Model Output Discussion - 05/01/2016 18z onwards

[Nouska]

13 minutes ago, BLAST FROM THE PAST said:

Can anyone find the post/research which said about the -ve AO in July and the corresponding -ve AO in following Jan?

 

BFTP

The original post was from the WSI blog - Tamara has been mentioning it in recent postings.

Somebody else did a big write up on here but cannot remember which thread.

Edit ... well done to Yarmy and David Morse 

Edited January 6, 2016 by Nouska

[Cloud 10]

6 minutes ago, BLAST FROM THE PAST said:

Can anyone find the post/research which said about the -ve AO in July and the corresponding -ve AO in following Jan?

 

BFTP

Here are the AO monthly figures since 1950.

 

ARCTIC OSCILLATION TABLE

 

[Singularity]

Well that's a good example of that mid-Atlantic low at work. Easy to imagine a shortwave feature breaking away and merging with the Scandi trough bringing heavy snow to some parts, despite the run not going for that idea. It would also serve to re-intensify the Sceuro trough. I know - I'm dreaming!

The run then steadily drifts into west-based -ve NAO territory. It's one way in which there could be interruptions to the cold spell, though I think this particular run goes a bit nuts with the Atlantic trough at the end - I'd expect more of a ridge to be thrown up ahead of the LP. 

But here's the thing - I'm talking about an interruption after about a week of cold, snowy conditions! 

[David Morse]

11 minutes ago, BLAST FROM THE PAST said:

Can anyone find the post/research which said about the -ve AO in July and the corresponding -ve AO in following Jan?

 

BFTP

http://www.chorleyweather.com/strong-arctic-summer-heights-linked-to-cold-uk-winter/

[Mair Snaw]

2 minutes ago, Singularity said:

Well that's a good example of that mid-Atlantic low at work. Easy to imagine a shortwave feature breaking away and merging with the Scandi trough bringing heavy snow to some parts, despite the run not going for that idea. It would also serve to re-intensify the Sceuro trough. I know - I'm dreaming!

The run then steadily drifts into west-based -ve NAO territory. It's one way in which there could be interruptions to the cold spell, though I think this particular run goes a bit nuts with the Atlantic trough at the end - I'd expect more of a ridge to be thrown up ahead of the LP. 

But here's the thing - I'm talking about an interruption after about a week of cold, snowy conditions! 

Didnt that happen back in 2010?? i seem to remember it becoming less cold for a week mid December before all hell broke loose again...

[Shuga ice]

Next week looks like turning mainly dry with plenty of sunshine around with night frost in places.

[That ECM]

What a rubbish run! Look at the warm air creeping back in to the SW. Cheeky smile with wink!!

Edited January 6, 2016 by That ECM

[Polar Maritime]

6 minutes ago, That ECM said:

What a rubbish run! Look at the warm air creeping sack in to the SW. Cheeky smile with wink!!

Yes it looks like taking it's last desperate breath! Expect many a choppy run into FI over the coming days with such heights transferring/altering over the poles. 

Edited January 6, 2016 by Polar Maritime

[BLAST FROM THE PAST]

Cheers team, one hell of a correlation if it verifies

 

BFTP

[Singularity]

14 minutes ago, bigsnow said:

Didnt that happen back in 2010?? i seem to remember it becoming less cold for a week mid December before all hell broke loose again...

Actually the block was flattened by a trough traversing Greenland, but then the trough dived sharply south through Scandinavia and viola... much like the GFS 00z run, as it happens, but with events further east.

Then came the big event as another low moved through Greenland while the upstream pattern became very supportive of blocking to our W and NW. The aforementioned low exploded and then dropped south with epic results:

Even after that 06z run just now, these charts still look bonkers, which is testament to just how extreme the conditions were that month.

[Cloud 10]

06z GEFS control run at day 10 going for a North Atlantic /Greenland super-ridge...

 

 

The GEFS ensemble mean for day 10 is a sight for sore eyes.

 

[SMU]

Morning - no change from me today, the image I used last night from the 6 day mean still stands as where I think we will land ( courtesy of NAVGEM )

a nice wedge of high pressure towards greenland but the all important 552 line not making it -

however if people remember the Greenland High post last night - Nearly All examples on offer of a cut off greenland high have come from High pressure forcing north from the azores-

The comments I certainly tried to put across was that round 1 wasnt enough but round 2 - a day or so later may have energy to get there-

Well the late models last night & indeed the early models today ( excluding the EC DET - which appears to be to progressive ) a trend positive towards this next key phase in getting our 552 line into greeny

indeed the 06z mean portrays exactly what we want to see - the azores heights forcing North & bludgening the jet along with it-

 

as above....

The cherry on the Mr kipling cake is the arctic high which if we get phasing will try to force the pattern more East to west ( like the JMA last night )

so thus far is a great day -  9/10

S

[Methuselah]

9 minutes ago, BLAST FROM THE PAST said:

Cheers team, one hell of a correlation if it verifies

 

BFTP

And if it's dependent upon the state of El Nino, in any way, it'd be more than a correlation, Fred?

