Model Output Discussion; into 2015

[Captain Shortwave]

Day 6 charts - a lot of small complications this morning which have a clear effect on things going forward.

ECM

Cold west/north west flow, note the 1014mb shallow low in the Atlantic, this is a major problem. The ECM develops a weak ridge which is undercut by the upstream trough. So the day 7 ECM chart is decent for those looking for cold, the 8-10 day charts are simply one evolution from that point.

 

UKMO

Cold west/north west flow, the model does not pick up the system shown on the ECM (has it already phased upstream?). There does seem to be a window of opportunity to develop a weak ridge which could aid colder weather down the line.

 

GFS

The PM shot will be a shorter in length here as the shallow low zips through the UK at day 7, so very different to the ECM.

 

Parallel

Similar to the GFS operational

 

GEM

Sort of sits halfway between the ECM and GFS solutions with a messy solution, a weak Iceland high forms later but is ineffective in bringing cold weather to the UK.

 

So at the moment there is still a chance of developing a potentially helpful weak high to our north, this clearly shown best in the ECM op with a clear undercut scenario at day 7, this allows heights to lower over Iberia later on. This would be the trend to watch out for. If the GFS is right on that low tracking quickly towards the UK then I expect this outside cold solution to disappear over coming runs.

[nick sussex]

Morning all

 

A mixed bag of overnight outputs but with a small opportunity at the moment for some snow next weekend.

 

The ECM is by far the best output today from a cold perspective, you can see that here:

 

T168hrs:

 

 

850's:

 

 

Theres a key difference at T144hrs with the shortwave to the north if you compare the GFS first:

 

 

Then the ECM;

 

 

You'll see the ECM makes much less of shortwave energy to the north, both models have similar overall patterns at that point, the ECM a touch more amplified.

 

Upstream there is likely to be a developing low deepening and crossing the USA, this helps to amplify a ridge ahead of it you can see that in the first image. This low is crucial and impacts the low to the west of the UK, both the GFS and ECM have this, however you'll note that the shortwave at T144hrs is the spoiler in the GFS, this phases with the low and doesn't allow more dig se of the jet near the UK.

 

The UKMO is a halfway house re the shortwave, that could clear and not phase given the upstream pattern.

 

In terms of the deep low crossing the USA NCEP note a large spread of solutions and uncertainty.

 

THE CRYSTAL BALL DARKENS CONSIDERABLY BY NEXT WEEKEND, WHEN THE
DEEP LOBE OF COLD AIR OVER THE SOUTHWEST FINALLY BEGINS TO KICK
EASTWARD. THE TIMING OF THE SHORTWAVES IN THE NORTHERN STREAM
VIS-A-VIS THE EJECTION OF THE SOUTHWESTERN VORTEX

 

 A
SIGNIFICANT NORTHERN STREAM SHORTWAVE DIPPING INTO THE GREAT LAKES
NEXT WEEKEND MAY VIE FOR DOMINANCE WITH THE HEART OF THE EJECTING
SOUTHWEST SYSTEM--SOMETHING BEST SORTED OUT AT THIS POINT BY A
HEAVY RELIANCE ON THE RECENT ENSEMBLE MEANS.

 

So a lot to keep an eye on, the movement of the Arctic high, events upstream and the shortwave to the north at T144hrs.

Edited December 28, 2014 by nick sussex

[Gibby]

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY SUNDAY DECEMBER 28TH 2014.

NEXT UPDATE MONDAY DECEMBER 29TH 08:00

THE CURRENT GENERAL SITUATION A large and intense Winter High pressure area will slip slowly SE over the UK through today and tomorrow.

MODELS-2 WEEK HEADLINE Becoming unsettled and windy later this week and onward with rain or showers at times and snow on Northern hills.

THE JET STREAM ENSEMBLE FORECAST The Jet Stream Forecast shows the flow ridging North over the UK currently. it is then shown to subside SE later this week with a strong West to East zonal flow enabling the Jet stream to undulate slightly North and South from a position close to Southern Britain and Northern France over the rest of the period.

