Model Output Discussion 29th December - Into mid-Winter.

[nick sussex]

Just now, chris55 said:

So true Nick, just like where "that" Azores low headed. Was that due to all those global factors or were we just governed by some small localised synoptics? Im not sure to be honest.

However, as I pointed out earlier, still plenty to keep us on our toes regarding colder outcomes and ECM is well within that sphere. In fact its looking rather nice.

 

 

Yes the ECM is a breath of fresh air this evening. The ECM from early doors though did build up a better start point going forward, again on a global scale a quick look at the NH charts and you'd think that won't make much difference but these early differences can snowball into big changes down the line.

Interestingly NCEP said this in their discussion from early on.

THE SYSTEM IN THE EAST WILL ENCOUNTER
BUILDING RIDGING TO ITS SOUTHEAST WHICH WILL PREVENT ITS MOVEMENT
SOUTH OF ABOUT 35N. NEXT SYSTEM IN ITS WAKE MAY SLOW AND STRETCH
NE-SW BY NEXT FRIDAY ALIGNED WITH THE UPPER FLOW.

Perhaps a pointer to which model might have the right pattern over the eastern USA at that time. Take a look at the ECM T168hrs. Of course it takes more than that to get to where we want to be but anyway at least the ECM keeps us interested moving forward.
 

[Pembroke Dangler]

48 minutes ago, PerfectStorm said:

You what!? ECM on the post-Christmas alcohol leftovers. 

It's what I was thinking there would be a link up of heights from the Azores all the way to Russia by day 11/12 the Russian high will meet up with it and show it the way in stead of it floundering around our shores all winter long as it has been doing 

[Froze were the Days]

Sorry...not sure if anybody else has mentioned this since the 12z ECM came out but does the 216-240z transition of the HP to Scandanavia look fesible?...I've seen many a winter chart over the years but not a HP from a few hundred miles off the Portugal coast to where it is at 240z. I'm not buying that.

Edited January 6, 2017 by Froze were the Days

[snowbunting]

2 minutes ago, knocker said:

Hi snowbunting they are behind a paywall I'm afraid. Actually not that cold

Thanku for sharing them then. Is that green blob mid atlantic have anything to do with those below average ocean temps in the atlantic that have been well documented?

Just seen the ECM run. Defo heading cooler/colder. 

[Man With Beard]

I note the GEM is still on yesterday's page regarding a slightly more extended northerly. It's not jumped on any cold bandwagons so far this winter so perhaps worth following a little.

[gottolovethisweather]

On 31/12/2016 at 17:26, gottolovethisweather said:

The thing is Nick; things ARE going to plan up to D6 or thereabouts, but the -18 850s aren't looking likely to verify at D10 or whichever range they were tempting us which is NO SURPRISE to me. Sorry if I offend, not digging at you but I'm digging at those who got caught up in the hype. This is not to say that cold to very cold air won't reappear in the outputs, but when such conditions are within D5 range I'll join in the celebration, but only then will I do so.

 

 

 

Hello all, I stated the above when the first round of snow-producing deep cold 850s showed up in the various outputs some seven days ago, the rest is history as they say and you know where the deep cold went, into Central Europe or stay bottled up due North of us. So, in order to NOT pee on anybody's expectations here, I would say currently the next wintry interlude provides us with a slim but reasonable 60/40 percent chance of coming off, given that it is set to begin by D5/D6 (Wednesday 11th/Thursday 12th January). How long will it last? Who will see those beautiful white crystals? Will it settle in lowland England (what a miracle)? All answers to these questions are only likely to be resolved by early next week. Due to my beady little eye watching each of the ECM operational runs roll out this past week and not being distracted by other runs, I can say I am quite confident stating the following given that these dates of interest have shown up repeatedly as timeframes to watch. The first watch date is the 9th January which will likely provide some wintry interest to coldies up North say past Coventry or the Midlands if you like. With my main watch period from 12th January - 16th January being of wider interest to those in England for once, suffice to say Wales, Scotland and Ireland will also likely join in the wintry fun and games IF the broader pattern verifies as currently modelled. 

Edited January 6, 2017 by gottolovethisweather

[knocker]

1 minute ago, snowbunting said:

Thanku for sharing them then. Is that green blob mid atlantic have anything to do with those below average ocean temps in the atlantic that have been well documented?

Just seen the ECM run. Defo heading cooler/colder. 

