Model Output Discussions 06z 04/11/16

[daz_4]

Well, GEFS ensembles cooled down a little bit in FI compared to the afternoon run. As Ali said already, many interesting charts after 20th.

[Singularity]

That western-Eurasian block is looking stronger and closer to hand with each new day of runs in the 5-7 day range. This will lead to one of two results, both of which are reflected by the GFS and ECM 12z respectively;

• The jet stream fires underneath with the Atlantic at least trying to undercut. 
  
  GFS has a go at this, but developments in the Atlantic prevent the jet from shifting south of the UK. From the looks of things this is the likely spanner in the works whether the jet undercuts the block or not - but who knows, stranger things have happened...
   
• The inflated subtropical ridge links with the block, resulting in the jet stream travelling some way north of the climatological norm, meaning not much rain reaches the south despite the westerly regime. More like we've often had in recent summers!
  
  ECM is fond of that idea this evening, and it looks pretty peculiar to be honest - but with the vortex transitioning across Greenland I can see how it could work.

Good luck to anyone (else) trying to second-guess the models on this one 

[Frosty.]

The GEFS 12z mean shows a change to much milder and more settled conditions for a time early next week, especially for the south of the uk as high pressure builds in close to the south with a feed of tropical maritime air flowing around it and across the uk with temps into the low teens celsius but it doesn't last and from midweek it becomes cooler and more unsettled from the W / NW. From then the atlantic cranks up with depressions zipping in with spells of wet and windy weather interspersed with colder, brighter more showery interludes with the most unsettled weather across the n / nw of the uk and the best of any fine weather further s / se.

Edited November 9, 2016 by Frosty.

[Man With Beard]

A big change on the ensembles in the last couple of days. By D10, height anomolies in the west Atlantic now easing off. Tendencies for a Euro trough now equally balanced with an increase in heights in the same area (roughly 50/50 on GEFS ensembles and ECM mean supports the idea tonight). Yes, there are some blocks to the east by this time, but in all honesty not a fantastic chance of affecting us - perhaps 20-30% chance at best.

The drop in height anomalies to our west reduce the chances of something much colder from the N/NW later in the month.

Looking fairly average to me for the next two weeks, then. 

Given the state of the PV, I'm pretty confident the UK's time for cold will come - just probably not yet.

[BLAST FROM THE PAST]

Displaced PV.... get ready for a volatile period....then look NW.  No panic

 

BFTP

[SMU]

23 hours ago, fergieweather said:

 

Evening All ^ not sure why quote box above-

So the steady rise in Westerly Winds out of Canada as highlighted yesterday do perculate across the atlantic in 1 singular wave of mild weather, until then we run the first third of November around -2C CET below the ave which is considerable against a backdrop of warmth.

This mild wave covering 2-3 days is almost the inverse of recent times where the first 10 days of Nov would be mild followed by a short chilly interlude.

So up till now its been all positive news, The record -AO for Oct & the low values at the start of November - plus a taste of Winter for some today has served to raise expectations ahead of Winter official on December 1-

However as most of the seasoned campaigners have highlighed the sustainability of the low zonal index & sedated AO ideally needs to replicated in H2 of November to really cement the proposal of 'blocky' weather in the Winter, its obviously not an exclusive correlation IE >-1AO Nov = -AO winter as there have been November Exceptions ( 1978 et'al ) however what we ideally want to see is this peak of zonal postiveness be short lived & back in to negativity quite quickly.

A note from the NOAA AO ensembles today is that trend has remained the same however the peak of positive values has increased over the last 24/36 hours & the albany strat site that has the zonal index forecast has also shown a considerable uplift in its outlooks -

Both shown below -

So ive had to revise H1 November AO forecast more towards the upper end at around -0.3 to -0.5 to the 15th.

Also an upward revision on the CET towards 6/6.5C

Its our first real reminder that at any point the vortex can become established...

however this positiveness does appear still to be shortlived- The ensembles + ECM op ( & probable clusters ) indicate that post day 8 the height fields over the pole look to increase again & the jet loses some of its synergy-

This starts to allow ridges to creep into 70N, however there are no well defined highs or cut off Highs appearing just yet so the signal is for a low end -AO with some wave 1 activity.