GFS OPERATIONAL The GFS operational this morning shows a cold High pressure area sinking away SE later this week taking it's frosty weather with it and replacing it with strengthening Westerly winds and a zonal pattern of spells of rain and strong winds alternating with colder, brighter conditions with showers, wintry on Northern hills. After a cold atrt normal temperatures look likely from the end of this week but a few colder incursions with wintry showers could affect Northern hills at times during the showery interludes beteen the rain bands.

THE GFS PARALLEL RUN The Parallel run is very similar to the operational this morning except that it delays the worst of the wet and windy Westerly winds from reaching the South in a big way to the second week when all areas could see the risk of gales and heavy rain at times mixed with short colder weather with wintry showrs in the North.

THE GFS CONTROL The GFS control run also shows a strongly zonal pattern under westerly winds developing for the North by later this week and to all areas by next weekend with strong winds and rain at times for all through the second half of the period in average temperatures apart from brief colder interludes at times in the North.

THE GEFS ENSEMBLES The GFS Ensembles show strong support for a Westerly flow to dominate the UK from later this week. With Low pressure biased to lie to the North and High near the Azores Westerly winds, strong at times will follow their normal characteristics of spells of wind and rain for all with slightly colder and more showery interludes in between, these most prolific across the North.

UKMO UKMO shows the High pressure and attendant cold weather leaving the South Thursday into Friday with the less cold and unsettled weather under Westerly winds reaching all areas thereafter with rain at times though hints of a chilly WNW flow are shown for the weekend with showers, wintry in the North.

THE FAX CHARTS The Fax Charts show High pressure moving SE over Southern Britain and NW Europe through the week followed by much stronger and milder SW to West winds with rain at times as troughs sink SE across Britain late in the week and into next weekend.

GEM GEM today also shows High pressure moving away SE later this week replacing the cold and frosty weather with more changeable conditions under Westerly winds as Low pressure crosses East to the North. Rain bands would be replaced by colder and showery conditions at times too with some wintry showers over the hills and it would steadily become very windy.

NAVGEM NAVGEM also shows High pressure sinking away through the week and setting up a Low to the North and High to the South scenario with the UK lying under stiff Westerly winds with troughs crossing through delivering rain at times.

ECM ECM this morning is rather different in that although the dispense of High pressure over Southern Britain is still shown the Westerly winds that follow are shown to include pulses of cold air from the NW within them. So spells of wind and rain yes but rather longer spells of colder polar maritime winds in between delivering sometimes wintry showers to all areas before another brief spell of wind and rain returns from the West to reignite the pattern.

ECM 10 DAY MEAN The ECM 10 Day Mean Chart shows Low pressure to the North and High well to the SW the most likely scenario at Day 10. This would indicate a strong Westerly flow veering WNW at times with spells of rain mixed in with colder and wintry weather in places with snow and sleet showers blown across in strong polar zonal winds.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend this morning remains strongly in flavour of Westerly winds over the period with spells of wind and rain alternating with colder periods with wintry showers as the flow tilts West or NW occasionally.

MY THOUGHTS This morning maintains the general theme of the weather becoming less cold later this week over all areas as the High over the UK sinks away to the SE and allows milder SW winds to take hold. From thereon all models show variations of a theme of these Westerly winds with a mixure of milder and wetter spells alternating with rather cold and showery periods when some wintry showers are still very likely over Northern hills. ECM is the most interesting in the latter regard as it shows more tilt to the Jet stream digging further South somewhat over nearby Europe at times and sending cold fronts deeper South and allowing many areas to be rather cold at times under a more NW or even North flow briefly. However, the ensemble data strongly suggests that there is no impending chance of anything from Europe developing anytine soon with a strong vortex remaining close to Greenland and Iceland for most if not all of the time continuing to throw spells of wet and windy weather across the UK in broadly Westerly winds so it remains for folks to look North for anything cold through the first half of January 2015 and while some Northern folks could fair quite well at times with a decent amount of snow at elevation for much of the UK south of the Midlands we remain on a waiting game to see anything in the way of snowfall this Winter.

