Model Output Discussions 12z 01/09/2016

[bluearmy]

7 minutes ago, January Snowstorm said:

I see a gradual weakening of heights / blocking on this evenings charts.

High pressure over or in situ shouldn't be taken as the same as northern blocking. It may not be the most popular post this evening but what I see is yellows over Greenland being eroded and being replaced with blues and purples. I have an inkling that the vortex is going to ramp up in about ten days time. In the meantime worth remembering that it isn't cold here or in near future nor will it be cold within a 1000 mile radius of Britain and Ireland. 

 

could be JS although not seeing any attempt by the vortex to strengthen would be very odd given th time of year

note yesterday's musings re the ens possibly pointing to a replenishing scandi trough with a mid Atlantic ridge that ebbs and flows is now playing out in the extending modelling. 

 

 

[knocker]

Interesting ecm run.

At T60 the Atlantic trough disrupts with the European HP ridging north over the UK and a deep trough eastern Europe.

The southern section of the disruption becomes a cut off upper low SW of Ireland whilst the northern trough swings around the north of the HP to be north of Scotland and compressing the HP over the UK by 00z Tuesday. And now the upper players are in position.

In the next 36 hours by 12z Wednesday (T144) the northern trough has tracked SE and deepened and quite importantly it has phased in with the cut off upper low to the south west which has important implications for both the orientation and placement of the cold air of the subsequent trough.

As previously stated the precise manner that the upper air has evolved does drag the cold air (and there's a lot of it around) down over the UK for the last four days of the run.

Edited October 27, 2016 by knocker

[Geordiesnow]

1 minute ago, January Snowstorm said:

I see a gradual weakening of heights / blocking on this evenings charts.

High pressure over or in situ shouldn't be taken as the same as northern blocking. It may not be the most popular post this evening but what I see is yellows over Greenland being eroded and being replaced with blues and purples. I have an inkling that the vortex is going to ramp up in about ten days time. In the meantime worth remembering that it isn't cold here or in near future nor will it be cold within a 1000 mile radius of Britain and Ireland. 

Some signs that finally the PV may get its act together over the Arctic also which would certainly be better news for the sea ice up there.

Problem with wanting cold early is that when you got such a negative AO as we have so far in October, the PV is just no-where near strong enough to deliver the goods at this early stage and lets not forget, blocking can occur even when there has been rampage of a PV so for me, I much rather the PV ramp up in the Arctic regions then perhaps get a warming event and we can hopefully get the goods if we get the right set ups. No good having nice blocking charts if the cold is quite diluted.

I also note once again, once the models get closer to the time, shortwaves do tend to pop up and can act as spoilers so whilst we got some ridging going on in the Atlantic, there is no real sustained heights, its something to bear in mind when viewing those GFS and ECM FI charts!

That said, we could get some seasonal weather next week of some frost and fog (good old Autumn fog, not fog that just occurs with warm moist air) with a weak Northerly and pressure rising again. Of course it may not fully work out like that so you can't rule something out a bit colder and convective than that but that seems to be the form horse at the moment

[weirpig]

18 minutes ago, January Snowstorm said:

I see a gradual weakening of heights / blocking on this evenings charts.

High pressure over or in situ shouldn't be taken as the same as northern blocking. It may not be the most popular post this evening but what I see is yellows over Greenland being eroded and being replaced with blues and purples. I have an inkling that the vortex is going to ramp up in about ten days time. In the meantime worth remembering that it isn't cold here or in near future nor will it be cold within a 1000 mile radius of Britain and Ireland. 

I'm not to sure what your seeing. Unable to post charts as on phone but the ecm does show heights eroding at the at the end of the run  but at the same timescale on the gfs it shows the same but then another ridge builds  then we finish with impressive heights towards Greenland  very early days and in my opinion the blocking will still be in place in 10 days time.  Differing opinions and all that  however the vortex will get its act together at some point  still it is very early so if the vortex does strengthen it's not a disaster by any means 

Edited October 27, 2016 by weirpig

[SLEETY]

If you use day 10 charts to make an assumption on what the weather is going to do,more fool you,never seen any 10 day chart verify,so lets write off northern blocking now based off one ten day ecm run,laughable

[winterof79]

37 minutes ago, January Snowstorm said:

I see a gradual weakening of heights / blocking on this evenings charts.