No it's just the colder air that has tracked SE via Canada/Greenland

[chris55]

9 minutes ago, Froze were the Days said:

Sorry...not sure if anybody else has mentioned this since the 12z ECM came out but does the 216-240z transition of the HP to Scandanavia look fesible?...I've seen many a winter chart over the years but not a HP from a few hundred miles off the Portugal coast to where it is at 240z. I'm not buying that.

Actually thats a pretty classic evolution to an easterly, it's the warm air advection from the low to our north west that helps to build the high north, although normally you would see a more favourable tilt out west for a sustained scandi high, and it does seem quite quick in its process.

[sawan]

8 minutes ago, knocker said:

No it's just the colder air that has tracked SE via Canada/Greenland

It's not GFS, GEM, or ECM on board .......it's knocker on board, Cold and Snow got to to come now . 

I hope Sidney has his nuts in safe location and is ready to overwinter. 

[Nouska]

12 minutes ago, Froze were the Days said:

Sorry...not sure if anybody else has mentioned this since the 12z ECM came out but does the 216-240z transition of the HP to Scandanavia look fesible?...I've seen many a winter chart over the years but not a HP from a few hundred miles off the Portugal coast to where it is at 240z. I'm not buying that.

The ECM jet stream charts for last few days of the run - evolution suspect? 

Perhaps but we have seen very sudden amplification before and it is a pattern that has been well trailed in the EC46 products.

 

 

[damianslaw]

As ever best stick to the reliable timeframe roughly 120 hrs, and in that timeframe we have much consistency from all the main models - mid atlantic high ridging northwards, jetstream tilting on a more NW-SE trajectory with a blast of polar maritime air invading the country, providing potential for some wintry weather in the north come Wednesday - the edge of the reliable.

In unstable polar maritime airstreams as being forecast, sudden micro small scale developments in the flow often develop - trough features, secondary low features, indeed even polar low features, which the models often struggle to forecast - given their sudden appearance nature.

GFS is keen on showing some form of secondary low development behind the initial low pressure system due to sweep in on the 11th / 12th, this maintains a predominantly NW flow, with less chance for ridging to build sufficiently northwards to produce more of a N flow, ECM however, isn't showing such developments, hence we see more northwards ridging, and a more direct northerly flow for next weekend, hence the ridge is able to topple in over the top and into scandi - indeed the forcing placed on the strong PV by russian heights appears to lock it into position and aid the scandi high development.

So keep an eye on the position of the PV, strength and forcing of the russian high, and expect sudden short term developments in the NW flow. 

In the short term the impending milder spell is being watered down somewhat, less of an atlantic influence at least over england and wales this weekend, so less mixing of air at the surface, which is preety cold thanks to the high pressure cell of the past 2 days, and come Monday the airflow looks much more WNW than SW.

 

[Jason M]

ECM is certainly different. Very good run indeed. Almost laughably implausible IMHO but a good run all the same

Certainly wasn't expecting that after looking through the earlier runs and ensembles. Anyway, either trend setter of the year or outlier (I know where my money is). 

[Ali1977]

Nice to come back to that ECM, not caught up and I thought after the ECM things were on for cold but that GFS ain't so good. 

[cheshire snow]

1 hour ago, Captain Shortwave said:

Indeed, though we could do with the models not putting in extra secondary lows which could potentially flatten the pattern, the ECM gets away with it and the UKMO looks likely to do the same.

ECM day 9/10, just plain naughty

   

That's a cold chart, oh for goodness sake ECM please tell me you haven't picked up the old ECM's tricks.

ECM day 9/10

He is not the Messiah...He is just a very Naughty Boy

C.S

Edited January 6, 2017 by cheshire snow

[bluearmy]

The ecm is probably in the right ball park but too amplified day 8/9 so imagine the day 10 chart further south and you have your MLB !

[Frosty.]

4 minutes ago, bluearmy said:

The ecm is probably in the right ball park but too amplified day 8/9 so imagine the day 10 chart further south and you have your MLB !

A bit further north would be perfick

Anyway, nice to see wintry charts that ain't in deep Fi!

[Iceaxecrampon]

12z

Fun and games still on for next Friday?

 

Looking ahead  - Greeny monster halted in its tracks by Euro high +210

 

....all in FI of course

 

 

Edited January 6, 2017 by Iceaxecrampon

[Connor Bailey Degnan]

Day 10 mean, not what we wanted to see

[Purga]

50 minutes ago, nick sussex said:

Yes the ECM is a breath of fresh air this evening. The ECM from early doors though did build up a better start point going forward, again on a global scale a quick look at the NH charts and you'd think that won't make much difference but these early differences can snowball into big changes down the line.

