Model Output Discussions 12z 01/09/2016

[Mucka]

 

Certainly big differences between the models this evening.

The Euros seeing potential for increased heights over Scandi and possible blocking to form though all a bit too flat and far East at the moment.

 

JMA also picking up on the theme.

 

 

Edited November 1, 2016 by Mucka

[Frosty.]

I wouldn't be concerned about how the Ecm 12z finishes, what's important is the 4/5 days of cold weather which comes before it which has more chance of verifying. We can't avoid at least short-lived milder interludes with the atlantic so close to us, besides, it doesn't matter at this stage, winter is still 4 weeks away..any cold wintry weather in november is a bonus, the icing on the cake so to speak!

Edited November 1, 2016 by Frosty.

[legritter]

Looking forward to some colder weather so I will just enjoy what mother nature is giving us .further outlook charts will change again come tomorrow and the day after too ,but I, m confident that it's going to be a very interesting period coming up ,upper Atmosphere vastly different than past years at this stage , Stella's all round ,whoops  wrong one  .

[Frosty.]

Speaking of cold weather, tonight brings the first widespread frost of the season..The first of many! I will drink to that

Tomorrow night looks even colder..enjoy the crisp bright weather.

Edited November 1, 2016 by Frosty.

[knocker]

An Atlantic plume! how far east will it track?

[gottolovethisweather]

2 hours ago, northwestsnow said:

Suits me Ian

I much prefer the colder stuff to come in Dec and Jan with the shorter days/weaker sun etc . As you say, time will tell..

 

 

 

And during November. November currently set to warm out/up slightly in seven to ten days time, believe it when I see it. For now, some most interesting Northern European synoptics before we even get there as there was throughout October as well. A November with a difference is upcoming, I'm almost certain.

 

Edited November 1, 2016 by gottolovethisweather

[chrisbell-nottheweatherman]

2 minutes ago, northwestsnow said:

Think you got the worng thread chris

Yes, but you've now given the Moderators more work (as have I, in fairness).  In future, if someone makes the mistake I now made, please send them a private message.

Edited November 1, 2016 by chrisbell-nottheweatherman

[gottolovethisweather]

8 minutes ago, knocker said:

An Atlantic plume! how far east will it track?

 

 

To the NW of the UK that is, is it not? Knocker. Defaulting back to the current pattern by then (D10), no panic for cold lovers for sure.

 

Edited November 1, 2016 by gottolovethisweather

[Faronstream]

Last days very mild runs from especially GFS in long range,a bit too early for that but still those frightening westerlies are getting closer to realistic and the geopotential sinks over greenland. Any small ridge of high pressure would be very welcome now to stop it

[Singularity]

  


So it looks like the polar vortex wants to work its way down into the troposphere just as the stratospheric component moves through Greenland. We see this all to often and perhaps the regional cooling feedback associated with the ice sheet of Greenland helps the vortex to achieve such downward propagation.

The stratospheric vortex is hardly hanging around though; just three days later it's already fringing into Scandinavia. By the end of the run it's elongated right over to central Asia.

The tropospheric vortex looks keen to follow suit, again with a lag of 2-4 days, but it faces the issue of blocking highs over Eurasia that will tend to interfere with its attempts to achieve a well organised state. As with last year, we can think of the 'bricks in a washing machine' analogy - but this time there's a much gentler spin, so although the bricks will still mess it up, it's less likely to shake itself to pieces unless perhaps we can find some bigger bricks. Or one big brick labelled 'SSW' . The jury's still out on that one, but there are some interesting murmurings.

[Frosty.]

4 minutes ago, Faronstream said:

Last days very mild runs from especially GFS in long range,a bit too early for that but still those frightening westerlies are getting closer to realistic and the geopotential sinks over greenland. Any small ridge of high pressure would be very welcome now to stop it

I'm going to enjoy these cold frosty nights and the colder weekend and first half of next week the models are showing and not concern myself beyond that. The Pv looks fairly weak, certainly compared to this time last year,  long may that continue!

Edited November 1, 2016 by Frosty.

[Scandinavian High.]

Looking very different to last year there something going on in  atmosphere very interesting ..

 

[Ali1977]

Some pretty nice charts in the GEFS in FI , hopefully these start showing up more and more in the coming days. Maybe we should start looking beyond the breakdown of this colder spell - if it indeed happens.

[Sperrin]

I wonder could someone point me in the direction of a blog/website that provides information on the basics of reading the PV charts singularity posted above. I am a rank amateur but can get my head around most aspects of the pressure charts/models, however, the charts above completely flumox me. Many thanks. 

[fergieweather]

34 minutes ago, Ali1977 said:

Some pretty nice charts in the GEFS in FI , hopefully these start showing up more and more in the coming days. Maybe we should start looking beyond the breakdown of this colder spell - if it indeed happens.

The tipping-point of key uncertainty emerges next week. Will the westerly pattern come blowing-through, heralding a steady return to average temperatures on towards mid-month (as now strongly indicated by sizeable majority of EC 12Z ENS)... and if so, will longevity of that phase prove rather transient further into the month? Imponderables, for now...

