Model Output Discussion - The Run In To Christmas

[Captain Shortwave]

Not to forget it was on the mild side of the ENS

Whilst it may be the case, it is clear from the ensembles over the past few days that the trend has been to remove the clean northerly and replace it with a slight pick up in temperatures from Boxing day before throwing another cold plunge. This looks like the more likely solution and would mean that the ECM has at least been on the correct path (even if over done on the mild stance).

So chilly Christmas and Boxing day, milder 27th/28th before turning colder perhaps towards new year. The second transition could involve some quite wild weather if the thermal gradient is steep enough.

 

The 06z is complete trash... standard 

Nice spot, the GFS (P) has returned to save the day

Edited December 20, 2014 by Captain shortwave

[Polar Maritime]

The 6z GFSP shows a much deeper low over the UK compared to the operational around the 27th. Drawing much colder air over the UK from the N/N/E.

 

Edited December 20, 2014 by Polar Maritime

[snowangel32]

The 6z GFSP shows a much deeper low over the UK compared to the operational around the 27th. Drawing much colder air over the UK from the N/N/E.

I would bank that 6z chart it looks good to me or am I reading it wrong

Edited December 20, 2014 by snowangel32

[Polar Maritime]

I would bank that 6z chart it looks good to me or am I reading it wrong

 

If you like snow and bitter winds yes, But don't bank on it ! A few miles E/W of the Low will make all the difference for the UK, As ever more run's needed. 

 

Edited December 20, 2014 by Polar Maritime

[Shunter]

Not sure if this has already been posted......

"Potential" for rapid change still in place despite poor operational guidance in the past 24 hours..................

Latest summary from AER issued yesterday.....

December 19, 2014

Summary

• The AO will remain positive for the next 5-7 days but then turn sharply negative near or just after Christmas. This negative state is expected to remain in place through the end of December and into early January.

• The North Atlantic Oscillation (NAO) will weaken substantially and also turn negative by the start of week 2 as ridging over Greenland builds during the period.

• Collectively, these changes will mean below to much below normal temperatures will invade the Northern Hemisphere continents after Christmas and lasting into early January. Colder than average conditions will also overtake much of Eurasia, with eastern Asia remaining cold.

• The state of the AO in the long-term (i.e., into mid-January) is uncertain given the lack of forcing from the stratosphere and current model run-to-run volatility

[TEITS]

As stated too many times previously, too much faith ( and emotion ) is placed on each Operational model run when experience tells to follow ensemble guidance. Ops are ok for identifying "possible" new trends and for fantasy eye candy purposes only.

Keep the faith....it is after all the most magical time of the year !

Normally I would agree with you but when the ECM operational is constantly an outlier and is followed by the control run then I tend to take less notice of the ensembles.

[mountain shadow]

So, from a couple days ago where we were looking for a cold spell, now becomes the hope of a brief toppler.

The models have over played any Greenland blocking with signs the PV wants to go home to SE Greenland in the longer term.

That would likely make a cold spell unlikely till after mid January.

[mushymanrob]

the gfs 06z is a shocker for coldies.... after yesterdays was such a promising one. it highlights the volatility within the atmosphere atm.

[Banbury]

Not sure if this has already been posted......

"Potential" for rapid change still in place despite poor operational guidance in the past 24 hours..................

Latest summary from AER issued yesterday.....

December 19, 2014

Summary

• The AO will remain positive for the next 5-7 days but then turn sharply negative near or just after Christmas. This negative state is expected to remain in place through the end of December and into early January.

• The North Atlantic Oscillation (NAO) will weaken substantially and also turn negative by the start of week 2 as ridging over Greenland builds during the period.

• Collectively, these changes will mean below to much below normal temperatures will invade the Northern Hemisphere continents after Christmas and lasting into early January. Colder than average conditions will also overtake much of Eurasia, with eastern Asia remaining cold.

• The state of the AO in the long-term (i.e., into mid-January) is uncertain given the lack of forcing from the stratosphere and current model run-to-run volatility

From who?

[TEITS]

Not sure if this has already been posted......

"Potential" for rapid change still in place despite poor operational guidance in the past 24 hours..................

Latest summary from AER issued yesterday.....

December 19, 2014

Summary

• The AO will remain positive for the next 5-7 days but then turn sharply negative near or just after Christmas. This negative state is expected to remain in place through the end of December and into early January.

• The North Atlantic Oscillation (NAO) will weaken substantially and also turn negative by the start of week 2 as ridging over Greenland builds during the period.

• Collectively, these changes will mean below to much below normal temperatures will invade the Northern Hemisphere continents after Christmas and lasting into early January. Colder than average conditions will also overtake much of Eurasia, with eastern Asia remaining cold.

