Model Output Discussions 12z 01/09/2016

[terrier]

Some nice looking charts this evening especially from the gfs and gem models. But i do feel it is all too early again. I would expect the polar vortex to get its act together towards the end of October early November. And of coarse see we're we go from there. But if I remember correctly we saw a lot of blocking this time last year from the output and we all know how that ended. 

[legritter]

22 hours ago, Frosty. said:

Well I make no apology that I'm seeking our first cold shot of the season and there are a few interesting GEFS 12z perturbations for the end of october with powerful scandi highs and others with potential arctic incursions!

I like P5 best

 

[legritter]

Sorry about above post ,clicked on it yesterday to give reply then changed my mind and cant get rid of it .

So thought i would send it blank to try to correct it ,PS  chart watching now becoming more interesting ,cheers all .

[Scandinavian High.]

Models getting very interesting now can the blocking hang around for winter .:.????

[Matthew.]

Heights impressively strong to the NE on the ECM this evening. The Atlantic is battling against the heights but neither wins out so we're left with a southerly influence. May the battle continue with the latter winning

Edited October 15, 2016 by Matthew Wilson

[knocker]

17 minutes ago, Matthew Wilson said:

Heights impressively strong to the NE on the ECM this evening. The Atlantic is battling against the heights but neither wins out so we're left with a southerly influence. May the battle continue with the latter winning

The Atlantic clearly ahead on points at the end of round ten.

Edited October 15, 2016 by knocker

[Scandinavian High.]

ecm looks blocked out in f1 where is the westerly gone???

[bobbydog]

1 hour ago, terrier said:

Some nice looking charts this evening especially from the gfs and gem models. But i do feel it is all too early again. I would expect the polar vortex to get its act together towards the end of October early November. And of coarse see we're we go from there. But if I remember correctly we saw a lot of blocking this time last year from the output and we all know how that ended. 

That is a possibility. However... here is day 10 on the GFS  (25th Oct)-

And here is the ECM -

Differences but generally the same pattern regarding position of the block and the main part of the PV 

Here is where we actually were on 25th Oct last year.

As you can see, very different. No scandi block and the PV fairly well formed over Greenland. 

If the models are correct on this crucial time this year, we should be looking at a very different winter.....

 

[DOdo]

1 hour ago, terrier said:

Some nice looking charts this evening especially from the gfs and gem models. But i do feel it is all too early again. I would expect the polar vortex to get its act together towards the end of October early November. And of coarse see we're we go from there. But if I remember correctly we saw a lot of blocking this time last year from the output and we all know how that ended. 

The difference being we knew what to expect this time last year especially with the strong El Nino that was expected. This year not so clear, completely different set up this year

[Singularity]

I'm struggling to comprehend the ramifications of such persistent and extensive poleward transport of warm air with some wave breaking into the stratosphere while the vortex is only in its early days. The below two charts show warming appearing first at 10 hPa and then 1 hPa by the end of the GFS 12z. Extremely speculative at this range of course - but interesting to note the possibilities at hand when there are such extreme blocking anomalies coupled with tropical cyclones transporting extra heat and moisture toward the high latitudes.

 

Internal variability might be about to make things very interesting for November, but the thing about internal variability is that it generally represents that which we can't reliably predict the behaviour of. So no reason to hang your hat on any particular expectations for the time being - perhaps even for a while, as we are only in mid-October after all.

If it does get exciting on here, rest assured I will be watching with interest and grinning from ear to ear (I can't contribute like I did last winter, for legal reasons).

Edited October 15, 2016 by Singularity

[SLEETY]

No sign of any change to atlantic domination,the longer a pattern persists,the longer it can take to break down ,looking forward to the next updates from glosea5 and ecm monthly models,are we on the cusp of something truly exceptional and unusual this winter,a once in a lifetime event ,maybe :-) 

[summer blizzard]

The GFS model can be incredible at times. 

At day 10 we have a well formed surface cold pool over Europe..

