM op looks promising.

Although the ens mean is not as promising and loooks flatter.

GFS continues to churn out mild outlier after mild outlier,why dont they just turn the lights out at HQ GFS?

HD, by definition, the mean will always be flatter the further it progresses. Fwiw, the ECM spreads at t240 shows blocking of sorts to our west, some runs clustering close to the uk, others closer to se Greenland. the NH pattern is amplified for an mean at 10 days.

[Tom D]

Also the CFS should come with a health warning!

Meteociel - Modèle Numérique américain CFS

The CFS is certainly showing a nice Greenland-Europe block after 400 hours. Will be interesting to keep track of this possible trend of a drastic change in weather patterns come mid-January.

While the ECM and CFS at +240/252hrs look very dissimilar, the CFS eventually brings a decidedly similar set-up by +372, at least for the North Atlantic.

ECM t+240

CFS t+252

CFS t+372

[phil nw.]

The models still show plenty of cyclonic activity to our North in the next few days with the stubborn high to our south relunctant to give way.

http://www.wetterzen...ics/Rukm721.gif

http://www.wetterzen...cs/Rukm1441.gif

so changeable with alternating mild and colder days as fronts move across with some rain bands followed by brighter conditions with showers,sometimes wintry for the north and west.

Some differences in detail further on-the GFS keeping a flatter pattern whereas the ECM digs a trough further south east into Europe- promising a much colder cyclonic regime at the end.

http://www.wetterzen...s/Rtavn1921.png

http://www.wetterzen...cs/Recm1921.gif

The differences are clearly illustrated on the 00z mean hts chart.

http://www.meteo.psu...WF_0z/test8.gif

The GFS Op. run whilst a milder run in the ENs,also goes against it`s own 8-14 day forecast from last night

http://www.cpc.ncep....y/814day.03.gif

which shows a similar NW/SE tilt to the flow further on and that Euro high pulled west into the Atlantic -simialr to the 00z ECM.

A step forward,albeit a small one if you are looking for a colder pattern later.

Edited December 27, 2011 by phil n.warks.

[dixonoid]

Is this the blocking us coldies have been searching for?

[nick sussex]

I wonder if the ECM is being too progressive with the PV split, we have seen this in the past from it.

Because of this I wouldn't read too much into its post 168hrs output, looking upstream NOAA are happy to go with the more amplified and slower solutions of the ECM/UKMO although they think the ECM operational run begins to lose support from next Tuesday.

BY

SUNDAY...THE 00Z GFS/00Z CANADIAN/00Z GEFS MEAN PROGRESS THE

TROUGH A BIT FARTHER EAST THAN THE 00Z UKMET/00Z ECMWF/12Z ECMWF

ENSEMBLE MEAN. SINCE THE FLOW IS SO AMPLIFIED UPSTREAM...A

SLOWER/MORE AMPLIFIED TROUGH EAST OF THE PLAINS MAKES SENSE.

Full discussions here:

http://www.hpc.ncep....epd/preepd.html

I should mention the GFS or its ensembles have not been used at all in their outlook which is probably a good thing if you're hoping for some colder conditions.

Looking at the ECM ensemble maps upto 168hrs:

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

Generally the same overall pattern but differences in the angle of the jet, there is some support in those for the GFS operational run so we still need that to come on board.

The key really is getting to the nw/se tilt in the jet before thinking of any possible change to colder conditions, so I'd put the champagne on hold until we see this agreed on across the board.

After that its down to the Russian high to help lock in lower heights over Europe and force the jet to remain angled favourably, where things go after that if we get to that stage is still uncertain.

Edited December 27, 2011 by nick sussex

[UV-RAY]

It all sounds so straight forward Nick, what could possibly go wrong!

[Duane S.]

Viewing the 00zs this morning and I have to say the most promising collection of charts of the winter so far. I was already loving the GFS (even more after viewing the ens later on) not obviously for its predicited outcome but for sheer potential. It has joined the ECM and unlike a couple of comments mistakenly suggesting otherwise, the ECM continues to offer up oodles of interest going towards that 2nd week of Jan.

Plenty of kicks in the teeth from the models in days to come no doubt but plenty of stonking charts are going to be on offer as well I strongly suspect. Keep watching the AO index forecasts, they will trend negative very soon.

Edited December 27, 2011 by Osbourne One-Nil
Quoted post has been removed

[nick sussex]

It all sounds so straight forward Nick, what could possibly go wrong!

