Model Output Discussion - 26th December - 1st January

[nick sussex]

Hope everyone had a good Christmas.

Models gave a tease in FI on the big day, so at least there is sign of some pattern change.

Mid Jan-Late March we can Still get an arctic blast, its not over till the fat lady sings, and what is this Bartlett nosence. All I see is High pressure displaced from the azores.

Nick I watched a Documentary on Snowstorm Britain regarding the January 09 snowfall, which is what I guess you was talking about? Look to our E/NE. Can such a pattern we have at the moment provide that?

At the moment any really cold weather isn't possible. Even if you take the ECM at face value that would still need time to develop.

The first thing though is to remove that high from the south and angle the jet nw/se, there is a good chance that we will see this. As long as you get the Russian high orientated nw/se this will exert some pressure on that trough and force lower heights into central Europe, remember the energy from the jet has to go somewhere as it runs east, as this gets diverted se it should help strengthen the high to the ne but to get from there to much colder conditions you need the pattern upstream to amplify more to help pull the displaced Azores high much further north and west, this in tandem with the sinking trough over Europe might eventually deliver something more interesting.

But as I've said today theres no chance of anything colder if we don't at least get to the nw/se jet, for the timebeing thats the most important aspect in the modelling.

[Robbie Garrett]

That does make some sort of sense, as a flat jet would just blast it out the way? I'm guessing, that once the jet does tilt if it does tilt it will push the high in another direction. Allowing floodgates to open.

When you mean amplification, you mean simething to change its velocity and angle in the states? So its direction over Europe is different.

Also am I correct in saying, if this happens without stratospheric warming, whateer the polar temps are, if and really cold air digs deep, its temperature would be far colder, then lets say if we had SSW?

[Duane S.]

True, the GFS is the 3rd or 4th more accurate model at the moment and the ECM and UKMO and consistently better. The GEM is almost as accurate and you don't get people obsessing over every detail of each of it's runs. ECM is king in my experience.

Current verifcation stats

Ensemble P4 is a stunner, beast from the east

Imagine if that showed up on the OP, total meltdown in here lol

Indeed. I watched through the the evolution of this one and it's plausable for sure. A shortwave heading over the top of our high pressure arrives as the PV splits, this allows the Russian high to ridge Westwards and voila! undercut occurs and suddenly we have robust low pressure sat underneath us & very dominant looking blocking bringing us in a cold continental airmass and a lot of hefty snow showers no doubt. Very progressive but certainly remains as an outside chance. That said we may face the prospect of a fightback from a reforming vortex EVEN if that happens but I'd take that right now!

[Alex]

Let's be honest upto a few days ago the CET was running around avg and with the current Synoptics I think this is very good for cold lovers. I think a change to a different pattern is a definite however when is the question!

There's been talk for a week now of things looking more favourable in the longer term but it's a long way off, the met office obviously aren't too convinced, their outlooks are more of the same zonal type weather.

Often or not especially in the last few years, seasons have been rather similar once something gets going, take this year for example and spring, summer and autumn all followed a similar pattern.

My point is that, yes the CFS shows a more favourable colder pattern in the new year but there isn't enough evidence yet to suggest a big change. Added to the fact that December is running just above average, even with the zonal type weather, cold lovers can be occasionally satisfied with a few cold days thrown in - nothing out of the ordinary for a typical UK winter. 2009, 10 and December last year were very abnormal.

[Frosty.]

The latest meto update is dominated by rain and strong winds, any snow confined to northern hills and mountains and temps generally average or above which suggests the gfs model is being followed more than the ecm 00z. The winter so far has been forgettable and up to now the experts don't foresee any changes that would push us into a colder phase. The meto update also continues to suggest that high pressure to the south won't be going anywhere as sunshine amounts in southern areas are expected to be above average but rainfall to remain above average in the far north which also implies that lows will continue to blast across northern britain from time to time...so while it doesn't look like the 14 and 15c on xmas day and boxing day will be repeated for a while, it doesn't look like there will be any lying snow in the southern half of the uk either.

Edited December 27, 2011 by Polar_ Low

[Backtrack]

The latest meto update is dominated by rain and strong winds, any snow confined to northern hills and mountains and temps generally average or above which suggests the gfs model is being followed more than the ecm 00z. The winter so far has been forgettable and up to now the experts don't foresee any changes that would push us into a colder phase. The meto update also continues to suggest that high pressure to the south won't be going anywhere as sunshine amounts in southern areas are expected to be above average but rainfall to remain above average in the far north which aslo implies that lows will continue to blast across northern britain from time to time.

If I remember correctly, am I right in thinking that the ECM was outshining the GFS the last 2 winters?

[Frosty.]

