Model Output Discussion - The Start Of Winter

[No Balls Like Snow Balls]

Yes please Santa :-)

[IDO]

GFS 06z Run is rather Wintry after day 10.......... A repeat of the pattern we are currently in now.

http://www.wetterzentrale.de/pics/Rtavn2401.gif

http://www.wetterzentrale.de/pics/Rtavn2881.gif

http://www.wetterzentrale.de/pics/Rtavn3361.gif

 

 

Yes another three possible PM shots in the next 16 days:

 

  

 

The last one is more amplified but it is possible at that range the model is over doing it like it did on the up coming Non-Northerly?

 

D16 NH profile, subtle differences to the 0z but the same drivers dictating the Long Wave flow:  

[No Balls Like Snow Balls]

It turns milder for a time, but a possibility of a cold NW/ N in 7 days time.

[MR EXTREMES]

Yes another three possible PM shots in the next 16 days:

 

gfs-1-162.png gfs-1-264-2.png gfs-1-360.png

 

The last one is more amplified but it is possible at that range the model is over doing it like it did on the up coming Non-Northerly?

 

D16 NH profile, subtle differences to the 0z but the same drivers dictating the Long Wave flow:  gfsnh-0-384-33.png

That last chart would ignite the sw weather thread in fact it would ignite the best chance of wintry weather more country wide.

Anything is possible with our current set up.

Good to see the interest in the charts near term medium and long term jingle bells all the way.

[SMU]

So this mornings runs are probably finely poised for some potential changes down the line at Day 10-12

 

How that manifests is obviously related to how the motion of the azores high plays out, clearly there is a concern that the pattern could flatten off to a more westerly or even south westerly regime.

 

Something like this from a positive start would be really unfortunate for the UK.

http://www.meteociel.fr/modeles/archives/archives.php?day=19&month=12&hour=0&year=1988&map=4&mode=2

 

Like I said this morning to get deep cold over the UK you need high pressure moving North towards the Pole, often ridging to another high pressure, see below

http://www.meteociel.fr/modeles/archives/archives.php?day=17&month=1&hour=0&year=1947&map=4&mode=2

 

If you look at the above 2 solutions both evolved from the azores high, one is the start of one of the mildest winters on record, the second was 2 or 3 days before the start of one of the coldest Jan/Feb combinations in UK history.

 

So at this stage with the models toying around how amplified the azores high will be - its unwise to write off any scenario in the near future - as everything is on the cards at day 10-

 

If we take the GFS GEM & ECM

 

http://modeles.meteociel.fr/modeles/gem/runs/2014121000/gem-0-240.png?00 Easterly GEM

 

http://www.meteociel.fr/modeles/ecmwf/runs/2014121000/ECM1-240.GIF?10-12 North westerly ECM

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014121006/gfsnh-0-240.png?6 North Westerly GFS

 

there doesn't seem to be much support for a flat westerly other than something transitory.

 

 

A clear 15 days to Christmas, NW winter forecast + my own had expectations of a pattern change in the third quarter of December- driven by the troposphere not the Strat- this comes later. So the area of interest still lies ahead between the 15th & 25th. - which I highlighted in the very last paragraph of the winter forecast.

 

For dave:

As for the models the reality is all the Model LRF's & METO were milder than ave & at this stage with the projected CET to the 15th is going to be around 4-4.3c (~ 0.7-1c below norm ) then I would say at this stage its 1-0 anyone who punted for a CET slightly below ave.- I haven't checked the NW December CET forecast, however my range was 3.7-4.7 which feels good at this stage......

 

 

S

Edited December 10, 2014 by Team Jo

[chionomaniac]

 

 

As for the models 1-0 TEITS, ( & to all those posters playing down any cold ) - well the reality is all the Model LRF's & METO were milder than ave & at this stage with the projected CET to the 15th is going to be around 4-4.3c (~ 0.7-1c below norm ) then I would say at this stage its 1-0 anyone who punted for a CET slightly below ave.- I haven't checked the NW December CET forecast, however my range was 3.7-4.7 feels good at this stage......