[Polar Maritime]

Lets continue on with Model Discussion please.

[raul_sbd]

Enjoy so much reading this forum.. Not only now when cold weather is likely to arrive!! That's the best present the 3 kings has brought today.. : perfect synoptics for next week!! Btw happy new year!

[Blake]

Thames streamer from the GEM anyone? Could be nice for some of the home counties, myself included!

[Harsh Climate]

So we finally have one of those great runs that's been showing up on the GFS esembles, on the GFS operational . As nice as it was to see, unfortunatly the UKMO/ECM isn't quite on the same page this morning, although still packed with potential.

For me we have crucial UKMO and ECM runs this afternoon, let's build some momentum and have THE BIG THREE singing from the same hymn sheet later today! Not too bothered about the next GFS operational as I can't see the esembles being too different as the agreement at day 8/9 is really quite unusually strong!   thus you would expect a similiarily good set of esembles on the gfs 12z.

 

If we look at the gfs, what makes it so great is the greenland high, without this in place in this kind of set-up there is no chance of a sustained cold spell/snowy cold spell. Really hope this is the developing story on future gfs/ecm/ukmo runs!

[fulham snow]

18 minutes ago, GUWeather said:

Thames streamer from the GEM anyone? Could be nice for some of the home counties, myself included!

The best chance of us in South London is a Thames streamer

[Tamara]

2 hours ago, Singularity said:

Your highlighted statement calls to mind a persistent mid-Atlantic trough propping up the blocking to our NW as it did during July's (extremely) -ve AO period, as a consequence of the jet being pushed so much further south. I like what I'm seeing there 

The idea that we may see lows coming up from under the block and bringing some nervous times with rain/snow boundaries was something I mused over about a week ago, again with respect to the possible effect of the 'Cold Pool'. Very glad to see that you are thinking along similar lines GP 

...and just look at the AAM go! I noticed GEFS still managed to slightly underestimate it even at just 1 day's range yesterday, and the longer-term guidance is reducing the drop-off slowly but surely. What a time to be following the model output!

 

Can't think who has been boring people for so long posting pages of 2015 atmospheric circulation history - and suggesting  possible July/Jan -AO/NAO connect

Seeing the model output reeling in the evolution to this starkly marked volte face in the winter pattern is something for sure to enjoy for the moment, and anticipating the micro details increasingly unfurling in the coming few days regarding the cold incursion that arrives next week. 

Those who revel in shorter term analysis have a due reward in this respect in terms of dealing with a change that looks set to actually happen, and without frustration of chasing elusive snow rainbows that remain on the synoptic horizon

In weeks gone by I mentioned, in my typically long preambles, regarding the evolution of the patterns into the second half of the winter, just how important such switches can be in the Annular Mode during January. Many, not all obviously, of our best winters have evolved this way.   That is not to predict an ice age second half of winter - but I do think that the prognosis ahead looks, imo, cautiously very very exciting at this stage for the second half of winter - and a world away from the first half whatever happens.

Most of the reasons (to be cheerful) were given in brief, by my standards, sentences yesterday. But to expand further.

I really don't 'do' forecasts as such - just usually these little summary analyses and suggestions of where things may be headed. But taking into account the frightening amount of coiled amplification loaded in the atmospheric circulation,  and, as GP re-affirms above, the rampant +ve AAM state that underpins it - with the bed now turning upside down in the flip in the annular mode there really is a chance we could see, in terms of this unprecedented Nino pattern type , a truly emphatically Jekyll and Hyde type winter have played out by the time we look back at all this in the Spring. Its subjective of course to individual preference which side of the season is deemed Jekyll and which is Hyde.

We shouldn't worry about any west based NAO too much - just welcome in the first instance that ensemble data is firming up on a cold spell and then a modular switch in the NAO. However, fwiw, this is my take on it anyway at this time.

The Global Wind Oscillation is passing through a stratospheric amplitude Phase 5/6  and on its way to Phase 7...which cues up the anticipated resurgent STJ.

With heights low over Scandinavia, pressure high over the Arctic and an amplified ridge in place over the NE Atlantic, the scene is set for GP'S torpedo to make a crucial difference to the angle of attack of returning low pressure in the Atlantic than we have seen so far this winter.

I think its true to say realistically that a trough setting up far enough west underneath the height anomaly directly above it, inherentlysuggests 'lifting out' of cold air from the south west. However, it gets more interesting beyond that because a) the long wave pattern heading towards, and especially into, February and b) the almost certainty of the GWO doing an orbit back to Phase 5 and 6 again suggests both the atlantic trough, and the height anomaly to the NW, shifting towards Iceland and maybe Scandinavia in the very extended period.