[Ali1977]

On 01/11/2016 at 22:17, fergieweather said:

The tipping-point of key uncertainty emerges next week. Will the westerly pattern come blowing-through, heralding a steady return to average temperatures on towards mid-month (as now strongly indicated by sizeable majority of EC 12Z ENS)... and if so, will longevity of that phase prove rather transient further into the month? Imponderables, for now...

Yes from what us amateurs can see it looks like the block is trying to hold out but is loosing the battle. How the westerly pattern could be stopped is where the ENS might give us an idea - maybe you have some insight into this!! To be honest I didn't expect see these westerlies coming and the PV ramping up quite so quick given the goings on higher up in the atmosphere.

The latest AO forecast actually looks better than yesterday's towards mid month at around -2 average, that may give us a clue!!

Edited November 1, 2016 by Ali1977

[Scandinavian High.]

Wow very impressive..

 

[knocker]

A look at the anomalies tonight to see where we stand regarding the upper pattern. As has been the case for a while now there is pretty good agreement on the overall pattern, and all definitely in the same ball park,

So we have the Aleutian low, with strong WAA continuing into north N. America, Canadian vortex, A trough down the eastern seaboard (not to be forgotten as energy from here is being thrown into the mix), the Atlantic ridge and Scandinavian trough. And for good measure some ridging in SE Europe with more WAA. So essentially we are looking at a NW upper air flow and temps below average for the UK. But the problems arise when attempting to get to grips with an idea of detail because slight variations in the orientation and strength of the Atlantic HP and Scandinavian trough are going to make a huge difference to the evolution of the surface features as get towards the end of this period.

For example note the difference between the GEFs and ECM in the orientation of the aforementioned. The position of the HP with the latter would indicate that any systems generated by the vortex and the trough down the eastern seaboard phasing together and winging east on what is obviously a very tight thermal gradient will track SE a tad further east than the GEFS indicates and thus mainly give the UK a miss apart from maybe northern Scotland.

So this a rather long winded way of saying the detail remains to be nailed down after a pretty cold and grotty weekend but the percentage play is for a quieter period with temps rising to perhaps near average as the HP ridges further east.

Edited November 2, 2016 by knocker

[knocker]

12 minutes ago, Ali1977 said:

Yes from what us amateurs can see it looks like the block is trying to hold out but is loosing the battle. How the westerly pattern could be stopped is where the ENS might give us an idea - maybe you have some insight into this!! To be honest I didn't expect see these westerlies coming and the PV ramping up quite so quick given the goings on higher up in the atmosphere.

The latest AO forecast actually looks better than yesterday's towards mid month at around -2 average, that may give us a clue!!

I'm not sure where  you got that from but the ecm ens actually goes slightly positive and the GEFs is around -1.

[Nick B]

On 24/10/2016 at 23:56, knocker said:

I don't have a huge previous knowledge of previously reading NOAA charts this is just my understanding of them, As I mentioned just now think roughly where the surface features will go. You perhaps get a better idea on this by comparing to the GEFS and ecm as they are actually in pretty reasonable agreement.

From my understanding, one of the key possibilities will be a transition of the main lobe of the PV albeit briefly through Greenland eastwards to Scandinavia/Northern Asia. I would hazard this absolutely cannot happen without this part of the globe being subject to Atlantic-sourced weather for a period of time. However, the potential benefits down the line for those seeking colder weather would then be heightened (with the caveat that it would be required that the lobe positions itself where the air mass arriving in the UK is once again sourced from a N/NE direction, only this time with more venom).

Edited November 1, 2016 by Nick B
typo

[Frosty.]

Nothing mild about the Gfs 18z for the next 10 days. It looks below average and with a colder weekend and early next week..nice to see.

Edited November 1, 2016 by Frosty.

[Ali1977]

6 minutes ago, knocker said:

I'm not sure where  you got that from but the ecm ens actually goes slightly positive and the GEFs is around -1.

Looks like an average of about -2 to me!! Am I looking at the wrong thing?

Last need these were edging up towards -1 

Edited November 1, 2016 by Ali1977

[Frosty.]

18z mild in low res looks short-lived with a brief arctic shot before it turns milder, chop and change low res with a much more mobile pattern.

Edited November 1, 2016 by Frosty.

[knocker]

Well i have the ecm ens graph in front of me (can't post it) updated this evening and it goes neutral on the 8th and rises slightly by the 16th. But no you aren't looking at the wrong thing but I was just looking at the two detailed GEFS and ecm ens graphs.

Edited November 1, 2016 by knocker

[Ali1977]

4 minutes ago, knocker said:

Well i have the ecm ens graph in front of me (can't post it) updated this evening and it goes neutral on the 8th and rises slightly by the 16th

Oh well, looks like 1 is wrong then or somewhere in the middle!! The pub run didn't look too Neg in FI though !! :-( although not much PV around.

Edited November 1, 2016 by Ali1977