Model Output Discussions 06z 04/11/16

[gottolovethisweather]

One thing to bear in mind, while our eyes are firmly fixed on future offerings, first thing tomorrow morning looks prime for a few wet snowflakes on the wind., even down in parts of the South, especially at elevation. Plenty of hill snow opportunities after that as mentioned up above. Marginal, transient and hill snow are words which we'll all hear a lot more of in the coming days, especially from the Midlands northwards.

[Captain Shortwave]

Day 6 charts

GFS/UKMO/GEM

      

To be honest going by the ensembles over the past couple of days this isn't actually far away from what they were showing, high pressure building towards the NW of the UK with low heights becoming cut off to our south. Whilst it is a little disappointing to not see the Greenland high build quickly like the GFS operationals of yesterday, this isn't a bad place to be as we head to the end of the month. Dry and chilly with frost and fog still looks to be the likeliest option, there could be a rather keen east/north east wind across the south so it could feel rather raw and there is also the risk of rain moving up from the continent towards the south coast.

[Mucka]

GFS 12z quicker with the trough and retrogression this afternoon as well. Northerly incoming?

Edited November 17, 2016 by Mucka

[SMU]

Afternoon All

after much musings over the last 24 hours the models have settled a little today on the locale of the block -homing on South East greenland as the most Northerly element, with the ECM being further SE.

..Either way we dont quite get the GH but could have the next best thing- the infamous 'sausage' High ! - more on that in a mo-

Whilst many have been looking at the ridging a colder & colder mid term has been creeping up in the models - the updated UKMO 12z through 72-120 shows a proggesivy colder Northerly flow with low heights- indicating probably wintry / showers pushing south-

 

The UKMO then allows the high to push up to Iceland like the GFS-

So whats the sausage? - not really much of a scientific description however its the next best thing to a Greenland high because 99% of the time it will retrograde west towards Greenland- it is a pebble shaped strip of high pressure that holds in situ usually from iceland all the way towards scandi- its very rare as the jet usually topples atlantic ridges- 

whats good is as it recarves a path towards Greenland it allows the troughing to drop on the NE flank-

it looks like this

 

So rather like yesterday the timelines havent changed -

day 6-8 - High pressure ridging into Iceland area

day 8-10 Holds in situ & starts to retrograde allowing significant troughing into Scandi

day 11 - NAO BLOCK...

The updated zonal wind means from the GFS today have not budged from yesterday in as much as they are going through the floor for a full reversal of winds

-

As shown the mean drops to around -15M/S -  Thats against the climo mean of + 30 M/S & Dec 15 was + 40 M/S -

in summary - its all good- expect some great charts coming soon !!

S

Edited November 17, 2016 by Steve Murr

[feb1991blizzard]

3 minutes ago, Steve Murr said:

 

 

in summary - its all good- expect some great charts coming soon !!

S

One coming up right away!!

[bluearmy]

The 12z gfs is broadly in line with my current expectations through week 2 and it isn't particularly at odds with the ecm op and para around day 10 

will it again find an Atlantic trough in deepest fi ??

[feb1991blizzard]

Here she comes this time - at last!!!!!!

[northwestsnow]

Beautiful Gfs 12z!!Blocking galore and plenty of cold weather to welcome in December ..

[SMU]

Just to add - AO ensembles updated (00z)

- better than yesterday with x2 -5 runs in there -

todays 12z GFS would be another sub -4 run !

s

 

 

[Ali1977]

1 minute ago, feb1991blizzard said:

Here she comes this time - at last!!!!!!

Yeah, looks good.  Just need another shift East to help build heights back over Greenland and it'll be proper game on.  Going to be an interesting set of Ens, potentially a few cold ones in FI which hasn't really happened yet.

[feb1991blizzard]

1 minute ago, Ali1977 said:

Yeah, looks good.  Just need another shift East to help build heights back over Greenland and it'll be proper game on.  Going to be an interesting set of Ens, potentially a few cold ones in FI which hasn't really happened yet.

A few snow events towards the end of that run I would think.

[Mucka]

2 minutes ago, Ali1977 said:

Yeah, looks good.  Just need another shift East to help build heights back over Greenland and it'll be proper game on.  Going to be an interesting set of Ens, potentially a few cold ones in FI which hasn't really happened yet.

I'm sure nick will be pleased with the rapid demise of the Russian high. so am I once it has played its part.

