Model output discussion - Post SSW - Will it turn cold?

[Snowy Hibbo]

2 minutes ago, Glacier Point said:

Tropical forcing will get impacted by the strat warming - most likely will get suppressed. Additionally, we have the convective coupling moving towards the far western Indian Ocean, negative frictional torque territory. Put the two together, and the engine house for aam will go into slow speed. We've also been in a solid Nina state for some period, which will have imprinted on the atmosphere. So some reduction in overall aam and negative tendency look the best place to look. I wouldn't go for a big -AAM target, maybe -1SD max given likely westerly additions through 30N-40N.

Interestingly, the likely strat impacts in the high latitudes are best expressed through tropical analogues for African and West Indian Ocean convective centres. Some sense of choreography there ?

Aka MJO > Strat > MJO feedback loop. There's also the GWO in that equation, but it is harder to point out how it fits in.

I wouldn't say really solid Niña atmosphere, the SOI has been into Niño stages at times, and now the AAM has shown Niña the door. Once we get some Oceanic feedback, we can proceed further into knowing how that impacts the later stages of the year. Stepping stones....

I am certainly not going for a big -AAM at that stage. I will be awaiting this tropical -FT  

[tight isobar]

The already minamal-milder slots evapotating!!..

Very stark signal for cold-deep cold continues...

6z london#ens...

[The Eagle]

NAVGEM on course by day 5

 

[ALL ABOARD]

Navgem is a humdinger 

 

 

[Southender]

1 hour ago, jvenge said:

Not sure why the EPS Mean only going out to the 23rd on yours, but the extended shows a drop of the mean between -2 and -3 in the 7 days after.

Also, the one I use for GEFS puts that differently as well. Attached, since i can post GFS output.

 

Are there any of these charts out there with an increased scale?

Annoying it doesn't show below -5, when it looks like quite a few of the ENS hit -6 or even lower!

A good sign though when things start going off the scale....

Edited February 14, 2018 by Southender

[Weathizard]

4 minutes ago, The Eagle said:

NAVGEM on course by day 5

 

About as likely to happen as me becoming king

 

[Southender]

6 minutes ago, The Eagle said:

NAVGEM on course by day 5

 

Rush hour could be tricky in the E/SE on Monday 

[bluearmy]

2 minutes ago, Weathizard said:

About as likely to happen as me becoming king

 

There is an eps cluster that’s isn’t too far from that NAVGEM evolution - been there for the past three suites on the spreads 

[ICE COLD]

Well it's definitely still scatter city ? 

There's some very cold runs in there still , achally there more than a few . We can't miss the train this time can we ? Certainly been the best set of ensembles for last 4 or 5 years in recent days . 

[Catacol]

2 hours ago, Glacier Point said:

However, phase 8 composites sifted for the La Nina years aren't what you would expect:

Transference of this to current situation makes this tricky, but the idea of not all of the atmosphere being totally cooperative to stratospheric lead should not be discounted.

That's the bad news out of the way.

The MJO is forecast to be centred over Africa and enter the Arabian Sea during week 2. 

Hi Stewart - complex picture. Knife edge stuff! Just for fun - an alternative possibility. MJO modelling has been less good from ECM on the current wave - GFS better. GFS ensemble forecast here

This signifies a much longer transition through phase 7 with phase 8 a long way off. Composite for all Nina (Weak and Moderate) Februarys since 1955 in phase 7 below

That ties in much more closely with GFS forecasts as opposed to this morning's ECM that follows the route you put out. Conclusion? Agree absolutely - dont ignore the pacific as it will tweak the SSW pattern for sure... but given recent performance on MJO modelling for once I'd back GFS. This also from CPC - 

"The GEFS forecasts the MJO to weaken and stall as an equatorial Rossby wave propagates westward from the Date Line, interfering with the MJO signal."

For a bit more fun - taking that Feb composite above... following Marchs for all years look like this

That is an EXTREMELY tasty composite. Very strong -NAO profile and screaming easterlies. Yes - the sun will be warmer but that means more convective action... and with an NAO like this we would see such cold air at 850 that the sun would be irrelevant.

... and all this without even discussing the SSW. 

MMMmmmmmm..... Tastyyyy.......

Edited February 14, 2018 by Catacol

[Catacol]

@Glacier Point And just for a bit more fun.... I took out the medium Nina years (our Nina is a curious mix... but definitely more weak than medium) and ran the March composite again for months following a weak Nina phase 7 February.

Gulp. With our projected SSW pattern imprinted on top? Bye bye Spring.

Edited February 14, 2018 by Catacol

[ALL ABOARD]

Ill take it.

"Wintry showers may develop,with the potential for some significant snowfalls focused on southern, central or eastern areas. The location and intensity of any snowfall will be uncertain until much nearer the time."

So met going for somthing akin to this? 

 

 

 

 

[Glacier Point]

Thanks Alastair - I like it when which ever way you dice the assessments, you get the same end result.

As per Ventrice's plot, week 2 looks good for convective wave to be centred with a bit more umph East Africa / West Indian Ocean ?

