Model output discussion - heading into 2018

[feb1991blizzard]

1 minute ago, bluearmy said:

I noted the number of members that amplified the n Pacific ridge well into the Arctic - at least two managed to make the full neg AO transfer to scandi block. far removed from the strat zonal onslaught we might be expecting to have manifested itself lower down by days 10 they 16 ...............

Yes I really wasn't expecting this kind of output once the potential Easterly projected for the first week of the new year had imploded.

[bluearmy]

3 minutes ago, northwestsnow said:

A lot of those members look very cold for London Blue- there must be a high centered somewhere to the north?

if anyone is tempted to look through all 50 members and count them then I suggest they don't bother - somewhere between 0 and 20% support for slp > 1030 mob over scandi days 10/15. That's not increasingly with any gusto, run to run. 

 

[northwestsnow]

9 minutes ago, feb1991blizzard said:

Yes I really wasn't expecting this kind of output once the potential Easterly projected for the first week of the new year had imploded.

I don't think anyone was- inc GP!

I'm still suspicious -but some kind of cell of HP does look increasingly likely to help push the jet more on a more southerly trajectory..

6 minutes ago, bluearmy said:

if anyone is tempted to look through all 50 members and count them then I suggest they don't bother - somewhere between 0 and 20% support for slp > 1030 mob over scandi days 10/15. That's not increasingly with any gusto, run to run. 

 

The period between 6th-9th has to have the vast majority of members showing a high to our north/north east- i can't see any other way the vast majority have those kind of temps..

the mean at 168 onwards confirms temps below average widely

 

Edited December 30, 2017 by northwestsnow

[feb1991blizzard]

1 minute ago, northwestsnow said:

I don't think anyone was- inc GP!

I'm still suspicious -but some kind of cell of HP does look increasingly likely to help push the jet more on a more southerly trajectory..

The period between 6th-9th has to have the vast majority of members showing a high to our north/north east- i can't see any other way the vast majority have those kind of temps..

They could be sliders with very slight +ve high anomalies (thin wedges) as opposed to genuine blocking highs.

[Allseasons-Si]

5 minutes ago, northwestsnow said:

I don't think anyone was- inc GP!

I'm still suspicious -but some kind of cell of HP does look increasingly likely to help push the jet more on a more southerly trajectory..

The period between 6th-9th has to have the vast majority of members showing a high to our north/north east- i can't see any other way the vast majority have those kind of temps..

As i posted earlier,the de-built was showing a few(bottoming=easterly)

Edited December 30, 2017 by Allseasons-si

[northwestsnow]

2 minutes ago, feb1991blizzard said:

They could be sliders with very slight +ve high anomalies (thin wedges) as opposed to genuine blocking highs.

Thats fine with me- the ens/ens mean looks cold mid term onwards- i'm not overly bothered if its a surface high or a fully fledged anticyclone..

[Allseasons-Si]

Navgem 180 going the gfs route

[Daniel*]

21 minutes ago, Allseasons-si said:

As i posted earlier,the de-built was showing a few(bottoming=easterly)

Control must have been very cold, 6 days of continental NE/E flow while the continent is not cold right now, it can cool very quickly at this time of year by late February there would have been issues - time is on our side. A lot more evidence of rather cold PM air looks about 20-30% have a continental flow on 6th.

[Allseasons-Si]

4 minutes ago, Daniel* said:

Control must have been very cold, 6 days of continental NE/E flow while the continent is not cold right now, it can cool very quickly at this time of year by late February there would have been issues - time is on our side. A lot more evidence of rather cold PM air looks about 20-30% have a continental flow on 6th.

I kept one from the 27th,compare it to tonights,i should save more of these in future.

[Snowy Hibbo]

5 hours ago, Singularity said:

Great post, thanks for your input 

It is fascinating to watch the observed GLAAM continue to stall when every new GEFS update wants to send it downward. Attached is an overlaid image of the latest GEFS mean (bright colours) on that of 20th Dec.

The longer this goes on, the more we will see the proposed increase in westerly momentum to overrun any fledgling Scandinavian Highs being reduced. Should GLAAM start rising as you predict instead, that'll cause even greater modifications and also increase the potential for a more sustained blocking event. At this time, I can't say for sure whether that'll happen or not, but I sure hope your outlook bears fruit! Coupled with more appetite for a mid-month phase 3 MJO from the models today... well, its been a decent one for trends .

The way ECM has been behaving over the past few days, I suspect a similar GLAAM error and subsequent correction has been taking place to that of GFS/GEFS, though probably not to such a large extent.

 

It's shocking that GEFS continues to be allowed to take GLAAM so far from realistic scenarios during the second week of any given model run; the extent to which this distorts the weather patterns means a significant amount of forecasting value is being thrown to the wind .

Yeah GEFS is so annoying with the -AAM bias. I wonder if someone could get their hands on the EPS version, that would very helpful. Perhaps FV3 (the new GFS in development) could be ridded of that bias. Sometimes you can notice the GFS -AAM bias by looking at the jetstream charts. That just mucks up the outlook.

But I have come to the realisation(thanks to an interesting PM and a subsequent reading of a bunch of papers), that forecast probably was to optimistic, based upon the underlying Niña state. But will be interesting to watch the GWO move around, and hope the AAM works out in your favour. Will be interesting to see how the EAMT event on GFS progresses, and the MJO convection.

[Ali1977]

Feast your eyes on some FIs from the latest ENS - some v good ones there!! 

plenty of -8c uppers, and a few of -10c.  I'd say best ENS yet although still a fair way out to be at all confident. 6-7th Jan now looking more like 10th before colder charts are in place.

