Model Output Discussions 12z 01/09/2016

[knocker]

Just now, johnholmes said:

go to the Guides for all the detail?

Funny you should say that as I was just going to add a similar comment to my post.

[feb1991blizzard]

Here is the page by John Holmes on snow forecasting from the NW guides.

https://www.netweather.tv/forum/topic/27989-how-to-try-and-forecast-snow/

 

[Mucka]

1 hour ago, knocker said:

Not to forget 850mb temps on their own are not a great guide for snow. You still need an indication of the layer temps such as the 1000mb-700mb thickness which is better guide. This is quite a complicated subject with a number of variables. Perhaps JH would summarize? Although thinking about it it's hardly on topic in this thread

Not worth thinking about such details over a theoretical chart 10+ days out. That is the sort of detail to look at within a much closer time-frame.

For the record though here is the extended JMA.

 

Edit.

Just to add. It is nice that Johns snow guide is being brought up in October though. 

Edited October 26, 2016 by Mucka

[Mucka]

Could be a pub run special due to the lack of phasing of Canadian/Atlantic trough.

By this time next week we should see snow cover throughout Russia and encroaching into Eastern Europe. 

Edited October 26, 2016 by Mucka

[Gael_Force]

3 hours ago, Singularity said:

Those narrow 'fingers' of higher heights, which often linger on following a bout of strong blocking features, are known to give the models a particularly hard time. Especially when they become 'cut off' from the mid-latitude ridges by disrupted or southerly-tracking troughs extending or moving across to the south of them. Mid-January 2013 was a classic example of what that sort of thing can lead to, both with the models and the actual outcome. I remember Steve Murr making some big points on this. If I had the time I'd dig out some historical charts etc.

The trick is figuring out whether the jet stream will slice through or be walled off, which due to the tendency for multiple disturbances to interact in a short space of time, can be very difficult to pin down until a mere 3-5 days range.

So if those 'fingers' keep on showing up then... brace yourselves for some model swings and roundabouts!

I do believe you are describing the legendary 'Murr Sausage' and it is quite disconcerting to hear about them being "sliced through".

[feb1991blizzard]

13 minutes ago, Mucka said:

Could be a pub run special due to the lack of phasing of Canadian/Atlantic trough.

By this time next week we should see snow cover throughout Russia and encroaching into Eastern Europe. 

Stonking run so far, wrt snow cover, we really need it to spread West as far and quickly as possible, especially Scandinavia.

[feb1991blizzard]

Here comes the first proper Arctic blast.

 

 

Edited October 26, 2016 by feb1991blizzard

[Mucka]

8 minutes ago, feb1991blizzard said:

Stonking run so far, wrt snow cover, we really need it to spread West as far and quickly as possible, especially Scandinavia.

Yes synoptically it is a great run but very much a slow burner as far as getting cold to the UK would go.

Other than the the European snow cover looking good for Western expansion it will be interesting to see if those positive downstream developments for Atlantic blocking are repeated in future runs or if it is just run to run variability.

All previous runs (all models) phased the troughs around 192h (12zs)

something else to look at for us model geeks anyway.

 

Edited October 26, 2016 by Mucka

[bryan629]

This makes for good reading .. 

 

[feb1991blizzard]

 

BULLSEYE!!!

[booferking]

GFS delivers a nice potent Arctic blast.

[Cheshire Freeze]

2 minutes ago, feb1991blizzard said:

 

BULLSEYE!!!

The thing I noticed was the constant rebuild of N Atlantic/S Greenland heights throughout FI. Everytime it looked like they were sunk they'd just build back. As for that chart you've posted, I'm not sure I've seen a tropospheric vortex look as feeble as that whilst approaching mid November. 

[feb1991blizzard]

15 minutes ago, CreweCold said:

The thing I noticed was the constant rebuild of N Atlantic/S Greenland heights throughout FI. Everytime it looked like they were sunk they'd just build back. As for that chart you've posted, I'm not sure I've seen a tropospheric vortex look as feeble as that whilst approaching mid November. 

Agree, my only concern though, is the ridges attacking the PV need to be as high as possible, the higher the heights the higher the wave breaks into the stratosphere thus more apt at stopping any VI in the Mid Strat from propagating downwards into the trop.

[Mucka]

Good morning everyone.

Very pleasing UKMO at 144h with the pattern amplified and backed West to the extent we are actually in a cool Northerly flow. Looks pretty good upstream too.

GEM 144 somewhat supportive of UKMO solution but not as favourable upstream

 

GFS much flatter in comparison but better upstream.

And again it keeps the Atlantic and Canadian troughs as separate entities so we get a decent Atlantic ridge form.

Ultimate result, a roaring Easterly with retrogressing high - not bad.

Rather chilly for much of Europe

 Might be a bit of waste of a dream synoptic in early Nov but what a chart to be modeled for the time of year even if it is FI?

Edited October 27, 2016 by Mucka

[knocker]

Today

Generally cloudy, some sunny intervals, and quite mild in the south. A few showers in N. Ireland and mainly fine and bright in eastern Scotland but rain will spread into western Scotland during the day and track SE overnight.