If I remember correctly, am I right in thinking that the ECM was outshining the GFS the last 2 winters?

i'm not sure about the verification stats but I tend to favour what the ecm shows as it is less liable to the wilder swings of the gfs but i'm not exactly thrilled with the latest meto update as it doesn't sound wintry at all.

[swilliam]

People always say that the models are more accurate during zonal periods but the latest data on model accuracy does not support this.

It can be seen that the verification rate was at about 0.9 a few days ago but has dropped to nearly 0.7 for all the models during the current mild spell. I think we believe they are more accurate during this kind of weather (uninteresting mild mush) because we skip over them. When they are showing cold and especially snow we examine them in every detail and criticise them when they are slightly out.

[weatherguy]

i'm not sure about the verification stats but I tend to favour what the ecm shows as it is less liable to the wilder swings of the gfs but i'm not exactly thrilled with the latest meto update as it doesn't sound wintry at all.

Do the met not wait until a pattern change is more or less set in stone before they change their long term forecast? They're probably waiting for the short term uncertainty to pass before they make any dramatic changes to their long term outlook.

[phil nw.]

Do the met not wait until a pattern change is more or less set in stone before they change their long term forecast? They're probably waiting for the short term uncertainty to pass before they make any dramatic changes to their long term outlook.

There`s nothing in the output to confirm any big pattern change yet though WG.

Essentially all that`s certain-as anything can be in the model world-is an Atlantic driven Westerly pattern--changeable some brief cooler days.

There are indications towards days 8-10 by the ECM in particular that we may get a more North Westerly tilt to the flow but that`s all-so the Met are not holding anything back wrt to their outlook.

[kev238]

From reading this forum, pattern change has been an ongoing discussion for weeks. Yet, the output still remains broadly similar in my opinion.

I think the met office 6-15 day and 16-30 day updates have been great the past couple of months. They picked out more unsettled weather with cool periods at start of december, mentioned milder in run up to christmas, more mildness just before new year. Now they are mentioning very average weather with potential for transient cold at best. There is no hard evidence of pattern change; just the odd glimpse from a model from time to time.

I reckon within the cet are area up to 15th Jan a cet of about 0.5 to 1 degree above average, rainfall slightly below.

[January Snowstorm]

I find it funny how there's so little credence given to GP's latest update.

Everything is on track for a bitterly cold late Winter & the models will soon be showing this.

He's been spot on so far

[leicsnow]

I find it funny how there's so little credence given to GP's latest update.

Everything is on track for a bitterly cold late Winter & the models will soon be showing this.

He's been spot on so far

GP's latest update? I'd like to read it. I can never find people's updated outlooks after their initial forecast, can you tell me how I can view it?

[lorenzo]

GP's latest update? I'd like to read it. I can never find people's updated outlooks after their initial forecast, can you tell me how I can view it?

GP updates in this thread and also in the Technical discussion threads.

Latest entry is here explaining the MJO analogs and their precision thus far in the forecast.

http://forum.netweather.tv/topic/58354-in-depth-technical-model-discussion/page__view__findpost__p__2198001

[weatherguy]

There`s nothing in the output to confirm any big pattern change yet though WG.

Essentially all that`s certain-as anything can be in the model world-is an Atlantic driven Westerly pattern--changeable some brief cooler days.

There are indications towards days 8-10 by the ECM in particular that we may get a more North Westerly tilt to the flow but that`s all-so the Met are not holding anything back wrt to their outlook.

Indeed, that's my point; all we have right now are indications with regards to the pattern change, far from set in stone. So we can't really expect the meto to change their outlook until, as I say, the short term uncertainty is behind us and a pattern change is a much greater probability.

GP's latest update? I'd like to read it. I can never find people's updated outlooks after their initial forecast, can you tell me how I can view it?

He posted it in the in-depth model discussion thread

[Mark Neal.]

I think the met office 6-15 day and 16-30 day updates have been great the past couple of months.

Who's to say they will won't start to go wrong, they will be considerably accurate .But perhaps they are waiting for a big change before entering a more seasonable look on there outlook.

[nick sussex]

The updated preliminary discussions from NOAA are interesting in terms of the GFS and the GEFS ensembles.

Bearing in mind that the earlier timeframe in terms of the amplification upstream is important for how the ensemble solutions can develop together with the operational run:

THE GUIDANCE SHARES THESE

IDEAS....EXCEPT THAT THE GEFS FAMILY OF ENSEMBLE SOLUTIONS IS MUCH

FLATTER AS THE TROF BEGINS TO DEVELOP SUN DAY 5. WHEN IT THE GEFS

FINALLY DOES DEVELOP THE TROUGH...IT IS STILL WEAKER AND FARTHER E

WITH IT EARLY NEXT WEEK THAN THE CORRESPONDING ECMWF FAMILY OF

SOLUTIONS.