S

We went for 4-4.5C for December so in the right ball park, unsettled first half of the month with the risk of an extreme wind event before any changes to a more blocked outlook linked to a possible stratospheric warming in early January.

 

Can't think that we are too far away at present too, Steve - considering it was written well before December.

 

Even the angle of the jet so far has been expected - Tony and I would just have expected more blocking to show for the second half of the month but that is still 5 days away......

[Frosty.]

The Gfs 06z op run shows a few weather bombs detonating with some stormy spells in the pipeline, funnily enough although the consensus is for generally less cold incursions next week, the 6z produces an even colder spell than this week, how ironic huh, anyhoo there is only a couple of technically mild days on the latest gfs run, it's still dominated by polar maritimes with a dash of the arctic in there too and xmas day starts and ends frosty, the bit in the middle looks cold too..anyhoo with all the talk of explosive cyclogenesis and exploding weather bombs..I  finally find a reason to use this....            BOOM 

Edited December 10, 2014 by Frosty.

[A.J]

A quick update for the LRF fans with the CFS continuing it's blocked theme for January with a general broadscale pattern of low heights in the Mediterranean Basin and a Sceuro HP migrating into a Scandi HP with a generally cold easterly feed.....I'll continue to be watching this with interest 

Edited December 10, 2014 by ajpoolshark
edited not for point scoring, I just can't spell for toffee

[BLAST FROM THE PAST]

Hints from 06z that GEM might not be too outlandish and certainly that a flatter/milder pattern isn't a given at this point, am looking forward to the 12z runs and tomorrows runs.  We can't write off next week IMO let alone th rest of Dec.  It seems to be slightly slower than anticipated [caveated] but GEM reun is generally/broadly what I thought/think would/may be happening during this month.  Still 2/3rds to go amd plenty to play for.

 

Edit - clearly the favourite as it stands though with the models is to look W and at times NW for a while.

 

BFTP

Edited December 10, 2014 by BLAST FROM THE PAST

[Tamara]

The shorter term sees a very seasonal prospect with an often below average week ahead with high impact weather conditions expected. High impact conditions that take on a more wintry flavour than those witnessed a year back when a cyclonic pattern was evident. Those in the north and in Scotland will indeed be wondering what the fuss is about with very high winds and blizzard conditions expected most particularly for upland regions. Wintriness penetrating a little further south at times too.

 

It is the modelling following this where the interference of the Azores High as a spoiler appears to raise it thorny head once more again. We see the prospect of a weak poleward Hadley cell. This is supportive of poleward propagating (sub tropical) anticyclones to mid latitudes (i.e Azores High) combined with positive Atmosphere and Angular Momentum (+AAM). The energy budget deficit and then rebalancing in the atmosphere poleward is contributory to a spike in the AO. It is this which largely (probably?) lies beyond your own obvious angst and maybe one or two others. But ( if taken like this in isolation and out of context with everything else that is going on right now, and expected to evolve through December) completely misses the bigger picture.

 

Further likely re-enforcing of warming of the western Nino regions is likely to weaken the Hadley Cell, especially as the other hemisphere feedbacks tighten their grip in tandem. Why is this relevant?

 

Weaker eddy heat flux into the mid latitudes occurs as ENSO warming occurs in the region which reverses the Ferrel Cell circulation and meridional mass field/Polar vortex gradient and that, self evidently, leads in turn to enhanced opportunity for stratospheric wave attack to lead to higher latitude blocking.  The sub tropical ridging (think Azores High again) is weakened and retracted in this process as the higher sea temperatures supporting these anticyclones is weakened. This is a key to the +NAO spoiling conundrum appearing in seasonal forecasts. But we have to be patient and watch to see when this happens.....

 

Much explained winter SAI feedbacks ( which, despite the recent delays due to a short period of Asian troughing) are back on track to re-strengthen the Siberian High and should resume strong wave activity on the vortex>.