At day 15 we have a completely dead Atlantic with no sub-1000mb low and a northerly..

 

 

[damianslaw]

23 hours ago, Singularity said:

 

Hitting that time of year, when the continent begins to cool rapidly, high pressure development over scandanvia from here on in, aids the development of cold surface air over the near continent, and easterlies change from becoming warm to cold.. this will be very evident come mid next week, sub 548 dam air firmly entrenched across the country, only 2-3 weeks ago, we would have been seeing the sub 548 dam air well away from our shores. However, southerly and southeasterly airstreams still pack a warm punch, and if the synoptics shown by the models verify, then we will see the return of milder SE flow, but nothing substantial with a tongue of warmer uppers advected north across the country, squeezed through by colder uppers just to the east and west, so unlikely to be long lasting.

So after a couple of milder days ahead, the outlook looks average temperature wise in the main, perhaps a bit below for a time, and then slightly above more so in the south for a short time, warmer maxes cancelled out by cooler nights, indeed later next week could deliver the first widespread ground frost for many, with a widespread air frost in the north, fog could become a troublesome feature aswell, especially given the late sunrise we see in late October.

Longer term - signs of retrogression of heights once again towards Greenland with a trough digging down into scandi and a very negative NAO type set up, and a southerly tracking jet, the alternative scenario is low pressure becoming anchored to our south/southwest with a very raw easterly/north easterly feed - very anamolous conditions for late october which traditionally is one of the most westerly dominated periods of the year. Indeed this October could go down as one of the most easterly in a long series..

Edited October 15, 2016 by damianslaw

[Ice Day]

3 hours ago, Singularity said:

I'm struggling to comprehend the ramifications of such persistent and extensive poleward transport of warm air with some wave breaking into the stratosphere while the vortex is only in its early days. The below two charts show warming appearing first at 10 hPa and then 1 hPa by the end of the GFS 12z. Extremely speculative at this range of course - but interesting to note the possibilities at hand when there are such extreme blocking anomalies coupled with tropical cyclones transporting extra heat and moisture toward the high latitudes.

Superb post Singularity.  The bit in bold is potentially really important. Given the now regular huge arctic summer ice loss the rules of the game have changed and we are into somewhat uncharted territory (as per Steve M's must read post in the 'Winter Thought's' thread).  The next 3-4 weeks are, in my humble opinion, going to dictate where winter goes.  If HLB comes to fruition in line with some predictions, the PV is going to be shunted away from its usual position (for the last couple of winters at least) and potential for extended cold for the UK is on the cards. However, if the PV does reform and migrate back west, we could be in for another mild and wet one.  

Whilst my normal optimism has been tempered massively by the last three dreadful winters (from a coldie's point of view), I really think we could be on the cusp of something quite extreme. As always, Netweather is going to be the place to watch the drama unfold.  It's going to be emotional!

 

[SMU]

a couple of cherrypickers from the 18z

 

 

[ItNeverSnowsInWindsor]

I can't remember seeing such HLB in October in the Scandi region for a long time. Bonfire night could well be a frosty one like back in the old days in the late 80s!

[knocker]

The next couple of days sees the depression currently just west of Ireland track slowly north and fill. Today a band of rain, perhaps heavy at times, currently over the south west will move NE during the day. Windy but relatively warm with the wind in the southerly quadrant. Tomorrow less wet but chances of showers.

As already noted the low has filled adjacent to Scotland but is reinforced by another upper low winging in from Canada which tracks SE to become a cut off low over Germany/Poland and en passant bringing some wet.showery weather on Tuesday particularly to the north.

In the wake of the passage of the low we see brief ridging NE from the Azores which should give a nice quiet few days before the Atlantic girds it's loins in with a cold plunge from Greenland in the form of a negatively tilted trough which will slowly erode the ridge and impact the UK by the weekend.

How much this impacts the UK is still very much open to debate as the upper trough deconstructs and causes a certain amount of surface mayhem. Best left for another day.

