Model Output Discussion. 3/12/2022. How cold will it get?

[MATTWOLVES 3]

1 hour ago, Mark Smithy said:

The 6z GFS is a bit of a horror show (for cold lovers) with a very mild, even warm, finale.

I'm expecting it to sit out on a limb on the ensembles but, even so, it does illustrate that this is far from nailed on. It remains on a knife-edge

It could also be the fact that most models revert back to climatology normal beyond a 10 day period...and when they're struggling for a final solution,again they will most likely revert back to the most common type of conditions for the UK.

This is why I have gr8 scepticism for Long Range Models..your always gonna have that bias factored in,plus the the fact that they will also take into account the Warming World!

A pretty decent set of 0s from Mogreps...many a cold cluster North to South...6s should be with us within the next hour.

Edited December 8, 2022 by MATTWOLVES

[Derecho]

37 minutes ago, Battleground Snow said:

It's a good point, we have seen how the greenland high is underestimated. Especially by the GFS 

Even at 72 hours it gained strength across all the models.

Gfs charts for the 11th, 2 days apart

Even more dramatic if you go back to a comparison from 5 days ago:

Edited December 8, 2022 by Quicksilver1989

[ItNeverSnowsInWindsor]

A bit of a worrying trend in FI from GFS so far today. 
 

Let’s see what the evening brings!

[Snowy L]

 

9 minutes ago, prolongedSnowLover said:

A bit of a worrying trend in FI from GFS so far today. 
 

Let’s see what the evening brings!

The rate at which the polar vortex in the Arctic goes from zero to 100 after day 10 (low res) is a bit suspicious to put it lightly.

Edited December 8, 2022 by Snowy L

[joggs]

7 minutes ago, Snowy L said:

The rate at whi

The rate at which the polar vortex in the Arctic goes from zero to 100 after day 10 (low res) is a bit suspicious to put it lightly.

The AO and NAO are now trending away from negative though. I guess we'll see.

[Snowy L]

1 minute ago, joggs said:

The AO and NAO are now trending away from negative though. I guess we'll see.

They are reflections of the pressure around the Arctic and North Atlantic the models are forecasting though I think? They are not a separate thing.

[Duane S.]

Putting aside the fact that the warm up supposedly starts from D10+ (proper FI territory), in the far more reliable time-frame that same Op keeps Dorset in sub -5 850s for 9 consecutive days . That is quite something at any point of any winter down here.

For the record though, the trend is there and I think there is a fair bit of substance to back up a 'warm up' in about 10 days' time. Thereafter (and assuming it does actually go a lot milder in the first place) it could go either way really.

[Jackski4]

Is it just me or does the PPN on radar due to head south this evening look more intense than what was forecast?

[Battleground Snow]

26 minutes ago, MATTWOLVES said:

It could also be the fact that most models revert back to climatology normal beyond a 10 day period...and when they're struggling for a final solution,again they will most likely revert back to the most common type of conditions for the UK.

This is why I have gr8 scepticism for Long Range Models..your always gonna have that bias factored in,plus the the fact that they will also take into account the Warming World!

A pretty decent set of 0s from Mogreps...many a cold cluster North to South...6s should be with us within the next hour.

The latest 06z continues the theme, no huge scatter like the Gefs shows

[feb1991blizzard]

 

Mogreps are still a stonker though.

[Nick2373]

 Going from observing the GFS For what feels like years and years I'm going say a slight warm on the 19th then a drop back down around the 20th 21st.

 

 

[MATTWOLVES 3]

Look at that mild straddler on the 6z mogreps for London and Brum....what a beauty...must have had a little gfs op programmed into it.

Looks like a cold set of runs again.

Wow guys we must be on the same wavelengths or we are fixed to the computer screens for the updates.. we need to get out more

Edited December 8, 2022 by MATTWOLVES

[Eagle Eye]

The jet 'recovery' across East Asia is about to begin, reloading the Pacific jet wave and PNA back to more neutral territory which may reload the Atlantic long-term and wane the Greenland block. Although, it may just change the basing of the Greenland block into a more west based block it's hard to tell just from any composites I could find. Hence forth we still see a slightly -VE NAO on about half of the ensembles despite the recovery of the AO that seems fairly likely on most. I do think this will increase the zonal westerlies beyond Christmas but that doesn't mean we can't see long term cold up until then with the -VE EAMT interacting with the lag of the +VE AAM looking pattern with an amplified North African wave potentially forming a UK and/or Scandinavian blocking and helping the -VE AO pattern slightly mid-term. The recovery of the AO can be expected eventually though as the Troposphere transfers energy through regressing Eddy's.

We simply cannot keep up the -VE AO and eventually the pattern will collapse but most importantly right now, the pattern is expected to keep steady(ish) for the mid-term and we've seen a recent trend towards longer term cold on about half the runs. A lot relies on a lot of different things but there's decent support for a more substantial cold spell to keep going and importantly, the trend on most of the recent days has been an increasing number of support for the longer-term (ish) cold and fairly substantial cold. I would keep up the positivity for now because we've got a lot to be positive about.

Compared to recent Decembers this simply outweighs every other December (in my opinion) for snow and cold potential since 2010. Worrying about precipitation isn't worth it considering the time scale especially because in years before we were looking for anything that supported colder trends yet this year we're getting that cold and people are now over-anlaysing. I can understand why though. It's a real shame that for all of the year's this could have happened, it had to have happened in a year with a significant energy crisis as well.