[Duane S.]

ECM op full of promise this morning. Not surprising after viewing the latest strat charts which (if correct) could send the forum rollercoaster into warp speed over the next week or so.

With the Arctic high coming into range on the ECM to start influencing matters on our side of the NH but a deep vortex still to our NW, I can see moods swinging back and forth between Atlantic depression and unmitigated elation as the models struggle to get a grip.

[nick sussex]

Looking at the ECM De Bilt ensembles its clear the control run has the jet quite far south with several lows tracking se or east either Channel Low type scenarios or shortwaves running se.

 

You can see by the switches in wind direction and the associated snow spikes on the 4th and 6th of January. These correlate with wind switches to the se then north east.

 

http://www.weerplaza.nl/15daagseverwachting/?r=midden&type=eps_pluim

[IDO]

Looking at the ECM De Bilt ensembles its clear the control run has the jet quite far south with several lows tracking se or east either Channel Low type scenarios or shortwaves running se.

 

You can see by the switches in wind direction and the associated snow spikes on the 4th and 6th of January. These correlate with wind switches to the se then north east.

 

http://www.weerplaza.nl/15daagseverwachting/?r=midden&type=eps_pluim

Yes but like the op one of the coldest solutions from D10. The mean wind is more a westerly compared to the op Northerly (and Control). So the ECM op looks unlikely from a mean perspective. That ties in with the GEFS comparison.

[Frosty.]

Looking at the latest modelling I can see lots of cold weather in the pipeline despite the usual doom and gloom assessments. January could be an exciting month for those of a cold disposition :-)

[Duane S.]

Yes but like the op one of the coldest solutions from D10. The mean wind is more a westerly compared to the op Northerly (and Control). So the ECM op looks unlikely from a mean perspective. That ties in with the GEFS comparison.

Yes but as always, there are two ways of looking at it.

Are the op and control out of kilter or are they leading the way? Guess we won't have the answer to that for a while yet.

[Gowon]

Wasn't the op the warm outlier last week and it turned out to be right?

[bluearmy]

Looking at the ECM De Bilt ensembles its clear the control run has the jet quite far south with several lows tracking se or east either Channel Low type scenarios or shortwaves running se.

 

You can see by the switches in wind direction and the associated snow spikes on the 4th and 6th of January. These correlate with wind switches to the se then north east.

 

http://www.weerplaza.nl/15daagseverwachting/?r=midden&type=eps_pluim

 

good call nick - the ecm control is the perfect snowmaker post day 10 for a swathe of the uk as two depressions run along the base of the upper trough. we see that sort of pattern evolving in the ecm op run. clearly an option, given all the recent output. the two week 2 runners predicated on a little ridge of heights thrown up towards iceland/greenland that has been showing on much recent output at various timescales.  prior to that, we have a runner on sunday that would probably induce a dump over n england, especially at elevation and then two systems that disrupt nw/se in our vicinity.

 

as far as the wider picture is concerned, the potential for a drop of the siberian segment of pv into scandinavia looks unlikely as the arctic ridge is unable to force is way this side of the pole before it is flattened somewhat by depressions running north from kamkatchka and dragging the siberian segment towards canada. the best result for coldies looks to be a general dropping of the extended vortex to our side of the NH (supressed by blocking the other side) and for us to end up in a sustained cold trough being fed with systems running into its base. that will relay on heights to our south and southeast giving way somewhat which hasnt seemed to be sustainable thus far this season.

 

so lots going on and no way a write off for those seeking the white stuff, even in the south. we retain the possibility of an upper pattern surprise cropping up at a short timescale because the behaviour of the arctic high is not always that predictable, especially with the azores throwing up ridges on a regular basis due to the variability of the upstream pattern.

