snowwman
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Posts posted by snowwman
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I thought from reading this thread this afternoon that the world had ended, and it seems to be centred around a single GFS run. Even this run's ensemble stamps at day 16 are in favour of blocking or blocking potential; 13 out of 20 go for this
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Not sure we need to worry too much about that UKMO low, as it seems to be being pushed North- East over us, by the high moving in said direction. The high is being fuelled by the Canadian PV lobe.
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Yup, Something between a Northery and and Easterly is where I think this run's headed. Most likely outcome: sustained Easterly (with undercutting latter on).
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To my thinking, ECM is going for a sustained Easterly- sort of like the 12Z GFS but which sticks around.
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26 minutes ago, supernova said:
It cannot be coincidence that charts like the ECM240 are as rare as rocking horse poo....and the chances of it actually verifying are similarly unlikely. That said, it's a delight to have some colder weather incoming in the reliable, and the number of ensemble members tending colder still are increasing as an overall trend despite the usual scatter.
Does seem unlikely with the strong vortex to the North, but GFS Para supports a shifting of the vortex to Siberia over the past 24 hours' available runs. This may be what ECM is in the process of doing in this chart.
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2 minutes ago, Purga said:
Omega, Omega wherefore art thou Qmega?
Steve M - energy going under to create a cut off High?
For coldies, an excellent ECM run, and the GEFS output is decent, too, even to day 16.
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12 minutes ago, SN0WM4N said:
Far the opposite I'm afraid. The 2nd trough in the Atlantic stops heights retrogressing west and will flatten the pattern faster.
It's tempting to think that- after all, it's what almost always happens in these scenarios. However, a check through charts dating to cold and snowy winters of the past often show "horrendous" set-ups, shortly before strong Northern blocking establishes. As far as GFS at 204 is concerned, it could easilly go Northerly from there.
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5 minutes ago, Man With Beard said:
You know what, maybe that ECM mean doesn't really mean anything this time. It's a pretty much 50/50 split between cold and less cold in FI.
Definitely a cold cluster in there towards the end of the run, though.
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Latest available ECMWF ensemble at mean for D10 maintains low heights into the Med, just about, and certainly leaves a reload of the Northerly open:
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2 minutes ago, frosty ground said:
It looks like a reload to me
Just what I was thinking.
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25 minutes ago, radiohead said:
I think it's PRX on this.
So basically, from what I can make out, it's done no worse than GFS and may even be somewhere between GFS and ECMWF. Tells me that perhaps we should taking this model's output more seriously.
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I'm interested in finding- out how GFS Para has performed since it became functional. Anyone have any stats?
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30 minutes ago, abbie123 said:
The Atlantic breaks through around Christmas time but not for long as the high to east says no I'm the boss I'm here to stay maybe this is first Hint That high wants to push north west or north east more runs needed.
Indeed, this is interesting. I noticed that yesterday's 12Z ECMWF retrograded the Siberian high, so this idea has support.
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10 minutes ago, ArHu3 said:
And we didn't have a weak (or strong) 10hPa vortex that winter, before the very cold February 1986.
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12 hours ago, bluearmy said:
Can anyone find an anaolagues for such a weak autumnal start vortex becoming so strong (in zonal wins speed) so quickly ? Just wondering what might happen to it as it shows little sign of relenting high up in its attempt to mimic last years chap yet has not had the same time to mature. Stewart mentioned some time back that word 'imposter'. is there precedent ??
Haven't found a close anologue, but examining some of the winters in the list here:
https://ozonewatch.gsfc.nasa.gov/meteorology/wind_1985_MERRA2_NH.html
I can't find any relationship between 10hPa wind speed and direction and surface cold in the UK, even factoring- in delays, but then haven't run a comprehensite analysis. Others may conclude otherwise.
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It's worth noting that the models in the above MJO chart have differing end-points. You have to examine each one separately to have a better idea of what they're saying. One might think, for example, that UKMO goes to the 25th, whereas is doesn't- the end of its run is much closer in, and that by said date might be much more impressive.
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Remarkable stuff from the GFS ensembles- everything from an Easterly to a Northerly!