Despite the timeframe of this it shows how good of a setup up we are within relative to recent years:

No one can guarantee you 3 foot snowdrifts in your back garden and if they could, they would be lying but they can say that there is chance of you seeing decent snowfall compared to anything really since around 2018 (especially away from Scotland) and to take this as it comes because looking into the distant FI won't solve anything (I know I used it there but that's on the GEFS ensembles and to demonstrate my point rather than analyse anything).

Edited December 8, 2022 by Eagle Eye

[damianslaw]

In the reliable its more of the same, the low pressure to the SW now looks unlikely to have any influence and instead we maintain the cold airflow from the north for the foreseeable. This looks like being a notably cold spell for December but at least for now not very snowy.

Changes are all beyond the reliable, GFS has played around with scandi highs recently, but now shows heights building to the SE aided by warm air advection through the UK, we then see a mild southerly and the atlantic breaks through - it often does this when it sees a signal for the atlantic to reawaken, but the changes that take place in a very short timescale look far too progressive to me. My hunch is we will see heights build in or to the east and these will hold back the atlantic some what, whether we see trough disruption/ slider or one of those battleine set ups with the atlantic inching through remains to be seen. 

The longer term GFS 6Z run is very poor for those wanting a cold run in to christmas - we've not has one since 2010! All have been mild or exceptionally mild, seems a regular thing. 

[Tim Bland]

14 minutes ago, Battleground Snow said:

The latest 06z continues the theme, no huge scatter like the Gefs shows

Scatter on GEFS starts after the MOGREPS time period (from 17th) though ? 

[Penicuikblizzard]

3 hours ago, Tim Bland said:

GFS sends the low into the Med and keeps the cold locked in. Mainly dry so far ....Good for the Alps though!

Fantastic charts keeps the cold locked in,,dry yes but there will always be surprises somewhere for some snowfall

[Cambrian]

If we start from the slightly more reliable period up to day 8, the 6z GFS mean nicely shows the resilience of the Siberian trough extending southwestwards towards the UK and Ireland. Notice a second wave of low heights pushing down across Scandinavia by the middle of next week and the merging of the Atlantic low with the base of the trough to our south. 

 

The same with the T850s, the incursion of mild air is kept as a ripple to our south by the continued reinforcement of cold air from the northeast. 

Thereafter, if we put the day 9 to 16 mean anomaly side by side with those for day 1-8, it’s pretty much a repeat pattern, slightly more feint over time as ever due to the averaging out - day 1-8; day 9-16

 

Continued attempts from the Atlantic to slip low pressure around the south of the block, but only meeting deep cold air where they do. Though the second low might have a trajectory slightly further north than the first one,  the standout feature is the reinforcement of heights over Greenland from day 14 onwards and notice too no build of heights over Europe. For now, it’s a one-way ticket to Slideville. 

[bluearmy]

Small area of vorticity picked up on Sunday on the ec 06z op and control over England 

they handle it’s track differently so for now, a waiting game for the next couple runs. 

the Thames estuary and Kent/se Essex could well see something form in the s North Sea on Sunday pm too - this has been a recurring feature so probably more to it 

the eps control 06z makes less of the Norwegian shortwave at day 5/6 so introduces what would be a cleaner northeaster flow 

[Biggin]

1 minute ago, bluearmy said:

Small area of vorticity picked up on Sunday on the ec 06z op and control over England 

they handle it’s track differently so for now, a waiting game for the next couple runs. 

the Thames estuary and Kent/se Essex could well see something form in the s North Sea on Sunday pm too - this has been a recurring feature so probably more to it 

the eps control 06z makes less of the Norwegian shortwave at day 5/6 so introduces what would be a cleaner northeaster flow 

What direction is the wind on sunday i hope its north of east...

[Downburst]

Mondays 46 day run did suggest temps back to near normal after the 19. But further out it still shows above normal pressure around Greenland and into the new year it has higher than normal surface over Scandi. So perhaps early days of picking up another major chance of cold. Remember 2010, after the first wave of extreme cold end of November, a brief warm up and then wham back into it with a vengeance. I don't know what is causing this, if I did I promise I'd write in plain english, but I do have a feeling after the breakdown we might get a reload as a consequence of whatever is going on now influencing the base state, if you follow

 

New Year pressure Anomaly, note new chart will be out later today for this period. Also second chart shows the anomaly, i.e. the pressure over or under normal for time of year at 500hpa. I'd always be happy to see that forecast any given winter, even if some weeks away.

[bluearmy]

6 minutes ago, Biggin said:

What direction is the wind on sunday i hope its north of east...

Very light and variable depending on these small upper features meandering about 

the mean direction across the day is likely to be ne but the first half of Sunday could even see a southerly for a time depending on track of said system 

[Paul]

Locking this one now - new thread up in 10-15 minutes.

[BlueHedgehog074]

Just one thing to add is for anyone currently typing out a post, would recommend copying it and pasting it over to the reply box when the new thread is up rock and rolling. 

Also been quite pleased how the thread has generally gone. A good amount of great discussion along with good number of informative posts too. Something we hope will continue into the new thread. 

New thread is here: