Model Output Discussion - 16th Jan 12z onwards - Smile While You Post!

[nick sussex]

Stinking FI coming.....

Don't worry about FI, its better to have the colder synoptics develop  slowly than have a great FI which downgrades with time.

 

Given the early changes and events of the last week do you honestly expect there to be no more changes? We're lucky that the models are improving in the earlier timeframe which builds a better chance in the medium term.

[bluearmy]

ECM op only out of line day 9 on temps.

[Ali1977]

Don't worry about FI, its better to have the colder synoptics develop  slowly than have a great FI which downgrades with time.

 

Given the early changes and events of the last week do you honestly expect there to be no more changes? We're lucky that the models are improving in the earlier timeframe which builds a better chance in the medium term.

Predictive text error

[Jason M]

GEFS could be interesting this morning.would be good to see a few pull some colder uppers into the mix. The earlier suite had plenty of easterly influence but we were feeding off scraps in terms of the upper profile. If the pattern backs any further West though a tipping point could quickly be reached.

Edited January 18, 2015 by Jason M

[Snowman.]

 

Hot up in there.

[Snowman.]

And the control run is almost a carbon copy of the OP.

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=192&code=0&mode=0&carte=1

[snowspotter]

I have a question on the modelled output we have this winter. In marginal events such as we have would the result say 40 years ago be any different to what we are currently seeing ? . What I am thinking is if we had an identical pattern then would the temperatures be lower?. January CET average 1961-1990  was 3.8c whilst 2001-2014 is 4.7c i.e substantially warmer. I appreciate different  synoptics are possibly the main cause?  but is there an element of 'warming' in the output difference between the two. Its a question that bugs me when we get patterns like this. Cant help but feel that if it was 1960 todays rain in the south might have been snow.

[snowangel32]

 

Hot up in there.

Hi I only know a little bit about start warming, would that chart lead to the vortex being displaced from greenland .

[Snowy L]

Remarkable shift these last couple of days from the models, after they made the shift 2 days ago to almost end our chances of snow. ECM and GS both keep it going until t192, UKMO not quite as good but a small shift west and we would be good.

 

Still no early warning for Tuesday's snow from met office?

Edited January 18, 2015 by Snowy L

[nick sussex]

I wonder whether we're seeing some response from the GFS in relation to the MJO signal.

 

We're now seeing yet another divergence of opinion, the last MJO forecast for the GEFS took this into the COD but then some members bring this out quickly into phase 8 and then phase 1. The bias corrected are less bullish about this but the other models initially weren't even interested in phase 7 and were wrong as the MJO although at lower amplitude did make it into that sector.

Edited January 18, 2015 by nick sussex

[MR EXTREMES]

Yet another undercut from an atlantic attacking low pressure. Run to run we are slowly getting there!

 

And retrogression towards eastern Greenland beautiful chart with vortex pushed west and southeast tracking jet don't come much better than this if it pans out this way.

[mulzy]

GEFS starting to show some interesting developments in the day 8-10 range.

[Tamara]

Asian M/T set to provide some further very important tropospheric/stratospheric interest in the next 10 days - and this aligns with further significant atmospheric signals that will determine whether our much more benign Atlantic jet patterns sustain an amplified profile, or attempt to flatten out. The second scenario however, I do think, has to be seen within the context of the polar field becoming finally more and more amenable to taking up that sustained -AO profile we have been waiting for.

 

< contrary to fears of further Nina-esque pattern spoiling this is where it might get interesting and may not necessarily follow the late December route of flattening the pattern out sustainably and leading us back to prolonged westerlies.

 

<Slow indicated progression of the GWO through phases 1/2 corresponds to a weak and amplified polar Jetstream in the Atlantic. It also supports therefore the cold pattern holding through next week at least.

 

<There is the alluring and credible suggestion that GWO Phases 1 and 2 might form an allegiance state for recurring Atlantic amplification and trough disruption beyond the coming week. In tandem with further vortex disturbance this actually supports the idea of renewed retrogression of high amplitude ridging occuring even if the Atlantic High eventually collapses on the back of an easterly next week - that follows the upcoming wintry speckled trough disruption phase.

 

<Eyes on the stratosphere, the polar vortex.....and importantly also the GWO and where it goes after what looks a supportive protracted 1/2 phase. The further we head towards and into February , the more likely it becomes to lock us into repeated Atlantic amplification and trough disruption.

