Model Output Discussion - Colder spell ending, what's to follow?

[swfc]

1 minute ago, bluearmy said:

Topper, drifter or sinker ??

I'd suspect a dopple danger blue but who knows 

[Ice Day]

So the 6z is going for a seasonal feel to Christmas day, chance of snow for Scotland, northern England and NI (not that it will happen like this of course!).

 

Looking at the GEFS from the 0z, there does appear a trend to colder conditions establishing towards the end of the year.

Not to be taken too seriously, but something to keep an eye on.  

 

 

 

[SLEETY]

GFs nailed christmas Northerly in fl some years ago and their was a white xmas for some,can lightening struck twice

It will be my favourite model now if this comes off

Edited December 13, 2020 by SLEETY

[feb1991blizzard]

48 minutes ago, That ECM said:

Yeah no one likes to see that in the Atlantic do they?

 

Transient again though, just doesn't get far North enough and collapses under pressure from vortex / upstream troughing.

[BLAST FROM THE PAST]

39 minutes ago, Drifter said:

White Xmas for Aberdeen on this run. 

*looks for Paddy Power account details*

Got 8/1 for Norwich.  It’s 3/1 now...

The timing is still consistent....last week of December, and as it gets closer the potential cold thrust remains at that time on the models.  It won’t be before as our window imo is and remains the last week.

 

 

 BFTP

[feb1991blizzard]

This is much better though, miles better than oz.

[BLAST FROM THE PAST]

36 minutes ago, bluearmy said:

Topper, drifter or sinker ??

Drifter

 

BFTP

[Allseasons-Si]

Look at that gefs mean at 240

[West is Best]

It's quite amazing how often, even in mild winters, we've seen a cold snap around Christmas. I have twice had festive snow in north Devon and once posted a pic on here of me dancing in a snowstorm on Christmas Day

The 0z operational though definitely headed colder than most members and in far flung FI was a brief outlier. 

The 6z continues the festive cheer but I'm wary about the height rises shown over continental Europe right at the end. It's a fine line but if we get one parking up over northern Germany then it's a problem as that puts us in mild south-westerlies and anything but cold over the UK.

To be frank though ever since summer I've stopped paying any real notice to the GFS past T168. It is so erratic.

[Anthony Burden]

Still a ways to go but the more runs that continue to show this encouraging set up

looks great for Christmas.High pressure orientation critical for continued cold weather.

[pdiddy]

10 minutes ago, BLAST FROM THE PAST said:

Got 8/1 for Norwich.  It’s 3/1 now...

The timing is still consistent....last week of December, and as it gets closer the potential cold thrust remains at that time on the models.  It won’t be before as our window imo is and remains the last week.

 

 

 BFTP

Off topic, but be careful when punting... Some bookies use different sites to get their evidence (mainly football grounds or airports).  Betfair refused to pay out 2 years ago for Edinburgh when there was sleet and snow at 11.30pm because it was not recorded by the met office.

[Frosty.]

The only thing I care about, give a damn about right now is..will it be a cold Xmas for a god damn change..,and, according to the latest GEFS 6z..it might be a cold festive period..for a god damn change!!!!

 

Edited December 13, 2020 by Jon Snow

[blizzard81]

For years the GFS outperformed the ECM with regards to correctly modelling amplification in the north atlantic. I have no reason to believe anything has changed on that front. 

[Drifter]

19 minutes ago, BLAST FROM THE PAST said:

Drifter

 

BFTP

You called?

We certainly seem to be in the raffle for a seasonal Christmas for a change. Let’s see what the atmosphere can concoct over the next few days to deny us. 

[SqueakheartLW]

My main update on the GFS runs for yesterday and here are the totals I got for them and the change compared with the day before

Temps        12/12          Precip        12/12
V Mild          3 (+3)         V Dry          0 (0)
Mild             12 (-10)      Dry             20 (0)
Average       38 (-8)       Average     76 (+1)
Cold             61 (+12)    Wet            31 (-1)
V Cold         14 (+3)       V Wet         0(0)
LEADER       CD             LEADER     AV

Overall despite the first very mild options showing up in the GFS runs yesterday the overall trend from the day before is clearly a swing back towards colder for Christmas Day overall with a drop in mild and average in favour of cold and very cold options. Precipitation is sticking firmly in the average category for now.

Even better news is the increasing number of cold and very cold options showing up in last nights 18z GFS and even more so today's 00z GFS. I have picked all of the cold and dry festive options as well as potential and definite snow makers but first I shall get rid of the doom and gloom milder options and thankfully there were no very mild options this time around. I have put these in order from least mild to mildest.

