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

[fromey]

4 minutes ago, bluearmy said:

Nope - that's the ec op 00z and we know from nick's excellent analysis that it's the extra wave in the flow that's the culprit here re the flatter pattern. 

Thanks, I really should learn to look at the time and dates on these things!!

[frosty ground]

46 minutes ago, TEITS said:

Much has changed in the output this morning.

For the reasons Nick and myself mentioned we are seeing the cold spell for next week being shorter in duration and potentially less cold. Based on todays output the potential for snowfall for low lying areas is only around 36hrs. Furthermore with the way it is going the NW,ly at +168 could be downgraded further. We need to see the models backtrack towards last nights ECM so the cold N,ly flow becomes sustained and not temporary.

With the exception of maybe one run 36-48 hours was all there ever was......

[blizzard81]

6 minutes ago, frosty ground said:

With the exception of maybe one run 36-48 hours was all there ever was......

I agree. Those who go by the teleconnections have been spot on these last couple of weeks. Kudos to both Tamara and Catacol in particular. 

Edited January 6, 2017 by blizzard81

[snowray]

2 minutes ago, frosty ground said:

With the exception of maybe one run 36-48 hours was all there ever was......

Thats true, the GFS started us off then ECM jumped on board for one run and then off again on its next run to show this 36hr NWly, could still upgrade a bit and there should be some decent disturbances in that flow of very cold uppers.

[NO LONGER POSTING]

Why are we even bothering looking past next Wednesday for a break down of any cold?  that's if it even gets here... 

As much as any flatter pattern is showing currently it could completely switch to cold and visa versa. 

I'm not interested in anyone commenting saying longer range models show it. They may do, but can't they switch too. It's a computer, letting that lead your weather mind would be a silly idea.. 

Past Wednesday really next week is up for debate. Anything past Friday next week might as well not exist as far as I'm concerned. 

Right up to an "event" things can change and will. 

Let's see what happens first (=

 

 

[Scandinavian High.]

could do with upgrades this evenings models with this cold shot to bring some wintery showers south .

Edited January 6, 2017 by abbie123

[blizzard81]

I think anyone hoping for upgrades tonight haven't been looking at the models for very long. Once they downgrade at the timescale of around 144hrs, then they only go one way I am afraid. 

[bluearmy]

Note the onset of the cold now almost within the remit of the ukmo

the 00z run at day 6 hung the ridge out well into Europe. If it shows continuity then we need to see evidence that it will pull that back west and allow the troughing to drop south. Looked like it would but nothing certain!!

[radiohead]

3 minutes ago, blizzard81 said:

I think anyone hoping for upgrades tonight haven't been looking at the models for very long. Once they downgrade at the timescale of around 144hrs, then they only go one way I am afraid. 

Depends on what you mean by upgrades. In terms of longevity of the cold spell, I agree it's unlikely that we'll see it being extended. But there certainly is still more than enough time for lows to pop up and develop more than previously modelled.

[pyrotech]

blizzard81 your right in many ways.

However in case of gfs I always compare 18z with previous 18z etc rather than 18z to the 06z . short term the output is similar but 3 days plus you find the out put is much better aligned and easier to compare differences.  That is one of main reason we see the highs and lows on here when people react to fi on 18z with excitement and then demoralised when wake up next day to see the 06z . Best comparison is same run times . However as you said seen downgrades or corrections too many times over two many years and only occasionally does it revert back to what we hoped for. Does seem to more often be Temps modified upwards

 

[Mucka]

As is often the case we are seeing the pattern being progressively modeled faster and flatter than generally was the case in FI.

If correct and firmed up upon then any PM flow will be relatively short lived (2/3 days) with the pattern quickly shunted East.

The heights to our E and NE have gradually been programmed to be weaker than initially so our trough is allowed to progress Eastward rather than forced on a more SE trajectory.

As things stand, and this is a rough synopsis of period 12th/13th on available output, I would think anyone expecting to see snow settle on low ground will likely be disappointed though it is possible the further North and West you go - I would expect to see wet snow/sleet falling in NW England, just not settling away from high ground.

A temporary cover could happen if the ppn is heavy enough and arrives when DP's are at their lowest more likely overnight.

Most likely period to see snow at the moment is still unchanged from overnight 12th/13th

Edited January 6, 2017 by Mucka

[JeffC]

Looking at 06Z for 168 for Fritter Friday as we now seem to be calling it, to my untrained eye it doesn't look that shabby...

 

Edited January 6, 2017 by phil nw.
Removed off topic chat

[frosty ground]

34 minutes ago, Mucka said:

As is often the case we are seeing the pattern being progressively modeled faster and flatter than generally was the case in FI.

If correct and firmed up upon then any PM flow will be relatively short lived (2/3 days) with the pattern quickly shunted East.

The heights to our E and NE have gradually been programmed to be weaker than initially so our trough is allowed to progress Eastward rather than forced on a more SE trajectory.

As things stand, and this is a rough synopsis of period 12th/13th on available output, I would think anyone expecting to see snow settle on low ground will likely be disappointed though it is possible the further North and West you go - I would expect to see wet snow/sleet falling in NW England, just not settling away from high ground.