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10 minutes ago, Starsail said:
With the focus that many people put on the stratospheric temperature, split pv's and ssw's it would seem almost incredible that your findings, if true, have been overlooked. I think people can agree that LRF's and global drivers are rightly under scrutiny just now. Lorenzo made a very honest, heart felt post a few days back where his exasperation was almost palpable. The conclusion may be that the forecast regarding blocking is actually not far off the mark but in terms of conditions on the ground on our small island, it would be hard to make a case for a front loaded winter (yet).
I have followed with real interest developments from early November.The front loaded winter, due to start early December initially, then mid December, now last third of December looks like it may not happen at all. Is it possible that in all the complexities, there could be something very simple, that is overlooked. I suspect the answer is no, but your post Snowman gives food for thought.
I used a very crude measure to evaluate the progress of such a forecast. From early December, I looked at the T850 GEFS ensemble mean for 15th December on the 00z, for my area and it oscillated +/- 2 C around the 0 C line but at no point was there any suggestion of something in the offing.regarding cold. The shorter range models simply did not buy it.
The important thing is don't take my word for it- I'm not a pro and have very limited access to data, and that data might contradict other data, but I concluded in honesty what I did from what I had. I would hope that any of what we know about the strat would be of a better quality than my own research, and that human error is minimized, in the implications for the model output.
And about the shape of the vortex, exactly, Steve- that's what it's about.
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3 minutes ago, Steve Murr said:
I will look later - however I didnt check whether a secondary warming perpetuated the winter
ERA data suggests no warming events - however obviously thats relating to the technical definition
It's surprizing how much variation there is between sources. As you suggest, it depends on how you define them. I do wonder, given all this, whether the weather models have properly integrated what we think we know about SSW data into their output.
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6 minutes ago, Steve Murr said:
Ive already checked on NCAR its 12th & 13th over siberia...
bang on 2 weeks later was the propergation-
Im on the road at the mo- will add a post in winter thread later
Will tag you
s
28th January:
, so couldn't have caused it. Not a criticism of your reaearch, Steve- in fact I'm a fan of your posts. Just thought I'dd add a little of my own research so we wouldn't be as worried about 10hPa forecasts from various models!
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6 minutes ago, Steve Murr said:
When you say negative CETs do you mean sub ave or sub zero?
Sub zero.
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12 minutes ago, Steve Murr said:
Good link
The Merra reanalysis will be very similar to the ERA interim reanalysis
it does surprise me around the negative CETS- did you consider the 2 week propergation window?
next level of analysis is whats the best case scenario with no SSW...
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just adding to that - The SSW correlations are more concentrated towards the -AO not UK CET
so a SSW enhances the probability of a could outbreak in the UK-
I did some personal research on 62/63 & 100% the SSW caused that opening outbreak of cold
anyone want any proof? Look at the 10hpa warming on 12-13 Dec 1962- same as 2009
S
As I recall, the SWW in 1962 happened way after the cold set in on in late December. I'll try to recover some of the data and get back to you.
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3 minutes ago, Steve Murr said:
Good link
The Merra reanalysis will be very similar to the ERA interim reanalysis
it does surprise me around the negative CETS- did you consider the 2 week propergation window?
next level of analysis is whats the best case scenario with no SSW...
As I recall, I factored that in, and even went to 4 weeks.
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3 minutes ago, Ed Stone said:
Well said. Of course SSWs and split PVs can increase the likelihood of a cold outbreak, but neither is strictly necessary, IMO...So, I'll no' be writing January off just yet. I just hope that this afternoon's GFS 12Z is a wee bit better than was the 06!
I'd like to re run my analysis, but I concluded the last time that a split strat is positively harmful for our chances of cold.
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Model Output Discussion 29th December - Into mid-Winter.
in Forecast Model Discussion
Posted · Edited by snowwman
Intense height anomaly in the strat over Greenland. If that were to propagate downwards and directly, that would spell a Greenland block. However, there's a question as to whether the downwelling would be vertical, as the stratospheric and tropospheric vortices are often in different locations.