 

in answer to JH|s question about the delay between events in the strat and trop - it currently looks like there is almost none with the trop/strat heights being very well connected right up to 10 hpa.

Edited December 28, 2014 by bluearmy

[Joe Levy]

Right at the very end of FI (well FI never ends really  ) but this is certainly an interesting chart! Low heights digging down into Europe with a high forming over us and undercutting lows from the Atlantic! Not to be taken too seriously obviously.

[Nick F]

Although ideally it would be nice to see a convoluted flow/blocked pattern this side of the northern Hemisphere rather than the zonal/progressive pattern shown from New Year's Day when we rid of the high, the mobile pattern could be worse for colder lovers, because:

 

1. There is no signal from either 00z GFS or ECMWF to build high pressure in the means across mainland Europe away from the Med (i.e. displaced Azores ridge):

 

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

 

2. Despite deep cold vortex over Nern Canada and Greenland driving a strong zonal flow over the Atlantic, deep troughing also advertised on the ECM ens chart below for day 10 over Scandinavia and into eastern Europe, would mean the jet dives SE, increasingly so, across France and Iberia - which means some longer-lasting bouts of cold zonality.

 

 

3. Should we see some amplification, as advertised by ECM op, then we could tap into the very cold air to our north via a transient northerly too, which would increase wintry potential towards the south aswell.

 

4. Persistent -EPO ridge torching over Alaska builds an arcitc high, jury's out whether this will extend it's influence this side of the pole, but the trop waves it creates may have ramifications for the polar vortex in January.

 

5. Already, as illustrated in the strat thread, there are signs of warming in the strat from wave number 1 activity, which may allow the pattern to develop more favourable for deep cold as we head through Jan.

 

6. Although the MJO is in an unfavourable phase for now, forecasts for it to motor through 4-5-6 and maybe towards 7 and 8 later in Jan, which could help drive a more favourable pattern.

Edited December 28, 2014 by Nick F

[mushymanrob]

Looking at the latest modelling I can see lots of cold weather in the pipeline despite the usual doom and gloom assessments. January could be an exciting month for those of a cold disposition :-)

 

im in agreement with you here karl... whilst the outlook in the models is fairly flat and unsettled, theres more cold then 'less cold' (ill not use the 'm' word lol) predicted. some of us are (un)lucky enough to have lying snow, and early (ish) snow events are often not the only ones we get in winter (unless theres a big freeze like 81, 10, ) , so id have thought theres a good chance of more, maybe a larger one for more to enjoy (or not lol)

as for our 'thawgate' discussion from the other day, i think (using my locale) that what we are getting is somewhere inbetween what we both were suggesting, with you perhaps overstating the severity and i was understating it. ive had more snow thats settled then i thought, but it is slowly thawing in the daytime...

[Man With Beard]

Wasn't the op the warm outlier last week and it turned out to be right?

Not at all I think, the op wanted to give a period of west-based -NAO; none of the models picked the eventual outcome until T120 - ensemble means or op runs.

[Harsh Climate]

I don't think the models are that great at the moment to be honest, all I can see for the next two weeks is a progression to cool zonality with the odd colder shot from the north west. If you live on a western facing hill in scotland then every reason to be happy, but for the other 99% of us, little chance of any meaningful snowfall anytime soon.

 

Still early days and a lot to play for but if we are to see any deep cold/snowy weather reaching our shores I don't think it will be until the latter part of january.

[Frosty.]

Hi mushy, I agree with your assessment :-)

As for models, there is much more promise in the output compared to the grim, awful winter of 2013 / 14. Lots of pm airmasses and even a chance of arctic flows at times with a northwest / southeast aligned jet, always a very good angle of attack for deeper cold zonality through mid winter.

Edited December 28, 2014 by Frosty.