 

A +PDO and a cool Kuroshio-Oyashio extension (basically in simple terms two water currents found over the NW Pacific) are a common product of El Nino. Warmer than normal SST's build up over the Bering Sea and Sea of Okhotsch. This correlates extremely highly with a displaced (strong) Pacific Jetstream (tick box checklist so far) and evolution to blocking over the pole.

 

The stratosphere is belying its apparently unfavourable strengthening at upper levels and looks destined to set itself up for a bigger fall by doing so. Best remember that bicycle wheel analogy here. The faster the vortex (wheel) spins..the more spectacular the outcome when something is suddenly jammed right into the heart of it. Think SSW  

  

< the changing wave lengths are increasingly on course to bring about a vortex that might spectacularly resemble a beaten up/crushed coke can into the New Year.

 

 

A further lack of apology for taking up space and copying chunks of previous post(s). They continue as an intended well meaning attempt to try and help manage expectations

 

Despite all the usual rollercoaster elasticity of opposite end-of-spectrum mood reactions to face value model output and snippets of varying news leaks   - very good continuity of progress continues for longer term trends (end of December and especially Jan). 

 

There really shouldn't be any frustration, disappointment or surprise that a rabbit hasn't yet appeared out of a hat for the coming two week period. Just my own little autopilot perhaps here

 

So, the seasonal evolutionary screw keeps tightening with longer term ensembles and even some FI operational output now clearly defining the re-ramping up of the Siberian High and Aleutian low combo. This surely has to underpin stratosphere modelling signals of very strong wave activity stacking up which *ramp disclaimer* we look towards ripping up the vortex and replacing with a big fat arctic high into the New Year. The modelling ramping up accordingly.... with time....

 

The usual charge will be that we shouldn't trust long term model data and stick to the reliable. This advice is of course very sensible and well founded - but when there is a loaded gun (as there has been for some weeks already) and too many factors priming the NH circulation then something usually gives eventually. It is these signals that GloSea5 will have picked up on - and whilst they are of course tentative at this stage, they are fully credible against expected evolving winter pattern trends.

  

So, as nothing is ever straightforward and certain of course -  what is there that isn't helping? Further to the detail I tried to provide the other day to answer these questions, the very well presented post by Vorticity0123 late yesterday evening covers in very easy to read language the  'fly in the ointment' factors regarding the erratic Pacific MJO tropical convective signal forecasts, the slight disconnect of oceanic (Nino) vs atmospheric responses, and the issues with the Ferrel cell signal/Azores High.

 

 

 

This signature is also indicative of a positive NAO (North Atlantic Oscillation).

 

Tropical-extratropical interactions

 

The interesting part comes when one checks the MJO forecasts, or more physical, the evolution of the tropical convection anomalies. These anomalies (which are partly explained by the MJO) tend to influence the weather in the midlatitudes (e.g. the UK). Note that this relationship is in both directions (i.e. the tropical convection anomalies influence the extratropical synoptics, but also vice versa). A good read about this can be found in the link below:

 

 (scientific article about the interaction between the pressure pattern in the extratropics and the tropical convection anomalies).

 

From the weekly discussion from the Climate Prediction Center (from the NOAA, given in the link below), it appears that the uncertainty in the weather pattern is very high in the tropics:

 

I will try to give a short summary, using quotes from the discussion in the link given above. 

