Model Output Discussion - The Start Of Winter

[Gibby]

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY MONDAY DECEMBER 15TH 2014.

NEXT UPDATE TUESDAY DECEMBER 16TH 08:00

THE CURRENT GENERAL SITUATION A slack and rather cold West or NW flow will back SW tomorrow as a warm front approached the West of the UK later tomorrow.

MODELS-2 WEEK HEADLINE Remaining changeable with rain at times especially across the North and West. Temperatures generally close to or a little above average but colder periods over the North when showers could turn wintry.

THE JET STREAM ENSEMBLE FORECAST The Jet Stream Ensemble forecast continues to show the flow weakening and meandering North and South in the vicinity of the UK over the next few weeks. It's trend though will be to edge first North a little and then back South through Week 2.

GFS OPERATIONAL The GFS operational this morning shows a continuation of the Westerly flow through the next 5- 7 days with rain at times and further wintry showery incursions across the North. In the days that follow including the Christmas period a Westerly flow looks the most likely option with any colder air resticted towards the North where some wintry showers could occur over the hills while there will be spells of mild and damp weather with rain at times across the South. Late in the run deep Low pressure is shown close to the NW with rain and gales across all areas followed by a brief Northerly incursion on the rear end of the depression as it moves away East. Otherwise temperatures will be largely maintained close to the average for late December.

THE GFS PARALLEL RUN The GFS Parallel run as one would expect in the short term very similar to the operational in theme while later in it's run there is much more influence across Southern Britain from High pressure to the South with a lot of dry and benign conditions developing with patchy frost and fog in average temperatures. This is shown to have a knock on effect over the North too with less colder incursions from the NW and more mild and rainy SW winds instead away from the far North and later NE.

THE GFS CONTROL The GFS control run is different in the aspect that High pressure albeit a small cell breaks this Westerly pattern towards Christmas as it drifts to Scandinavia from Scotland and intensifies later over Europe. This sets up a block there and brings the UK under mild SW winds with the Jet flow unfortunately for the UK riding over the block over Europe and keeping any cold air harmlessly away over Eastern Europe.

THE GEFS ENSEMBLES The GEFS Ensembles members show a concoction of different options this morning ranging from mild Westerlies and various other options including Northerlies which could bring colder weather to the UK. However, the general theme is for a Westerly bias to be maintained towards Low pressure to the North and High to the South albeit weaker in structure than of late.

UKMO UKMO today shows the UK lying in a unstable WNW flow at the end of the week and weekend between a Low pressure belt from Scandinavia to Iceland and High pressure between the Azores and Portugal. The basic alternation between mild and damp weather and colder showery conditions is shown to persist with the most emphasis on the colder, wintry shower type conditions held across Northern areas more than the South in quite fresh to strong winds at times.

THE FAX CHARTS The Fax Charts today show the current slack flow across the UK gradually becoming replaced by a stronger SW flow following a warm front NE later tomorrow. Trailing fronts then get strung out across Southern Britain later in the week with a cold and showery Westerly flow to the North which extends SE to all areas by Friday and next weekend.

GEM GEM shows a strong WNW flow across the UK next weekend with showers or rain at times, wintry in the North. Following a ridge of High pressure late in the weekend the run up to Christmas looks mild and rather cloudy with a little rain as High pressure to the South edges ever close to Southern England pushing rain bearing fronts more towards the far North and NW.

NAVGEM NAVGEMlooks quite similar to GEM in theme bringing mild SW winds on the Northern flank of High pressure over the near Continent. All areas would likely become quite mild and beign in the South while the North and NW see rain at times in the run up to Christmas..

ECM ECM this morning shows a mobile Westerly type pattern through the period gradually becoming less unstable and milder with time as High pressure over nearby Europe becomes more influential in pulling milder uppers across the UK ina SW airflow on the run up to Christmas. Christmas Day which is at the close of the run this morning shows an active cold front crossing the Uk from the NW with rain follwed by wintry showers across the North and West.

ECM ENSEMBLES The ECM Ensembles continue to illustrate a bias towards Low pressure being to the North of the UK and High to the South in 10 days time with the balance still well in favour of Westerly maritime winds driving rain and showers across the UK with brief colder interludes across the North in otherwise average temperature values.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS Trends remain weak this morning with the trend for longer milder sectors across the UK towards Christmas perhaps being pushed away over the holiday itself by another shot of colder polar maritime conditions with showers, wintry in the North although this is by far a done deal as there are plenty of other options shown none of which translate to anything particularly cold within that time juncture.