• The state of the AO in the long-term (i.e., into mid-January) is uncertain given the lack of forcing from the stratosphere and current model run-to-run volatility

The GFS 06Z isn't reading that script!

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014122006/gfsnh-0-348.png?6

 

960mb low pressure over Iceland and a 1030mb pressure over the Azores!

 

As someone else mentioned I think I shall stick with the Met O for longer term guidance.

[Polar Maritime]

So, from a couple days ago where we were looking for a cold spell, now becomes the hope of a brief toppler.

The models have over played any Greenland blocking with signs the PV wants to go home to SE Greenland in the longer term.

That would likely make a cold spell unlikely till after mid January.

 

I would't look further than the 27th MS, As mentioned by Mush the Models/signals are very volatile at the moment.

Edited December 20, 2014 by Polar Maritime

[Weathizard]

Normally I would agree with you but when the ECM operational is constantly an outlier and is followed by the control run then I tend to take less notice of the ensembles.

This, the funny thing with this is I often read people on here saying in messy/difficult scenarios to look more to the operational runs as they run at a higher resolution this are more accurate, then when they don't show what we want they are outliers and won't happen haha!

For me, the ECM although out of kilter with the majority of it's ensembles, must be taken extremely seriously especially given it's been the same for 3-4 runs now despite being an 'outlier' amongst the ensembles. I personally do not see any prolonged cold setting up, just perhaps a slightly more potent northerly shot than normal, standard winter fare really with cold rain for the south and some snow for the north.

With the Azores so prominent I think if we miss the boat this time we could be up the proverbial creek!

[KyleHenry]

For those that aren't into SADOMASOCHISM I recommend reading the latest from Judah Cohen as posted by I'm dreaming on Strat thread

https://www.aer.com/science-research/climate-weather/arctic-oscillation

[Snowman.]

 

The para is setting up an easterly.

[festivalking]

Flip flop flip flop only one run. Have another mince pie and wait for a different scenario to emerge from the 12z

[Banbury]

I would't look further than the 27th MS, As mentioned by Mush the Models are very volatile at the moment.

or Atmosphere

[Polar Maritime]

or Atmosphere

 

Yip, Models/Atmosphere.. Very skitty signals prevail.   :smiliz19:  

Edited December 20, 2014 by Polar Maritime

[karlos1983]

the gfs 06z is a shocker for coldies.... after yesterdays was such a promising one. it highlights the volatility within the atmosphere atm.

Yes but the grown up of the GFS, (P) has seen sense! :-/ there I was thinking it was having the weekend off.

[Banbury]

Yip, Models/Atmosphere :smiliz19:  

I knew what you meant

[Sweatyman]

Yes but the grown up of the GFS, (P) has seen sense! :-/ there I was thinking it was having the weekend off.

yes I thought it wasn't running this weekend?

[Mark Bayley]

Not sure if this has already been posted......

"Potential" for rapid change still in place despite poor operational guidance in the past 24 hours..................

Latest summary from AER issued yesterday.....

December 19, 2014

Summary

• The AO will remain positive for the next 5-7 days but then turn sharply negative near or just after Christmas. This negative state is expected to remain in place through the end of December and into early January.

• The North Atlantic Oscillation (NAO) will weaken substantially and also turn negative by the start of week 2 as ridging over Greenland builds during the period.

• Collectively, these changes will mean below to much below normal temperatures will invade the Northern Hemisphere continents after Christmas and lasting into early January. Colder than average conditions will also overtake much of Eurasia, with eastern Asia remaining cold.

• The state of the AO in the long-term (i.e., into mid-January) is uncertain given the lack of forcing from the stratosphere and current model run-to-run volatility

 

Interesting to note they predict a return towards +AO/NAO through to mid-January (with any SSW occurring after this), although with some uncertainty. I suspect the GFS has overdone the strength of the PV, given it has an obsession with this in FI, however longer term, sustained cold into and through January may not be on the cards. The ECM is more interesting with a strong ridge over Alaska attacking the PV, perhaps one to watch. 

Edited December 20, 2014 by Mark Bayley

[Downpour]

GFSp = cold ramper

[Downpour]

Last we heard the GFSp was having the weekend off, due to a dicky tummy no doubt born of too many mince pies and sherries. Now it is "back" - should we be worried?

Edited December 20, 2014 by Downpour

[Blizzardof82]

The GFSP is back for the 6z, sooner than planned.

[karlos1983]

I'm going to approach that GFS(P) run with extreme caution. It's not even supposed to be here.