Model output discussion - Into 2021

[Battleground Snow]

1 minute ago, Skullzrulerz said:

Is there a link to this please ?

Are you referring to very cold weather/more widespread snowfall? 

Unfortunately there's a lot of uncertainty with the SSW and being that FI seems to start a lot sooner timeframe 

I do share you're frustration though 

Anything could possibly happen at this point so we just have to wait and see

For non french meteociel, arome and arpege on here

WXCHARTS

WXCHARTS.COM

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A new weather forecast model data viewer for Europe and North America. Clickable forecast and ensemble plots, hourly GFS, ECMWF, ARPEGE and GEFS plots

 

Here is the link for Harmonie

WWW.METEOCIEL.FR

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Meteociel propose de manière régulière le modèle à maille fine HARMONIE 0.03° de KNMI (météo néerlandaise) sur 2 zones (Belgique, Pays-Bas)

 

 

[Tim Bland]

36 minutes ago, winterof79 said:

Simply lovely ....snow city

 

What location is that for please?

[Tim Bland]

Mean stays at or below -5 in London for the entire suite

[winterof79]

GFS// Dew point forecast for next week. Thursday around 13.00 hours it looks dodgy but not for long ........Laters #bbc

[winterof79]

5 minutes ago, Tim Bland said:

What location is that for please?

West Yorkshire near Pennines 

[Weather-history]

GFS 06z op run charts for 4th January from 19th December to current 

 

 

[Battleground Snow]

14 minutes ago, saintkip said:

Sounds exciting. 

If you remember 2018, people were bemoaning the charts looks dry and boring even with -14 uppers moving over us. When it got in the nearer, disturbances popped up all over the place and many places got decent falls. We are only forecast -8 or -9 with higher dam heights this time, but the same principal applies. Some places will get lucky next week with moderate showers or streamers

[Man With Beard]

Although some of the GEFS members may look like their skirting with milder air, they come up with the same result as the ECM ensembles for surface temperatures. This is for Birmingham. The fairy broad consensus is that no day will be as mild as today for the next two weeks!

[joggs]

Just now, saintkip said:

What day can we expect the Thames to freeze over? 

Day 10 on all models

Edited January 1, 2021 by joggs

[danm]

3 minutes ago, saintkip said:

What day can we expect the Thames to freeze over? 

Your sarcasm is hilarious. 

[That ECM]

43 minutes ago, saintkip said:

Are we still at day 10 for the good stuff?

Had an incredible frost here and everything is white. Just went to get some tomato soup, it’s that kind of day, the car said it was zero at midday. Many places are seeing and have seen snow with some having snow on the ground for days. That’s all good stuff in my book If what you are referring to is snow county wide then there is more than sufficient output that opportunities are many over the coming days both short and longer term.

 

Here is the 10 day mean for the gfs with plenty of interest on all the days prior to this.

[feb1991blizzard]

D16 OF GEFS!!!!!!

[Catacol]

The ongoing strength of the HP anomaly over Kara/Ural region is notable. And still EPS is flagging an ongoing North Pacific / Aleutian Low setup. Can’t remember seeing such a sustained pattern like this, though admittedly my serious scanning of winter weather models is probably only just hitting 10 years or so - pretty small sample really. However - for that 10 year period this is a significant, ongoing point of stress for the vortex.

As part of that picture there is quite a lot of noise from across the pond regarding the strength of the current Aleutian Low spinning along on a substantial jet streak courtesy of a strong EAMT. This chart shows the depth of that low, a potential record breaker, and I would suggest adds significant variability to NWP products for the foreseeable.

And while we are talking about points of significance the heights being forecast over Western Greenland as a 10 day anomaly are also significant. Not often a 10 day anomaly hits the pink shading. This point is Webb’s - not a spot I made myself. Anyway a west based setup - but with such stagnant Atlantic flow not really a major problem for U.K. cold.

 

And if we look at the vortex - and given higher resolution this has to be an ECM analysis as we approach the well advertised SSW - we have a 150hpa pattern at 240 that is as un-winter like as you will see. Temps up positive with warmth cutting through the core, average westerly momentum scarcely above 0. Vortex energy dissipated all over the place.

So....record breaking Aleutian Low alongside a stubborn Ural signal, very high Greenland ensemble mean heights, vortex in pieces...... = very unusual context for NWP to work within. Stick to human interpretation of the context - amplification in a week or so, downwelling imprint likely before too long, arctic high a likely result, cold incursions into mid latitudes likely. Comfortably the best setup in 10 years and with more long term potential than back then. 2 weeks down, 8-10 to go and zonal influence dead in the water.

And to finish. Reversal now nailed on. 13 day minimum and rising. Note the model tendency this winter to underestimate the degree of warming and flux up top. By the time this lands I suspect the reversal will last more than a fortnight and in that period a split is a distinct possibility. 

 

Edited January 1, 2021 by Catacol

[phil nw.]

Hi all and a Happy New Year.

A few posts have had to be removed this morning unfortunately.

Just a friendly reminder to keep any banter with no model discussion in the relevant threads.Links are in the opening post by Paul.

Ok thanks- on we go.

 

Edited January 1, 2021 by phil nw.

[Drifter]

12 minutes ago, feb1991blizzard said:

D16 OF GEFS!!!!!!

What do you mean?

[johnholmes]

48 minutes ago, Tim Bland said:

What location is that for please?

It tells you at the bottom 53.5N 1.8W

[Battleground Snow]

Great post @Catacol

Do you think the split will eventually happen?

Does it matter from a UK perspective if it doesn't split, with average westerly momentum scarcely above 0 and do you think the vortex will recover at all the rest of the winter?