 

This, instead of any flattening of the pattern leading us back to prolonged westerlies.

 

Too soon to be sure yet, but I suspect if this happens at all, it will be a transitory phase>

 

The worm, I cautiously think, has turned.

 

But lots to look out for and enjoy for some time to come anyway

 

----------------------------------

 

As posted a couple of days back

 

Twin MT events are occurring. A strong Asian +MT (GWO Phase 4/5)  and then a strong US -MT (GWO Phase 8/1) as fast acceleration of frictional torques are compensated by consecutive MT events which will send AAM tendency sharply downwards.

 

These twin torques are important for two reasons.

 

First because acceleration phases of global torque events (without going into the atmospheric complexities) signify weakening of sub tropical ridging and mean that the interference of the Azores High in the trough disruption process will be reduced more and more as time goes on.

 

Look how the ECM operational this morning picks up on this with the jet heading southward and the Azores High starting to decline towards days 8 to 10

 

http://www.meteociel.com/modeles/ecmwf/runs/2015011800/ECH1-240.GIF?18-12

 

This is not a discontinuous FI signal - it is underpinned as a logical evolutionary way ahead.

 

Taken at face value, the chart suggests that eastward push of energy displacing the cold eastwards and trough disruption ending and returning back to the same westerly phasing of the first half of the winter. So on the one hand one could suppose quite reasonably that the decline of the Azores High just leaves room for a fast jet to barrel through and the westerlies are back to stay - but it is nowhere near as simple as that.

 

The southward moving jet is an early stage signal of the AO starting to tank negative. Polar ridging likely to return with -EPO ridge. Sounds familiar here but worth reading on

 

Phase 1/2 GWO looks protracted as suspected and signals a continuation of weak polar jet flow - no surprise to see the models put back the flatter pattern and westerly return beyond the t120 to t144 time period. Ian F's confirmation that UKMO operational is once again too progressive end of week underpins this notion very well.

 

With the timetable put back once more to the post day 6/7 period - we now turn to the second reason those twin torques are very important.

 

The stratospheric vortex remains ( seemingly as ever!) a punch away from knock out. We have drawn the short straw this winter so far with a junior SSW split vortex that, thanks a bunch, created a Canadian/Greenland vortex little brat family which has gone about wreaking havoc with seasonal prospects and delivered further extended chilly autumn conditions instead. At least away from more northern parts who have benefitted better from colder zonality conditions

 

That is up to now of course.

 

I completely realise we have been here before too many times, but I think that current stratospheric model indications are building towards something more favourably placed than last time.

 

A pincer type process is developing across the polar field. Already mentioned return of the -EPO poleward ridge. Cold air also this time is becoming entrenched close to us and especially to our north and east with, on the other side of the arctic, the Siberian High extending a strong ridge westwards and creating an increasingly disruptive wall to Atlantic troughing. 

 

With the GWO set on a protracted Phase 1/2 and meaning that amplified polar flow is encouraged in the Atlantic (along with the signal to weaken the Azores High) we *could* be looking at the first signals that the NAO is finally going to head negative more and more towards months end and more especially into the new month.

 

I say this especially, because although more modelling is obviously required both tropospherically and stratospherically, indications of a possible displacement vortex event give us a much improved chance of benefitting this time around with a better Atlantic profile and much more pressure to eject the upper vortex to our North west. With GWO induced strong twin MT wave activity likely to manifest on the vortex over the coming 10 to 15 days there is enough vertical wave activity programmed there to assist a tanking -AO profile, under the weakening polar westerly profile.

 

Transitions like this can be messy and liable to temporary setbacks - but there is plenty of ammunition in the pipeline to ensure that any transitional phase when the jet comes south and vortex energy is ejected out is blunted by dropping out of zonal westerlies as negative zonal wind build up is burst out to the surface. Most important in this regard, is that sufficient vorticity energy is displaced away from the Atlantic sector for the first time this winter 

 

This means that we *could* see a protracted and messy trough disruption process finally lead to a cut off low and a better amplified ridge extension over the top then extending eastwards across the NE Atlantic towards Iceland and Scandinavia. This is an attractor state to pull the Siberian High westwards and sets up the enticing prospect of something akin to a Feb 91 scenario coming into focus by end of the month but perhaps more especially so into February. *Shameless ramp disclaimer* 

 

A bold prediction (obviously) maybe and lots of modelling to get through first..... but lets just see.