[IDO]

ECM -v- GFS mean at D8-10 and the former is more amplified:

 

The 06z from GFS follows the 0z with a flatter pattern and little amplification in our sector at D10 from the GEFS:

 

 

To be honest up to D12 and there was nothing of interest on the GEFS, only one member offering respite, with a token UK transient high. I do not see the GFS going more amplified at the moment and suspect ECM will move towards GFS later. The GEM D12 ensembles very similar to the GEFS so at the moment I am not seeing any pattern change:

 

 

See how ECM goes tonight...

 

 

[TEITS]

I don't think the models are that great at the moment to be honest, all I can see for the next two weeks is a progression to cool zonality with the odd colder shot from the north west. If you live on a western facing hill in scotland then every reason to be happy, but for the other 99% of us, little chance of any meaningful snowfall anytime soon.

 

Still early days and a lot to play for but if we are to see any deep cold/snowy weather reaching our shores I don't think it will be until the latter part of january.

Really depends on your location. Those who live further N with elevation are at greater risk of snow with the pattern currently modelled coming up. However this does not exclude those low lying areas in the S. However for those in the S it will depend on how far S the jet digs and the track of the spin off lows from the base of the trough.

 

I would also like to apologise to members for my incorrect forecast after xmas. I have to be honest I wasn't expecting this cold, zonal pattern and expected the block to our E to remain in situ and then move further N

[nick sussex]

You can clearly see how important that low is upstream at around T162hrs by the dismal attempt at cold by the GFS P.

 

This doesn't develop the low over the ne of Canada, is flatter and just runs this into the low to the west of the UK, you must see the ridge develop ahead of that Canadian low like the ECM.

 

It's essential to carve enough amplitude in that troughing to the west of the UK to divert energy se, if that happens then a decent chance of some snow. If not the GFS P horror show is possible.

 

The USA state forecasts  suggest that the GFS P won't verify with that weak low, the low is expected to deepen and the trend in their view is  a track more northwest however I'd be happier to see this flat solution dropped quickly like tonight!

Edited December 28, 2014 by nick sussex

[Harsh Climate]

Really depends on your location. Those who live further N with elevation are at greater risk of snow with the pattern currently modelled coming up. However this does not exclude those low lying areas in the S. However for those in the S it will depend on how far S the jet digs and the track of the spin off lows from the base of the trough.

 

I would also like to apologise to members for my incorrect forecast after xmas. I have to be honest I wasn't expecting this cold, zonal pattern and expected the block to our E to remain in situ and then move further N

 

 

Yes , it may be cold enough at times for a little snow further south and more low lying areas. But in this type of set-up it will always be transient and any snowfall away from the favoured areas will quickly become slush/melt in between the short/sharp colder shots. 

 

 

I suppose like some on here I'm guilty of constantly searching for the holy grail (greenland high, bitterly cold easterly) and find it hard to get too excited from a less favourable set-up. But each to their own I suppose : )

[blizzard81]

I don't think the models are that great at the moment to be honest, all I can see for the next two weeks is a progression to cool zonality with the odd colder shot from the north west. If you live on a western facing hill in scotland then every reason to be happy, but for the other 99% of us, little chance of any meaningful snowfall anytime soon.

 

Still early days and a lot to play for but if we are to see any deep cold/snowy weather reaching our shores I don't think it will be until the latter part of january.

Yes, I totally agree with your comments. I am finding the model output very underwhelming at the moment. I cannot trust the ECM anymore when it shows amplification towards Greenland, especially when the GFS disagrees.

[Mucka]

The models have really been ramping up the zonal theme through the holiday period and pretty much zero sign of any blocking within them at the moment so any deep sustained cold looks very unlikely for the first half of January.

Much more mobile than I was expecting TBH but that is only what is currently on offer and there are windows of opportunity where the output could turn around and we could get a shot at something better.

 

One such window exists toward the end of the first week of January where there is a weak signal for a ridge to build either over or West of the UK with a more Southerly jet and low pressure diving into Europe.

At the moment it looks like any such ridge will be quickly overrun but that could change.

 

Otherwise there will be transient snow possibilities mainly in the North as colder air tucks in behind the deep lows.