[claret047]

1 hour ago, karlos1983 said:

here's the panel for D7

Good afternoon Karlos1983.

As someone still very much on a learning curve, I struggle to understand how given the same information is entered into the computer why you should receive 20 different outcomes. Surely it should be the same. 

Am I being too simplistic?

Kind Regards

Dave

[Frosty.]

The GEFS 6z mean makes great viewing for coldies, indeed it gets better and better right through to the end..very cold spell from the east is on the way according to this! ❄❄❄❄❄❄❄❄

[karlos1983]

3 minutes ago, claret047 said:

Good afternoon Karlos1983.

As someone still very much on a learning curve, I struggle to understand how given the same information is entered into the computer why you should receive 20 different outcomes. Surely it should be the same. 

Am I being too simplistic?

Kind Regards

Dave

Well in simplistic form, you can put 20 F1 cars (as it's topical) on the same starting line, but the further they go into the race the more they will differ in speed, accuracy and reliability. Once you get to fl, you might as well be driving with a blindfold on, yes you may remember the track, but it's not likely you'll take many corners correctly .....

Edited February 14, 2018 by karlos1983

[markw2680]

45 minutes ago, ALL ABOARD said:

Navgem is a humdinger 

 

 

That’s more like it, plus it’s closer to the original dates that was mentioned, although I really don’t care when the beast comes as long as it comes before spring sets in

[bobbydog]

5 minutes ago, claret047 said:

Good afternoon Karlos1983.

As someone still very much on a learning curve, I struggle to understand how given the same information is entered into the computer why you should receive 20 different outcomes. Surely it should be the same. 

Am I being too simplistic?

Kind Regards

Dave

its not exactly the same information. each perturbation has slightly different starting info, to allow for and even cause deviations along the way, to see how the outcomes may differ. the only one that has the same starting data as the op run is the control run. all the perturbations, including the control, are run at lower resolution. 

[Catacol]

13 minutes ago, Glacier Point said:

Thanks Alastair - I like it when which ever way you dice the assessments, you get the same end result.

As per Ventrice's plot, week 2 looks good for convective wave to be centred with a bit more umph East Africa / West Indian Ocean ?

Hi Stewart - yes - agreed. By week 2 we really should be seeing MJO transition towards 8/1. Fingers crossed we can get the properly positioned high lat block in place during week 1 or 1.5... :-)

Impact of SSW still uncertain. I see Masiello has tweeted latest plots suggesting the 2 vortex shards will not manage to reunite especially quickly and that their first attempt will be thwarted by another wave break. All feels good. If only today was Jan 1 and not Feb 14!!

 

[bluearmy]

Interestingly the eps only have two clusters in the day 4/10 period

50/5 split 

the op and control cluster is fairly clear (from the op run) but the other one drops an upper low through Denmark by the end of the weekend 

If the op jumps clusters later then the mood on here lifts - looks to be at least 60% on a very wintry extended period days 10/15 

[Catacol]

Just a quick note - a fairly significant error in my composites this morning - not filtered for phase 7 after all... just for Nina Februarys. Too late to edit - dull of me! Short of time now... but I'll post again later, hopefully with a bit more accuracy this time. :-)

Still - weak to moderate Nina Feb signal is still good as shown.

[Youcan'tbecirrus]

58 minutes ago, Catacol said:

@Glacier Point And just for a bit more fun.... I took out the medium Nina years (our Nina is a curious mix... but definitely more weak than medium) and ran the March composite again for months following a weak Nina phase 7 February.

Gulp. With our projected SSW pattern imprinted on top? Bye bye Spring.

In layman's terms, can you relay what this is indicating please.    

[Catacol]

1 minute ago, Youcan'tbecirrus said:

In layman's terms, can you relay what this is indicating please.    

Ignore my comment on MJO phase 7 because I hadnt filtered it properly... but the gist of the Nina February composite lagged by 1 month into March suggests a continental air flow which would be cold. However the composite is a lot less useful than it should be because of my duff filtering.... :-(

[tight isobar]

8 minutes ago, Youcan'tbecirrus said:

In layman's terms, can you relay what this is indicating please.    

A locked in blocking scenario..

And deep cold into eurasia-nw europe!!!

Edit; an'out of date below chart...but echos very much the likely prognosis.

Edited February 14, 2018 by tight isobar

[Badgers01]

35 minutes ago, Catacol said:

Hi Stewart - yes - agreed. By week 2 we really should be seeing MJO transition towards 8/1. Fingers crossed we can get the properly positioned high lat block in place during week 1 or 1.5... :-)

Impact of SSW still uncertain. I see Masiello has tweeted latest plots suggesting the 2 vortex shards will not manage to reunite especially quickly and that their first attempt will be thwarted by another wave break. All feels good. If only today was Jan 1 and not Feb 14!!

 

Interesting to me at least that even contributors whom we probs all hold in high esteem are flagging up the fact the clock is ticking if we are going to get anything interesting from this !!