Model output discussion - cold spell approaching?

[Methuselah]

2 minutes ago, Nicholas B said:

all important for snow chances and so often the difference between rain and snow for low levels, from the 21st the dew points are looking good too!  

And it's fundamentally different to last weeks garbage: then, it was quite legitimate to follow the isobars back to the Med; this time it is not! This time (should it materialise) any air from the NE will be of Arctic origin -- ergo lower T850s and much lower dps... Precipitation at 2C and 30% RH, sure beats the crap out of what falls at 5C and 99% RH? 

[wellington boot]

35 minutes ago, johnholmes said:

Very kind-thank you

Another source of what 'might happen' is this link, from ECMWF

http://www2.wetter3.de/Fax/00_ECMWF_ENS_p0_500hPa+144_240.gif

*Shudder* Nothing moves and 528 and -5 never get as far even as London... Awful outcome for the SE (as far as it goes...)

[winterof79]

47 minutes ago, chris55 said:

I can see why talk of the Pacific Ridge has been about, this is a good visualisation of how helps, it moves over the pole and re-enforces the negative flow and supports the Greenland ridge!

Lovely charts!

Yes the "Pumpathon" over the Pacific has to be balanced out by the atmosphere hence very shortly there will be a "Dumpathon" over our side. 

[NewEra21]

9 minutes ago, warrenb said:

So going by the mean we have 3 days of -5 before the high drifts west and the Atlantic comes up from underneath. For a good cold spell you want solid -8 to -10. Note the control and the Op both go warmer toward the end as the pattern backs west.

I think we're all just happy to finally see some more agreement within the ENS on getting the cold in to begin with, once we get the cold in we'll see what happens. 

Edited January 12, 2021 by NewEra21

[seajamiet]

11 minutes ago, warrenb said:

So going by the mean we have 3 days of -5 before the high drifts west and the Atlantic comes up from underneath. For a good cold spell you want solid -8 to -10. Note the control and the Op both go warmer toward the end as the pattern backs west.

At the point they go warmer you are talking deep FI.

Are you chasing a mild chart at 384 hours?

[goosey007]

14 minutes ago, Nicholas B said:

all important for snow chances and so often the difference between rain and snow for low levels, from the 21st the dew points are looking good too!  

Outstanding ....best set of data (or cold agreement ) on one run I have seen in many a year.....hard to believe its not going to got this way looking at it. Of course we all know better. Just hope the trend continues in the next few runs!

 

[Methuselah]

So, the GEFS T850s favour a plummet just after Jan 19, though not to anything all that spectacular... After that, things could stay cold for a month or 'normality' might resume... Who knows? But, one thing's certain -- nothing's 'nailded'!

     

But at least the NH profile mean still wants to 'play ball'!

    

    

Edited January 12, 2021 by General Cluster
grammer!

[Guest]

10 minutes ago, seajamiet said:

At the point they go warmer you are talking deep FI.

Are you chasing a mild chart at 384 hours?

To be fair we're lacking mild boosters on this forum

[legritter]

Lets chill out gang ,very good possibilities are lurking just over the horizon  ,no guarantee but im excited, and so is my dog , sausage baps brown sauce ,and STELLAs on me ,at this range details of 850s and will it SNOW will always be unknown, but something is afoot, Squirrel s are going crazy up the woods , take care all and keep the good posts coming ,cheers .

[That ECM]

23 minutes ago, Frosty Winter said:

1. The mean is currently being skewed by the milder ensemble members as @That ECM has already noted. The vast majority of the runs go much colder than -5C.

2. Why on earth are you already looking for the breakdown of a cold spell that hasn’t even begun yet?

People always do and I think it’s fine tbh. If you have so much data available you will and can make an argument for numerous outcomes. Realistic or not. Sometimes it’s best to smile and move on. 
 

No one can convince me that this will be done in a couple of days. The data strongly points to cold. Details and length will be for later. All good in my book. Remember the high was going to topple yesterday. Now it’s going to go to high and west. 

Edited January 12, 2021 by That ECM

[Griff]

1 hour ago, Battleground Snow said:

The control shows how it can be perfect even in a slightly west based NAO. As the Pacific / Arctic high forces the Asian vortex further south along with the colder uppers.

Huge signal for the Pacific ridge at this range on the mean. 

Also attached graph which is showing a decent cluster of cold members. Screams snowy more than deep cold.

Excellent steps forward this morning. Looking forward to the later model runs of the day. 