There is still a little criticism for the ECM operational run by next Tuesday but overall they are happy to go with it and its ensemble mean, if the GEFS solutions are all too flat to begin with then this will become compounded as they go out in terms of timeframe.

So in a nutshell you can bin them!

Other interesting quotes from NOAA

HOWEVER....THERE IS

STRONG SUPPORT FROM ECENS ENSEMBLE SPAGHETTI PLOTS FOR A

DEEP...YET LESS DRASTIC...FULL LATITUDE TROUGH MARCHING EWD ACROSS

THE ERN HALF OF THE NATION SUN-TUE. THE RUN TO RUN CONSISTENCY OF

THE DETERMINISTIC ECMWF WITH THIS AMPLIFYING

TREND FOR EARLY NEXT WEEK...AND THE LONG TERM GOOD SCORING OF THE

ECENS MEAN...PERSUADED US TO LEAN HEAVILY ON THE ECENS MEAN AFTER

DAY 5.

Full discussions here:

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

Edited December 27, 2011 by nick sussex

[leicsnow]

I think everything until the end of the first week of January is pretty much set-in-stone, and with the second half of the month there is nothing set-in-stone IMO. So the second week sort of falls somewhere inbetween. The Met Office probably won't start to change their outlook until the models start to consistently show pattern change in the short to moderate term.

GP updates in this thread and also in the Technical discussion threads.

Latest entry is here explaining the MJO analogs and their precision thus far in the forecast.

http://forum.netweat...ost__p__2198001

Thanks!

Edited December 27, 2011 by Tellow

[weatherguy]

HOWEVER....THERE IS

STRONG SUPPORT FROM ECENS ENSEMBLE SPAGHETTI PLOTS FOR A

DEEP...YET LESS DRASTIC...FULL LATITUDE TROUGH MARCHING EWD ACROSS

THE ERN HALF OF THE NATION SUN-TUE. THE RUN TO RUN CONSISTENCY OF

THE DETERMINISTIC ECMWF WITH THIS AMPLIFYING

TREND FOR EARLY NEXT WEEK...AND THE LONG TERM GOOD SCORING OF THE

ECENS MEAN...PERSUADED US TO LEAN HEAVILY ON THE ECENS MEAN AFTER

DAY 5.

Thanks Nick, might this be supportive of a weakening of the PV as energy is diverted southwards away from the pole? Or is my understanding of this some way off?

[recklessabandon]

From reading this forum, pattern change has been an ongoing discussion for weeks. Yet, the output still remains broadly similar in my opinion.

I think the met office 6-15 day and 16-30 day updates have been great the past couple of months. They picked out more unsettled weather with cool periods at start of december, mentioned milder in run up to christmas, more mildness just before new year. Now they are mentioning very average weather with potential for transient cold at best. There is no hard evidence of pattern change; just the odd glimpse from a model from time to time.

I reckon within the cet are area up to 15th Jan a cet of about 0.5 to 1 degree above average, rainfall slightly below.

To be fair Kev you make a point, but I think if you cut through the 'hopecasting' and people trying to find pattern change which isn't really robust/supported, you will be left with the LRFs from more experienced members of the forum who have been generally consistent with a mid (ish) January pattern shift. With a lack of perceived interest through December in the models, it has been inevitable that people are looking for the upstream signals for the pattern changes GP, BFTP etc have been talking about.

BTW, IMO it is far easier to create a wooley generic 15-30 dayer during zonal conditions....fair chance of some element being correct...

[PubliusEnigma]

Not too dissimilar to when the Polar Vortex dropped out of the Arctic towards the UK just over a year ago at the end of November 2010.!

[Robbie Garrett]

Is that todays GFS?? Sorry not at home, mobile.

[Grimsby Snow Lover]

Is that todays GFS?? Sorry not at home, mobile.

This morning ECM chart. Lovely isn't it!!

On a positive note todays NAO forecast looks negative as we enter January.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.sprd2.gif

[Cloud 10]

Is that todays GFS?? Sorry not at home, mobile.

Its the +240hr chart from the ECM 00z.

[IDO]

The Met Office are playing it safe, however they are probably close to the mark as there is little sign of change. The AO isn't forecast to go neutral/negative till around Jan 11th, so assuming the ENS are correct, that is when a change maybe on the cards to a more stable lasting cold spell. The ECM have a colder zonal pattern to the GFS's milder zonal and the former is basing that on height rises around North America. Too early to say who is right, but the ECM forecast, if correct, is no panacea to prolonged cold, although it does give us a better starting position if other synoptics fall in the right place and obviously a few interesting days. The next 48 hours should answer our questions, so until then we can only align to one of the models and wait...

"If you spend your whole life waiting for a storm, you'll never enjoy the sunshine"

Edited December 27, 2011 by i'm dreaming of...