Edited October 16, 2016 by knocker

[Ali1977]

Day 10 on the ECM would be a pretty impressive snowstorm in the south if we were in January - this is the end of October though, just wet and windy, but will still feel cold. 

[Blessed Weather]

10 hours ago, Singularity said:

I'm struggling to comprehend the ramifications of such persistent and extensive poleward transport of warm air ...... (snipped)

With apologies to mods for being a little off topic, there's a very interesting report suggesting that the Northern Hemisphere 'cold pool' of 850 hPa air (measured as the area within the -5C isotherm) has been shrinking for the last 66 years. If I'm reading the abstract correctly, the current synoptics we are watching playing out look like being a primary cause of the shrinkage, i.e. a displaced and meandering jet and more storms being driven poleward.

"Systematic poleward encroachment of the −5°C isotherm in the exit regions of the storm tracks accounts for nearly 50% of the observed contraction of the hemispheric wintertime cold pool since 1948. It is suggested that this trend is linked to displacement of the storm tracks associated with global warming".

So these events might be good news in displacing cold air towards the mid latitudes (short term gain) but bad for future prospects (long term pain)??

Abstract here, but full report behind a paywall. http://journals.ametsoc.org/doi/full/10.1175/JCLI-D-14-00496.1

[Matthew.]

On 14 October 2016 at 19:02, Man With Beard said:

It's cropping up in different places but I'm seeing lots of HLB on recent runs - GFS op, 1050mb over Iceland, surely a collector's item!

Just to note that 1050mb has now cropped up at the end of the ECM run over Greenland

Edited October 16, 2016 by Matthew Wilson

[MR EXTREMES]

14 hours ago, Steve Murr said:

spectacular GFS & GEM ( not to mention ECM was similar at 240 )

**IF** this varifies we are looking at a tanked -AO at around the 28th of October just days before the curtains raise for November AO stats...

the key period is 168- 216 getting enough greenland heights up against that low to reverse the 60N circultation-

goodbye zonal wind !

yep and ecm today has on offer a neg ao and nao start to november garden path perhaps but a chart certainly would open the flood gates further on.

09/10 winter had 1050mb blocking alot and stratospheric warmings can we get a 1060mb block im containing my excitement but soon as the low solar activity through out this year stayed very low and the increased power of the hurricaine season amongst other things it wouldnt surprise me if this winter is more exciting than the last few at least. 

Edited October 16, 2016 by MR EXTREMES

[MR EXTREMES]

8 hours ago, Steve Murr said:

a couple of cherrypickers from the 18z

 

 

this reminds me of 09/10 how that began.

trouble is with charts like these is most of the time we come close only for it all to be shunted east...

but these charts are ver much 09/10 like with arctic blast that then goes northeasterly then easterly  but there fair few exciting charts being thrown out but im going to stay on the fence until its within t96 at least.

[bluearmy]

20 minutes ago, Matthew Wilson said:

Just to note that 1050mb has now cropped up at the end of the ECM run over Greenland

a reminder that ECM is notorious for over amplifying towards the end of its OP runs. This high is built in the back of a system tracking north in ne America and dragging some impressive WAA up the GIN sea. 

the op runs will continue to play with scenarios like this whilst the background ens anomolys stay like this.  In two weeks , GEFS has the mean vortex just north of the aleutians but with a fair spread over the Arctic. Still little appetite for Canada/Greenland to become home for the fledgling chap. 

[Summer Sun]

56 minutes ago, Ali1977 said:

Day 10 on the ECM would be a pretty impressive snowstorm in the south if we were in January - this is the end of October though, just wet and windy, but will still feel cold. 

 

 

Yup like last week it's a case of right set-up wrong time of year

Edited October 16, 2016 by Summer Sun

[Grimers]

The GFS model and the ECMWF model show a low over NW Northern Ireland bringing moderate SW winds and cool temperatures to all parts of the UK tomorrow and a low over the Faroe Islands bringing moderate W winds and cool temperatures to all parts of the UK on Tuesday.

       

Edited October 16, 2016 by Grimers