 

[winterof79]

So looks like agreement on trough/energy dropping around 144z at the moment but could change

//

ECM

UKMO

UKMO looks a little suspect but should go on to drop.

Check out the 850 s  dropping between 120 and 144z

 

[Battleground Snow]

3 minutes ago, Drifter said:

What do you mean?

Maybe this?

 

[feb1991blizzard]

3 minutes ago, Drifter said:

What do you mean?

There is a steep drop in about 5 or 6 members at the same time in about 24 hours, taking them to -8c ish,  could it be a response signal from the SSW, looking at them the ridges that were rounded and flatter are now sharper and possibly near to very cold air to the East, and kind of reverses slightly the trend of milder at the end of previous runs, watch following suites carefully right at the end, it could just be nothing and random but looks a tell tale sign to me that some of those insane runs could be just around the corner.

[Catacol]

Just now, Battleground Snow said:

Great post @Catacol

Do you think the split will eventually happen?

Does it matter from a UK perspective if it doesn't split, with average westerly momentum scarcely above 0 and do you think the vortex will recover at all the rest of the winter?

 

Chio has pointed out quite rightly that we are getting a knackered vortex whether it splits or not. Reversal happening, westerly influence effectively ended. My thoughts though are around reformation, and I’m greedy. I want the vortex to be dead in the water for the rest of the season, and 4 weeks is not enough for my greedy side. I think if it splits we get greater longevity, and also possibly better support for undercut scenarios.

This kind of thing isn’t a 100% ticket to nirvana though. Things can go wrong, and the idea that a major split might knock our favourable current blocking pattern out of shape has to be given some thought. However - I don’t think so. If we end up with no vortex influence of any note my own personal no 1 concern would be an MJO refusing to budge from the Indian Ocean...and a phase 3/4 response that might put the trough further west into the Atlantic. We saw how the amazing sight of too much reversal back in 2018 turned what could have been a 2-3 week Beast into something shorter. So amidst the enthusiasm and awesome context a degree of caution must remain.

To conclude, and answering your question directly, I remain a bit uncertain as to whether it will split. A week ago my confidence was up....but the forecast for 4/5/6 has backed away from a split and we have to see whether wave 2 can gather again. Looking at the EPS anomalies and the strength of the EAMT happening now it is a definite possibility but I’ll keep my powder dry for a day or three longer. We are getting a good long cold spell whatever. For it to be historic I think we need significantly low CETs in both Jan and Feb and that’s what I’m crossing fingers for! 

[phil nw.]

Just flicking through the charts for next week's easterly and i get the impression snow chances have increased a little from yesterday's runs.

If we look at the fax for T84 and the 850's from the UKMO raw at t96hrs the air s coming from a more northerly source now with a more direct feed from S.Scandinavia.

Dew points are the right side of marginal the further away from the north sea coast you are looking at the nw med/range model.

The precipitation and dew points above.

Some places should get lucky based on that output i should think.

Looking ahead uncertainty is the watchword and beyond mid-week it's whether we get a decent northerly with a trough dropping down far enough to refresh the cold.We don't want a complex low left hanging to mix out the cold pool over us.

The ens graph shows a continuing cold outlook for the next 10days anyway

It's going to a little while longer i think before the NWP starts to show some agreed way forward as we await the SSW factoring to feed into the daily charts. 

Just a look at the the 850 ecm mean at t240

We can see the cold just coming sw through Scandinavia there.

I am waiting to see modeling increase Arctic blocking and hoping when reversal shows we see all that Siberian cold jumping on board the express -destination UK.Then we are really talking about deep cold.

[snow mad]

16 minutes ago, Catacol said:

Chio has pointed out quite rightly that we are getting a knackered vortex whether it splits or not. Reversal happening, westerly influence effectively ended. My thoughts though are around reformation, and I’m greedy. I want the vortex to be dead in the water for the rest of the season, and 4 weeks is not enough for my greedy side. I think if it splits we get greater longevity, and also possibly better support for undercut scenarios.

This kind of thing isn’t a 100% ticket to nirvana though. Things can go wrong, and the idea that a major split might knock our favourable current blocking pattern out of shape has to be given some thought. However - I don’t think so. If we end up with no vortex influence of any note my own personal no 1 concern would be an MJO refusing to budge from the Indian Ocean...and a phase 3/4 response that might put the trough further west into the Atlantic. We saw how the amazing sight of too much reversal back in 2018 turned what could have been a 2-3 week Beast into something shorter. So amidst the enthusiasm and awesome context a degree of caution must remain.

To conclude, and answering your question directly, I remain a bit uncertain as to whether it will split. A week ago my confidence was up....but the forecast for 4/5/6 has backed away from a split and we have to see whether wave 2 can gather again. Looking at the EPS anomalies and the strength of the EAMT happening now it is a definite possibility but I’ll keep my powder dry for a day or three longer. We are getting a good long cold spell whatever. For it to be historic I think we need significantly low CETs in both Jan and Feb and that’s what I’m crossing fingers for! 

I always love your analysis catacol it really is brilliant. Just such a shame the nearer term isn’t colder. With 5/6 degrees for the coming week and rain on the east coast this really is torture. Keep up the great work!

[northwestsnow]

I've looked at the EC ens for Manchester and the max as far as I can see is 3 degrees.

For the next 10 days .

With uppers around -7 for much of that time I dont think the odd dusting can be ruled out  in Manchester in this instance.

[jules216]

Happy New Year Weather followers around Europe.Enjoying cold spell?Hopefully more Snow on the way soon.I had to take Serious action and hit High Ground AS no Snow below 900m here but boy above that IT was a joy.This part of Slovakia is the most unspoiled part of Europe for sure as hardly anyone was around.Almost I feel I got it All for myself and my dog Molly of course