[Weather-history]

There must be a lot of ensembles that are going for higher pressures between Greenland and Norway to produce this mean pressure chart at 192hrs. 

[Nick F]

Pretty underwhelming 00z GFS until deep FI, but the lesser GEM looks good this morning 

Edited December 30, 2017 by Nick F

[Dennis]

goodmorning do we see december-spring this day in south UK..... 

[knocker]

Overall picture with this morning's gfs, is unsettled and very windy at times

Today a front and rain, some snow on the higher ground, will track north east leaving clearer weather behind apart from the SW where it will remain cloudy. Quite windy in the south. This evening a new low 963mb will arrive west of Ireland and the associated fronts and heavy rain will start impacting the south west Overnight and through to morrow morning the low will move north east to eastern Scotland and the heavy rain, again with snow on the high ground, will also track NE and it also could become very windy over N.Ireland, northern England and Scotland.  Clearer weather behind but blustery showers in the resulting south westerly winds that also introduce milder air.

By 0600 Monday the low has moved north east to southern Norway but lows are queuing up to the west where we have the not unfamiliar picture of energy sweeping out of the south eastern seaboard in the form of a strong jet that is the boundary between the warm and cold air. Thus on the surface analysis there is a low 976mb wst of Hebrides associated with the main trough to the north east and a wave forming on the front delineating the boundary already mentioned 

By 12 Tuesday there is a deep low 967mb in mid Atlantic which started life a couple of days earlier  at the base of the upper trough and deepened rapidly as it tracked north east. The front associated with this is down the Irish Sea with rain already affecting the western parts of the UK probably falling as snow over the high ground in Scotland.

The front quickly crosses the country leaving the UK in a strong westerly, which veers north westerly, and under a two pronged attack us a wave swings south east across the south west en route to France and the main low drifts east over Scotland.

From this point things start to get interesting. Another low has bombed up from the eastern seaboard and is 957mb in mid Atlantic with associated fronts affecting the western UK but at the same time amplification is occurring and the surging high pressure splits the upper trough creating a high cell in the Iceland area whilst to the east of the UK it will deconstruct.

The amplification of the Azores HP forces the main low to fill and track south east over the UK as the west-east momentum is disrupted but there is still a huge amount of energy exiting the eastern seaboard so the question  is can the ridge withstand the pressure? Almost certainly not but best left here.

 

Edited December 30, 2017 by knocker

[Ali1977]

18z and 00z GEFS for central England - a Definite Dropbox off on the latter.

[Nick F]

Not so great for coldies from the 00z GFS and EC, still show the amplification over the Atlantic at the end of next week, but the low moving in off the Atlantic ahead of the building ridge loiters over the UK too long rather than ideally clearing southeast, which allows the next trough of cold upper and jet streak surge coming out of NE Canada to catch up and move into the NW to bring us into mild southwesterlies. 

There are 2 issues IMO that prevent a cold Ely or NEly:

1. is that the disrupting trough digs so far south over western Europe and as far south as NW Africa it throws up a ridge N across Eastern Europe, which prevents the low moving in across the UK later next week moving.SE into mainland Europe,

2. There’s too much energy / cold upper air spilling into the Atlantic from the trop PV to the NW which prevents any sustained ridging.

Too early to throw the towel in yet, given the ensemble guidance from GEFS and yesterday’s EPS, and the 00z GEM shows what’s still possible, but a step in the wrong direction from the most reliable ops this morning.

Edited December 30, 2017 by Nick F

[knocker]

The ecm is a bit of a nightmare next week with a couple of deep depressions bringing rain and strong winds, perhaps severe gales at times. It also amplifies the Azores HP which forces the last low south east to fill over the UK but again it is transitory as the east bound energy overwhelms any amplification by the end of the run

[Dennis]

hope to see a strong blocking for winter options

[nick sussex]

Short and sweet from me this morning !

GFS and ECM crap .

UKMO juries out as we don’t have the T168 hrs, but it looks a touch better because of the weaker low near the UK.

GEM great.

Nick F has already highlighted the problems . Either the low clears more quickly to the se or its game over I’m afraid .

Last chance saloon today , still enough ensembles are better but the ops need to move ASAP.

[knocker]

The ext EPS mean anomalies are pretty much the same as last evening.

[Frosty.]

Hardly the last chance saloon with 2 months of winter left!..anyway, I'm not seeing a prolonged mild mush fest from the latest models, there does at least look like there are some colder periods too..and always the chance of a more substantially wintry spell popping up.

[Scandinavian High.]

This looks much colder easterly flow with some deep cold pools to the north east this 384 hours way so very unlucky but it could be pop up nearer to a reliable time frame lets see what gfs 6z frows out .

[Sky Full]

Nick F and Nick S have both mentioned the 0Z GEM having some promise this morning and I thought the evolution from the 5th January was worth looking at.....

 . 

Showing a two to three day NE/E'ly setting up dragging colder uppers in from Scandinavia.  This is not in agreement with the other, more respected, models but can't be discounted completely.  This is one of several possible outcomes currently being shown and although it's probably the least likely we all know that the other models dont have this period nailed down yet either. 

[northwestsnow]

20 minutes ago, Frosty. said:

Hardly the last chance saloon with 2 months of winter left!..anyway, I'm not seeing a prolonged mild mush fest from the latest models, there does at least look like there are some colder periods too..and always the chance of a more substantially wintry spell popping up.

Dont think Nick meant last chance saloon for winter mate.

I'm pretty sure he was referring to the medium term and the ops are very disappointing this morning- neither GFS/EC shows the trough/low diving far enough into Europe so we see by day 10 the problem - 

The ens look OK but we need to see an op from the colder cluster, sharpish.