Model Output Discussion 01/09/17

[jvenge]

It's not really worth dwelling on the run details, especially in the later frames. Sufficed to say, it keeps the UK quite toasty and a certain squirrel is likely coming over quite faint now. 

[swfc]

4 minutes ago, johnholmes said:

I think you will find the point I was trying to make about a 'surface' high is correct. Remember also that Greenland, most of it, is not at sea level anyway, it being covered by a thick layer of ice.

You are indeed correct john.greenland does have a semi permanent high .graphically correct also.if you look at historic events ie greenland highs the colours do show yellow-orange

[Zakos]

Despite a ghastly 12z run for the UK, the bigger picture remains very good, and there is still plenty of scope for us to see cold weather. The polar vortex looks like it's taking a good pummeling on this run, a lot of warm air advection into the canadian arctic aswell, which can only be good news as winter approaches

Even right out to the very end of the run, the vortex and jet stream appear to be in disarray.

I think there is every chance we could see a notable cold spell before the months end, and there seems to be little to indicate that atlantic will take hold of our weather anytime soon 

 

 

Edited November 14, 2017 by Zakos

[Frosty.]

The Gfs 12z shows some very mild tropical maritime air spreading up across the UK during next week, especially further south with some rain and breezy conditions, particularly further west and north with spells of dry and brighter weather, especially further south and east..feeling quite spring like which would encourage the early daffodils.

 

[knocker]

Interesting feature on this evenings gfs  run,

A surface  low forms at the base of the upper trough to south west at T126 and develops quite nicely as it tracks north east to be 955mb west of the Hebrides at T204 Be afraid, be very afraid.

Edited November 14, 2017 by knocker

[Zakos]

 

Thats a pretty big shift in the space of 96 hours.

I think the models can be excellent at predicting incoming atlantic depressions for example, but I have great difficulty taking any output beyond 96 hours seriously in a situation like this, there is simply no way that the models will be able to accurately predict such a drastic change.

Once the block sets up, we should have a clearer idea of what will occur. Until then, I personally wouldnt get disheartened by any output, expect wild swings in the coming days.

Edited November 14, 2017 by Zakos

[Summer Sun]

17 minutes ago, Frosty. said:

The Gfs 12z shows some very mild tropical maritime air spreading up across the UK during next week, especially further south with some rain and breezy conditions, particularly further west and north with spells of dry and brighter weather, especially further south and east..feeling quite spring like which would encourage the early daffodils.

1

Even running GFS on further it still shows some pretty mild air

Not to be taken seriously of course at 2 weeks out

[Paul_1978]

15 minutes ago, knocker said:

Interesting feature on this evenings gfs  run,

A surface  low forms at the base of the upper trough to south west at T126 and develops quite nicely as it tracks north east to be 955mb west of the Hebrides at T204 Be afraid, be very afraid.

Afraid of what??

Edit, yes 955mb is pretty deep!

Edited November 14, 2017 by Paul_1978
Point of clarity.

[Singularity]

Seems to be two distinct routes to improving from the 12z GFS;

Route one sees the shortwave low breaking away cleanly and scooting across across the UK fast enough that it's at least in the N. Sea by noon Monday and ideally into Norway, with this quick motion separating it sufficiently from the main trough to the west for that trough to interact more with the next one off the U.S. as opposed to the low that's crossed the UK. This interaction encourages the Atlantic trough to stall, and potentially take on a negative tilt. The ridge may then build N or NW from the UK and link with the HLB, however it's possible that another low could break free from the Atlanitc trough as it takes on the negative tilt (such is the nature of trough disruption) and cut through beforehand as per the 00z ECM. 

Route two, very nearly achieved by the 12z GEM today, sees the shortwave low moving much more slowly, so much so that it misses the chance to cut east through the ridge, and must instead slide southeast. In this scenario, the main Atlantic trough could feasibly develop an extension on the SE flank that stretches the system out from NW to NE, so producing a negative tilt with a ridge building NW from the UK to link with the HLB.

 

Now this does put us in a strange position, as for one outcome, we need faster eastward progression of the shortwave low (but not trough to its west!), and for the other, we need slower eastward progression. That's going to make anticipating the path of the next few model runs a bit difficult to say the least .

[Summer Sun]

12z mean shows a colder blip later this week then a return to average or slightly above average temps from next week

[bluearmy]

one positive to take from the gefs suite is that there aren't many members building a strong p/v by day 16

[The PIT]

Full steam ahead from the GFS for a very mild second half of November. UKMO differing at T144 where it drives the low over Ireland south east while the GFS drives it north east. The only saving grace is UKMO performs better than GFS even at this time period. So we will have to hope GFS is going to lose this one. All eyes on the casting vote by ECM. 

[phil nw.]

Difficult to see cold air coming this way with such a pattern modelled currently.