It may not happen but at a challenging period for many of us, it's great to have something to occupy our minds with other than doom and gloom. That said, I'm finding the ignore users in account settings very handy and good for my mental health. Live and let live, no need to argue. Side step those that antagonise. 

[Snowman.]

12 minutes ago, Griff said:

Excellent steps forward this morning. Looking forward to the later model runs of the day. 

It may not happen but at a challenging period for many of us, it's great to have something to occupy our minds with other than doom and gloom. That said, I'm finding the ignore users in account settings very handy and good for my mental health. Live and let live, no need to argue. Side step those that antagonise. 

Thinks are looking good, the means are nice and the almost horror that 0z UKMO brought to me at 4:30 in the morning has been eased. 

[pureasthedriven]

20 minutes ago, That ECM said:

People always do and I think it’s fine tbh. If you have so much data available you will and can make an argument for numerous outcomes. Realistic or not. Sometimes it’s best to smile and move on. 
 

No one can convince me that this will be done in a couple of days. The data strongly points to cold. Details and length will be for later. All good in my book. Remember the high was going to topple yesterday. Now it’s going to go to high and west. 

I would say the data strongly points to below average. Which will deliver handsomely for some and not for others. I’ve not been collecting empirical data for my location (Gatwick) but would be very surprised if we’ve not been broadly below average - give or take - here since Dec 1st. And yet not a flake of snow to date. 

Edited January 12, 2021 by pureasthedriven

[Frosty.]

 

 

Just been looking through the GEFS 6z..and..I haven’t said boom yet this winter but I hope you won’t mind if I now say..BOOM!!! ...we are defo in the game coldies!   ️ 

 

 

[Snowman.]

If you want to see what locked in cold looks like Ensemble 8 is the run for you!

 

This is 2010 re-imagined. It's actuall colder and brings the -18 line in Scotland!

Meteociel - Cartes Ensemble GFS (ENS/GEFS)

WWW.METEOCIEL.FR

---

meteociel propose des rubriques météo temps réel, forums, modeles...

 

[sub zero]

I really don't see a prolonged very cold spell from the chats atm, yes I see a snowy spell with maybe some severe temperatures at times lasting a week maybe 10 days from these charts, which in itself is amazing to see and has me glued to this forum and meteociel..

But the only chance we get of seriously cold uppers, is from channel lows passing under the block and giving us a brief easterly, the rest of the time the general wind direction is a northerly , which will be cold enough for snow but not severe, as too long a sea track...

It seems there is only one outcome (as far as I can see) as the cold pool makes its way towards us then floods into the Atlantic, ruining the amega block by cutting off the waa into Greenland and giving us a west based NAO..

I don't see how we can get long sustained cold unless we can get heights over Iceland or scandy giving us more of an easterly feed...

Are there many times when the trough stays out to the east (with no heights to the north or east) staying put and delivering  cold for the uk for long periods, or do we need to see height rises to the north/east...?

an unusual set up and intriguing to say the least..

Don't get me wrong I'm not trying to put a dampner on things , I just want to put things in perspective..

I'm a coldie through and through .. honest...!

 

[Snowman.]

6 minutes ago, sub zero said:

I really don't see a prolonged very cold spell from the chats atm, yes I see a snowy spell with maybe some severe temperatures at times lasting a week maybe 10 days from these charts, which in itself is amazing to see and has me glued to this forum and meteociel..

But the only chance we get of seriously cold uppers, is from channel lows passing under the block and giving us a brief easterly, the rest of the time the general wind direction is a northerly , which will be cold enough for snow but not severe, as too long a sea track...

It seems there is only one outcome (as far as I can see) as the cold pool makes its way towards us then floods into the Atlantic, ruining the amega block by cutting off the waa into Greenland and giving us a west based NAO..

I don't see how we can get long sustained cold unless we can get heights over Iceland or scandy giving us more of an easterly feed...

Are there many times when the trough stays out to the east (with no heights to the north or east) staying put and delivering  cold for the uk for long periods, or do we need to see height rises to the north/east...?

an unusual set up and intriguing to say the least..

Don't get me wrong I'm not trying to put a dampner on things , I just want to put things in perspective..

I'm a coldie through and through .. honest...!

 

My friend, as someone who lives in the SE I will take 5cm of snow and be done with winter! I haven't seen falling snow since 2018 and after the year we've just had I would very much like to enjoy a walk in the snow!

