Model Output Discussion - cold spell to end Autumn

[karlos1983]

2 minutes ago, nick sussex said:

The GFS is better for backedge snow as it doesn’t develop a shortwave in the flow from the north . The UKMO because of that has a slower push south of the cold.

 looks like it would produce a more potent Northerly though Nick as that GFS low will take an age to drop SE, if ever and drag the coldest uppers away?

I prefer the ukmo personally 

[Nick F]

Wow at the 12z GFS, blizzard/snow storm of the century for northern and western parts of UK next Friday into Saturday!

Caveat that GFS tends to overblow depressions at that range, but the fact that it's been showing for a few runs or more now, worth keeping an eye on.

The slow-movement of the deep low over the N Sea very unusual and appears to be tied in with the stationary long wave trough over Europe and its removal from the strong NLy jet further west meaning it doesn't have the impetus to move quickly on like normal depressions that move west to east or southwest to northeast.

Alarming charts!

 

[nick sussex]

1 minute ago, karlos1983 said:

 looks like it would produce a more potent Northerly though Nick as that GFS low will take an age to drop SE, if ever and drag the coldest uppers away?

I prefer the ukmo personally 

Yes it’s a case of one better for the initial snow and one for a better northerly . It’s great to be discussing these options. 

[J-Man]

Surface sea temps in the north sea are lower than average thanks to the cold November, this will only have a positive impact for any potential snow event for coastal areas next week.

[Nick F]

12z UKMO and GEM not quite so alarmingly deep or slow with the Nly trigger low, tending to track the low away NE into Scandi as per UKMO or NE across N Germany then Baltic as per GEM - where it deepens rapidly.

[karlos1983]

3 minutes ago, nick sussex said:

Yes it’s a case of one better for the initial snow and one for a better northerly . It’s great to be discussing these options. 

The GFS wouldn't deliver the goods for me (or the majority of the south), unless I go to HSS and build a big precarious mother of all Scaffold towers on a big hill!

for that reason.......

Edited December 1, 2017 by karlos1983

[Day 10]

In simplistic terms, the GFS mid-term equals this:

[SMU]

Evening All

again the GFS repeats its winter storm for 7-8 December 

peak Blocking still on course for 9th December!

FWIW I think the chances of the storm a la GFS is very slim - at 5% with the moderated UKMO raw version a little more realistic..

either way a high chance of more snow - The north & poss NW look to fair well here but storm tracks are notorious in their difficulty to pinpoint- expect some corrections south ..

S

[knocker]

T144 just about explosive cyclogenesis, I'll believe it when I see it

Edited December 1, 2017 by knocker

[Summer Sun]

UKMO at t144 showing colder air gradually moving further south

t168 should be interesting around 19:30

Edited December 1, 2017 by Summer Sun

[karlos1983]

Our next trigger low is riding the Atlantic ridge (AKA UK Northerly incursion express)

 

JFF, but this is rather pretty to look at. what NH Profile that is!

Edited December 1, 2017 by karlos1983

[knocker]

1 minute ago, Summer Sun said:

UKMO at t144 showing colder air gradually moving further south

t168 should be interesting around 19:30

I'll take a wager it doesn't track it south west and deepen it by 20mb

[northwestsnow]

Blimey theres another in deep FI!!!

[snowice]

15 minutes ago, RAIN RAIN RAIN said:

Could be worse! 

You might have to change your name to

SNOW SNOW SNOW

 

[booferking]

1 minute ago, Steve Murr said:

Evening All

again the GFS repeats its winter storm for 7-8 December 

peak Blocking still on course for 9th December!

FWIW I think the chances of the storm a la GFS is very slim - at 5% with the moderated UKMO raw version a little more realistic..

either way a high chance of more snow - The north & poss NW look to fair well here but storm tracks are notorious in their difficulty to pinpoint- expect some corrections south ..

S

But would the percentage not be a bit more as the boundary between warm and cold air is very sharp.

[Weather-history]

500hpa northern hemisphere chart at 360hrs

Edited December 1, 2017 by Weather-history

[Glacier Point]

Just getting the inclining that the Pacific pattern is edging westwards (mjo would be a proxy here - heading towards phase 7). GEFS members should be well worth a view wrt mid Atlantic and Greenland areas as the North American trough is pulled slightly further west. Hope to get a blog entry on thoughts up asap.

[karlos1983]

Just now, Glacier Point said:

Just getting the inclining that the Pacific pattern is edging westwards (mjo would be a proxy here - heading towards phase 7). GEFS members should be well worth a view wrt mid Atlantic and Greenland areas as the North American trough is pulled slightly further west. Hope to get a blog entry on thoughts up asap.

Hi GP, where would we find said blog please  TIA Karlos

[northwestsnow]

2 minutes ago, Glacier Point said:

Just getting the inclining that the Pacific pattern is edging westwards (mjo would be a proxy here - heading towards phase 7). GEFS members should be well worth a view wrt mid Atlantic and Greenland areas as the North American trough is pulled slightly further west. Hope to get a blog entry on thoughts up asap.

Great news Stewart- on both counts- things seem to be developing very quickly at the moment- exciting times again...

looks like one of your key components- euro low, is on the menu!!

Edited December 1, 2017 by northwestsnow

[Thunder Snow]

16 minutes ago, Nick F said:

Wow at the 12z GFS, blizzard/snow storm of the century for northern and western parts of UK next Friday into Saturday!

Caveat that GFS tends to overblow depressions at that range, but the fact that it's been showing for a few runs or more now, worth keeping an eye on.

The slow-movement of the deep low over the N Sea very unusual and appears to be tied in with the stationary long wave trough over Europe and its removal from the strong NLy jet further west meaning it doesn't have the impetus to move quickly on like normal depressions that move west to east or southwest to northeast.

Alarming charts!

 

yes please 

[❄️❄️❄️❄️❄️❄️❄️❄️❄️]

2 minutes ago, snowice said:

You might have to change your name to

SNOW SNOW SNOW

 

If the next Friday afternoon is 12 z, BLIZZARD BLIZZARD BLIZZARD will change!

[Frosty.]

To be sure, these Gfs 12z charts are very pretty

Edited December 1, 2017 by Frosty.

[ukpaul]

And just for fun GFS ends up with a 1050 Arctic high.

[northwestsnow]

GEM brings a very transient Northerly- and it looks very similar to UKMO- i prefer GFS...

[Met4Cast]

11 minutes ago, booferking said:

But would the percentage not be a bit more as the boundary between warm and cold air is very sharp.

I think the 5% Steve was referring to was the likelihood of the GFS winter storm coming off. Given the current lack of support, although broadly speaking there's good support for the Northerly/Cold air returning next week. 

See what happens. I try and take a break from the models and the GFS goes and produces the storm of a century.