Model Output Discussions 06z 04/11/16

[nick sussex]

22 minutes ago, knocker said:

I'm afraid I'm not following that. Both at T120 and T144 there is very much a meridional flow over the central US with a deep upper low situated there/

If you look at the ECM op compared to the GFS you'll see the latter is more amplified at day 5 and 6 over the central USA. Once I get back on the laptop I'll stick some pics up to show this.

[Frosty.]

8 minutes ago, nick sussex said:

If you look at the ECM op compared to the GFS you'll see the latter is more amplified at day 5 and 6 over the central USA. Once I get back on the laptop I'll stick some pics up to show this.

I agree with Nick, now where have I heard that before!

[Man With Beard]

Well this is awkward...

  

That's a monstrous difference for a mean chart - absolute chalk and cheese. Are we on the new ECM now? If so, they've well and truly dealt with its north Atlantic amplification bias - hopefully too much!!

 

 

[Glacier Point]

Seems to me the reasons not to go cold are being removed one by one...

Compare Tuesday's week 2 forecast for upper level velocity potential in the tropics and today's..

You'll get some idea of the pace of change here - not fast, but the steady trend is to shift the convective wave associated with this towards the Maritime continent. Trend in GFS modelling a reflection of this, mid Atlantic ridge and developing North Pacific ridge. Notably EC modelling has been much slower with this wave, and more broadly convective wave passage through the Maritimes shows lower skill. So expect poor model reliability to get worse.

GEFS and GEM modelling of the stratosphere is different to EPS, although broad agreement on a Canadian Warming and slight rotation of the stratospheric ridge on an anticlockwise rotation towards Greenland. GFS is a good representation of this, although on the weak side for this run, but the prospects of a squeeze on the upper vortex from both sides of the Pole from Atlantic and Pacific sides looks like a long term trend here.

Where that takes us.. should see increasing propensity for tropospheric ridge across the polar region, and increasing meridionality in the Atlantic sector. Latest EPS very unconvincing in its anomaly fields being very weak signature across its mean with the exception of the North Pacific ridge.

Edited November 24, 2016 by Glacier Point

[knocker]

13 minutes ago, nick sussex said:

If you look at the ECM op compared to the GFS you'll see the latter is more amplified at day 5 and 6 over the central USA. Once I get back on the laptop I'll stick some pics up to show this.

I agree it's more amplified in general over North America because it introduces the GOA trough but on both the flow is very meridional. So much flatter is not really that obvious. Anyway at the end of the day, and now having looked at the EPS, the ecm certainly has a different take on the evolution.

Edited November 24, 2016 by knocker

[Frosty.]

17 minutes ago, Man With Beard said:

Are we on the new ECM now? 

 

 

If we are on the new one, I want to see the old one come back..but seriously, there is support for a cold and unsettled early December with a nwly / nly flow..everything crossed!

Edited November 24, 2016 by Frosty.

[Scandinavian High.]

Cold is the name of game as we move in to December models all over place at minute still week away  but a firming up of models on way 

[Ravelin]

Fascination discussions regarding the ECM/GFS differences this morning. Anyway GFS 6z is rolling out and some westwards shift of the cold air at t78...

0Z    6z

 

0Z   6Z

Still not enough to make any practical difference though at this stage.

[karlos1983]

More poor model reliability, great news considering the junk that ECM is throwing out twice a day presently!

Great post GP, thank you very much.

[supernova]

Lack of cross-model consistency (even in the semi reliable) and, thereafter, a messy solution 144hrs onwards makes me doubt the surety of any upcoming cold shot (or any other shot) in the short term but there's one thing I know for certain, the words 'upgrade', 'potential' and 'blocking' were in very short supply at any point last year and those same words have aleady been bandied about quite a bit on this thread as we head towards winter proper. Also, there are still any number of positive synoptics (solar slumber, disorganised PV, Siberian warming, sea ice levels, advancing Eurasian snow cover) in place to make this year far less disappointing than the boring sludge we've endured over recent times. Although all models appear to have their own strengths and weaknesses, I'm as yet unconvinced by the latest ECM updates which appear to have over compensated for its propensity to exagerate Atlantic amplification (am reluctant to recall THAT notorious occasion but there have been other unforgivable teases too). What I have more confidence in, is the quality of analysis and knowledge on this forum, and I'm grateful to all those characters who share their time and expertise so generously....giving followers like me a welcome weather insight, unavailable anywhere else. Keep it up (you know who you are), we don't all have the knowledge to post on here with confidence but that doesn't mean we can't enjoy the ride.

