Model output discussion - Winter has arrived

[Daniel*]

12 hours ago, Daniel* said:

Trust UKMO to dangle a big carrot.

So predictable from this model a snap of the fingers and blocking disappears. It’s the best so far this evening though.

 

[Scott Ingham]

1 minute ago, Catacol said:

Along those lines. Need to see just how much stretch the wave 1 displacement attack mid month will create, and just how sizeable an MJO forcing we can get after that hopefully enhanced with another +EAMT and substantive wave breaking. That would be the second hit - but I reckon it will take a third via the next round of momentum uptick in mid/late January.

My hopes are stacked on the next lot of MJO forcing being under modeled. It doesn't look substantive on the RMM plotting but neither did the first in November 

[heath]

Compare and contrast as ideas at day 10.

GFS

And GEM

No idea which will be nearest. 

[Mark wheeler]

56 minutes ago, nick sussex said:

NAVGEM- Not out yet but does anyone really care !

 

I do

[mountain shadow]

3 minutes ago, heath said:

Compare and contrast as ideas at day 10.

GFS

And GEM

No idea which will be nearest. 

The ECM will be rolling out shortly and will give us an idea.

Some say the GEM run gives a guide to the ECM.

[IDO]

3 minutes ago, heath said:

Compare and contrast as ideas at day 10.

GFS

And GEM

No idea which will be nearest. 

GEM matches the best at D6 but by D10 it is a lot less useful; verification stats:

d6>> d10>>

[chionomaniac]

54 minutes ago, Scott Ingham said:

Whats your opinion in regards to the strat? I have an outside opinion we could see a split last week into first week of January 

I’m more along the same thoughts of @Catacol slightly later split SSW similar to 2009. Certainly enough of interest in the early Synoptics to suggest we are not heading zonal for a while, and with the current wave 1 upper forecast, the strat may take a hit just at the right time, pre VI. 

Also take note of the negative AAM 50°N anomaly as highlighted by Matt Hugo tweets - this may bring any GFS jet stream strengthening to an abrupt buckling halt with a resultant amplified flow leading to meridional flow.

[Catacol]

Other data to whet the appetite. Wave 1 forcing looking decent

JMA monthly forecasts with a good look for week 2

And still a blocked pattern into weeks 3 and 4

And a 10 day EPS that shows some retrogression of the Ural signal.

I dont see anything above average about any of this, and if this is the STARTING point for the upcoming period of tropospheric led inroads into the arctic then all has surely got to be good. Some fascinating model watching coming...and more than this some fascinating wider interpretation of teleconnections and drivers in the offing.

Edited December 5, 2020 by Catacol

[Allseasons-Si]

Urals block opening up on some of the ext gefs ens

certainly some interest in the outputs to come no doubt

nice to see @chionomaniac posting again,welcome back Ed

[Methuselah]

I don't know what's worse... a swift kick to the Trossachs or blocked Urals!

Edited December 5, 2020 by General Cluster

[Day 10]

23 minutes ago, heath said:

Compare and contrast as ideas at day 10.

GFS

And GEM

No idea which will be nearest. 

The Navgem (GEM'S wife by the way so she's always right). 

[Catacol]

14 minutes ago, chionomaniac said:

I’m more along the same thoughts of @Catacol slightly later split SSW similar to 2009. Certainly enough of interest in the early Synoptics to suggest we are not heading zonal for a while, and with the current wave 1 upper forecast, the strat may take a hit just at the right time, pre VI. 

Also take note of the negative AAM 50°N anomaly as highlighted by Matt Hugo tweets - this may bring any GFS jet stream strengthening to an abrupt buckling halt with a resultant amplified flow leading to meridional flow.

Very clear in the Berlin charts Ed where this negative anomaly grows towards the end of the run.

The displacement hit on the vortex may add a bit of westerly momentum locally to our sector, but with such an ongoing disconnect at the moment between the upper and lower layers it may make little difference. And then we get another momentum surge enhanced as the MJO hits the maritimes, and the block strengthens? Split vortex then in the wings to follow?

