Model Output Discussion - Into the new year

[rdt123]

in 15 years of lurking around this forum i'm a little bewildered by what i'm seeing at present. On the face of it some of the charts look spectacular, high pressure to the north and an obvious E/NE fetch. For us up here on the north east coast first glance would indicate a snow fest. Very rare we've been able to enjoy models like this and some charts seem extremely rare. Close inspection reveals that the cold isn't quite there at present though and this morning we have rain, even the amazing 06z shows milder sectors wrapped in the low that descends late on and conditions again look marginal. Could be climate change or just bad luck i guess - strange days

[pureasthedriven]

12 minutes ago, Eskimo said:

Anyone else finding that the ECM is becoming increasingly unreliable? We all joke about the GFS being the comedian but I've found it to be far more reliable (up to 10 days) than the ECM.

Did post this a couple of days ago but here’s the GFS chart for 31st 19:00 from 16th Dec. There are some obvious differences to today’s 06z for the same day and time but overall in terms of ‘broad mesoscale pattern’, pretty impressive, I’d say. 
And yes, I’m aware the 31st hasn’t happened yet! 

[tight isobar]

Snow boarding and anti freeze -bbqs and shorts on 6z full run .. I love this rollercoaster

Edited December 29, 2020 by tight isobar

[Tim Bland]

GFS & GFS(p) in FI give me a bad feeling....

[Methuselah]

Barbecues out lads, we're in for a mid-winter sizzler... I can't wait for the Daily Express's next headline!

    

But seriously, peeps, the reason I post these 'fag-end' charts is twofold: 1) they're even less likely to verify than I'm about to win the Lottery -- without having bought a ticket; and 2) we really do have zero 'options' -- the weather will do what it does irrespective of what models/experts might say!

PS: I knew you'd love this chart, Fred ( @BLAST FROM THE PAST)!

[bluearmy]

The para takes one from the top shelf for its 00z run and one from the bottom for the 06z .....

[bluearmy]

7 minutes ago, Tim Bland said:

GFS & GFS(p) in FI give me a bad feeling....

Why not show the 06z para ?? 

[feb1991blizzard]

This has West based -NAO written all over it.

 

That is why the uptick at the end of the eps.

[Snowman.]

7 minutes ago, Tim Bland said:

GFS & GFS(p) in FI give me a bad feeling....

We loose low heights to the south and that is our destiny. We cannot allow heights to rise there or we’re looking at a warm SWly feed.  

[Daniel*]

You do see a danger of w -NAO on EPS albeit far into FI therefore don’t make much of it. Continued signal for wider Europe to cool... northerly Arctic air perhaps favoured.

[IDO]

gefs at d10:

As you were per 0z, lots of entropy as to how the wedge of northern heights interacts with the rest of the players, so little help. The op just being shuffled within the pack so expect another card on the 12z. As the trop is leading, we are at its whim, and the models will struggle with the ebb and flow especially in the Atlantic sector.

Still looking like below average temps for the next 7-10 days but nothing dramatic in terms of cold or snow, but some of us should see the white stuff with a bit of luck! Not sure what happens next...

[kold weather]

ECM ensembles are all over the place out to 240hrs, there really isn't a huge amount of support for any solution in particular. If anything there does develop stronger agreement lat into the run for a more +ve NAO developing but that really can't be depended upon given how the stuff before hand is very up in the air.

GFS ensembles on the 06z look a little more in agreement. There is a definate trend to towards LP attacking from the SW which at the least we will see some warmer air try to come up from the south, but lots of time for that to shift around.

 

[Man With Beard]

I'm seeing a lot of posts downplaying the set-up in the coming days, some latching onto John Holmes post this morning and I think misinterpreting his intent. For someone seeking cold and snow, there is absolutely no reason to downplay chances in the D4-D8 period, except perhaps for those near the east coast or to the west of very high ground.

The important guiders for me are 1. the mean charts, and 2. don't think you can predict too far out.

Latest GEFS & ECM means for D7 

The key ensemble mean is the ECM really, the GEFS us prone to sudden flips.

When I look at that D7 chart from ECM, it 100% ticks the box. The Atlantic is blocked, and the flow comes from a long way east. I don't care how warm the med is, a flow with 1000 miles over the continent in early January will cool enough to be snow friendly by the time it reaches the UK, except for E coasts on a very slack flow. I do recall a great fail from such an easterly in 2005, but that was late February, where solar heating was already much more significant. In early January, long nights and low solar power allows even mild air from the Greece area to cool by the time it reaches the UK. Also, if it's frozen over Europe, uppers really really aren't as important, far less than on a northerly without very low pressure.

Above this, it must be remembered that these are not usual weather patterns for models, and we must not hold great expectations of what will evolve after such a D7 or D8 chart. Anyone who thinks they can confidently predict a two week freeze even on amazing charts is overstepping the mark. In unusual synoptics, you concern yourself with D1-D6, maybe up to D8/D9 if the mean is really solid and consistent, but anything beyond that is just trends (unlike locked in zonal situations), though some like Caracol, Chinomanic or Snowking have a better handle than others.

I happen to think the D7 means today give plenty of reason to expect sufficient cold/snow may arise. As John Holmes says, not deep cold like Feb 2018 -yet- , and so no North Sea convection, but if frontal activity develops, it may not be needed.

 

[Frosty.]

In a normal British winter we (coldies) would be desperately looking at T+372 hours for any hints of cold but in this case, it’s the depths of low res hinting at mild..and just for fun I’ve included the wet bulb and snow risk charts for that timeframe!..anyway, enough of that nonsense, there’s plenty of cold weather to look forward to.,as long as you like cold?..have a great Tuesday gang!