Month long cold and snow spells are extremely rare and a unrealistic expectation, 10 days of cold and snow before we move back to normality is fine. I do appreciate your caution always that possibilty of a west based -NAO. But we need to make sure the block sets first before we worry about that.

Edited January 12, 2021 by Snowman.

[goosey007]

7 minutes ago, Snowman. said:

My friend, as someone who lives in the SE I will take 5cm of snow and be done with winter! I haven't seen falling snow since 2018 and after the year we've just had I would very much like to enjoy a walk in the snow!

Month long cold and snow spells are extremely rare and a unrealistic expectation. There's been what 2 in the past 100 years?

Spot on Snowman..........hand on heart if the models offered me a widespread and significant snow event that stuck around for 5 days to a week ...id say come on are you saying you wouldn't put a big tick in the winter 2021 cold and snow box!!??

Edited January 12, 2021 by goosey007

[ICE COLD]

4 minutes ago, Snowman. said:

My friend, as someone who lives in the SE I will take 5cm of snow and be done with winter! I haven't seen falling snow since 2018 and after the year we've just had I would very much like to enjoy a walk in the snow!

Month long cold and snow spells are extremely rare and a unrealistic expectation, 10 days of cold and snow before we move back to normality is fine.

Yep I’m pretty sure if the majority of this forum got a 7 -10 day cold spell with at least 1 dumping of snow we’d be happy ? Don’t get me wrong I want more a lot more but let’s just see how it pans out . I can still see us getting multiple attempts at cold and snow from now until March because of what’s going on up top . Good times ahead

These are a stunning set of GEFS

[danm]

20 minutes ago, sub zero said:

I really don't see a prolonged very cold spell from the chats atm, yes I see a snowy spell with maybe some severe temperatures at times lasting a week maybe 10 days from these charts, which in itself is amazing to see and has me glued to this forum and meteociel..

But the only chance we get of seriously cold uppers, is from channel lows passing under the block and giving us a brief easterly, the rest of the time the general wind direction is a northerly , which will be cold enough for snow but not severe, as too long a sea track...

It seems there is only one outcome (as far as I can see) as the cold pool makes its way towards us then floods into the Atlantic, ruining the amega block by cutting off the waa into Greenland and giving us a west based NAO..

I don't see how we can get long sustained cold unless we can get heights over Iceland or scandy giving us more of an easterly feed...

Are there many times when the trough stays out to the east (with no heights to the north or east) staying put and delivering  cold for the uk for long periods, or do we need to see height rises to the north/east...?

an unusual set up and intriguing to say the least..

Don't get me wrong I'm not trying to put a dampner on things , I just want to put things in perspective..

I'm a coldie through and through .. honest...!

 

 

18 minutes ago, Snowman. said:

My friend, as someone who lives in the SE I will take 5cm of snow and be done with winter! I haven't seen falling snow since 2018 and after the year we've just had I would very much like to enjoy a walk in the snow!

Month long cold and snow spells are extremely rare and a unrealistic expectation, 10 days of cold and snow before we move back to normality is fine. I do appreciate your caution always that possibilty of a west based -NAO. But we need to make sure the block sets first before we worry about that.

 

12 minutes ago, goosey007 said:

Spot on Snowman..........hand on heart if the models offered me a widespread and significant snow event that stuck around for 5 days to a week ...id say come on are you saying you wouldn't put a big tick in the winter 2021 cold and snow box!!??

 

Two things I'd add to the above posts .

Firstly, we have no idea of knowing at the moment if the cold spell (when/if it arrives) will be short or lengthy. We can't call that now, so there's little point in people saying "I don't see a lengthy cold spell". How do you know? 

Secondly, it is also very true that a prolonged freeze is rare for the UK - it is why we talk about December 2010, 62/63, 1947 etc so much because they don't happen very often. However, does it need to be a month long freeze for it to be memorable? I don't think so. Some of our best cold and snowy spells of weather have lasted a week or two. For my part of the world (the SE) two of the best winter weather events in the last 35 years are Jan 87 and Feb 91. Both bitter easterlies that delivered huge amounts of snow and sub zero temperatures. However, both spells lasted little more than about 7-10 days before mild air came back in. There was nothing particularly exceptional about either the winter of 86/87 or 90/91 as a whole. 

Let's see what happens, but whether any cold spell lasts 7 days or a month, it could still deliver something very memorable. 