MY THOUGHTS It's still like looking for a needle in a haystack in our quest for cold weather or at least a break from this well worn pattern of High to the South and Low to the North of the UK that has been persistent over the last few weeks. This week seems like the usual mix of wet and mild or cold and showery weather that has been the case for a while now where the North hogs most of the chance of any wintriness in the form of showers while the South stays milder and less wet but generally non-descript in weather terms. It then appears that after a brief shot of colder air at some point next weekend for us all things get worse as High pressure settles over nearby Europe steering mild SW winds across all of the UK in the run up to Christmas with leaden skies and rain at times no doubt. ECM then shows an active cold front moving SE Chrismas Day morning which could turn things more seasonal over Northern hills at Christmas along with frosts at night almost anywhere but this looks unlikely to last as many output members follow the well worn track of a ridge followed by a return to a relatively mild and Westerly pattern post Christmas. With the ECM Ensemble pack looking far from anything exciting this morning citing a continuing spell of Westerly winds between Low to the North and High to the South at Day 10 there has to be little optimism from me this morning that we are looking to any major change anytime soon. With it now being several days since rumblings of a change in pattern could be on the horizon from those best in the know we continue to see little evidence of this being translated to the models and it will be interesting as a result of this whether the Met Office revise their thoughts over the coming days to something that we don't want to here. My own feeling is that this looks like shaping up to be a very Azores High driven Winter and while it is always a pain in the backside even in our colder Winter scenarios of the past this year it looks particularly strong which is why I maintain our best shot of cold will be from a Northerly rather than Eastern quadrant with the caveat if at one or two times in the coming months the Azores High ridges to Greenland it may deliver us some real cold later in the season even if any particular spell will not last that long. Meanwhile we have to sit and wait and wait. One thing that looks very certain this morning is that away from hill of the North it is unlikely that there will be a widespread White Christmas across the UK this year.

[Frosty.]

I see no downgrades and it looks like more of same with plenty of pm shots at least for the north but with mild days, mainly across southern UK. Very snowy in far north today and I think Xmas week will bring wintry days to the south too..patience will be rewarded in the long run.. the background signals are far superior to last winter.

[IDO]

You can see from the D8-10 ECM & GFS mean comparison how they handle differently the split flow of the jet as it exits the eastern seaboard:

 

 

No difference to the UK in that time period; pure zonal. But the GEFS indicate that a wedge of higher heights can edge towards Greenland. The ECM mean is convinced this is wrong. So the GEFS hint at a slightly more amplified Greenland/Atlantic after D10. If ECM is right then the flat upstream pattern will continue towards D15+ as the D10 mean suggests:

 

 

Nice to see the ECM mean (now in that range) also trend (like the GFS) towards the Alaskan Ridge and the Polar Heights migrating to that area.

[mushymanrob]

to me, 'mild' is most likely to occur when we have the 0c+ upper isotherm over us... and its 'cold' (as in below the seasonan norm) when we have the -5c isotherm over us. in between the 0c and the -5c is what i take to be average/normal. just as a guide of course its not a golden rule.

heres the gfs 00z, and the ecm out to t240 is broadly the same.

note the azores high sat right over the azores, and the uk in a chilly northwesterly. and the approaching mild spell

 

the mild exits later on thursday, the azores high starts to flatten out by friday

 

another pulse of milder air follows the cooler pm air. high pressure to our south shifts eastwards slowly.

 

the high continues drifting east, and the pattern of mild/cool continues but what is telling is the appearance of that large vortex just west of baffin.

unless theres a major shift in these outputs there appears to be no pattern change this side of the new year, assuming of course that charts like this verify. to me its looking like a pretty average winter. (within the forseeable, im not suggesting any form of prediction/expectation for jan/feb).

[MR EXTREMES]

Just looked at the cycle 24 page at solar activity prior to November it was rather low !

But now it's really ramped up and although not directly linked to our weather patterns there's plenty to suggest this helps specific drivers.

And I'm now starting to see that the models do seem to be moving away from the idea of hlb !.

Since the Azores heights has established its home to our sw in higher solar years the Azores was a very strong feature.

Although there are no actual findings on this theory it's something I've been keen on keeping a close eye on since the spotless start of cycle 24.

And I strongly believe that this may hold some of the answers to the hard to get hlb.

So it's possible this could be over riding the conflicting signs that may produce hope in January.

I hope I'm wrong and at the end of winter id be glad to see this not be a factor.

