Model Output Discussion - Into the new year

[SMU]

5 minutes ago, Hullsnow87 said:

Are we looking good then steve

Yes

Also highlighting the GFS flaws

The implosion from the south wont happen this run due to additional strength moving SW in the jet & the southern arm over europe less attenuated 

12z first

Edited December 29, 2020 by Steve Murr

[winterof79]

Island in the streamers

[Snowman.]

Low over canada stops any retrogression of the high too far west. IF the downstream plays out correctly should be a decent run.

[Uncertainty]

 

A simply stunning chart from the UKMO which has been all over this evolution. The Europe view shows the high getting ‘sucked’ up towards central Greenland and a polar trough about to come down from the North.

GFS is very different and has the high to the North weaker, still cold medium term and snow showers NE coasts moving inland. 
 

GFS para is further North with the block and also looks to be heading for retrogression.

Given ICONs Nward adjustment expect ECM to be closer to UKMO than its 0z. 
 

A great start to the 12z runs!
 

[sebastiaan1973]

2 minutes ago, Skullzrulerz said:

So you're thinking that the UKMO is a bust if it went on for longer ? 

May well trend the same way with the GFS/ECM?

Short term vs Long term. I wish for a long enduring SSW effect on the tropshere. This is the response of a SSW with a European blocking at the onset.

[Griff]

Para... 150

[Ian Price]

6 minutes ago, Mike Poole said:

South of the M4 event tomorrow according to HARMONIE 12z at T33:

But at least some of us are seeing snow on this run.

Are the orange lines on the HARMONIE charts sleet?

[sheikhy]

Amazing 12zs!!normal service resumes!!!ecm please join ukmo or gfs tonight!!any will do!!

[Matt H]

Biggest positive for me is that we seem to have moved away from the 00z trend to sit the high closer to, or over the UK. Comparing the 3 GFS runs today so far it does appear to be the less likely outcome for now (all eyes on the ECM later though).

00z:

06z:

12z:

Parallel run is slowly seeing the light hopefully as well:

Edited December 29, 2020 by Frosty Winter

[Captain Shortwave]

The two GFS runs do show enough instability to produce showers down North Sea coasts once the ENE wind sets in. The only issue appears to be whether they fall as rain/wintry mix or snow. I would assume that the UKMO would be in the same boat.

Later on, this is an absolute beauty of a chart...

Wouldn’t bet against this happening at some point in the next couple of weeks.

Edited December 29, 2020 by Captain Shortwave

[chionomaniac]

Here is the wetter view of the UKMO with the next 24 hours suggested. And I don’t think it too far west either.

 

Furthermore, any effects that we are looking for from a SSW is the dramatic fall of trop jet stream to aid blocking. But look already, without the SSW even occurred and downwelled we see 100hPa zonal u winds at the upper trop showing almost record low values forecast. We can’t get much lower than that!

This has to be one of the most amazing mean u wind charts ever seen before an SSW!

[SMU]

@Met4Cast

Hirlam out. My go to model since 2010.

Dont cancel just yet.... The channel track looks fine but the little flick NE up into Kent is what brings the snow...

 

GFS op & Mean on board

Edited December 29, 2020 by Steve Murr

[Weathizard]

Open those floodgates  

[bobbydog]

9 minutes ago, Mike Poole said:

South of the M4 event tomorrow according to HARMONIE 12z at T33:

But at least some of us are seeing snow on this run.

Yep. GFS still going with it also,

 

Meto forecast update still says snow risk with warnings still in place. I believe the weather icons are produced from raw model data and updated hourly. This has actually increased the snow chances for me here in Sussex.

This is going to down to radars and lamp-posts....

[weathercold]

I highlighted this earlier when a few downbeat posts popped up after the 6z.

Expect many changes over the next few days with the placement of the high.

However, anyone wanting cold and potentially snow should be very pleased with the 12z.

UKMO is stunning!

