Model output discussion 25th Jan - The final third of winter beckons..

[Iceberg]

06 ens  are the best I've seen yet for the northern energy forecasting out to t144 much much better. 

The switch has been flipped. 

[Iceberg]

Worth mentioning as well that the upper atmospheric forecasts from ec 00z fully supported a stand alone almost omega block towards the end of the run with strong energy south. 

[nick sussex]

The expected pattern from NCEP over the USA towards next weekend doesn't support a downstream flattening of the high.

THERE IS A STRONG CONSENSUS
IN A SPLIT FLOW REGIME SETTING UP NEXT WEEKEND. ENSEMBLE MEANS ALL
DEPICT SOME SORT OF POSITIVELY-TILTED TROUGH SETTLING OVER THE
FOUR CORNERS REGION WITH GENERAL AMPLIFIED FLOW WITHIN THE
NORTHERN STREAM ACROSS THE NORTH-CENTRAL STATES.
 

This could be a timing issue with the GFS 06hrs run picking up that amplitude sooner, even the ECM ensembles develop that amplitude but a bit later. Because of the MJO more amplitude is likely so that's our background signal which should keep us positive about the outlook. Just as when we see ops pick out amplitude which isn't supported by the teleconnections its right to be dubious of outputs which show too much flattening which isn't supported the other way.

Todays MacRitchie MJO is even quicker with the signal and rock solid on taking that into phases 7 and 8:

 

 

Edited February 5, 2017 by nick sussex

[Ali1977]

Control is very similar to the Op to 174, always a good sign to have those 2 singing off the same song sheet 

[SMU]

All things considered & the trending -

PTB 18 seems to be the Lewis Hamilton of todays runs- Ie the firm favourite !

lets hope the Easterly engine doesnt blow up

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=0&code=18&mode=0&carte=1

shades of 2009 in that type of flow...

Edited February 5, 2017 by Steve Murr

[Tamara]

On ‎31‎/‎01‎/‎2017 at 17:58, Tamara said:

What is key is that the downstream amplification posse is clearly coming over the hill at day 10 into complete model ensemble suites. Look at the wider hemispheric model plots and see the retracted Atlantic ridge providing the ambush of the troughing from the west to squeeze the vorticity energy out, while the continental influence bumps it from the east.

The intra model operational details do not matter a jot at this stage within that time as long as the polar field and NE Europe is modelled the way it is. The jet deceleration downstream will take care of itself as the amplification comes closer into model radar. Then, just perhaps, we can start to think about the prize

Copied for intended emphasis and perspective of just how far we have come in several days

Insistence that the Azores High would not prevent the easterly vector in the medium term period has prevailed a suggested. Almost insidiously, each ensemble suite for the medium term has got colder as it has come within the 3 to 5 day period. The process is still continuing  - its only over focus on face value operational variances and worrying about micro details at ranges that are going to change dozens more times yet that blur the reality and make this a less enjoyable experience than it should be

The GSDM continues to provide both forward guidance and also show solid background support for NWP to rollout an increasingly higher latitude programme as we head through the month

In the Pacific we have the enticing prospect of a tropical convective wave that has been gaining suggested forecasting amplitude in recent days, and this has a lot to do with why we should expect upgraded prospects for amplification and Atlantic energy sliding southwards under the block to the NE. The latter as underpinned by the stratospheric rationale that ED/chiono and others have provided.

So what evidence is there for increased amplification prospects from tropical and extra tropical forcings?

The eastern portion of the ENSO zone has been undergoing some very impressive warming as the beginnings are in place towards neutral to weak El Nino in 2017.

This warming provides compellingly good support for the prospect of intensification of the MJO through Phases 7 and culminating in Phase 8.  The stronger the forcing at its more eastward, the greater amplification potential and prospects for cold air advection. A strong Phase 7 to 8 orbit suggests the most intense downward repercussions are maximised in our Atlantic and European sector.

Also cloudiness, (as an obvious flagger of increased convection potential) has been increasing close to the dateline -.see the diminishing yellow shading, indicative of rapidly declining OLR. Further signs that the Pacific is becoming more and more conducive to adding westerly winds to the planetary atmospheric system.

The importance of these westerly winds, is that with co-operation from the extra tropics in the form of mountain torques they can propagate and eddy poleward to assist mid latitude < graduating to higher latitude blocking. 

The effects of eastward moving tropical forcing is already impacting frictional torque and translating to the start of a bounce in relative atmospheric angular momentum. At the moment what has been holding this back a little is the protracted -ve mountain torque over the Rockies. But this in itself helped set up the changes we are seeing as posted last week.

But on the basis of the suggested size of the upcoming Pacific signal we should expect a large Asian torque response - also good news for extra vortex punishment. This will be the second part of sucker punch from the atmospheric circulation that was suggested to be programmed for the extended period as far back as last Sunday - when the NWP models were still highly cyclogenesis and zonal orientated moving forward. Its been catch up ever since.

With all this in mind, the Global Wind Oscillation is already being indicated to attain a higher amplitude Phase 4 by the usually low AAM bias GEFS.  Taking into account the backdated two day lag from WDT (a highly accurate site depiction of the tropical and extra tropical wind flows as registered by the GWO) increasing amplitude through Phase 4 began with the turn of the month

A GWO orbit through Phases 5,6,7,8 seems reasonable with interesting synthesis of both tropical and extra tropical forcings coming together to create a strong wind flow signal for retrogression of the block and advection of deeper cold uppers tucked up over the Urals.

The two day lag of the data means that these really solid amplification signals will be appearing over the coming days. But suffice to say, it would be best to take extended attempts to remove the block and send energy over the top with a very large truck load of salt. The evidence is stacked against this, and suggests the converse holds much better logical persuasion.