The models today do seem to be declining there ideas of hlb ,

with the Azores moving east to our South any further movement East and we could be seeing the dreaded bartlet .

as john has suggest after new year if there is to be a change.

I'm starting to fear the worst but it's certainly different to last year.

and another point john made was heights over the uk although it still can be cold this will only generate high heating bills but without the excitement.

and I must confess although not 100% ,

there's most certainly a high possibility.

Disappointed but still interested.

[legritter]

A very painfull Analysis from Gibby this morning ,If its cold and snow you crave for .A big thank you Gibby for your loyalty and giving us your time everyday ,the good thing with regards our daily Models is the fact that Gibby updates everyday ,which in a nut shell tells you that things can change so lets all remember that in our everchanging Meteorological pastime ,there will be more bad times as regards what we want but gains every now and again .todays later frames of ECM with a bit of adjustment could bring us a good n westerly feed with some seasonal fun for some .Dont write off talk several days ago of a pattern change with cooler temperatures as quite often things get changed only to come back a little later .The professionals must have seen some data to suggest this and being at a far range would have only mentioned this with a fair certainty .looking at current charts and all other data available to me this morning i think that in about 10/12 days we will see a very active trough over us or to our east and n/east with the azores high relaxed somewhat but relatively high pressure over western med .IM still finding it a problem posting charts as computer i think needs replacing [christmas fingers crossed]   

[Frosty.]

I see another cold shot pushing SE by Friday into the weekend and more cold weather next week. : > )

[Tim Bland]

Looks like the Forum crashed for a while?!  06Z GFS ensembles still show 850s sliding down Post Xmas with the Op very much on the warm side.  Sorry I can't post a link (at work). 

[IDO]

The GFS 06z op continues the theme to downgrade the Greenland high after Christmas and maintain the Alaskan Ridge/Polar Heights leading to some extraordinary cold…

 

 

…to the US. Stunning if that came off. The UK remains in a warm sector:

 

 

The US also has this cold spell start around D8-10 and recycle for over a week.  I don’t know but this is a pattern that keeps recurring; trop led US cold and UK non-cold!  When the US get cold is seems more likely the UK misses the wave response cold flow. ECM similar:

 

 

WSI_Energy
Deep magenta's representing cold air looks to surge down across N. America during the 11-15 day period forecast http://t.co/YfoOQfiHtm
15/12/2014 12:07

 

 

D11 US anomalous uppers (Parallel): 

 

The P also keeps the Alaskan Ridge and some significant cold to the US and builds a cold MLB over the UK:

 

 

The control is awful; the worse case scenario, the PV lobe setting up residence to our north as the NH becomes more meridional:

 

 

Again about 60% have the Alaskan Ridge at D16 on the GEFS. The GEM Mean at D16 also showing the development of the Alaskan Ridge:

 

 

So a mild ten days as a whole for the south then a trend for temps to slowly slide to below average for the New Year and then we see how the Alaskan Ridge changes the pattern?

 

[mountain shadow]

Pretty universal agreement on the NAO to return to neutral or negative by month end...

 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/new.nao_index_ensm.html

 

Whether that is enough to show a cold spell is unlikely but at least any Euro slug should be temporary. In the meantime, pretty mundane weather with the odd colder day in the North and West.

 

As ever, patience, patience patience.

[stodge]

Afternoon all

 

As we seem to have had a little break in transmission, I've quickly perused the 06Z which is not without interest in the deepest recesses of FI but in the medium term here's the Christmas Day chart:

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014121506/gfs-0-240.png?6

 

Nothing too exciting there to be honest.

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014121506/gfs-0-336.png?6

 

Four days later and that looks like a west-based negative NAO with a southerly tracking jet.

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014121506/gfsnh-0-384.png?6

 

Well now....where would we go from there ?

 

http://modeles.meteociel.fr/modeles/gfsp/runs/2014121506/gfs-0-240.png?6

 

Christmas Day on the Parallel - very similar to the main Op to be honest.

 

http://modeles.meteociel.fr/modeles/gfsp/runs/2014121506/gfs-0-372.png?6

 

Classic MLB but at this time of year plenty of fog and frost would be on offer.

 

http://modeles.meteociel.fr/modeles/gfsp/runs/2014121506/gfsnh-0-372.png?6

 

The equivalent NH chart - interesting to note the PV over Canada trying to head west

 

Far from certain where this will go - the two runners look to be MLB (possibly becoming HLB with time and good fortune) and a West-based NAO hopefully shifting more in our favour with time and good fortune.

