Model output discussion - winter proper underway

[jvenge]

ECM control is mild out till the end and if you had hopes of chilling the bubbly outside on Christmas day, you will be hoping its well off mark. The mean seems to suggest the control option would be on the extreme side, but it is also not favouring a seasonal feel.

 

 

[northwestsnow]

Pondering if the EC day 10 mean is setting us up for atlantic amplification-

Edit cant post todays for some reason but it looks better than yesterdays IMHO..

Edited December 14, 2017 by northwestsnow

[nick sussex]

Great detail from New Hampshire state forecast talking about the overall NH pattern into late December:

Overview...

Interpreting through late December. Considerable forecast warming in
the stratosphere, polar low / night-time jet displaced to the other
side of the N hemisphere subsequent of noteworthy anomalous ridging
across Northern N America. Beneath which warm air continues to surge
into the Arctic from the NW Pacific (with perhaps MJO contributions)
and the NW Atlantic displacing colder air S where it becomes bowled
up across NE Asia / NE N America. Ensemble means continue to signal
an active weather pattern with an amplified H5 ridge-trof pattern
over the CONUS, anomalous H85 T warming over the N Pacific with cold
anomalies continually reloaded over Central/E N America, however a
trend towards higher heights / surface mean sea level pressure with
stratospheric cross-polar flow shifting into NW Europe.
 

 

[carinthian]

15 hours ago, carinthian said:

I think most who want the cold to return will settle for this latest run from GFS. Chart below at t210 . In relation to the above post I earlier sent, we need to see those lower heights showing to the NE to drop. I think now that the holding pattern over Central Russia is becoming less abnormal this process is possible and would allow pressure to rise to the north again. Good to see at this stage and room for much more colder scopes over the Christmas and New Year period. Blighty still on the outside but a cold Christmas now upgraded from 40% to 50 %. I am pleased to see heading in the right direction.

C

Re: the above post. GFS model doing everything right to lead us to a colder Christmas and New Year. Most importantly it drops the heights into Euroland and allows pressure rises to the north. That's where we want it.  T10 chart below from GFS shows a massive difference with the ECM , which basically keeps much of Europe under a high pressure and a milder outlook for the British Isles. Not sure where UKMO is going but probably the one to watch in later runs but looks mild in the medium term out to 192t. Will look forward to see how the American Navy Models looks at 180t shortly. That will be a critical time to see if evolution to cold is going to take place. Anything better than Euro slug mildness .

 C

[northwestsnow]

1 minute ago, nick sussex said:

Great detail from New Hampshire state forecast talking about the overall NH pattern into late December:

Overview...

Interpreting through late December. Considerable forecast warming in
the stratosphere, polar low / night-time jet displaced to the other
side of the N hemisphere subsequent of noteworthy anomalous ridging
across Northern N America. Beneath which warm air continues to surge
into the Arctic from the NW Pacific (with perhaps MJO contributions)
and the NW Atlantic displacing colder air S where it becomes bowled
up across NE Asia / NE N America. Ensemble means continue to signal
an active weather pattern with an amplified H5 ridge-trof pattern
over the CONUS, anomalous H85 T warming over the N Pacific with cold
anomalies continually reloaded over Central/E N America, however a
trend towards higher heights / surface mean sea level pressure with
stratospheric cross-polar flow shifting into NW Europe.
 

 

Sounds good Nick!!

I posted the gfs00z strat charts which point in this direction...

I have had a hunch for a few days that things will look very different between christmas and new year,heres hoping!!

[Summer Sun]

ECM and UKMO at t168 not a million miles apart for the UK

[northwestsnow]

11 minutes ago, Summer Sun said:

ECM and UKMO at t168 not a million miles apart for the UK

I think they are quite apart personally.

UKMO looks to be putting quite a bit more into the southern arm of the jet than EC..

edit sorry Gavin yes they are similar for the UK but down the line i'm not so sure they are

Edited December 14, 2017 by northwestsnow

[comet]

21 minutes ago, nick sussex said:

Great detail from New Hampshire state forecast talking about the overall NH pattern into late December:

Overview...

Interpreting through late December. Considerable forecast warming in
the stratosphere, polar low / night-time jet displaced to the other
side of the N hemisphere subsequent of noteworthy anomalous ridging
across Northern N America. Beneath which warm air continues to surge
into the Arctic from the NW Pacific (with perhaps MJO contributions)
and the NW Atlantic displacing colder air S where it becomes bowled
up across NE Asia / NE N America. Ensemble means continue to signal
an active weather pattern with an amplified H5 ridge-trof pattern
over the CONUS, anomalous H85 T warming over the N Pacific with cold
anomalies continually reloaded over Central/E N America, however a
trend towards higher heights / surface mean sea level pressure with
stratospheric cross-polar flow shifting into NW Europe.
 

 

Sounds great for NW Europe and the UK but is this not just an interpretation of what the gfs op run is showing rather than a detailed view of what the mets in this area are expecting to see happen. Not saying it will not happen though.

[Summer Sun]

Next week is going to feel tropical with temperatures widely getting into double figures

Something colder towards the end of the week?

[northwestsnow]

Fingers crossed gfs6z carries on where it left off on the 00z..

Of course the run up to christmas will not show anything cold wise- its the period around christmas and afterwards that holds the interest for me personally..

 

[TEITS]

As many know I have been rather negative towards any chance of a cold spell into Xmas and even extending into the New year. However despite the ECM continuing to be poor, im not as confident as I was yesterday. What has raised my interest is the fact that the GFS Op is continually being an outlier and when that happens I take note.