Edited December 29, 2020 by weathercold

[Scott Ingham]

5 minutes ago, chionomaniac said:

Here is the wetter view of the UKMO with the next 24 hours suggested. And I don’t think it too far west either.

 

Furthermore, any effects that we are looking for from a SSW is the dramatic fall of trop jet stream to aid blocking. But look already, without the SSW even occurred and downwelled we see 100hPa zonal u winds at the upper trop showing almost record low values forecast. We can’t get much lower than that!

This has to be one of the most amazing mean u wind charts ever seen before an SSW!

Whats your latest thoughts i.e strat? Type? And also impacts? Im seeing conflocting views

[Tim Bland]

4 minutes ago, Steve Murr said:

@Met4Cast

Hirlam out. My go to model since 2010.

Dont cancel just yet.... The channel track looks fine but the little flick NE up into Kent is what brings the snow...

 

GFS op & Mean on board

You might want to create a kent and Sussex discussion Steve  

re UKMO would it bring snow showers inland do you think?

[Ali1977]

1 minute ago, weathercold said:

I highlighted this earlier when a few downbeat posts popped up after the 6z.

Expect many changes over the next few days with the placement of the high.

However, anyone who wanting cold and potentially snow should be very pleased with the 12z.

UKMO is stunning!

Agree , this is day 9 (semi reliable) and what it shows is at least another week of freezing temps. Uppers now good for U.K. wide snow at day 9, showers kicking in off North Sea.

 

very very good for coldies.

[Griff]

Just now, Ali1977 said:

Agree , this is day 9 (semi reliable) and what it shows is at least another week of freezing temps. Uppers now good for U.K. wide snow at day 9, showers kicking in off North Sea.

 

very very good for coldies.

You'd certainly have to hope GFSP isn't ready for public consumption and is still work in progress, not as keen. 

[Uncertainty]

3 minutes ago, sebastiaan1973 said:

Short term vs Long term. I wish for a long enduring SSW effect on the tropshere. This is the response of a SSW with a European blocking at the onset.

Yes Seb if the research is correct then bizarrely we should really be wanting to avoid a Greenland high... which for most on this forum I imagine almost impossible...Jam tomorrow and all that...

However, does a well supported evolution such as the GFS para not already have a good amount of NW Euro blocking? A 1030mb Scandi ridge at around the time of peak onset?

 

 

This, along with the Icelandic block leaves a large high covering, at least initially, both sectors? Surely that would make it hard to classify either way?

I realise this is about timing but as you know every event is different and we could get a perfect trop anomaly and no significant downwelling, we’ll just have to wait and see...

[chionomaniac]

10 minutes ago, sebastiaan1973 said:

Short term vs Long term. I wish for a long enduring SSW effect on the tropshere. This is the response of a SSW with a European blocking at the onset.

Sebastiaan. See my post above. Damage to trop is already occurring. It is like you are looking up for a bomb to explode when in reality it has already blown up behind you.....

[winterof79]

4 minutes ago, Captain Shortwave said:

The two GFS runs do show enough instability to produce showers down North Sea coasts once the ENE wind sets in. The only issue appears to be whether they fall as rain/wintry mix or snow. I would assume that the UKMO would be in the same boat.
 

Should be fine Matt.

[chionomaniac]

4 minutes ago, Scott Ingham said:

Whats your latest thoughts i.e strat? Type? And also impacts? Im seeing conflocting views

A bird in the hand is worth two in the bush

[Griff]

Don't shoot the messenger, the upgrade is going for downgrades

Edit: seems I should have used inverted commas or something to demonstrate intended sarcasm. 

In any case, this is what's showing. 

Edited December 29, 2020 by Griff

[Stu_London]

Biggest worry remains is that there is not enough mid latitude cold pools on our side of the globe.

GFSP demonstrates how despite reasonable favourable patterns, the cold can run out of steam quickly.