 

Lack of Atmospheric El Niño response

The first thing that comes to mind is the lack of coupling of atmospheric conditions with the El-Niño like conditions in the ocean. Usually, an El Niño event tends to influence the general weather pattern quite a bit, but this does not seem to be the case at the moment. From the discussion:

 

A link to very brief information of what the influence of an El Niño event on the weather patterns in the midlatitudes can be found in the link below:

 

MJO evolution uncertainty

The next thing that is notable is the uncertainty regarding the evolution of the MJO (madden-julian oscillation). A few days ago, it seemed that the MJO could move into phase 7 or 8. Without going into too much detail, this phase tends to coincide with positive anomalies (higher than average 500 hPa pressure, or in other words, a ridge) near Scandinavia. A whole set of composites can be found in the link below:

 

However, for now, some models are forecasting the MJO to weaken (i.e. decrease in amplitude), which would result in its influence being negligible over the weather over the midlatitudes. It has to be stressed, though, that uncertainty associated with this forecast is very high. This is also noted in the discussion of the Climate Prediction Center

 

Long-term summary

Given the all above, it appears that uncertainty is very high regarding the weather in the tropics. This could have implications on the predictability (read: a decrease in predictability) of the weather in the extratropics. This is nicely summarised by the CPC:

 

Overall summary

At first glance, the forecast for the next few days looks pretty straightforward, with slightly amplified (wavy) zonality continuing for the next several days. Thereafter, there are signs that the weather will not change (e.g. the 8-14 day anomalies from the CPC), but given the large uncertainty in the tropical weather, the predictability of the weather in the extratropics after about 7 days could be very uncertain, regardless of what the models are showing. And then the stratosphere, and the other hints mentioned by other members are not even considered in this post  . So I would suggest an exciting period lies ahead in terms of model watching, which I will followed with interest!

 

Of a final cautionary note: the uncertainty mentioned in the tropics does in no way gurantee any pattern change in the extratropics, it only shows that a pattern change is possible in the midlatitudes.

 

 

He covers those uncertainties very well I think.

 

As stated a few times by various members - there is no need to get too hung up on the MJO forcing to amplify the pattern. *If* its influence should wane in terms of how it might affect our midlatitude, it should only be looked on as one method of assistance to switch the pattern.

 

We are seeing as early winter unfolds, how factors simply affect timing of changes rather than eliminating changes altogether. Lets only revisit the latter scenario if required in several weeks time...only then would there be some explaining to do

 

As things stand though, timing is very much all we need concern ourselves with in relation to a New Year -AO loaded pattern change in tandem with a heart of season flip of the NAO away from the current positive Ferrel cell signal (which as I reasoned the other day should fade) and submission to the strong negative polar field feedbacks... to eventually undercut and back the pattern west

Edited December 10, 2014 by Tamara תָּמָר

[No Balls Like Snow Balls]

From WSI via twitter

Another colder spell for Europe 17th/18th followed by quick recovery (GFS ensemble). ECMWF slightly less cold option.



Latest ECMWF daily centimetres snow accumulation. 3 cm,or less, per day thereafter to the 16th.




The latest 16-30 meto update is saying that there is a signal that conditions may become colder particularly into the new year.

Edited December 10, 2014 by No Balls Like Snow Balls

[Mucka]

Had a look through all the output and IMO not much has changed this morning, the models have each toyed around with having the Azores high ridge in at some stage but they have also chopped and changed from run to run. They may show a more amplified pattern again this evening.

 

Putting a positive spin on things down the line;

 

There were always going to be warm sectors thrown across us between the bouts of PM air and I think it is too early to say these will become more prominent as the pattern flattens because as far as I can see it is by no means certain the pattern will flatten, certainly not over the timescales being discussed up to and through Christmas.

I can see a less cold interlude being quite possible, with a flatter pattern over several days, though it's by no means certain and anyway I think the trough will stall once it has moved East and met the Russian high which would once again lower heights in our vicinity and displace the Azores high West once more only this time the lobe of PV fueling the trough will be to our NE rather than N/NW which means winds would be more N/NE than W/NW as we have now.

 

If I were to assume this pattern is locked in for 10 days than I would still say there is a good chance of a colder flow setting up in around 12-14 days rather than a milder one. If the pattern remains more amplified than what the models currently show it could be sooner. 

Unfortunately it still would not be sustained cold with blocking but it could potentially be quite snowy and if the trough was deep enough the pattern would amplify so who knows what could come later by Christmas time should that happen.