This morning's GFS

the Upper low along the eastern seaboard tracks NE and phases with the Canadian vortex inspired trough to the north to form a new trough mid Atlantic which quickly deconstructs as HP surges NE to form a cut off upper low west of Coruna by 18z Monday. During this period most of the UK remains under the influence of high pressure so dry but probably cloudy.

Now comes the tricky bit. The aforementioned upper low remains more or less in situ whilst we have high pressure in the Atlantic interacting with energy from  the Canadian vortex shooting east and running around the northern perimeter. Thus by Friday we have two low pressure area, one down to the SW and the other much more adjacent NW of Ireland,

 

Whilst this has been going on the UK is in a very slack HP regime which should continue to give mainly dry and relatively warm weather to most but by the weekend what has briefly been described above has morphed into a large, slack low pressure area to the west and over the UK with showers and perhaps thundery outbreaks. I have little confidence that this will end up being the solution.

Edited October 27, 2016 by knocker

[doctor32]

I'm very much in the cold/snow camp when it comes to model watching... and the charts over the past few weeks are very different to what we have all been used too over the past few years to start off the winter season. Plus with many other signals in favour of a more blocked pattern in the months ahead that doesn't mean that is what we will get as always the weather does as it wants and come december we could be looking at charts with low after low rushing across the atlantic on a strong jet, desperatly looking for our next cold shot as per last couple winters.

Hopefully this wont be the case... i mentioned a couple weeks back that it probably wont be till start of november before we get a better feel of what charts will bring (in cold weather terms) for our little world, that still the case i think. As the charts from all models show a cooling trend in november with plenty blocking, but exact details unkown which has a big impact on what weather we see on the ground due to mainly direction of wind around high pressure which has been such a big player for the last month bringing a prolonged spell of easterly's and now a more south westerly bringing milder temps over next few days to many.

Like many in here i'm no expert in model watching but love the weather in the UK, i enjoy everyones opinion on this subject wether they love heat, cold, snow or storms and because everyone has a different take on things this is why this site works so good. Not to add the more professional people who run the site and from others who work in the field @fergieweather  and @Tamarafor example who provide a real insight to details we don't know.

Anyways, lets hope the charts keep us chatting and discussing away throughout the years to come 

[knocker]

The five day GEFS tending to support this morning's det. run

And I can report that Sidney is not  impressed with all the recent witterings about a cold winter and he's cancelled his xmas chestnut order

[Matthew.]

The ECM 0z introduces colder air for the 2nd November. A lot of northern blocking around with the trough dropping through Scandinavia pulling cold air towards the UK. Frost and fog the name of the game for next Thursday:

Edited October 27, 2016 by Matthew Wilson

[jvenge]

More GFS ensembles showing a colder outlook for Russia and Eastern Europe out into the far reaches. Too far away to be considered reliable, of course, but the depth of cold greater than yesterdays runs and in more ensembles.

Knocker, could you post than nice 2m anomaly? Just curious where we are at over the next 10 days.

[Captain Shortwave]

Very good agreement between the UKMO and ECM at day 6

   

Both developing a chilly northerly and both look pretty good for holding that high west of the UK. Night frosts and temperatures probably scraping double figures by day at best.

ECM at day 8

We can see a reload of cooler air coming south as heights pull further west still.

The GFS keeps the high closer to the UK around the day6/7 mark before turning things more unsettled albeit not the typical zonal set up as low pressure sinks SSE from Iceland. 

 

[knocker]

8 minutes ago, jvenge said:

More GFS ensembles showing a colder outlook for Russia and Eastern Europe out into the far reaches. Too far away to be considered reliable, of course, but the depth of cold greater than yesterdays runs and in more ensembles.

Knocker, could you post than nice 2m anomaly? Just curious where we are at over the next 10 days.

Cooling below average near the end of the period

[jvenge]

1 minute ago, knocker said:

Cooling below average near the end of the period

I'm out of luck for a warm wedding day then. Oh well. I'll settle for dry.

[Seasonality]

2 minutes ago, knocker said:

Cooling below average near the end of the period

You are a gentleman as always knocker. This fits with my own thoughts for a continued cooler than average spell in central and eastern europe. I'm glad I've got the new winter tyres ready to go! We're up to 9 ensembles on the snow row for Warsaw around 9 November and plenty of sub zero T2M runs starting to creep in on the GEFS. Fingers crossed this cold air can be shared with the UK as well.

 

[knocker]

The main, vital difference, between the ecm and gfs is that exaggerated HP ridging NE on the ecm blocks any energy transport from Canada ergo the evolution next week takes a different turn.

Edited October 27, 2016 by knocker

[carinthian]

Not seen this early extensive cover of snow for a long time ( forecast date 10TH November 2016). Quite a significant depth throughout the heart of Russia and even snow cover as far west as Dutch/ North German border. All as a result of the persistent Northern Blocking and no length of zonal blasting.  Warms the cockles of your heart !

 C

Edited October 27, 2016 by carinthian