Descending eQBO is also quite significant on this forecast. Door opening to greater flux access to the vortex at just the right time?

Hmmm. It's all rather interesting...... 

[Scott Ingham]

23 minutes ago, chionomaniac said:

I’m more along the same thoughts of @Catacol slightly later split SSW similar to 2009. Certainly enough of interest in the early Synoptics to suggest we are not heading zonal for a while, and with the current wave 1 upper forecast, the strat may take a hit just at the right time, pre VI. 

Also take note of the negative AAM 50°N anomaly as highlighted by Matt Hugo tweets - this may bring any GFS jet stream strengthening to an abrupt buckling halt with a resultant amplified flow leading to meridional flow.

Yes I noticed that friendly green blob at 50 degrees. Just at the right time along with current wave 1 activity. Either late December early Jan or mid jan to late jan all roads lead to a potential snowy rome

[Ols500]

is there a video to explain what a wave 1 is. thanks.

[feb1991blizzard]

Just now, Catacol said:

 

Descending eQBO.

 

Was wondering about this, this is what has lead me to change my winter forecast at the last minute to a cold blocked Feb as opposed to just a cold last dregs late feb into March, but the Nov QBO only reduced from 11 to 10 i think, will it come in time or will just a weakening of westerlies do the trick?, what level of the atmosphere would the E-qbo have to get down to, perhaps not all that low to assist an over the top SSW, also with the nina reducing in intensity we are so close to a GP combination as we are just after solar min now, that should really help shut the jetstream off in February.

[chionomaniac]

So already at T+96 the ECM has better heights north of the UK and this should lead to an increased chance of an undercut when compared to the GFS

[Radiating Dendrite]

2 minutes ago, Ols500 said:

is there a video to explain what a wave 1 is. thanks.

From my limited understanding it is warming on one side of the vortex - can lead to a displacement (moving) of the vortex.

[Radiating Dendrite]

Just now, chionomaniac said:

So already at T+96 the ECM has better heights north of the UK and this should lead to an increased chance of an undercut when compared to the GFS

Great to have you back!

[Ols500]

1 minute ago, Radiating Dendrite said:

From my limited understanding it is warming on one side of the vortex - can lead to a displacement (moving) of the vortex.

ah thank you!

[chionomaniac]

10 minutes ago, Radiating Dendrite said:

From my limited understanding it is warming on one side of the vortex - can lead to a displacement (moving) of the vortex.

It’s large scale planetary wave activity that can lead to a warming. I may have explained it in a previous first post of a strat thread from years gone by..

in fact a good starting point is clicking the outdated link in my bio below nd getting some background info there. Lol I should really update this

Edited December 5, 2020 by chionomaniac

[alexisj9]

1 hour ago, Geordiesnow said:

All transient snowfall which did not even stick around for long. Yes admittedly, more areas did see more snow than I thought but it was always going to be transient in nature. 

Reality is now, low pressure in charge, no real significant cold on the way and no real signs of the PV dropping into Scandi so any chilly air will be scraps only. Quite poor for December really. 

In my experience, it's actually quite good for early December. Transient snow is far more likely at this time of year, down south, than lasting snow, it was a very nice surprise for those who got some.

[sheikhy]

Ecm fantastic at 120 hours!!!sliders alert!!

[Ols500]

1 minute ago, alexisj9 said:

In my experience, it's actually quite good for early December. Transient snow is far more likely at this time of year, down south, than lasting snow, it was a very nice surprise for those who got some.

This Dec (in my opinion) is far better than any Dec since 2010. It feels seasonal, other Decs where 11-14c...

[TSNWK]

3 minutes ago, sheikhy said:

Ecm fantastic at 120 hours!!!sliders alert!!

But are the muddy sliders or icy

[ICE COLD]

Yes the ECM is having none of gfs runs . Looks so much better .

 

PS I do love it when @chionomaniac starts to get involved