 

Of course there is still the possibility of something unexpected popping up in the meanwhile as well but the point being that even if there is no real sign of blocking we could still get cold snap of 2 or 3 days with a chance of snow if things fall our way and we still have the current spell and the chance of upgrades for the mid term prospects so not too bad early Dec though I appreciate transient nothwesterlies aren't all that.

 

Fingers crossed the AH doesn't go all slug like on us and drape itself across NW Europe.

[garbagebags]

It turns milder for a time, but a possibility of a cold NW/ N in 7 days time.

 

Problem with NW'erlys is they are a bit like a stripper. Your all excited about it before it happens but after its happened, you are just left feeling frustrated and wishing you had got more

[Polar Maritime]

The latest 16-30 meto update is saying that there is a signal that conditions may become colder particularly into the new year.

 

Can i just say the 16-30 update is no change to it's last, With no mention of any colder signals, But cold shots from the N/W.

Edited December 10, 2014 by Polar Maritime

[Gavin Hannah]

What a mess lol....but teasing the scandi link up.. Oh, FI you tease.

[No Balls Like Snow Balls]

Can i just say the 16-30 update is no change it's last, With no mention of any signals.

Ummm sorry yes it does.

The last week of December will most likely stay unsettled and often windy with weather systems arriving from the west or northwest. It is likely that the UK will see cloudy periods with spells of rain, but that these will probably be interspersed by clearer and colder conditions with showers, which could turn wintry at times, mainly in the north. The most unsettled conditions are likely to be in the north and west. However, there is a signal that conditions may become colder particularly into the New Year, although the is a large amount of uncertainty surrounding this. Temperatures are expected be around average for the time of year, the may turn colder than normal in the New Year.

Edited December 10, 2014 by No Balls Like Snow Balls

[weirpig]

Ummm sorry yes it does.

The last week of December will most likely stay unsettled and often windy with weather systems arriving from the west or northwest. It is likely that the UK will see cloudy periods with spells of rain, but that these will probably be interspersed by clearer and colder conditions with showers, which could turn wintry at times, mainly in the north. The most unsettled conditions are likely to be in the north and west. However, there is a signal that conditions may become colder particularly into the New Year, although the is a large amount of uncertainty surrounding this. Temperatures are expected be around average for the time of year, the may turn colder than normal in the New Year.

Yep  signals seem to be pointing perhaps to a more blocked set up as we enter new year   hopefully in the next few days  some nice fi charts will start appearing

[Barry12]

Based on today's 06z GFS it does look like there is a strong possibility now of getting a below average December. The CET is forecast to be 0.7-1C below the average for the 15th, and with the PM incursions looking like continuing into the Christmas period this looks like almost a certainty now. So far we've had snow for many places, and more snow is forecast to continue during this coming week. Snow is possible at lower levels with 2-5cm possible for places in Northern England. While the south is unlikely to get much snow at lower levels this side of Christmas, there has still been plenty of frosts, which makes it a lot better than last year. Many of the LRF's, including the Met Office model were forecasting an average/mild December, so that's already 1-0 to the OPI in my opinion. January is still looking interesting to me, with the stratoshperic warming continuing to show during the Christmas period.

 

 

A quick look at the cold and snow chances this week:

 

Thursday

 

 

Thursday will feel bitterly cold with snow for Scotland, Northern England and Northern Ireland.

 

Friday

 

#

 

Friday will feel like the middle of Winter in Norway with highs of 0-2C in the North, and feeling like -5 to -8 in parts of the North. More snow for Northern England and Scotland.

 

Saturday

 

 

The South will join the rest of the UK on Saturday with highs of just 2-3C, and again it will feel far colder than that with feel like temperatures widely below freezing. I'd wrap up warm in Central Scotland with it feeling below -10C! Precipitation does look minimal, but wherever there is any it will surely fall as snow even at lower levels.

 

So yeah, this position in December isn't bad at all!