High pressure over or in situ shouldn't be taken as the same as northern blocking. It may not be the most popular post this evening but what I see is yellows over Greenland being eroded and being replaced with blues and purples. I have an inkling that the vortex is going to ramp up in about ten days time. In the meantime worth remembering that it isn't cold here or in near future nor will it be cold within a 1000 mile radius of Britain and Ireland. 

I ,personally do not see purples overtaking the Greenland area in the 10 day period. Plenty of Vortex disruption on offer.

GFS

ECM

Even the GEM which shows this is highly unlikely to spawn any vigorous depressions toward us

 

[Ali1977]

When is the next long range METO model out? EC monthly etc? Might tell a story

[Summer Sun]

As Matt Hugo says cooling down yes but only to the seasonal average

 

[knocker]

2 minutes ago, Ali1977 said:

When is the next long range METO model out? EC monthly etc? Might tell a story

The EC 46 is tonight

[karlos1983]

I can understand the caution here. It's been a tough few years of winter model watching, being as it is very early doors in the season, it probably pays to not get to carried away. We don't want the Prozac coming out in the first week of November. But that said, it's not like we are looking at northern blocking charts that have appeared from nowhere, with little explanation as to how that pattern evolved. This has been on the cards for a while now and consistently modelled with obviously varying themes. Low sea ice, cold in Eurasia, PV not got going and the strat also playing ball, I would be somewhat surprised if this pattern doesn't play out, I guess the only question is whether we benefit from a coldie perspective. Even if we don't initially, we are certainly in a much better position synoptically than this time last year and the year before that. Exciting model watching that's for sure. Some great posts as always the past few days. A joy to read. Let's all enjoy the ride, after all we can't control the outcome, but we can hope. 

Edited October 27, 2016 by karlos1983

[bluearmy]

Time for some meandering of my mind and where we could be headed through November. the modelling is not keen on any kind of strong Canadian vortex. signs of a chap setting up home nw of Greenland but displaced north of where it might cause trouble re ramping up the northern arm. on the other side of the NH, the Siberian high should really get its act together through the month as the snowcover becomes extensive through N Russia.  So a weak Atlantic northern arm and a potentially strong Siberian high building west. 

no real appetite to build euro heights and a southern arm which should provide support for the mid Atlantic ridge to sustain. (And possibly provide further depressions running into Europe to our south to sustain the lower than average euro heights).

this background provides a few options for the broad pattern around nw Europe - tough to suggest where we may sit in any but overall looking like a cool or cold outlook. If the weak northern arm allows the Siberian ridge to head west in a general retrogressive manner wit euro low beneath then you never know how wintry the second half of the month could turn out. 

will be very interesting to see just how the month pans out from where we start. how the hemispheric patterns change and whether we can retain a disjointed weak strat vortex which allows the trop to take the lead.  It's a long time since we were in a position as now with no strong ENSO signal or strat activity to over ride the meridional pattern in which we find ourselves. 

If the mid latitudes are to miss out on unusual cold later this month and December (note this doesn't necessarily mean our little part of the planet) then will be great to actually see how the pattern changed back over the period. 

[Eskimo]

Not sure why there is any caution? I mean, it doesn't look like last year...and it doesn't look like the year before, so, what are we all being cautious about? 

Even at day 10 on the ECM I'd take this...



Over this (from last year)...                          Or this from 2014....

Edited October 27, 2016 by PerfectStorm

[East_England_Stormchaser91]

Still, remarkably we have yet to see the Atlantic get into full swing. Can't recall many if barely any times where we haven't seen autumnal gales by now. This time 3 years ago we had st Jude bearing down upon us! We have not seen any real strong wind activity at all here. 

A foggy few days to come. I will add also that my grandfather very much concurs that foggy and still autumns often led to properly cold winters and blizzards. Dec 62 being the most prime example! He would often go by preliminary conditions as they had no computer outputs back then! 

[Frosty.]

The main question about next week, specifically later next week onwards is how much influence high pressure will have and ditto regarding the scandi trough's influence which will determine what kind of NWly / Nly flow we end up with..The Ecm 12z ens mean at least indicates relatively colder air will be spreading south after a mild anticyclonic start to next week.

Edited October 27, 2016 by Frosty.