[Tamara]

It would be of interest to know how many view the NH maps and look at longer range tools available when they make posts? I keep wondering if I am alone in looking at different charts and from a quite different perspective to others

 

First of all though, as apparent from the postings last night especially, there still remains a myth that a colder pattern was/is likely to emerge before Christmas. There have been repeated explanations from various quarters, not least myself, that any outside chance of a cold pattern emerging pre festive season was based on accelerated -AO feedbacks throughout the autumn. No further embellishment is required to resurrect this discussion from the subsoil in terms of the transitory spoiling pattern that emerged across NW Asia and the consequential postponement of resumption of WAF that had been significantly robust up to this time .

 

On that basis, guidance in respect of continuation of broadscale westerly theme has been consistently accurate, and there should be no disappointment at the elusiveness of upstream amplification within this particular trend period  

 

This morning, same medium/longer term trends are apparent (if one can stop taking the presence of heights still apparent at day 10 to the south of the UK in isolation.... and then making long term assumptions based on the apparent 'refusal' of them to wane....)

 

Increasing amounts of both operational and ensemble guidance is advertising the retrogressed Pacific pattern as discussed over recent days as well as vortex energy transport across the pole towards Scandinavia and Siberia. Stratospheric WAF flux is once more showing poleward trending, and evidence that wave 1 activity is doing its job in this energy transport process. 

 

Across the Pacific, the emphasis is growing on repeated GEFS suites for poleward -EPO ridging,  Aleutian low prevalent, and emerging Atlantic amplification. ECM operational, slightly slower, but same post 10 day trend in evidence.

 

So, in summary, heading around the NH : Trough (Aleutians) ridge (poleward East Pacific) trough (Hudsons/central US) ridge (amplified Atlantic developing) and trough (NW Europe and Scandinavia) all evident as next stage development to keep watching evolve in post festive season and New Year modelling.

 

Evidence that downward AAM momentum is set to do its work on stifling jet energy and increasing these amplification signals downstream from the changing Pacific pattern that has dominated the first part of winter.

 

We should not 'fear' the Azores High into the New Year

[Rollo]

A very painfull Analysis from Gibby this morning ,If its cold and snow you crave for .A big thank you Gibby for your loyalty and giving us your time everyday ,the good thing with regards our daily Models is the fact that Gibby updates everyday ,which in a nut shell tells you that things can change so lets all remember that in our everchanging Meteorological pastime ,there will be more bad times as regards what we want but gains every now and again .todays later frames of ECM with a bit of adjustment could bring us a good n westerly feed with some seasonal fun for some .Dont write off talk several days ago of a pattern change with cooler temperatures as quite often things get changed only to come back a little later .The professionals must have seen some data to suggest this and being at a far range would have only mentioned this with a fair certainty .looking at current charts and all other data available to me this morning i think that in about 10/12 days we will see a very active trough over us or to our east and n/east with the azores high relaxed somewhat but relatively high pressure over western med .IM still finding it a problem posting charts as computer i think needs replacing [christmas fingers crossed]   

Regretfully I think Gibby is right,at present we are clutching at straws. Best to wait until early January and perhaps see more favourable charts.

[SE Blizzards]

Fantastic post as always Tamara 

 

Looking at today's updated AO forecast, many members taking a nose dive into negative territory as we head towards the New Year.

 

[Hocus Pocus]

to me, 'mild' is most likely to occur when we have the 0c+ upper isotherm over us... and its 'cold' (as in below the seasonan norm) when we have the -5c isotherm over us. in between the 0c and the -5c is what i take to be average/normal. just as a guide of course its not a golden rule.

heres the gfs 00z, and the ecm out to t240 is broadly the same.

1.gif note the azores high sat right over the azores, and the uk in a chilly northwesterly. and the approaching mild spell

 

2.gif the mild exits later on thursday, the azores high starts to flatten out by friday

 

3.gif 4.gif

another pulse of milder air follows the cooler pm air. high pressure to our south shifts eastwards slowly.

 

5.gif 6.gif

the high continues drifting east, and the pattern of mild/cool continues but what is telling is the appearance of that large vortex just west of baffin.

unless theres a major shift in these outputs there appears to be no pattern change this side of the new year, assuming of course that charts like this verify. to me its looking like a pretty average winter. (within the forseeable, im not suggesting any form of prediction/expectation for jan/feb).