Interestingly NCEP said this in their discussion from early on.

THE SYSTEM IN THE EAST WILL ENCOUNTER
BUILDING RIDGING TO ITS SOUTHEAST WHICH WILL PREVENT ITS MOVEMENT
SOUTH OF ABOUT 35N. NEXT SYSTEM IN ITS WAKE MAY SLOW AND STRETCH
NE-SW BY NEXT FRIDAY ALIGNED WITH THE UPPER FLOW.

Perhaps a pointer to which model might have the right pattern over the eastern USA at that time. Take a look at the ECM T168hrs. Of course it takes more than that to get to where we want to be but anyway at least the ECM keeps us interested moving forward.
 

ECM 12z is great in the latter stages Nick but to paraphrase John Cleese's quote “It's not the despair, I can take the despair. It's the hope I can't stand" !

ECM 12z 240hrs

GFS 12z 240hrs

Compare and bear in mind ECM verification stats are at 70% for day 10 whilst GFS is at 50%.- no guarantees of course but the odds a bit in our (cold) favour.

Edited January 6, 2017 by Purga

[weirpig]

5 minutes ago, Connor Bailey Degnan said:

Day 10 mean, not what we wanted to see

I'd have been more shocked if there had of been  240 is way out  but there does look like good agreement to 168. And really anything past that is spitting in the wind. I guess we can see more when we are aware of the clusters 

[SMU]

16 minutes ago, Connor Bailey Degnan said:

Day 10 mean, not what we wanted to see

 Remember the mean wont ever be as good as the op at the 10 day range - & with such a tricky evolution there will certainly be a cluster whereby the pattern flattens off -

however if you look at the 500 anomaly from the mean & the other little tell tail signs like the cut off low then actually the mean is pretty supportive of a ridge @ day 10-

also the negative heights im euro- its just the positive heights muted out/

Best

s

 

 

[bluearmy]

The eps post day 10 flatten the pattern a bit more than the 00z suite did. However, there is some encouragement at day 10 in respect of the op and the control is on the same page (but suppressed a bit further south). Will be a frigid run for de bilt. The scandi ridge stays in place till day 13/14 and slowly pulls away day 14/15. 

the eps are basically MLB sinking south to become euro/s uk high 

[Dancerwithwings]

5 minutes ago, Steve Murr said:

 Remember the mean wont ever be as good as the op at the 10 day range - & with such a tricky evolution there will certainly be a cluster whereby the pattern flattens off -

however if you look at the 500 anomaly from the mean & the other little tell tail signs like the cut off low then actually the mean is pretty supportive of a ridge @ day 10-

also the negative heights im euro- its just the positive heights muted out/

Best

s

 

 

Steve is this the Anom spread chart that Ive highlighted in your post ?

[Stuie]

1 hour ago, knocker said:

Hi snowbunting they are behind a paywall I'm afraid. Actually not that cold

Evening Knocker, blimey so after all this looking to the East/ North/ NW for cold we are actually looking West for a cold pool? Wow.

[Nick F]

48 minutes ago, Nouska said:

The ECM jet stream charts for last few days of the run - evolution suspect? 

Perhaps but we have seen very sudden amplification before and it is a pattern that has been well trailed in the EC46 products.

 

 

Looking at 00z v 12z EC deterministic runs, there appear to be differences with regards to how the model handles the the lobe of the tropospheric vortex over Canada, 12z det. looks deeper and more intense than the 00z as it rotates it across NE Canada toward Greenland by day 9-10, thus we see more ampliification downstream across the N Atlantic.

I see there's sensibly not too many getting excited, as EC has put an easterly on the table at the end of the medium range once too many times and then changed back to a more zonal pattern - it does have a tendency to over amplify.

12z EPS z500 mean does show ridging NE across the UK day 10 - with deep -ve height anomaly over mainland Europe and over Greenland. But the ridge does slide SE days 11-15 and so Atlantic flattens out.

12z EPS control supportive of the determinsitic though, pretty much the same evolution to day 10, then builds a Scandi high proper days 11-15 with undercutting by Atlantic troughing too.

So, the rollercoaster continues into tomorrow, with probably still no clear path by the end of the weekend!

Edited January 6, 2017 by Nick F