[nick sussex]

42 minutes ago, PerfectStorm said:

Not sure why there is any caution? I mean, it doesn't look like last year...and it doesn't look like the year before, so, what are we all being cautious about? 

Even at day 10 on the ECM I'd take this...



Over this (from last year)...                          Or this from 2014....

Good post, things are looking a lot different than last year so far. Theres no sign of the PV setting up over Greenland .At the moment the greater uncertainty is how much cold air gets south. Looking to the east it does look like an early start to winter and if the cold air doesn't get displaced then any easterly could have more bite than usual this early in the season. 

[knocker]

This could have some knock on affects downstream

 

[blizzard81]

14 minutes ago, knocker said:

This could have some knock on affects downstream

 

Would this support the longevity of the aleutian low? The ECM 12z op Michael Ventrice refers to actually amplifies upstream days 8 to 10.

Edited October 27, 2016 by blizzard81

[knocker]

1 minute ago, blizzard81 said:

Would this support the longevity of the aleutian low?

The short answer to that is I don't know but I suspect it might disrupt it.

[karlos1983]

3 minutes ago, blizzard81 said:

Would this support the longevity of the aleutian low?

I would say right now, who knows. Tropical storms are incredibly hard to predict track wise, strength wise etc. So monitor being the key word I reckon. Woodshed still needs to be stocked imo. 

[blizzard81]

Just now, knocker said:

The short answer to that is I don't know but I suspect it might disrupt it.

ECM 12z op seems to amplify upstream at days 9 and 10.

[Cheshire Freeze]

2 hours ago, January Snowstorm said:

I see a gradual weakening of heights / blocking on this evenings charts.

High pressure over or in situ shouldn't be taken as the same as northern blocking. It may not be the most popular post this evening but what I see is yellows over Greenland being eroded and being replaced with blues and purples. I have an inkling that the vortex is going to ramp up in about ten days time. In the meantime worth remembering that it isn't cold here or in near future nor will it be cold within a 1000 mile radius of Britain and Ireland. 

The general gist of what I've seen in today's modelling is a slight relaxation in the very blocked Arctic profile days 7-10 before renewed tanking of the AO possible days 10-14. This ebb and flow is to be expected (given the battle for vortex intensification being repeatedly offset by minor stratospheric warming episodes which will not allow the vortex to settle for any protracted length of time). There also looks to be a hint in the 12z GFS of another wave breaking attempt post day 10/11 (as pointed out by Feb1991). All in all a lot to keep tabs on in the coming weeks.

[johnholmes]

Well the NOAA output 6-10 and 8-14 both keep the idea of the meridional flow and the UK on the cold side of the ridge. Contour heights are emanating from north of the Gt Lakes for south of the UK. In winter that would equate to cold air at 500mb and the surface, with cold lovers trying to 6th guess where any snow, if any, might fall. I have to admit I cannot recall charts like we are seeing at this stage in October since I joined Net Wx in 2004/5. But I have no idea what may happen through the winter!

[bluearmy]

With ref to a possible west Pacific typhoon, I mentioned one appearing in a couple, weeks on some GFS op runs. The one Michael ventrice refers to seems to be headed towards se Asia and would probably  dissipate thereafter and not affect the Pacific jet. However, the one shown back end week 2 on some GFS ops looks more likely to get involved if it verifies. my memory seems to recall a late season typhoon being very useful to an aleutian or North Pacific low in driving additional WAA into the Arctic some years ago. whilst it's always possible that an ex typhoon could upset the pattern, I would punt that given the existence of the aleutian low to begin with, an injection of extra tropical air would be useful in sustaining wave breaking from the trop into the strat. 

[bluearmy]

The extended eps are very slow out this evening. What is noticeable day 12 is a far more defined East Alaskan upper ridge developing. If we are to see a more amplified pattern sustain then we could do with a ridge/trough/ridge setting up (nw America/east coast America/mid Atlantic ). Sometimes this set up upstream is viewed with caution as it creates a strong jet off the eastern seaboard. However, given the lack of Greenland/east Canadian vortex, I am not so concerned and expect a downstream ridge would be maintained. 

[knocker]

The ext EPS finally out and still looking familiar with ridging in the Atlantic and the trough to the east still adapting the positive tilt configuration brought about by the trough to the SW of the UK. This does allow for some interesting surface interpretations.