The hunt for cold - Model discussion (late November)

[Paul]

Here we go with a fresh hunt for cold thread as we move into a colder spell of weather and towards the end of Autumn.

As this is a new thread for this season, there's perhaps been a bit of confusion over what does or doesn't fit in here. So to help out, and be transparent in terms of our moderation of the thread, these are the guidelines we're working to, so if everyone can aim to stay within them, happy days!

This is a model related thread, so a general, frequent theme of the model output is a given, but it will not be strictly enforced:

• Some topic drift, humorous responses etc are fine
• Posts likely to lead the thread off on an entirely off topic tangent are not ok. For example (but not solely limited to): Posts entirely or mainly about Met Office, BBC or media forecasts with little or no model context, and posts solely asking for a weather forecast in a specific location.
• Posts which start with something like 'I know this is off topic but ...' are not ok.
• Posts which break the forum guidelines are not ok (eg trolling, troll-hunting, weather guilt tripping, overly defensive/aggressive, abusive, disrespectful to others)

Hopefully this helps, if in doubt please ask a member of the team, and if you see a post you think may fall outside of these guidelines, please report it. 

If you'd prefer a slower paced, more general (not cold slanted) model discussion, please head over to the general thread here.

Model Output And Charts On Netweather:
GFS
GEFS Ensembles
ECMWF
ECMWF EPS
NetWx-SR
NetWx-MR
Met-Office
Fax
GEM
GFS Hourly

Model Comparison
Global Jet Stream
Stratosphere

[Methuselah]

I just get the feeling, I suspect from recalling charts from way back when, that the pattern that appears to be slowly establishing itself (strong blocking to the northeast and northwest, and only weak HPs to our south) that this winter will be more analogous to those of the 1960s/late 1970s, than to many of our more recent efforts?

But, of course, the usual caveat (that I may well be spouting horse poo!) applies!

[Met4Cast]

1 minute ago, feb1991blizzard said:

Just as i say that the GEFS mean looks flat at 384! (although less pronounced than those usual purple looking Greenland profiles at this time of the year) and the EPS graph suggests similar, however, its not one of those times when i think that another dip wont start coming into the D10-15 timeframe soon, I dont care what people think of me, sometimes you can just write of December at this point but this is definitely not one of those times, i still personally think January the best bet for the best spell of the winter but December still holds interest - for now anyway.

I think anybody writing off this cold spell should still do so with a word of caution, I'm not entirely convinced the models wont end up undercutting that low and keep heights propped to the North, especially so since the overnight runs have all taken a slight step towards doing exactly that. 

Models do tend to underestimate blocks & over-do lows in the extended, if this is one of those times it wouldn't take a whole lot of upgrading to get to the cold synoptics of a few days ago, though I do think it's a lower probability outcome for now, I certainly don't think it's one we can rule out yet.

[karlos1983]

As @Man With Beard said in the previous thread, it looks like we need upgrades now for this initial attempt at an extended cold spell.

my overly obsessive use of the ENS has over the last 3 days shown quite clearly a climb down, from a very big majority of cold members, to now a substantial amount of milder members in comparison. But there are still some very cold members, and the overall NH profile should make everyone of a cold loving disposition pretty Optimistic as we head towards winter proper.

been some good chat over the weekend in here, I’ve enjoyed reading it all. 

 

 

[DiagonalRedLine]

Same here. Despite some up and downs in the Hunt For Cold thread (which, to be fair, will happen with the wild swings of the models), people, mostly, been quite good at keeping toys in the prams.  

[GeordieX9v]

14 minutes ago, DiagonalRedLine said:

Same here. Despite some up and downs in the Hunt For Cold thread (which, to be fair, will happen with the wild swings of the models), people, mostly, been quite good at keeping toys in the prams.  

FV3 & UKMO have done a good job keeping them in so far. 

 

GFS 18z would've blown the shop down 

[Froze were the Days]

20 minutes ago, DiagonalRedLine said:

Same here. Despite some up and downs in the Hunt For Cold thread (which, to be fair, will happen with the wild swings of the models), people, mostly, been quite good at keeping toys in the prams.  

Just purely because it's November and you need really good cold synoptics for widespread low level snow...I fancy the mood might have been different if we were heading into the New Year...should be a fascinating winter for at least model watching.

[Midlander]

Such a dissapointment when considering a few days ago the mean was consistently below the average even into FL, a growing number of exceptionally mild runs there as well as we enter Winter. Also it seems the the snow row has dropped significantly as well... 
A monumental improvement needed by all models on the 12Z runs.

[WalsallWeather123]

We are into the range of the short range models and I found this chart interesting from the WRF-NMM. Shows a widespread snow risk on Wednesday morning. The models could well be underestimating the depth of cold coming up. A few weeks ago we had snow in the midlands from the brief northerly which wasn't forecast by any model so a few surprises could be in store.

[Midlander]

4 minutes ago, WalsallWeather123 said:

We are into the range of the short range models and I found this chart interesting from the WRF-NMM. Shows a widespread snow risk on Wednesday morning. The models could well be underestimating the depth of cold coming up. A few weeks ago we had snow in the midlands from the brief northerly which wasn't forecast by any model so a few surprises could be in store.

Hello WalsallWeather123 I concur with you. This seems to be an occasion where I would like an increased precipitation signal as well as increase intensity. I believe timing of such precipitation will be crucial in determining the precipitation type. 

[nick sussex]

The key timeframe looks around day 7 to 8.

The high pressure edging ne towards Iberia needs to be blocked off , much depends at this point on the low pressure centered to the sw of the UK .