Edited January 12, 2021 by danm

[carinthian]

On 11/01/2021 at 13:15, carinthian said:

Ok just have an update with specifics regarding UK snowfall Wed-Fri this week. Going by the graphics shown on the snow model, the front appears to push through slowly but has what looks like the makings of a returning cold front to lie across the east. So snow potential being flagged up for the Eastern Pennine region especially Thursday into Friday. Maybe some transient snowfall on Wednesday in Scotland and NE England. With-in the parameters a current 20% confidence rating with high complexity , so changes could be swift.

c

Ok, I have an update regarding the above ( RE: UK snowfall ).The outer parameter results from the snow computer currently show snowfall tomorrow, mainly on the high ground of Northern England and Southern Scotland. It would appear that the progress of the front is of some concern in its analytical output. The upper 300mb wind flow from NW ahead of the front is still strong enough to retard much progress NE. So positioning of the front and movement is crucial to the potential snowfall. Looks like cold air block ahead of the front will not be that easy to displace based on this current output but flags up the area most at risk. Into Thursday , snow could come down to lower levels and a bit further west. Current confidence ratings increased to 40%  now  its shown with-in the 24 -48 hour time span but high level of complexity remains in providing snowfall amounts.

Hope this helps. Its definitely a period of now forecasting.

C

[Rollo]

This has always been the problem with warm air trying to replace cold condition. These situations used to occur with greater frequency up here in NE England years ago and several time we were forecast rain or sleet but ended up with 5 to 8 cams of pretty wet snow.

[Battleground Snow]

I think the SSW and developments high above are going to override any tropical forcing at the moment, but both ECM and GEFS forecasts are hinting at a run into 6 or 7 later in the month, which may prolong blocking once the SSW has flushed through. It may mean we turn a 10-14 day cold spell into something much more notable.

 

[Cold Winter Night]

From a coldie's perspective there is much reason to remain cautious today, but just as much reason for hope in the longer term.

The negative IMO is still what I feared yesterday, a Greenland High that sits too far North and West for most of us to profit optimally. Others have mentioned this too this morning.
In these situations we probably should do well to check an excited poster's location first, because it may well come down to a North vs South split. Although more movement of the West Greenland High towards Ellesmere Island could even make the North miss out on the deepest cold.

The problem is that the best Greenland Highs have their origins in a High either over the UK (Jan 1947 style) or over Scandinavia (Nov 2010 style). Retrogression then moves the core of the heights towards Iceland and Greenland. This succession pulls in the deep cold from Russia, across the Baltic or Poland towards the Low Countries and ultimately the UK.

The GH we see in the output around +200 now originates in the Labrador/West Atlantic area. The High goes up towards Greenland, but the following retrogression moves it towards Baffin/Ellesmere Island in the Canadian Arctic, leaving room for the jet to move back North, towards us, where we don't want it.

Also, the early Scandi High option I mentioned yesterday does not seem to develop further, so I'm ready to dismiss that after the 12Z's.

The positives are still there though. Models are still jumping around like crazy so nothing is set in stone at all.
Some GEFS members have the Greenland High extending a bit more East, the GFS Op too, so I'd like to see more of that.

The EC surprised me at +240h with more cold moving through the Baltic, couresy of a surface high over Nova Zembla, see the circled area in the image. EPS also shows clusters post +240h that extend the Arctic High into the Eastern Hemisphere.

In these circumstances, a surface High can develop and become a stronger feature later on. Those are options that might come on the table once the cold pool moves our way, even if the Greenland High is too far NW for direct impact, so that is a big positive for me, definitely something to watch out for in the coming days.

[Severe Siberian icy blast]

18 minutes ago, carinthian said:

Ok, I have an update regarding the above ( RE: UK snowfall ).The outer parameter results from the snow computer currently show snowfall tomorrow, mainly on the high ground of Northern England and Southern Scotland. It would appear that the progress of the front is of some concern in its analytical output. The upper 300mb wind flow from NW ahead of the front is still strong enough to retard much progress NE. So positioning of the front and movement is crucial to the potential snowfall. Looks like cold air block ahead of the front will not be that easy to displace based on this current output but flags up the area most at risk. Into Thursday , snow could come down to lower levels and a bit further west. Current confidence ratings increased to 40%  now  its shown with-in the 24 -48 hour time span but high level of complexity remains in providing snowfall amounts.

Hope this helps. Its definitely a period of now forecasting.

C

The midlands are slowly but surely becoming a threat to see snow, the latest met video has it snowing in Cambridge Thurs, another 50 miles west and the central spine will be having snow fall