00z GFS Member 25

The least mild option on the table with some cooler air in the east and the mild air further out to the west. Mildest temps late in the day as this milder air moves over the UK

18z GFS Member 24

Very mild air on the way for Christmas Day here but not soon enough to push the big day into the very mild category. May be early transitional snow in the far NE near the colder air up there otherwise rain for most

18z GFS Member 10

A wedge of milder air is working its way in here for Christmas Day. Probably just scraping double digits in eastern areas late in the day after a chilly start. Milder most of the day in the west and a band of rain pushing east too

00z GFS Member 22

Really similar to the above option but different distribution of temps with the cooler air pushing away north rather than east and milder air involved compared with the last option

18z GFS Member 18

Mild air looks to be in place for the whole of Christmas Day here. Widespread double digit maximums no doubt and mild overnight minimums too

00z GFS Member 26

The third similar option but even milder uppers to come compared with the previous 2 options.

00z GFS Member 10

Generally mild here within a warm sector. Early rain clearing the east then mostly dry and cloudy with drizzle in the west and brighter further east. Double digit temps

Got that one out of the way. Now time to feature the much more festive options and I have done my best to order these from least cold to coldest since there were so many options here, especially from the 00z GFS

18z GFS Member 14

A potential transitional snow event here for Christmas Day before that annoying milder sector arrives from the west later in the day

18z GFS Member 1

Similar to the above option but a different distribution of the snow. Less for the south but probably more for the north to compensate and a slower transition likely here too

00z GFS Member 19

A glancing blow from an Arctic northerly here. Probably a snow shower risk for the N and the E coast too. Less cold further west with rain/sleet showers on exposed W facing coastlines

18z GFS Member 6

A more anticyclonic option here, especially further N and W. The S will likely be dry but the E could see a few wintry showers coming in off the N Sea

18z GFS Member 7

This could be a marginal snow maker in the E close to that low pressure engaging with the cold uppers. A white Christmas chance for the E anyway

18z GFS Member 5

Yet again another marginal snow maker here but more widespread than the last option. Cold uppers in the mix too

00z GFS Member 20

A band of wintry precipitation sinking south here on Christmas Day. Quite a slack flow and cold uppers could be the ideal ingredients to get some snow out of it

18z GFS Member 17

A cold and dry option here under that ridge of high pressure. Frost, fog and sunshine the order of the day here for Christmas

18z GFS Member 27

A risk of snow here in the N and E with those cold uppers close to that low pressure. The west likely to be dry and cold under the higher pressure.

00z GFS Member 6

The first easterly option for a while. Hope this is the start of a fightback for the easterlies and hopefully even beasterlies coming back into the mix again. This is a dry and cold option with the lowest temps in the south. Least cold furthest to the north here but cold and frosty for all

00z GFS Member 12

Another cold anticyclonic option but with more widespread -5c isotherm above makes this one a slightly colder option than the last one. A risk of snow showers in the far NE, otherwise dry, cold and frosty

00z GFS Member 27

A significant wind chill here in the early stages of an Arctic northerly. Snow likely near the low pressure as well as in the north too. Even colder air is waiting to move down from the north too

00z GFS Control Run

A dry, cold and frosty option again and very likely even colder than the other options of this nature. Under an area of high pressure so little if any snow around

00z GFS Member 23

A real snow maker here for the N and E where there is exposure to these northerly winds. Dry and cold in the S and W for Christmas Day

18z GFS Member 25

Mainly dry and cold here for Christmas Day but a snow threat near that low pressure in the east so a risk of a white Christmas here

00z GFS Operational Run

Even the operational run has come out to play cold Christmas today with this mostly anticyclonic option which will deliver cold and frosty for the day at least. A risk of snow showers coming in off the N Sea into E and SE parts could give a white Christmas here at least

00z GFS Member 8

Dry, cold and frosty Christmas on the cards here and the coldest of these options so far with the -10c isotherm getting into the north of Scotland on this run

00z GFS Member 11

The 2nd coldest anticyclonic option on the table between the 18z and 00z runs. Widespread -5c uppers and like the previous option the -10c isotherm into the north of the UK

00z GFS Member 7

A true ice day risk here with the most widespread -10c isotherm coverage over the UK compared to any other run. Very low minimums expected under that ridge