 

Edit: FWIW, I think that the MJO signal, with shortening wavelengths heading into the final third of winter is likely to increasingly have different implications as tropical versus mid-latitude feedbacks change

Edited January 18, 2015 by Tamara

[stratty]

By Thursday am, we now have this projected (the best so far for the south?)

.............more great charts appearing all the time!

worth a gander through some of these!

Edited January 18, 2015 by stratty

[nick sussex]

Deleted! for some reason if I try and edit by adding attachments I get logged out!

Edited January 18, 2015 by nick sussex

[stewfox]

I have a question on the modelled output we have this winter. In marginal events such as we have would the result say 40 years ago be any different to what we are currently seeing ? . What I am thinking is if we had an identical pattern then would the temperatures be lower?. January CET average 1961-1990  was 3.8c whilst 2001-2014 is 4.7c i.e substantially warmer. I appreciate different  synoptics are possibly the main cause?  but is there an element of 'warming' in the output difference between the two. Its a question that bugs me when we get patterns like this. Cant help but feel that if it was 1960 todays rain in the south might have been snow.

 

You can of course look at historic charts and look at synoptics and CET comparisons etc 

 

However so many variables I do wonder that increase+  sea temp abnormalities may modify marginal situation which is the case for next week for many.

[snowking]

I wonder whether we're seeing some response from the GFS in relation to the MJO signal.

 

We're now seeing yet another divergence of opinion, the last MJO forecast for the GEFS took this into the COD but then some members bring this out quickly into phase 8 and then phase 1. The bias corrected are less bullish about this but the other models initially weren't even interested in phase 7 and were wrong as the MJO although at lower amplitude did make it into that sector.

Indeed and this is why I remain cautious:

 

GEFS:

 

 

However GEFS BC much more in line with ECMWF consensus:

 

 

Ultimately last time I think we ended up with a solution half way between the two, but in terms of the exact placement of the OLR anomalies GEFS did indeed end up closer to the mark.

 

So plenty to keep us guessing!

 

SK

[nick sussex]

I'll try again heres the MJO forecasts for the GEFS and ECM:

 

GEFS

 

ECM

 

The GEFS does take some members into a decent amplitude phase 8 and 1, these generally correlate with a colder pattern for the UK during the current ENSO conditions during the winter season.

 

Lol! Snowking thanks , you beat me to it, it will be interesting to see if the update early next week starts moving the bias corrected more towards the normal GEFS.

Edited January 18, 2015 by nick sussex

[MR EXTREMES]

Don't worry about FI, its better to have the colder synoptics develop  slowly than have a great FI which downgrades with time.

 

Given the early changes and events of the last week do you honestly expect there to be no more changes? We're lucky that the models are improving in the earlier timeframe which builds a better chance in the medium term.

Well founded post Nick models certainly find these setups difficult most likely because of the very nature that the uk is not an area these day we associate with extreme wintry weather what with the boundary between the east and the boundary with the west we are often in the middle and this is often chaotic for the models extra factors in the uk include Azores and being that we have the alantic Ocean to.

But there was mention yesterday of possible mjo signal to move into 8/1 but also phase 6 which if I remember rightly is supportive of high latitude blocking Id of also thought recent minor warnings in the stratosphere is now starting to pile on pressure on an already weakened vortex.

And feb is a month when changes to a more block signal are more common than not although we're still in jan of coarse.

Certainly nice to look at but be better to see support this evening from other models.

[nick sussex]

Well founded post Nick models certainly find these setups difficult most likely because of the very nature that the uk is not an area these day we associate with extreme wintry weather what with the boundary between the east and the boundary with the west we are often in the middle and this is often chaotic for the models extra factors in the uk include Azores and being that we have the alantic Ocean to.

But there was mention yesterday of possible mjo signal to move into 8/1 but also phase 6 which if I remember rightly is supportive of high latitude blocking Id of also thought recent minor warnings in the stratosphere is now starting to pile on pressure on an already weakened vortex.

And feb is a month when changes to a more block signal are more common than not although we're still in jan of coarse.

Certainly nice to look at but be better to see support this evening from other models.