So there is a test provided to those who nerves must customarily oscillate with the face value nuances of each and every NWP roll-out.....

Later edit:    To back up above ^^ updated AAM tendency taking off further (still two day lag)

 

 

Edited February 5, 2017 by Tamara

[Summer Sun]

GFS op and control on the cold side of the mean lots of spread amongst the runs though

Edited February 5, 2017 by Summer Sun

[SMU]

18 minutes ago, pureasthedriven said:

Thought you didn't trust the 06, Steve..?! I jest. 

Lol -

I dont generally - depends if it follows the trending

if I have time later I will post up how 2009 easterly developed- it started like todays models are showing...

[Luke Attwood]

So the op was a cold outlier?

[Banbury]

2 minutes ago, Luke Attwood said:

So the op was a cold outlier?

I wouldn't say that , had support and on occasions some runs were colder

[Luke Attwood]

2 minutes ago, Banbury said:

I wouldn't say that , had support and on occasions some runs were colder

Ok thanks,how long would u say this cold spell will last? If starting from Wednesday,it looks cold throughout next weekend to me.and it could get even colder during the following week,that's my view on it

Edited February 5, 2017 by Luke Attwood

[Summer Sun]

Just now, Luke Attwood said:

Ok thanks,how long would u say this cold spell will last? If starting from Wednesday.

That's the million-dollar question at the moment no one knows for certain

[Ali1977]

10 minutes ago, Summer Sun said:

GFS op and control on the cold side of the mean lots of spread amongst the runs though

Lets hope the ENS trend with the Op and Ctl on the 12z - if they do stay cold that is.

A fair few go and stay cold thoughout but still some mild runs in there. 

Edited February 5, 2017 by Ali1977

[radiohead]

3 minutes ago, Luke Attwood said:

So the op was a cold outlier?

Not an outlier but on the colder side for sure. I'm more interested in seeing the 12Z ECM.

06Z and 18Z are slightly worse in terms of accuracy than 0Z and 12Z for the Northern Hemisphere so we have to remember that regardless if they are showing what we want to see or what we don't want to see.

[blizzard81]

And just to add to Tamara's excellent post,  there are some very cold 06z ensembles in the 8 to 12 day time frame. 

[Banbury]

2 minutes ago, Luke Attwood said:

Ok thanks,how long would u say this cold spell will last? If starting from Wednesday,it looks cold throughout next weekend to me.and it could get even colder during the following week,that's my view on it

If we all had our way GFS 6z would be banked . The GFS 6z changed very early on which shows the uncertainty not only in this situation but out weather in general.

If you just keep looking at a maximum of 5 days ahead you wont be far off

[A.J]

a quick reminder, please don't submit posts with the words "sorry, off topic mods, but I couldn't resist" and the like will be removed as soon as they are seen....Everyone knows the score regarding model output discussion and 99.9% of members respect that and we thank you for that .....The remaining 0.1% who deliberately post off topic content are simply wasting time, making work for us for the sake of it, and unless they quickly see the error of their ways, will quickly find out that their posting privileges are revoked............Sorry to the vast majority for the sunday morning rant but it has to be said

Edited February 5, 2017 by Paul

[blizzard81]

Just now, Banbury said:

If we all had our way GFS 6z would be banked . The GFS 6z changed very early on which shows the uncertainty not only in this situation but out weather in general.

If you just keep looking at a maximum of 5 days ahead you wont be far off

I think most on here are very wary of the 06z runs and it's poor reputation. Whether that is justified or not I am not too sure. However,  because these positive changes are happening in the 2 to 3 day range, I am feeling very excited about the prospects now. 

[Fourty Point Three Degrees]

1 hour ago, Matthew Wilson said:

Great 6z run. Much better than the ECM 0z for very cold and snow from next weekend

Looks like its only for Scotland and the far North. Theres nothing in there for Midlands or SE

[Frosty.]

We are very much trending towards a cold outlook, reinforced by the Gfs 6z which although it gets criticism it's the newest data available so it's all good..

Ps..fantastic post again from Tamara, she got my last available like for the day as I've used up my 100 available so apologies if I don't like your posts from now..I can't.

[Matthew.]

2 minutes ago, 40*C said:

Looks like its only for Scotland and the far North. Theres nothing in there for Midlands or SE

The general trend is towards -10 uppers on the 6z and more showery possibilities on the whole. Bit hard to pick out locations at this point but i think its positive nationwide imo

[Banbury]

6 minutes ago, 40*C said:

Looks like its only for Scotland and the far North. Theres nothing in there for Midlands or SE

That's not what the 6z GFS suggested , snow was a plenty across many areas

[weirpig]

13 minutes ago, 40*C said:

Looks like its only for Scotland and the far North. Theres nothing in there for Midlands or SE

All conjecture but the gfs showed quite abit of snow across a swath of the country  from wales across the north and the midlands  

[Ali1977]

1 minute ago, weirpig said:

All conjecture but the gfs showed quite abit of snow across a swath of the country  from wales across the north and the midlands  

The snow isn't showing up for many southerners yet, but isn't this type of set up better in the south as LP swing past or lift out of France. I don't think this will just be a cold dry week or so , plenty of chances for many - even if it is a light flurry 

[TEITS]

A fasinating change in the 06Z GEFS ensembles.

At times for the 9th Feb the mean was as high as -3C on most runs hence my earlier post. A switch has occurred with the mean now at -6C with some runs at -10C and below.

The next chart could be my eyesight but to me the Euro4 at +48 has colder uppers temps further S&W than the GFS suggests.