Lol!

Nothings ever straightforward with trying to get colder conditions into the UK, maybe the last few winters have made things seem easier but thats not the norm and what we have at the moment is trying to break out of a very common UK winter pattern.

If we get to the nw/se jet tilt then I could find a plausible route to something much more interesting but for the moment given the overall NH pattern thats absolutely essential, no nw/se jet then get the prozac out!!!

Early stages of the GFS 06hrs run has slowed the trough moving east out of the US plains and also a bit more amplified upstream.

Edited December 27, 2011 by nick sussex

[wolvesfan]

Morning all,

I for one am going to enjoy ECM, clearly the best output we've seen for a while,its not deep cold by any means but a clear pattern change nevertheless.A cold period IMHO could well develop from ECM,mid atlantic high pressure building further north,Russian block building and NAO,AO trending more -ve.

UK met not as amplified as ECM at around t144,but both models much better viewing than GFS thats spewing relentless mild at the moment.

[shedhead]

There appears to be a general assumption by most on here that ECM will be right, probably because we want it to be and it ties in with the current strat warming. However as Nick has pointed out, NOAA are not overly happy with the ECM evolution post 168hrs and GFS has been the model of consistancy recently, so as ever more runs are needed before any of us can become complacent re any change to a cold, blocked pattern.

[Duane S.]

There appears to be a general assumption by most on here that ECM will be right, probably because we want it to be and it ties in with the current strat warming. However as Nick has pointed out, NOAA are not overly happy with the ECM evolution post 168hrs and GFS has been the model of consistancy recently, so as ever more runs are needed before any of us can become complacent re any change to a cold, blocked pattern.

For me it's not about any sort of complacency or the ECM coming off as it's showing, I too think it is very progressive and unlikely to break up the vortex with that much apparent ease but more about the increasing hints in FI that a pattern change is on the way. If this had happened in November / very early December I would have dismissed it as unlikely but now it ties in with other signals. We don't have everything in our favour and the charts/changes are not perfect but it's probably the best we could hope for from this point and time. PLUS... this time last year the fun and games were drawing to an end for the winter, this year we've got a much more interesting 2nd half of winter in prospect!

[Uncle_Barty]

Is this the blocking us coldies have been searching for?

Not really. Look at the colours over most of Greenland. Still blue, indicating low heights at the 500mb level. Surface high pressure over Greenland is just that - you need blocking at higher levels too otherwise any high pressure there will most likely be transitory.

This is a proper Greeny block -

Edited December 27, 2011 by Jim_AFCB

[nick sussex]

There appears to be a general assumption by most on here that ECM will be right, probably because we want it to be and it ties in with the current strat warming. However as Nick has pointed out, NOAA are not overly happy with the ECM evolution post 168hrs and GFS has been the model of consistancy recently, so as ever more runs are needed before any of us can become complacent re any change to a cold, blocked pattern.

The GFS 06hrs run at least within 168hrs has moved towards the ECM with more amplification in the USA but the lower resolution looks poor from a cold perspective.

For the timebeing I'd stick to within 168hrs regardless of what the FI output shows, I wouldn't bank on any PV split unless its shown within that timeframe.

Edited December 27, 2011 by nick sussex

[Cecil Hogmanay Melchett]

The GFS 06hrs run at least within 168hrs has moved towards the ECM with more amplification in the USA but the lower resolution looks poor from a cold perspective.

For the timebeing I'd stick to within 168hrs regardless of what the output shows, I wouldn't bank on any PV split unless its shown within that timeframe.

we really are stuck in the most awful rut nick.

Every time you think potential along comes another jet streak out of the states and flattens the whole thing out.

I really can't for the life of me see a way out of tis pattern before mid Jan at the earliest personally.

[Jason M]

They don't ' choose it'. It's the operational run. It's at a higher resolution than the ens throughout so it should be more accurate (but if it generally isn't, expecially when it disagrees with it's ens and other nap)

I have a feeling that the opp runs in lower resolution to the ensemble suite in the low res timeframe. I'm sure this has been raised on TWO a number of times. Assuming that is / remains correct you can pretty much discount the opp run in la la land if the opp and ensembles pretty much agree at the end of the high res part of the run. I suspect it also explains why the opp run nearly always defaults to zonal and is usually amongst the mildest of the runs at the end.

Jason