 

[pureasthedriven]

10 minutes ago, bluearmy said:

The para takes one from the top shelf for its 00z run and one from the bottom for the 06z .....

And our trusty MetO one from the middle. I know where my money would be... 

[tinybill]

i  know its cherry picking  we should all be going back to work on the 4 Th   its looking interesting to say  the least

[blizzard81]

7 minutes ago, Daniel* said:

You do see a danger of w -NAO on EPS albeit far into FI therefore don’t make much of it. Continued signal for wider Europe to cool... northerly Arctic air perhaps favoured.

Thankfully a long way off so plenty of time for that to change. The most striking thing by far on that simulation is the amazing positive temp anomalies over the north eastern US and Canada. Almost unheard of. 

[sheikhy]

Those ridiculous ecm snow charts from ecm 12z seem to have dissapeared this morning?these kinda little shortwaves normally trend south so its no surprise!!thursday friday more snow chances in the north and west!!

[Met4Cast]

If we wouldn't take a day 16 cold GFS chart seriously.. why are we taking a day 16 mild chart seriously? Worth noting the GFS wont be including impacts from the SSW yet, the GFS strat is essentially a different model to the GFS trop and they don't "connect" until downwelling begins to occur. 

[MATTWOLVES 3]

Decent 6z mean.. perhaps a reload from the North beyond day 10...possibilities galore...keep it cool folks..many tweaks in the coming days...some for better,some for worse...a bit like your wedding vows... know drama here..second day of falling snow,I think u need some smelling salts...im in shock  

Edit..wish I had taken a picture from the front of the house now..snow piling up on main road.

Edited December 29, 2020 by MATTWOLVES

[kold weather]

Ok so Wednesday will looks *highly* uncertain. 

On the face of it the nodels have reshifted back south again, and has sped up. Both things are obviously bad for snow chances.

However the GFS ensembles on the 06z are basically all giving S.England some snow (might 1-2 runs that go south). The ECM ensembles also have a fairly decent percent that give some snow to at least the far south. ICON 06z also giving some snow to the far soth as well. Meanwhile Euro4 still remains totally on the southern edge of the suite for where it goes, so much to see.

Its highly likely to come down to a nowcasting situation. I agree with others who say these things usually trend south, but it does remain to be seen...

[phil nw.]

Anyone new to chart viewing and wondering what a west based -ve NAO looks like then the 06z GFS run from days 10/11 is an example.

This is just for illustration purposes-i hope it doesn't happen of course!

The deep cold is ushered into the mid-Atlantic as the block sets up too far west and  by day 15 it eventually fades allowing the south westerlies to move in south of the Atlantic trough.The Iberian high ridges up in re-enforcing the milder pattern.A development that older members have bad memories of when expecting something much colder from the north/east.

Fortunately for cold chances the 00z mean charts are showing the ridging further east so far,with a mean Scandinavian trough.

 

Keeping us in a colder regime.Steady as we go with the ens out to day 10 with the mean 850's pretty flat for here(warks.) at -4/-5c.

That West based -ve NAO could crop up in future again until the evolution settles as the models continue to factor in the expected MT and Strat.warming.My thoughts are until we see a real switch in all outputs at closer range on that it should just be something to bear in the back of our minds as a possible until we see where any Arctic blocking finally sets up.

Edited December 29, 2020 by phil nw.
added west based

[Bullseye]

5 minutes ago, Met4Cast said:

If we wouldn't take a day 16 cold GFS chart seriously.. why are we taking a day 16 mild chart seriously? Worth noting the GFS wont be including impacts from the SSW yet, the GFS strat is essentially a different model to the GFS trop and they don't "connect" until downwelling begins to occur. 

On top of the the strat warming with the GFS. With the warming now likely to occur within next 5-7days still disagreement between GFS and ECM/JMA. Further to this, Simon Lee on twitter tweeted some thoughts on this. Should the GFS have the strat warming wrong would the current GFS runs (including last night) be wrong too?

 

Edited December 29, 2020 by Bullseye

[Daniel*]

I’m confused as well @Man With Beard it’s the case of people misunderstanding fiction from reality, there’s been no indication of significant cold spell imminent this week we have a maritime Pm influence currently with deeply low geopotential heights, and slack flows making things not as marginal, as always expected a marginal affair people are kidding themselves if they got indication it would be otherwise with widespread powder snow, and when you consider with -3°C 850hPa temps a fair chunk of country is doing bloody good with cold/snow considering.
 

People confuse discussions/descriptions of model output with forecasts they often miss out on the small details which are often important to depth of cold and snow, but getting the broad pattern is always critically important first and in that regard the model output has looked very encouraging, this is what gets the excitement. Just seeing cold charts like this are a novelty.

We have charts like this, within this week and they are very cold charts indeed, cold NE’ly, not chilly, for us in the east much greater interests to be had late this week into next. 

[Alexis]

4 minutes ago, Daniel* said:

I’m confused as well @Man With Beard it’s the case of people misunderstanding fiction from reality, there’s been no indication of significant cold spell imminent this week we have a maritime Pm influence currently with deeply low geopotential heights, and slack flows making things not as marginal, as always expected a marginal affair people are kidding themselves if they got indication it would be otherwise with widespread powder snow, and when you consider with -3°C 850hPa temps a fair chunk of country is doing bloody good with cold/snow considering.
 

People confuse discussions/descriptions of model output with forecasts they often miss out on the small details which are often important to depth of cold and snow, but getting the broad pattern is always critically important first and in that regard the model output has looked very encouraging, this is what gets the excitement. Just seeing cold charts like this are a novelty.

We have charts like this, within this week and they are very cold charts indeed, cold NE’ly, not chilly, for us in the east much greater interests to be had late this week into next.