However im not confident of the GFS being right either. When you have such a big difference between the models it raises doubt in my mind that any models are correct for the period in question. I do think though that Tamara, GP may think the GFS is a little too early in bringing in the E,ly.

So in summary I haven't a clue what is going to happen for Xmas!

[Nick F]

Good to see the ensemble mean pull cold air down across eastern Europe and NW Russia in the medium to extended range, there is a lack of deep cold to the east right now, so to develop a cold pool to our E and NE will set up nicely if an easterly does transpire to end the year or early New Year.

In the meantime, we are likely to be stuck with a protracted spell of flow off the Atlantic from the W or SW, perhaps lasting through Xmas, given the colder operationals from GFS (yesterday's 06z & 12z and this morning 00z) were at the cold end or cold outliers of the ensemble spread. But the strong signal for the -EPO ridging to the pole with help of MJO, should in theory, eventually shift the tropospheric PV over Canada and Baffin S and SE, as per extended EPS H500 mean, which may mean a more southerly jet and storm track after Xmas, but perhaps encouraging height rises to the NE which could be aided by cross polar +heights / developing -AO.

But a lot of water to flow under the bridge before we may see concrete evidence from the model guidance for a pattern change to bring cold back after it turns milder from the west from Sunday. GFS operationals maybe too eager to change the pattern around Xmas, we could be looking at the period between then and New Year.  A fairly reliable indicator of the braodscale 500mb pattern into the extended period is the CPC prognostic H500 charts - which suggest little indication of amplification over the Atlantic:

Edited December 14, 2017 by Nick F

[Devonshire]

1 hour ago, Summer Sun said:

Next week is going to feel tropical with temperatures widely getting into double figures

Um, no. Unless you are off on holiday next week?

"A tropical climate in the Köppen climate classification is a non-arid climate in which all twelve months have mean temperatures of at least 18 °C (64 °F)."

Edit: Ah, unless you mean comparable to half way up Kilimanjaro?

[Chesil View]

Just now, TEITS said:

As many know I have been rather negative towards any chance of a cold spell into Xmas and even extending into the New year. However despite the ECM continuing to be poor, im not as confident as I was yesterday. What has raised my interest is the fact that the GFS Op is continually being an outlier and when that happens I take note.

However im not confident of the GFS being right either. When you have such a big difference between the models it raises doubt in my mind that any models are correct for the period in question. I do think though that Tamara, GP may think the GFS is a little too early in bringing in the E,ly.

So in summary I haven't a clue what is going to happen for Xmas!

Join the club teits. its defininetly an interesting period at the moment model wise

[bluearmy]

The eps clusters could be very revealing shortly

the op not nearly amplified enough at day 9 through the uk and out ne

Looking more closely at the spreads there looks to be a cluster which follows the gfs op at day 9 and the eps lose their resolution post day 10 so solutions less reliable after that. Again, expect to see a more amplified cluster percentage than yesterday’s 

the mean seems keen on a broad Atlantic trough as week two progresses with developing mean sceuro ridge anomoly 

Putting the two themes together and potentially an extended cluster showing the Atlantic undercutting a developing ridge to our northeast ???

 Wonder what percentage that would be ??

[northwestsnow]

3 minutes ago, bluearmy said:

The eps clusters could be very revealing shortly

the op not nearly amplified enough at day 9 through the uk and out ne

Looking more closely at the spreads there looks to be a cluster which follows the gfs op at day 9 and the eps lose their resolution post day 10 so solutions less reliable after that. Again, expect to see a more amplified cluster percentage than yesterday’s 

the mean seems keen on a broad Atlantic trough as week two progresses with developing mean sceuro ridge anomoly 

Putting the two themes together and potentially an extended cluster showing the Atlantic undercutting a developing ridge to our northeast ???

 Wonder what percentage that would be ??

I'm watching your posts blue, and eagerly awaiting GPs input.

Again i'm thinking/hoping for a change post christmas..

6z showing some dense cold air building over the baltics  by the 22ns..

Edited December 14, 2017 by northwestsnow

[northwestsnow]

Desperately need the Atlantic to quieten down on this run-

Looks ripe for some retrogression at 222hrs but we need to see an end to these systems coming off the ES!!

[bluearmy]

The 06z looks more plausible given the eps spreads. The 00z was a bit over amplified at this stage of the modelling although things could still change in this regard 

[Summer Sun]

06z a lot milder for the south on Friday compared to the 00z

Wednesday, on the other hand, isn't quite as mild

[northwestsnow]

hmmmmm- the profile to the NE and SE looks great !! Just we have a pretty huge PV setting up exactly where we don't want it..

[Singularity]

3 minutes ago, bluearmy said:

The 06z looks more plausible given the eps spreads. The 00z was a bit over amplified at this stage of the modelling although things could still change in this regard 

Agreed - on balance, a general theme of strong ridging across the UK makes the most sense as our ‘holding pattern’ while awaiting sufficient upstream changes, which do tend to take more than one bite of the cherry when it comes to Scandi Highs.

Encouraging to see GFS finding a route despite the less optimal day 7-9 progression than the 00z produced.

[ICE COLD]

8 minutes ago, northwestsnow said:

hmmmmm- the profile to the NE and SE looks great !! Just we have a pretty huge PV setting up exactly where we don't want it..

She gets there in the end ?

[northwestsnow]

6Z shows the 2m temps nosediving as we hit boxing day!!

OK its a waiting game but lets just says its ends well....

[Ali1977]

Another great looking FI

[feb1991blizzard]

 

Imagine the state of the bottom half of the stratosphere if that verified, protracted cold spell inevitable from there, that's a corporal Jones special, the upward thrust!!