For us we appear 'just' to sit on the cold side of the jet as the core of the vortex is forced out of position to a more easterly locale thus supporting some sort of attenuating NW flow over the UK.

Thereafter comes an important timeline for what I mention above- Whether the wave 1 activity can be enough to force another split in the vortex & whether this translates to a significant High pressure building into the pole forcing the AO metric sub -2.

Im going to take a few days off to avoid early model fatigue-

Keep your eyes both of Greenland & Scandi for opportunities to retrograde post days 8/9/10 transitions-  This isnt anything different to what I posted the other day-

The timeline being around the 18th....to set up the final third of the month.

Fingers crossed this next 5 days sees some good positive developments for Nov month End....

 

S

 

 

Edited November 9, 2016 by Steve Murr

[lorenzo]

Yesterday saw the peak of the Wave 1 work through in the Stratosphere and to that point model flux beckons, the avenues for evolution are sporadic given the after effects in modelling, Steve calls it well above i.e the few days to settle down and his experience is telling for model fatigue. It is easy to to get caught up in the evolution of each nuance and each run - however to pull a phrase from Fergie that is almost folklore - Shannon Entropy - the decider system am sure at these points of flux will peak - level then moderate.

No holds barred Hannah Attards u plot for the 65N level of the strat is new. The uptick in u has not been seen thus far in Winter given the hugely anomalous October.

Within a winter of so many leading anomalies going to throw in the MJO to let the trop get in on the action..

Sorry browser issues had to quit post then recommence as MJO plot would not attach - this plot from yesterdays run shows the MJO inflecting in phases 2-3 in fcsat period. Given the uptick in vortex activity and also the notable impacts of MJO P3 events very interesting from an SSW perspective as winter progresses.

Below is a slide from Limpasauvan et al on Vortex intensification given particular consideration to when the MJO is kicking off..

Add that to Tamaras as ever excellent dissection of Pacific AAM anomalies then we are left with a few days of maybe 'meh' modelling until we see a couple of things  - the play in the system for W2 anoms, the MJO or AAM lead for P3 on MJO and what that may herald.. so many anomalies this year and clearly a couple of different avenues.

For me the conditioning of the vortex, it's intensification period, the latency of October blocking to imprint across winter are three modelling clues we can look at - even outwith the normal modes of where the models have their biases.

 

Edited November 9, 2016 by lorenzo

[Summer Sun]

GEM shows a mild start to next week

From mid-week colder air slowly moves down from the northwest

How long the colder air lasts is going to depend on the high by D10 it's closer by and starting to cut off the north-westerly winds

 

Edited November 9, 2016 by Summer Sun

[fergieweather]

45 minutes ago, Steve Murr said:

Keep your eyes both of Greenland & Scandi for opportunities to retrograde post days 8/9/10 transitions-  This isnt anything different to what I posted the other day-

The timeline being around the 18th....to set up the final third of the month.

Fingers crossed this next 5 days sees some good positive developments for Nov month End....

 

S

 

 

If anything, the proportion of members showing deep cyclonic NW-W-SW'ly solutions in vicinity of the UK have markedly increased in 12z EC-ENS as we start the last calendar week of the month (some of these clusters look especially sporting). Fascinating and highly uncertain times ahead to keep us engaged.

[Ali1977]

3 minutes ago, fergieweather said:

If anything, the proportion of members showing deep cyclonic NW-W-SW'ly solutions in vicinity of the UK have markedly increased in 12z EC-ENS as we start the last calendar week of the month (some of these clusters look especially sporting). Fascinating and highly uncertain times ahead to keep us engaged.

Sounds like we are losing some of those signals for a blocked late Nov - luckily it's late Nov not mid Winter!! 

[SMU]

16 minutes ago, fergieweather said:

If anything, the proportion of members showing deep cyclonic NW-W-SW'ly solutions in vicinity of the UK have markedly increased in 12z EC-ENS as we start the last calendar week of the month (some of these clusters look especially sporting). Fascinating and highly uncertain times ahead to keep us engaged.