As you say we will likely see a new cold signal appearing within GFS ensembles not unlike this mornings ECM set.

Edited November 17, 2016 by Mucka

[bluearmy]

The gfs 12z fi is a reasonable fit for the general fi ens output - the system engaging late on would probably come in further south if it verified. Look at the potential of that broad set up!!  We don't need a proper greeny block and sometimes, the best events come from less clean scenarios. 

Next is the ecm to see if the latter frames continue the trend of retrogression to the high coming out of eastern Canada and also, as Steve has noted, the generally cold theme for next week. 

Beyind that, the ec weekly eagerly anticipated to see what it might make of the ramifications of any upper strat reversal approaching xmas 

[Methuselah]

I refuse to get over-excited over one run...But, I really do hope Mr Murr is on the money...Oh, I never felt more like singin' the blues!

[Frosty.]

The Gfs 12z low res turns into wintry heaven / hell depending on what side of the fence you are on..from where I'm sat it looks glorious!

[Snowy L]

So GFS now more similar to the ECM with the high not retrogressing at t120-t168. Imo that suits us far better. This gives the South Russian high time to go away.

[East_England_Stormchaser91]

My word, the 12z is a beautiful ending. A full locked in pattern of a continuous feed of cold straight out of the Siberian polar field. 

The thing to keep an eye on is the non existent jet coming out of the North American eastern coast. This seems to be the key, as the models have been hinting on this surge of air for days now, ever slowly bringing it into the closer time frames. As long as we see those unusually moderated temperatures in the Labrador/New Foundland and Greenland areas, this will scupper the usually powerful jet from forming, therefore, giving opportunity for near on reverse zonal flow and leading onto those brutal cold uppers flooding out of the 'right' side of Greenland!   (Excuse the pun!) 

Quite possibly the most exciting period of model watching I have experienced since joining netweather 

[weatherguy]

It was only yesterday that I mentioned the presence of a "Murr Sausage", just saying

 

Absolute belter of a 12z GFS today:

Going from this starting position

 

At t+69 we see the trigger low cross the UK, notice the complete lack of any energy pouring out of Canada as would normally be expected at this time of year....

 

t+111 here, heights have pushed into Greenland somewhat, buckling and therefore we don't get a classic GH, however, enough has been done to prevent a toppler high, as low heights extend further into S Europe.

The inevitable outcome is an easterly of sorts at +165, shown below.  Also throwing in an NH view to show how weak the PV is by this stage.

At +219 we see a holding of the pattern, yet looking at Greenland you can clearly see a renewed push of WAA into Greenland, and a gradual "sucking up" of the sausage high towards this area.

Oh look, a nice PV lobe is lurking to our north while this has been happening...I wonder what will happen next...

 

Wonderful viewing 

[nick sussex]

Given the strong signal to push high pressure ne over the UK the ECM should agree with this as its earlier output has the same set up but just with the high a bit further south. Its ensembles though suggest that the op had things too far south so I think we should expect good agreement at T144hrs.

The GFS evolution is one we've seen many times before with the high edging west and troughing heading into Scandi and its not one of those Da Vinci Code type evolutions which needs a leap of faith.

The problem this far out is trying to get the right angle of attack of cold air into the UK, maintaining a decent block not too far west but that's well into the future.

So lets hope the ECM will retrogress the high and not try and make a drama over it.

[Captain Shortwave]

Just to echo the thoughts of many on here, GEFs

      

Above average heights over Greenland and Canada with the higher heights near the UK retrograding with a deepening trough just to our east. So certainly a chance of a chilly easterly becoming a much colder north to north easterly by the turn of the month. A long way to go but the signs are definitely encouraging. 

[knocker]

Temps still holding up quite well but cooling slightly as the run progresses

 

[Robbie Garrett]

8 minutes ago, weatherguy said:

Oh look, a nice PV lobe is lurking to our north while this has been happening...I wonder what will happen next...

 

Wonderful viewing 

You never know. Be careful what you wish for.

[feb1991blizzard]

Just now, knocker said:

Temps still holding up quite well but cooling slightly as the run progresses

 

As an average of 5 day periods, there is a lot more below average than above average over those 2 maps.

[Summer Sun]

Nothing too cold on the ens beyond Sunday or Monday

Temps a touch below average to end the month and going into December, not by much though

[ITSY]

Ens not particularly impressive on the cold front, least not in line with some expectations. ECM should be interesting