Edited November 24, 2016 by supernova

[Singularity]

32 minutes ago, Glacier Point said:

 Notably EC modelling has been much slower with this wave, and more broadly convective wave passage through the Maritimes shows lower skill. So expect poor model reliability to get worse.

GEFS and GEM modelling of the stratosphere is different to EPS, although broad agreement on a Canadian Warming and slight rotation of the stratospheric ridge on an anticlockwise rotation towards Greenland. GFS is a good representation of this, although on the weak side for this run, but the prospects of a squeeze on the upper vortex from both sides of the Pole from Atlantic and Pacific sides looks like a long term trend here.

Where that takes us.. should see increasing propensity for tropospheric ridge across the polar region, and increasing meridionality in the Atlantic sector. Latest EPS very unconvincing in its anomaly fields being very weak signature across its mean with the exception of the North Pacific ridge.

Reading an unpublished thesis last year, evidence was shown that ECM has a low-propagation speed bias for MJO type activity. This was only significant in the W-C Pacific but perhaps on occasion it could lead to divergence from other models for the India-Martimes sector, such as we're seeing at the moment.

GEFS is impressing me with the strength of trend toward what theory suggests we should expect mid-Dec. This a case where we really so wish for it to be leading the way!

[karlos1983]

No back tracking from the GFS 06z, it is determined to bring us the Northerly. If it sticks to it's guns and gets agreement from the UKMO this afternoon, I think we will see an ECM with it's tail between it's legs this evening. 

 

Edited November 24, 2016 by karlos1983

[Ravelin]

Well if the GFS is going to win out in the ECM/GFS battle it's looking to throw everything at it. By t144 the 6z is much better than the 0z around Greenland and a slightly more NW->SE tilt to the flow.

0Z     6Z

Edit: And by t168...

0Z    6Z

Recently the GFS 6Z has been becoming my favorite run, I just hope it doesn't let me down.

Edited November 24, 2016 by Ravelin

[karlos1983]

Much more favorable Northerly with better ridging in the Atlantic and closer to us on this run

 

[booferking]

The 510 line 180hr almost touching Scotland. WOW

[Paul_1978]

Well by T+171, it's more Northerly and lest North-Westerly than the 0z. Much sharper ridging in the Atlantic.

[tight isobar]

6z....

Dog with a bone.

This further highlighting' ecm negative'response to evolution. 

Gfs overiding the solution of waa.and responding exceptional well imo.

[Seasonality]

6 minutes ago, Ravelin said:

Well if the GFS is going to win out in the ECM/GFS battle it's looking to throw everything at it. By t144 the 6z is much better than the 0z around Greenland and a slightly more NW->SE tilt to the flow.

0Z     6Z

A real battle royale between the two heavyweights of the NWP world. Who will come out on top with the title belt for the latest bout? ECM and GFS still chalk and cheese.

[snowice]

1060hp cell over Greenland AT 180hrs 6Z gfs.

[Gavin Hannah]

Oh my god I don't think this thread saw this much excitement at any point last year!  If that HP in the Atlantic was able to link up with the Greenie HP or Nova Scotia HP, that would be veeeeerrrry interesting.

[tight isobar]

Solid ridge...deep waa eastern seaboard' Atlantic shut off point accomplish. 

Deep set pv eastern pole....

[northwestsnow]

Gfs6z is much more pleasing than that horrid Ecm, oh i do hope Gfs can Donald Ecm here, very cold north wester with cold, frosts and snow showers...

[Man With Beard]

There may be snow for everyone on this GFS run

What would be the halfway position between the current GFS output and the Euros? I would guess even a halfway position would still look wintry for northern areas.

[Ravelin]

Interestingly, the low that lands over Norway at t168...

Is still sat there at t216

Not bringing hugely cold t850 temps though

[Jonan92]

It's going to link the polar low with the atlantic one...