Well that would add a tinge of disappointment to proceedings - however with the spike in the zonal means that hasnt been capped yet ( on the albany strat site ) you could say thats not totally unexpected-

Still Westerly / North Westerly solutions arent the end of the world, especially if the storm track is south of Climo, EG if we took the ECM OP at day 10 as an example you can create some potential wintry solutions even at day 11 as atlantic systems phase with the polar air -

Much to resolve & for once it isnt 'all' bad...

Edited November 9, 2016 by Steve Murr

[blizzard81]

5 minutes ago, fergieweather said:

If anything, the proportion of members showing deep cyclonic NW-W-SW'ly solutions in vicinity of the UK have markedly increased in 12z EC-ENS as we start the last calendar week of the month (some of these clusters look especially sporting). Fascinating and highly uncertain times ahead to keep us engaged.

Not what us coldies wanted to hear. Unfortunately, I am not surprised by this. The meto updates over the last couple of days have been slightly less bullish about the prospects for blocking as we head towards December.

[Nouska]

I do not know if any of you follow Anthony Masiello on twitter but he has been looking at solar geomagnetic activity and linking with some climate indices. A suggestion there that recent uptick may be altering expectations in the NAO field.

I did say earlier that I was wary about this but the research is new and not established so may be just co-incidental.

Have a read through recent offerings and you'll also see references to what @Tamara was mentioning in her post.

https://twitter.com/antmasiello

An edit to say that this is no pointer for the future but may be a reason for some of the current ramping in the vortex.

All other scientific theory indications are good for this winter and we may just need to wait a bit for early signals to re-emerge.

 

 

 

Edited November 9, 2016 by Nouska

[booferking]

Netweather meltdown is just about to commence with that news. Hope this changes let see what 18z throw out.

[Sweatyman]

8 minutes ago, blizzard81 said:

Not what us coldies wanted to hear. Unfortunately, I am not surprised by this. The meto updates over the last couple of days have been slightly less bullish about the prospects for blocking as we head towards December.

Like they're letting us down gently

[Frosty.]

13 minutes ago, Ali1977 said:

Sounds like we are losing some of those signals for a blocked late Nov - luckily it's late Nov not mid Winter!! 

Luckily it's still early november..although it currently feels like winter in the north

The models indicate cooler / colder incursions from the w / nw at times during the next few weeks as well as mild..beyond that its very uncertain.

Edited November 9, 2016 by Frosty.

[blizzard81]

Just now, Sweatyman said:

Like they're letting us down gently

Ha ha, it does feel that way doesn't it. A little deflating on here this evening. 

[SMU]

18z through 138

what would be nice is seeing a bit of energy go under that block around 156/162

[blizzard81]

2 minutes ago, Steve Murr said:

18z through 138

what would be nice is seeing a bit of energy go under that block around 156/162

It would indeed but what we see is that all too familiar refusal for heights to lower over central Europe. The curse of recent winters.

[Frosty.]

1 minute ago, blizzard81 said:

The curse of recent winters.

Except winter is still 3 weeks away and the current models certainly don't show constant mild, it looks quite variable with some colder shots for sure.

[fergieweather]

29 minutes ago, Ali1977 said:

Sounds like we are losing some of those signals for a blocked late Nov - luckily it's late Nov not mid Winter!! 

Ah, but other blocked solutions remain too. All to play for. :-)

[blizzard81]

1 minute ago, fergieweather said:

Ah, but other blocked solutions remain too. All to play for. :-)

Sounds like we have gone from uncertain to very uncertain over the last 24 hours.

[blizzard81]

4 minutes ago, Frosty. said:

Except winter is still 3 weeks away and the current models certainly don't show constant mild, it looks quite variable with some colder shots for sure.

Indeed you are correct, we are still weeks away from winter. Not that we would have thought that this morning though

[fergieweather]

2 minutes ago, blizzard81 said:

Sounds like we have gone from uncertain to very uncertain over the last 24 hours.

It has been thus for many days. Tricky.

[feb1991blizzard]

Really beginning to think now that we are headed into a pseudo / quasi zonal flow into early December now based on the increasing blocked signal in models and Ian's updates.