Although we see a perturbed pv there is no real Blocking to our north as mentioned earlier by John H..

We can see ridging towards Greenland yes,but not a standing block of heights at 500hPa.A look at the jet split flow,here at T96hrs for example.

Effective Greenland highs send all the jet energy into the southern arm,unfortunately currently this is not modelled.The split flow sees sub-tropic ridging as well, pushing the Azores high too close to the UK limiting any colder air from coming much further south-UKMO day 5

-perhaps Scotland may see some polar maritime incursions from time to time,but honestly we just lack enough amplification in the Atlantic pattern to really take us into a proper cold setup currently.

Edited November 14, 2017 by phil nw.

[danthetan]

One thing I've noticed over the years of model watching is a correction south of low pressure systems coming up against an area of high pressure by the models. It seems the heights to the north are developing rather than established as the low pressure systems are moving across the Atlantic, so this might not be the case but we shall see.

[Stozzy]

Southwesterly at 168 on the ecm . Quite a big turn around from the other day . Maybe the gfs was on the right path days ago 

[tight isobar]

Ecm 168...

Into a mild south westerly flow..

Amplification is even worse than gfs!!!!

The wheels are rapidly falling of this one!!!

[karlos1983]

Hmm, not convinced, think we need to see tomorrow’s runs. It was Sod’s law ECM would do this. No agreememt in the short term, so everything remains on the table imo 

[Geordiesnow]

I think there is more than enough evidence to suggest a west based NAO will now occur, seems no getting away from this so its going to be a case of so near yet so far although its far a disaster as the uppers never really suggested it was ever going to be cold enough for snowfall anyways.

If the northwesterly coming up towards the weekend bought some meaningful cold uppers then that slider low could of provided a snow threat, that may of happened in the 70's with a stronger PV but not now and it won't this time either.

Still as others have said, with the PV split and heights across the poles then you never know down the line even if the weather for us does end up being on the mild side so its still going to be interesting model watching that is for sure.

[The PIT]

Yup the trend has now reversed to mild and the theme is generally being picked up on all models. The fat lady is out and singing but something may appear more promising later on next week.

[tight isobar]

An very familiar story...

Uk no mans land-triangle...

And as a result the cold -8/-12 850hpa digs into southeastern europe!!!

No towel throwing just yet..

But its in my hand!..on this one.

 

Notice: i have posted euro view snaps only...

Unless theres a flip back nxt 24-hrs.. there maybe no point ie 'northern hemisphercal' If this chance is missed its likely a ramp up of te vortex-pv- and zonality' will have to occur..

Before another worthy shot.

Edited November 14, 2017 by tight isobar

[Frosty.]

I'm seeing lots of potential for a change to mild next week from the Gfs  / Ecm  12z, no point trying to sugar coat it. On the plus side, it's still autumn!!.

Edited November 14, 2017 by Frosty.

[Geordiesnow]

6 minutes ago, karlos1983 said:

Hmm, not convinced, think we need to see tomorrow’s runs. It was Sod’s law ECM would do this. No agreememt in the short term, so everything remains on the table imo 

Think your being optimistic there in all honesty, from what I can see, the models are in solid agreement on a west based Nao and perhaps a slider low heading through the UK but nothing is suggesting the UK will see NE'lies next week, that looks very much the outside bet and instead the weather will be milder as the case is with west based NAO's.

Its one of those in that if the first part of the jigsaw is wrong then you can scrap all the output which showed the cold NE'lies heading our way because that will just not happen under a west based NAO, infact its probably meteologically impossible. In fairness, all the models(apart from the UKMO but then that model showed something else at times) hinted at times we may see a west based NAO and some others shown an Atlantic ridge so the threat was always theren and unfortunately for cold lovers, its the former that is set to become the reality.

As ever with model watching things can alter again and details will still no doubt change but the trend is there I'm afraid.

[Paul_1978]

2 minutes ago, Frosty. said:

I'm seeing lots of potential for a change to mild next week, no point trying to sugar coat it. On the plus side, it's still autumn!!.

I was just going to say the same - it's 14th November - we aren't even in winter yet! Easy to forget. 

Even 2010's snow didn't occur til the 27th and even that was considered early. 

[BLAST FROM THE PAST]

Too much reliance on model inter runs.  ECM still ok, UKMO still pretty ok, GFS......pffft.  Look there is some resolving to do yet......but the fact things are chopping and adjusting....is just that.  However, this isn’t in my view the winter of freeze...

 

BFTP

[Frosty.]

19 minutes ago, tight isobar said:

Ecm 168...

Into a mild south westerly flow..

Amplification is even worse than gfs!!!!

The wheels are rapidly falling of this one!!!

Yes I think coldies will have to take this on the chin this time but as has been said, it's still autumn and hopefully there will be better times during the coming winter.