Put together, this suggests a cold arctic maritime/polar maritime regime, and then attempted milder conditions coming in from the south west and potential battle ground scenario. Beyond this, based on the above, I do think there is room for cold to return from the north and north east and set up perhaps the real cold spell of the winter

Based on the -AO/NAO profile Nino type atmospheric circulation pattern  as described above, we can look beyond 1983 which was mentioned yesterday, and think of other late Januarys/into Februaries that have typified classic high orbit GWO phases through 5/6/7 and have shifted HLB between Greenland, Iceland and Scandinavia. Another year that is coming to mind is 1978 - the GWO stayed glued in Phase 6 for long periods, and as well as sunshine and snow showers.....

....., culminated in metallic cold atlantic undercuts and some spectacular blizzards for the SW.

In other words, following a west based -NAO phase (after the northerly) and *possible* milder interlude in January, we could be looking at  'real deal' undercuts through February

The 'reasons to be cheerful' post yesterday underlined the rationale for all this. Renewed westerly wind anomalies in the Pacific will bolster the high AAM state yet again and we need to closely watch tropical convection for further Pacific engagement as the MJO re-cycles. Crucially, as GP posted recently, the MJO will be an active prospect under a -NAO regime, so there is good credence for faster orbit back to the Pacific, and futher toprdeo top up alerts to maintain -ve NAO parity.

Something of a ramp-ette, but hopefully you get some idea of the rationale behind it.

Finally, in case of wondering about where an SSW being required to secure all of this?  Well, we are already seeing the damage that can be done through the 'right' sort of trop >strat bottom up attack - and I do think in this sense at least, that while this Nino has not resembled in any way whatsoever so far that of 09/10, its mature stage is evolving in such a way that we can draw part- parallels with 09/10 in terms of how we were able to secure very cold and spectacular blocking conditions based on warm trop/lower strat layers - despite the anomalously cold conditions that prevailed at 30mb and above levels. I'm sure that chiono and Lorenzo could give their expert guidance and opinion on this though

And as we know in 09/10, an SSW did arrive - largely after the main event had already occurred. But it was enough to keep February cold when earlier on a milder end to the winter had been envisaged to follow the cold.

In that sense the METO look increasingly correct with their suggestion that an SSW may occur in February, but as we seeing already, the pattern is changing markedly to an -AO regime and increasing cold potential without one

Anyway, lots to look forward to well before any of that - but thought I would go beyond the usual boundaries. I'd call it a little 'reasoned vision' (with a bit of an admitted ramp for added flavour) though rather than a forecast

Edit: @BFTP: I hadn't seen your post or others about the July/Jan connect till after I finished typing and sending this post - it was simply a response to what Singularity had said. The article on that blog raised something which I think is very pertinent in terms of seasonal sign posts every year, so it was a very valuable source to define my own interpretations in terms of how intra seasonal and sub seasonal phenomenon in 2015 might influence weather patterns cyclically further on into the start of 2016.

 

Edited January 6, 2016 by Tamara

[nick sussex]

Time to get the Christmas decorations back out! I suddenly feel all festive again.

A really great GFS 06hrs run which would be the perfect tonic to get rid of those January blues. Its nice when the operational runs edge slowly towards the colder ensembles as you feel they're picking up momentum.

The ECM was a big relief this morning, although its not as good as both GFS's today the trend is going in the right direction.

 

[Man With Beard]

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=6&ech=240

On my goodness - what on earth has happened here? Has Steve Murr hacked into the GFS mega-computer and altered the outputs of the GEFS??

Out of 21 runs (20 ens + op) at T240, I see just 4 runs which could even be called average, another 4 runs which are pretty cold, but 13 runs which are outstanding for sustained wintery weather across the UK.

In fact the mean from T144 out to about T252 is very cold. 

Now this is where the mean is actually very useful - it's taken some bashing in recent weeks - but when the mean is a BIG diversion from the norm, you can have increased confidence that the clustering is lop-sided, and hence more confidence in the evolution.

And I've usually found when the GEFS mean and the ECM ens mean are in agreement, then you're probably on to something. Is the ECM similar? Not far off at all.

If tonight's 12Z runs keep this up, I think we can start talking about a 7 day plus cold spell.

 

 

[summer blizzard]

12 minutes ago, fulham snow said:

The best chance of us in South London is a Thames streamer

Pressure is far too high. You'll struggle to get any precipitation at all above 1030mb and really you want sub 1020mb.

[Rocheydub]

Absolutely correct, but all subject to change at this range. I'm concerned that some of the runs show in my locale that we'll be too high in pressure at times for precip.

If the runs are still like this after the 12z's I'll be telling the family.

[summer blizzard]

GFS 6z has some truly stunning potential for surface cold. Coupled with the forecast uppers we'd be looking at minima down the spine breaching -10C. 

 

[Frosty.]

Models have upgraded both the intensity and duration of the cold spell next week, yesterday it looked like being a short cold snap lasting a few days but it now looks more substantial. The wheel turns, it's been a mild mush fest so far but next week winter will arrive with a BANG

Edited January 6, 2016 by Paul