A temporary cover could happen if the ppn is heavy enough and arrives when DP's are at their lowest more likely overnight.

Most likely period to see snow at the moment is still unchanged from overnight 12th/13th

Basically all bases covered we won't see snow to love levels unless it's heavy and then we will..... 

Again the north / north westerly was only ever going to be a 2 -3 day event it was never going to be anything more than that with the exception of one or two rouge runs. 

 

[bluearmy]

Gfs hangs the trough back to s Greenland at day 6 whilst UKMO clears is se by then 

it's a common problem with delaying the onset of a toppler over recent years 

see what gem and ecm do with it 

[Mucka]

19 minutes ago, frosty ground said:

Basically all bases covered we won't see snow to love levels unless it's heavy and then we will..... 

Again the north / north westerly was only ever going to be a 2 -3 day event it was never going to be anything more than that with the exception of one or two rouge runs. 

 

Well that isn't all bases covered then is it?

I'm saying we will only see snow fall in heavier ppn and the only chance of it settling on low ground is if we get lucky with timing and will be a brief and temporary because some expectations seem somewhat higher.

Maybe yours weren't but then I wasn't addressing you personally.

How about you give a more definitive forecast if you're such a smart weeble? (and that word wasn't weebie!)

 

Edited January 6, 2017 by Mucka

[Polar Maritime]

Many posts are having to be hidden by the team, Please use the banter thread for chit/chat.

Thanks please continue.

Edited January 6, 2017 by Polar Maritime

[Hotspur62]

Well the models seem to be firming up on the PM spell for late next week that will really only affect NW Britain and those above 500ft asl may see snow imho.I was expecting/hoping in late 2016 for mid Jan to provide a UK cold spell but that seems to have gone out the window and with IFs comments and other expert opinions in last 24hrs it seems very unlikely we will see a cold spell in next fortnight.That takes us to 20th Jan and pretty much halfway point of winter and many still to see their first flake of snow.Maybe the SSW muted for late January could be a trigger but with time lag effect it takes us to mid Feb.All in all a winter that provided more promise than the last 2 has yet to deliver any significant cold spell and with the NH pattern looking as flat as a pancake things not looking too clever atm 

[tight isobar]

Minimal' but points of note..

12z more vivacious Russian alignment/ridge..

And certainly a more vertical aligned in flow n/w ..

Highlighted because exactions are everything atm!

Edited January 6, 2017 by tight isobar

[mountain shadow]

6 minutes ago, bluearmy said:

Gfs hangs the trough back to s Greenland at day 6 whilst UKMO clears is se by then 

it's a common problem with delaying the onset of a toppler over recent years 

see what gem and ecm do with it 

Is the hanging back of the trough a good thing or a bad thing for a more prolonged snowyish period, I cannot access the charts at the moment.

Thanks

[That ECM]

8 minutes ago, bluearmy said:

Gfs hangs the trough back to s Greenland at day 6 whilst UKMO clears is se by then 

it's a common problem with delaying the onset of a toppler over recent years 

see what gem and ecm do with it 

Doesn't the ukmo offer the potential for the high to go further north between the two lows?

[bluearmy]

5 minutes ago, mountain shadow said:

Is the hanging back of the trough a good thing or a bad thing for a more prolonged snowyish period, I cannot access the charts at the moment.

Thanks

It's a bad thing as it prevents any amplification to slow down the mobility 

GEM finds some amplification but is still quicker to push the trough through than the 00z run 

[tight isobar]

Again without scrutinize of every run..

Short waving could enable aiding. ..

Via south eastern progress and aiding of hp linking. .

And eventually waa decent n/w

Edited January 6, 2017 by tight isobar

[radiohead]

What a mess. 12Z GFS yesterday, 12Z GFS today.

12Z GEM

Edited January 6, 2017 by radiohead

[frosty ground]

16 minutes ago, Mucka said:

Well that isn't all bases covered then is it?

I'm saying we will only see snow fall in heavier ppn and the only chance of it settling on low ground is if we get lucky with timing and will be a brief and temporary because some expectations seem somewhat higher.

Maybe yours weren't but then I wasn't addressing you personally.

How about you give a more definitive forecast if you're such a smart weeble? (and that word wasn't weebie!)

 

Not sure anyone can forecast snow 6 days away..... the models show snow at the moment that can change.

[Cheshire Freeze]

Just now, bluearmy said:

It's a bad thing as it prevents any amplification to slow down the mobility 

GEM finds some amplification but is still quicker to push the trough through than the 00z run 

A familiar tale of semi-promising charts disintegrating into the all too familiar as we head towards the reliable. It has been the same all winter. 

As it stands, the nail in the coffin is being hammered in for widespread lowland snow in S UK this winter- that's not being dramatic in the slightest, we just don't have any forcing to the prevailing pattern which means that ultimately we're still left with a broadly +NAO

We're not going to see any widespread and lasting cold/snow with a +NAO

Radiohead's post above shows the disintegration of the pattern in just 24 hours and is completely symptomatic of winter 16/17