Summary

We may have increased the colder options here but many of the coldest ones are anticyclonic so marginal snow events at best but if the coldest ones can join in with lower air pressure or more direct flows off the sea then we could be back in business again

ENS charts latest

The first chart here is yesterday's 12z. All 51 members going for a similar option with above average pressure to the NW and below above and to our SE. An increased risk of NE winds here for Christmas Day. All we need now is colder air to engage with this too

Today's 00z has a bit more variety but most members are still going for similar setup with above average pressure to the NW and below to the SE. There is an outlier option today of high pressure over the UK so could still be cold and dry with this option

After today I will have more models to look at when ECM and GEM come into range of Christmas Day tomorrow

[blizzard81]

Much better mean on the 06z gfs compared to the 00z mean for Christmas day. It is the 06z run though so usual caveats apply. 

[Uncertainty]

Yes @Allseasons-siStrongest signal yet for Atlantic amplification from the GEFS. But can we trust it?

Not yet, if this is to come off we at least need a string of EC ops to go with it soon. Last night’s effort wasn’t bad but this morning’s is ugly and has weak, transient amplification and a continuation of the wet and mild pattern we have now, perhaps focused a little further north with weak ridging over the south. A representative example of this solution from the GEFS

Notice how the next low Leaving the states is already toppling the ridge ahead of it

The jet doesn’t even amplify to southern Greenland and hence the low simply powers through the Atlantic with our name now Stamped firmly on it.

What those of a cold persuasion want of course is for the Northern stream jet to amplify sufficiently to allow a more significant high to develop to the NW. 

Here you can see the jet has moved Northwards up the southwestern coast of Greenland, allowing cold air to flood south.

Despite the improved signal on the 6z there are very few that build a long lasting ridge to the NW so a severe, long lasting cold spell is not signposted at present. As BA has rightfully mentioned, there’s more than just the MJO at play here, the Atlantic SSTs don’t fill me with confidence vis the strong Atlantic ridge and there are countless examples of the GEFS at day 9 overplaying Atlantic ridging, the 18z from last Thursday a case in point.

Indeed looking at the EPS/GEPS the ridging looks transient, but a 2-3 day cold ‘snap’, especially for Northern areas is very much in the possibility space around the 23rd, so plenty to keep coldies (or ‘not southwesterlies’ like me!) interested over the festive period.

Edited December 13, 2020 by Uncertainy

[Eagle Eye]

I may have hated this planet before but now I've seen this I love this planet.

[TSNWK]

13 minutes ago, dragan said:

This post was removed

I have now drawn the conclusion after noting your posts recently that you're boarding on trolling and have placed you on ignore. Dismissed

Edited December 13, 2020 by Blessed Weather

[blizzard81]

14 minutes ago, dragan said:

This post was removed

You need to have some of the control run for your lunch  

Edited December 13, 2020 by Blessed Weather

[bluearmy]

@Uncertainy - I was expecting the ridge to be flattened but ops are trying to extend it more ne allowing heights to drop somewhat over Europe 

in addition, the trend on the gefs suites is to lower euro heights and I also note the last couple runs have begun to undercut griceland heights/wedge .......that’s risks a west based neg NAO but also offers a small chance of the trough running into the base of a cold Nw euro/W scandi trough .....  its way more interesting than many thought possible just 36 hours ago 

the middle ground solution will likely be a cold high of sorts in our vicinity 

Edited December 13, 2020 by bluearmy

[NewEra21]

14 minutes ago, dragan said:

This post was removed

While I respect your opinions, all your posts seem to come across as mild ramping/ just trolling coldies.

The Christmas cold snap isn't even set in stone yet, so calling anything after that is even more speculative.

Edited December 13, 2020 by Blessed Weather

[TSNWK]

Just now, bluearmy said:

@Uncertainy - I was expecting the ridge to be flattened but ops are trying to extend it more ne allowing heights to drop somewhat over Europe 

in addition, the trend on the gefs suites is to lower euro heights and I also note the last couple runs have begun to undercut griceland heights/wedge .......that’s risks a west based neg NAO but also offers a small chance of the trough running into the base of a cold W euro trough .....  its way more interesting than many thought possible just 36 hours ago 

Thank you BA. And perfectly articulates why this hobby is fun.  The unpredictable nature and frankly with this all science we still cannot account for chaos effect. 

[matty40s]

Steve Murr

...

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[Eagle Eye]

Bigger high than the UAE, that hasn't happened since I was born in 1432.

That low's giving a good go at starting Winter.

 

Edited December 13, 2020 by Sheldon Cooper