That's the way I see it really alternating TM and PM air with temps coming in around average overall. To me the pattern looks flat for the foreseeable and unless we see a more favourable upstream pattern then all I can see is this waxing and waning continuing well into the New Year.

 

 

 

 

Edited December 15, 2014 by Hocus Pocus

[Frosty.]

Regretfully I think Gibby is right,at present we are clutching at straws. Best to wait until early January and perhaps see more favourable charts.

At least there is some wintry weather in the UK but you have to head north to find it, for now. It looks generally milder through the midweek period with Tm air sweeping across the UK but again, northern UK soon back into colder, showery weather with snow on hills and colder air will then sweep SE by Friday with overnight frosts returning..then Xmas week brings more Atlantic lows but with cold incursions in their wake. If we are lucky with timings, some of us may wake up to a covering of snow on the big day but I'm now looking further ahead to January when we could enter a colder phase of winter, hoping the MO will put some meat on the bone as to what shape this colder spell will take..i.e. Will it be settled and cold or something snowy from the east or north.

Edited December 15, 2014 by Frosty.

[OldMetMan]

Having been searching (rather desperately at times I’ll admit!) for some sign, any sign of a breakdown in the relentlessly progressive flow affecting us, no such sign has been forthcoming. The 500mb vortex over the W Atlantic is continuing to spawn LPs in the southern stream, destined for our shores, which has been added to at times by LP in the northern stream which have kept crossing Greenland, preventing any prolonged build-up of cold air, and thus HP there.

The GFS has been coming up with some intriguing long-term fantasies, but the short to mid-term has been fairly consistent across the models in the run up to Christmas, including the cold-lover’s worst nightmare – HP over France and Biscay!

However, I am with TEITS on this and feel strongly that a major pattern shift is gearing up for after Christmas and into the New Year. One of the first tentative signs of that today I think is the appearance of an upper high over W Canada, not much in itself but maybe an early sign of a trend to greater upper flow amplification, at least in the W hemisphere.

That flow does, I think, have a most peculiar look for mid-winter, with quite a number of fairly shallow vortices, showing little sign of moving. Indeed, between the vortex over the W Atlantic and the one over Iberia, that has done much to keep the Azores high firmly entrenched.

But what I am seeing as a possibility is for the slow but steady build-up of cold air and thus HP to the N, The Greenland HP would at last have a chance to intensify.

Many notable cold spells in the past have been preceded by a string of LPs heading across us from the SW, as cold air deepens to the N and NE, and the track of these has shifted slowly but steadily SE, finally allowing the cold air to break through. Here’s a spectacular example from 1978, a few days before a bitter E-NE flow set in.

In one of its many end of run variations, the GFS actually showed such a development recently, not that it means much admittedly, but it must have come up with this idea from somewhere!

OK, a certain amount of straw-clutching you might think, but even in the face of current evidence, I am still inclined to trust my instincts here. If such a development is going to happen, then I suspect it will take a while for the models to catch on.

So if the current setup looks bleak, then look ahead and watch for the signs!

[johnholmes]

You can see from the D8-10 ECM & GFS mean comparison how they handle differently the split flow of the jet as it exits the eastern seaboard:

 

test8 (1).gif

 

No difference to the UK in that time period; pure zonal. But the GEFS indicate that a wedge of higher heights can edge towards Greenland. The ECM mean is convinced this is wrong. So the GEFS hint at a slightly more amplified Greenland/Atlantic after D10. If ECM is right then the flat upstream pattern will continue towards D15+ as the D10 mean suggests:

 

EDH1-240 (1).gif

 

Nice to see the ECM mean (now in that range) also trend (like the GFS) towards the Alaskan Ridge and the Polar Heights migrating to that area.

 

Well iluustrated comment there re the flow difference on the EC-GFS anomaly charts and the additional comment that it makes little difference to the UK in that time frame. Likewise my comment last evening using the NOAA 6-10 and 8-14 to show that there is no change in the wavelength pattern likely in the 15 day time scale either.

[knocker]

The low that needs to kept an eye on. First it was there and then it was there.

Charts courtesy weatherbell

 

Edited December 15, 2014 by knocker

[Frosty.]

I have this intriguing long term fantasy that January and February might be wintry but I just want to know what the trigger will be which brings about this change. In the meantime, the broad scale pattern remains similar with some ebb and flow of the Azores high and also of depressions pushing east from Iceland into scandinavia which basically means a continuation of milder swly and colder nwly winds for the next few weeks or so.:-)

[nick sussex]

I still think its too early to write off some colder weather at Christmas.