How much energy disrupts off this se is the crucial factor , and this is effected by forcing from any blocking to the nw .

Models at this range aren’t good at energy distribution . The ensembles because of this set up are likely to be volatile because the boundary between cold and milder weather depends greatly on that trough disruption .

So for the timebeing best to not rule anything in or out . 

 

[DiagonalRedLine]

33 minutes ago, evans1892 said:

FV3 & UKMO have done a good job keeping them in so far. 

 

GFS 18z would've blown the shop down 

You said it! Particularly thanks to those mouth-drooling Greenland/Iceland Highs the FV3 churned out, not giving up on the idea of a longer lasting and deeper cold spell. One of the things that did help to keep those missiles and toys staying put. 

25 minutes ago, Froze were the Days said:

I fancy the mood might have been different if we were heading into the New Year...should be a fascinating winter for at least model watching.

Can imagine so. The risk of flying teddies I’m sure will become greater towards Christmas as it gets even busier.  And I have to agree. 

[Mike Poole]

I think there's a good deal of uncertainty crept into the output today, and hopefully that may be somewhat resolved by the 12z suite, but on the 6z runs at T192, the FV3 does look more amplified than the GFS at the same time, FV3 first:

 

[matt111]

As always it’s a big rollercoaster ride throughout the winter in here so I wouldn’t expect any less. I enjoy this rollercoaster, and I don’t even like rollercoasters.  

[Spah1]

What times does the FV3 come out pls? 

Does it mirror the gfs or are the times different? 

[Paul]

Just now, Spah1 said:

What times does the FV3 come out pls? 

Does it mirror the gfs or are the times different? 

The para is usually a bit later, it can be a bit variable. 

[Midlander]

Just now, Spah1 said:

What times does the FV3 come out pls? 

Does it mirror the gfs or are the times different? 

FV3 is later than the GFS, by the time the Operation GFS has concluded the FV3 will only have just started. Hope that is of use Spah1.

[Wilxy]

Just out of interest, when did the new FV3 come out? 

[Summer Sun]

2 minutes ago, Spah1 said:

What times does the FV3 come out pls? 

Does it mirror the gfs or are the times different? 

Normally within 1 or 2 hours of the main GFS 

Quote

These maps present the data of the GFS model pre-parallel 1.0 ° with a new computational heart (FV3: Finite Volume Cubed-Sphere). The data are available for the moment almost regularly but lagged by 1-2 hours compared to the operational run.

 

[Met4Cast]

Looking at the entire GFS run in gif form, it's clear to see there's no suggestion of a raging vortex/jet stream.

A few low pressure systems go up the Western side of Greenland and straight into the Greenland Shredder and as soon as heights move away from Griceland/Greenland theres a new load of heights already building in. 

At no point during the entire run does an area of blue colours sit over Greenland for any period of time. To me, I think we need to look away from the detail for the UK and look at the bigger picture. 

The area of high pressure/cold spell we're watching for at the moment might fail, but the bigger picture is that they'll likely be another one along very shortly after. Incredible for a mid November chart.

[Spah1]

10 minutes ago, tomjwlx said:

Just out of interest, when did the new FV3 come out? 

https://en.m.wikipedia.org/wiki/Global_Forecast_System

[Midlander]

9 minutes ago, Daniel Smith said:

Looking at the entire GFS run in gif form, it's clear to see there's no suggestion of a raging vortex/jet stream.

A few low pressure systems go up the Western side of Greenland and straight into the Greenland Shredder and as soon as heights move away from Griceland/Greenland theres a new load of heights already building in. 

At no point during the entire run does an area of blue colours sit over Greenland for any period of time. To me, I think we need to look away from the detail for the UK and look at the bigger picture. 

The area of high pressure/cold spell we're watching for at the moment might fail, but the bigger picture is that they'll likely be another one along very shortly after. Incredible for a mid November chart.

Important to mention that although we are seeing  blocking it is by no means a guarantee for cold and snowy weather. It is plausible that even in blocked conditions we can be just as mild as when the Atlantic is barrelling through.  I would find it a great shame if all that blocking went to waste for us here in the UK.

[Met4Cast]

2 minutes ago, Spah1 said:

https://en.m.wikipedia.org/wiki/Global_Forecast_System

Interesting that it proved it be more accurate in predicting hurricane paths - I wonder if that same accuracy extended to ordinary areas of low pressure, too. Could explain why it never dropped the idea of the undercutting low and resultant stronger heights to the North that the GFS/ECM have no begun backtracking towards.

UKMO & FV3 have been leaning the way by and large given the subtle backtrack from the other models overnight/this morning.

[snowray]

2 hours ago, Ed Stone said:

I just get the feeling, I suspect from recalling charts from way back when, that the pattern that appears to be slowly establishing itself (strong blocking to the northeast and northwest, and only weak HPs to our south) that this winter will be more analogous to those of the 1960s/late 1970s, than to many of our more recent efforts?

But, of course, the usual caveat (that I may well be spouting horse poo!) applies!

Considering that we are still in mid November still I feel it's more a case of sitting back and watching developments, it would drive you mad commenting on every single run and taking all the ups and downs too seriously. The ingredients are all there, and it's a developing situation that we have, lots to look forward to.

 

Even short term we have upgrades on next weeks cold pool from the ICON, somewhat colder air there on the continent making inroads across the channel. I think that there could be more sleet and snow around than people expect.

[Midlander]

A ever so slight improvement unto 90hrs on the ICON, with the low pressure a bit further east.