[bluearmy]

im sure ian can help us re the updated meto 30 dayer. its either those ecm clusters coming back, latest mogreps having some colder clusters or the latest run of glosea showing a ssw and this caveat is there in case of a quick trop response.

 

as far as the morning ens runs are concerned, little of apparent interest via the means but i do note some colder london ecm members appearing approaching xmas

[Nick L]

im sure ian can help us re the updated meto 30 dayer. its either those ecm clusters coming back, latest mogreps having some colder clusters or the latest run of glosea showing a ssw and this caveat is there in case of a quick trop response.

 

as far as the morning ens runs are concerned, little of apparent interest via the means but i do note some colder london ecm members appearing approaching xmas

 

The regular ECM clusters don't reach into New Year yet, and the ECM monthly hasn't been updated for a couple of days, so I'm not sure the ECM has anything to do with it. I certainly can't find anything on the EPS or the EC monthly to suggest an overriding signal for cold. The monthly tends to show a westerly dominated pattern with chances of north-westerly spells at times as we had into the start of January, continuing the average-to-cool theme.

[TSNWK]

Ummm sorry yes it does.The last week of December will most likely stay unsettled and often windy with weather systems arriving from the west or northwest. It is likely that the UK will see cloudy periods with spells of rain, but that these will probably be interspersed by clearer and colder conditions with showers, which could turn wintry at times, mainly in the north. The most unsettled conditions are likely to be in the north and west. However, there is a signal that conditions may become colder particularly into the New Year, although the is a large amount of uncertainty surrounding this. Temperatures are expected be around average for the time of year, the may turn colder than normal in the New Year.

Sadly for coldies I believe that weeks 3 and 4 are updated twice a week and that the above update might have been driven by the increase in cold members picked up by the mets long range models over the weekend. This signal was quickly dropped and I would expect the next 3 and 4 update to drop these references to cold in weeks 3 and 4 in their next update.

[Polar Maritime]

Ummm sorry yes it does.

 

My error, Yes quite correct, I looked at yesterdays as not been updated yet in the Meto thread, But good news all the same    

Edited December 10, 2014 by Polar Maritime

[TEITS]

Im not sure I agree with some of the comments made this morning.

 

Firstly the outlook does not look like bringing any signifiant cold spell via blocking and this can clearly be seen on the SLP ensembles.

 

https://max.nwstatic.co.uk/ensimages/ens.20141210/06/prmslOslo.png

https://max.nwstatic.co.uk/ensimages/ens.20141210/06/prmslReyjavic.png

 

The best we can get from this period is what we are seeing i.e brief colder NW,lys followed by brief milder spells.

 

infact it is quiet notable the lack of cold across most of Europe in the forecast period.

 

https://max.nwstatic.co.uk/ensimages/ens.20141210/06/t850Berlin.png

https://max.nwstatic.co.uk/ensimages/ens.20141210/06/t850Oslo.png

 

Even poor Moscow struggles to get below -5C!

 

https://max.nwstatic.co.uk/ensimages/ens.20141210/06/t850Moscow.png

 

This is all because so far this month the NAO has been positive as predicted by the seasonal models. At this stage nothing in the model output suggests this is likely to change in the near future.

 

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

[Bishop Brennan]

A quick update for the LRF fans with the CFS continuing it's blocked theme for January with a general broadscale pattern of low heights in the Mediterranean Basin and a Sceuro HP migrating into a Scandi HP with a generally cold easterly feed.....I'll continue to be watching this with interest 

 

At risk of sounding terribly thick, but can somebody please enlighten me as to what the term "Sceuro" means?

 

Scandi Euro?

Southern/Central Euro?

 

Bish

Edited December 10, 2014 by Bishop Brennan

[garbagebags]

At risk of sounding terribly thick, but can somebody please enlighten me as to what the term "Sceuro" means?

 

Scandi Euro?

Southern/Central Euro?

 

Bish

 Think its Scandi