 

Just taking the GEFS mean at T240hrs:

 

 

You can see the PV is located further east with some weak pressure rises over Greenland and troughing in the eastern USA, the Azores high is still a little too close for comfort but the mean will cover a wide breadth of solutions some flatter and some more amplified at that stage.

 

This far out come the day itself the pattern might be more or less amplified so you can make a case for different outcomes, bearing in mind that the pattern upstream will be undergoing some change with more amplitude during that timeframe, at this stage that amplification doesn't look like being sustained but its really a case of whether the UK can benefit during that more favourable window.

 

Of course the anti is raised because that window of opportunity falls around the Christmas period so is getting a lot more attention than normal.

 

I'd keep an open mind whilst the models decide on the downstream impacts of the troughing in the central USA, you never know some might have a nice surprise come Christmas morning.

 

 

 

[MR EXTREMES]

certainly no white christmas anywhere with this type of chart.

pretty mild.

 

this is well into the met office range of forecasting and they certainly dont call any colder conditions over the christmas period so id be happy to call against anything other than average maybe a little above possibly white in a frost sense but nothing exciting showing.

Edited December 15, 2014 by emotional rollercoaster

[phil nw.]

Nice post from Tamara and again restating the background factors and underlining that a notable cold outbreak in December was never likely .

I think many now appreciate that and a lot of the disappointment recently is the flattening out somewhat of the expected pattern in the next 10 days or so.

The approach of the Azores high will likely minimise the chance of any real cold getting established this side of Christmas with the flow looking to back more into the west or south west.

I think however we are just starting to see hints of something different towards month end.

As Tamara and others have already said there are increasing signs of the return of the Alaskan ridge and downstream Canadian trough around that time.

A look at the Naefs ht  anomaly forecasts for days 5/10/15 from the 00z run

 

and the 06z GFS mean run

 

 

and gefs at the end link

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=6&ech=384

 

around 50% with the idea of an Alaskan ridge.

 

so if we get the Alaskan ridge this should help create a Canadian trough and hopefully downstream Atlantic ridging.

 

We have good signs of the first stage wrt Alaskan ridge but then we need to see some support for Atlantic height rises and the shift away of the Greenland vortex.

This is probably just beyond the range of current daily modelling but something to look out for in the next week or so if this pattern is to evolve.

i am not yet convinced it will be a smooth transition to cold-it never is in the UK i guess-but there are enough hints to show maybe something maybe is afoot after the holiday period.

[knocker]

Nice post from Tamara and again restating the background factors and underlining that a notable cold outbreak in December was never likely .

I think many now appreciate that and a lot of the disappointment recently is the flattening out somewhat of the expected pattern in the next 10 days or so.

The approach of the Azores high will likely minimise the chance of any real cold getting established this side of Christmas with the flow looking to back more into the west or south west.

I think however we are just starting to see hints of something different towards month end.

As Tamara and others have already said there are increasing signs of the return of the Alaskan ridge and downstream Canadian trough around that time.

A look at the Naefs ht  anomaly forecasts for days 5/10/15 from the 00z run

naefsnh-0-0-120.pngnaefsnh-0-0-240.pngnaefsnh-0-0-384.png

 

and the 06z GFS mean run

gensnh-21-1-384.png

 

 

and gefs at the end link

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=6&ech=384

 

around 50% with the idea of an Alaskan ridge.

 

so if we get the Alaskan ridge this should help create a Canadian trough and hopefully downstream Atlantic ridging.

 

We have good signs of the first stage wrt Alaskan ridge but then we need to see some support for Atlantic height rises and the shift away of the Greenland vortex.

This is probably just beyond the range of current daily modelling but something to look out for in the next week or so if this pattern is to evolve.

i am not yet convinced it will be a smooth transition to cold-it never is in the UK i guess-but there are enough hints to show maybe something maybe is afoot after the holiday period.

 

Well possible signs of this on the 06z GEFS but it still seems to me to leave a westerly flow and no transition to cold.

Edited December 15, 2014 by knocker

[phil nw.]

Well possible signs of this on the 06z GEFS but it still seems to me to leave a westerly flow and no transition to cold.

No surprise really Knocker.

If we are to see any changes it will be beyond that as i suggested.Those +ve height anomalies in the Atlantic on that second 384hrs mean towards Greenland are what we would need to develop and strengthen.

 

 

Edited December 15, 2014 by phil nw.