NCEP do a weekly update and interestingly a few weeks back whilst the Euros and others bar the GEFS  were indicating phase 6 then the COD,  NCEP continued to suggest phase 7, the next update is due tomorrow but I think they factor in both dynamical modelling aswell as statistical and I think the latter is what made them edge towards the GEFS solutions.

 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/forca.shtml

 

That shows the three statistical methods and their forecasts, not as bullish as the GEFS but all take the MJO into phase 8 with the CA model into phase 1.

Edited January 18, 2015 by nick sussex

[mushymanrob]

I know people might think that big high over Siberia on the GFS 00hrs looked good but its centred too far east, its better to develop a smaller high to the ne as this has a better chance of directing much colder air into the UK.

 

 

 

i dont care nick, because there was no scandi high modelled earlier, it was expected to sink into central europe and the jet was heading scandi-bound. its a move in the right direction , and imho based on experience this is a crucial time..... and remember, i DONT want to see a beasterly, i just think theres a good chance of one...

let me illustrate...

 

looks familiar? (jan 30 1986)

 

todays

 

by feb 8th 1986.. one of the bitterest febs in recent times (if nearly 30 short years is recent lol)

ok, its not a law that similar synoptic patterns follow the exact same evolution. but they often do follow similar evolutions. as a 'non cold fan' im worried!

[summer blizzard]

Brilliant 6z, the cold spell never stops. 

 

More interestingly though, the Euro mean suggests that Friday's front will be a dud. There's always the chance it will be held further west as well..

 

 

Looking at the GFS it seems that it has a stronger low over the Med than post models which may or may not be the case but the important low for our long term prospects i think is the low exiting Canada at day 5. The slower and weaker this is, the longer our cold spell goes on. 

 

If we look at NAVGEM for example (has the weakest low) then it never really phases with the primary low over Greenland and may have more chance of heading into Europe.

 

 

[nick sussex]

i dont care nick, because there was no scandi high modelled earlier, it was expected to sink into central europe and the jet was heading scandi-bound. its a move in the right direction , and imho based on experience this is a crucial time..... and remember, i DONT want to see a beasterly, i just think theres a good chance of one...

let me illustrate...

 

Rrea00119860130.gif looks familiar? (jan 30 1986)

 

todays Rtavn961.gif

 

by feb 8th 1986.. cold.gif one of the bitterest febs in recent times (if nearly 30 short years is recent lol)

ok, its not a law that similar synoptic patterns follow the exact same evolution. but they often do follow similar evolutions. as a 'non cold fan' im worried!

Lol! if you're worried then that's a positive for us coldies! Given the overall pattern there is a chance especially given the MJO discrepancy but easterlies are a pain to verify. As most people would testify to in here given the last week. We'll see how it goes over the next few days but I wouldn't be too worried Mushy for the timebeing. I don't really want to ramp up any sort of easterly because we need a lot to go right to get there. The trend today is interesting but given recent model volatility its whether this gathers pace or hits the buffers again.

[blizzard81]

Lol! if you're worried then that's a positive for us coldies! Given the overall pattern there is a chance especially given the MJO discrepancy but easterlies are a pain to verify. As most people would testify to in here given the last week. We'll see how it goes over the next few days but I wouldn't be too worried Mushy for the timebeing. I don't really want to ramp up any sort of easterly because we need a lot to go right to get there. The trend today is interesting but given recent model volatility its whether this gathers pace or hits the buffers again.

I don't know why but the gfs 6z often throws out amplified runs only for the 12z to burst our bubble.

[nick sussex]

I don't know why but the gfs 6z often throws out amplified runs only for the 12z to burst our bubble.

If you're going on just trends then theres more appetite to disrupt more energy se'wards, I suspect the GFS 06hrs run is going with the more favourable MJO signal.

 

Normally I would be more sceptical but its that MJO divergence of opinion which means that the GFS 06hrs run in terms of trend hasn't just been plucked from one of its fantasy solutions catalogue, there is some basis for it. But its a long way out and again I'll stress to newcomers don't bank on an easterly even with cross model agreement until this is shown within T96hrs, preferably I go with the T72hrs because if it can go wrong it will with an easterly!

 

By easterly in that sense one which could deliver deep cold and snow showers, a slackish easterly which could still happen briefly within T144hrs is a different scenario.

Edited January 18, 2015 by nick sussex