For most though it looks like a wet and windy phase of Winter is on the way which is where the doom and gloom is coming from.

I understand the pessimism because thus far the winter out to mid Jan at least looks like being a let down but it has been fairly typical winter fare for the UK and much better than last year. Actually it is a lovely crisp winters day here today as I type.

 

On a  positive note there is plenty of winter left yet and no reason why we can't see at least one good cold snowy spell for the UK. Certainly the prospects are much better than this time last year and as always with the model output things can change pretty quickly for better or worse and I expect there will be more optimism around early next week as the models toy with the idea of a diving low.

[Jason M]

Really depends on your location. Those who live further N with elevation are at greater risk of snow with the pattern currently modelled coming up. However this does not exclude those low lying areas in the S. However for those in the S it will depend on how far S the jet digs and the track of the spin off lows from the base of the trough.

 

I would also like to apologise to members for my incorrect forecast after xmas. I have to be honest I wasn't expecting this cold, zonal pattern and expected the block to our E to remain in situ and then move further N

To be fair, did anyone really expect to be seeing charts like this? Nothing unusual in a period of zonality around new year, but looking at the charts I'm really quite shocked by just how awful they are. Yet again the GEFS are totally zonal this morning. You would normally expect to see the odd Stella chart just through natural scatter in deep FI, but I've hardly seen a cold chart in FI for days.

For me the biggest trend in the long range charts is a complete absence of any meaningful HLB whatsoever. The best thing that can be said is that we will get a shiny new set of charts later this afternoon and as we all know things can change.

[MR EXTREMES]

ECM -v- GFS mean at D8-10 and the former is more amplified:test8 (1).gif

 

The 06z from GFS follows the 0z with a flatter pattern and little amplification in our sector at D10 from the GEFS:

 

Meteociel_-_Panel_GEFS 6.png

 

To be honest up to D12 and there was nothing of interest on the GEFS, only one member offering respite, with a token UK transient high. I do not see the GFS going more amplified at the moment and suspect ECM will move towards GFS later. The GEM D12 ensembles very similar to the GEFS so at the moment I am not seeing any pattern change:

 

Meteociel_-_Panel_GEM.png

 

See how ECM goes tonight...

Whole heartedly agree.

There is once again a glimmer of hope all be it a very very tiny opotuinity!.

With no heights to our North East or no heights to our northwest clearly the same weather patterns we have recently been getting.

Like I said yesterday the northern hemisphere really does need to switch no high latitude blocking means the best we can get is a North west flow perhaps a northerly and this would only be a transition as it passes throw the uk.

The Azores although some what held back does not do us any favours with the vortex still dictating our pattern.

Although northern half of the uk may be in the primary area for cold attacks I'm afraid the rest of the uk especially the southern half is still stuck in the north south split.

We need the blocking to take hold otherwise this pattern will be continued.

The models still have the Azores hanging around and is the most consistent feature of all the model runs with it there it's not doing the southern areas especially any favours what so ever.

The models are pretty much in tune with each other after the continued uncertainty awhile back.

So with such high model confidence it does show that the more North you are the better chances of cold although it is chilly here in the south it's nothing truly exciting.

I will add that although rubbish in the south there is little support on above average temps although slightly milder here and there in the south.

But further north average to below.

[karyo]

To be fair, did anyone really expect to be seeing charts like this? Nothing unusual in a period of zonality around new year, but looking at the charts I'm really quite shocked by just how awful they are. Yet again the GEFS are totally zonal this morning. You would normally expect to see the odd Stella chart just through natural scatter in deep FI, but I've hardly seen a cold chart in FI for days.

For me the biggest trend in the long range charts is a complete absence of any meaningful HLB whatsoever. The best thing that can be said is that we will get a shiny new set of charts later this afternoon and as we all know things can change.

Agreed if there was a chance for a cold spell the GEFS would be showing it. I expect the ECM to lose its amplification later today.