Model output discussion - 5th December 2016 - Into Winter we go

[snowbunting]

Positive height anomolies over greenland and swalvbard would suggest a potential for Nly blocking? And therefore a change in air mass for us in the uk? From polar martime to polar continental. 

[johnholmes]

8 minutes ago, snowbunting said:

Positive height anomolies over greenland and swalvbard would suggest a potential for Nly blocking? And therefore a change in air mass for us in the uk? From polar martime to polar continental. 

not PC but Am, it is over water not land?

below are the UK Met definitions of air masses

http://www.metoffice.gov.uk/learning/learn-about-the-weather/how-weather-works/air-masses/types

Edited December 29, 2016 by johnholmes

[SMU]

38 minutes ago, frosty ground said:

Wouldn't your theory be backed by evidence thou and therefore the more likely one.

What does that actually mean ? More evidence? 

How can 1 comment on a day 10 chart have more evidence than another?

 

Edited December 29, 2016 by Polar Maritime
To move discussion on.

[MR EXTREMES]

9 minutes ago, snowbunting said:

Positive height anomolies over greenland and swalvbard would suggest a potential for Nly blocking? And therefore a change in air mass for us in the uk? From polar martime to polar continental. 

but there are no positive heights over greenland.

and the latter part of the ecm starts to see a renewed surge of vortex over the canadian side of the pole and still higher pressure to our south and way to much energy in the northern arm of the jet and continued toppling of atlantic heights.

but this does not mean it wont be settled with cool/cold lid over the uk.

Edited December 29, 2016 by MR EXTREMES

[Summer Sun]

 

[Johnp]

Am I correct in saying we will no longer be getting any nuggets from Ian F because some plonker copied everything to Facebook?

Shame if so as it'd be interesting to hear the Met office view.

[SMU]

18 minutes ago, Nick F said:

Looking at the GEFS z500 mean/anomalies days 7-11 and 11-15, there seems little impetus to push the mean N Atlantic block SE into Europe as per some of the operational runs yesterday, thanks to cold air / low heights draining down from NE Europe into central Europe

Stunning 00z EPS mean days 11-15, can't show them, but picture the troughing beginning to undercut at day 10 near the Azores at day 10 on chart below spreading further east into SW Europe, with a blue band of -ve anomalies from SE of New Foundland all the way east  into southern and central Europe beneath +ve HGHT anomaly over Iceland.

@frosty ground

read above as I can't be bothered to type out the same

[northwestsnow]

Nice tweet from Matt this morning.Clusters supporting blocking highs at northern latitudes.

Would of been nice to hear from fergie but im now expecting upgrades from the metoffice Medium ranger..

[carinthian]

16 minutes ago, carinthian said:

Major cold spell coming for Europe if that set up comes off. Could eventually see a link with the Arctic high and Atlantic block and then an easterly possible as indicated by the GFS in post 240h. At this stage all dependant where the Euro trough is centred and where the cold high relocates. Good charts this morning for cold weather fans. Its getting there, slowly but surely.

C

This earlier chart below from ECM at 168T shows the cold already in place to the Northeast with the first cold wave ( upper trough ) established. The second trough forming in Mid Atlantic ( this is the one forecast to develop and extend the cold into much of The British Isles as shown on the 240t chart . It looks like this same trough development is shown on the latest Day 7 fc Atlantic chart from UKMO , so may be some support from them for the eventual outcome.

Edited December 29, 2016 by carinthian

[swfc]

1 hour ago, Johnp said:

Am I correct in saying we will no longer be getting any nuggets from Ian F because some plonker copied everything to Facebook?

Shame if so as it'd be interesting to hear the Met office view.

Would seem that way and yes hes been a great help during his time on here.The models this morning esp the gfs oz to my eye have later in the run the makings of a proper scan based easterly and more blocking moving into iceland.May be a slow process but imo thats where its heading 

Edited December 29, 2016 by swfc

[snowbunting]

5 minutes ago, johnholmes said:

not PC but Am, it is over water not land?

below are the UK Met definitions of air masses

http://www.metoffice.gov.uk/learning/learn-about-the-weather/how-weather-works/air-masses/types

I was thinking more land than water as per the run of the GFS 0z. Its not showing the blocking that Glacier Point was talking about in a previous post. But I can imagine alot of potential for cold air for the UK in January. 

[frosty ground]

20 minutes ago, Steve Murr said:

What does that actually mean ? More evidence? 

How can 1 comment on a day 10 chart have more evidence than another?

It means knockers version has more evidence to back up his claim than your version.

I don't see anything that shows cold air backing West. I do see what knocker says. I am not saying it won't happen that their is no evidence of it. No support from models.

Edited December 29, 2016 by Polar Maritime
To move discussion on.

[MR EXTREMES]

but saying this looking closer with 10x optical zoom the ecm does look like a possible club banger if it follows the arrows.

but surely this kind of pattern would be big disruption to the vortex?

 

[Summer Sun]

A good chunk of Jan looks cold this is the updated weeklies from Monday

Jan 2nd to 22nd ^

Precipitation is below average on all weeks bar the 9th to 15th where the signal currently is weak

[mulzy]

the 0z GFS P keeps the general trend of Atlantic amplification in the day 7-11 range.

 

[Tim Bland]

Potential exists for a covering of snow for some on 02nd Jan (only 4 days away) Below is from the 00z GFS and ECM looks similar.   If it does materialize as per below then that area (Central Southern England) will see its deepest or only laying snow for years! With any luck the front will stall for longer and it will be a bit deeper.  Could also disappear on the next run or amount to an hour of sleet though.    Will be interesting to monitor this over the weekend when it gets into High res (NAM Euro4 etc) territory)

 

[bluearmy]

Not much to add to what nick and Stewart have said re the extended ens. Knocker would seem to have a slightly different view and I get where he is coming from a bit. Af the moment, the second bite at the cherry seems to be too Far East again but look so less likely that the blocking will sink away. seems to want to establish across w uk edging north over the next couple days and allowing the undercut from the Atlantic trough. The potential for this solution easily visible from the day 10 ECM op. the chances of an easterly flow looking better with each run and for once, no sign at the moment that the Euro low anomolies wil disappoint. however, we need to see this 12/15 day pattern of undercut get to day 10 when the eps lose their high resolution. 

looks like cold stays on the menu but the potential for the type of cold most in here are looking for is slowly increasing. 

[bluearmy]

6 minutes ago, frosty ground said:

It means knockers version has more evidence to back up his claim than your version.

I don't see anything that shows cold air backing West. I do see what knocker says. I am not saying it won't happen that their is no evidence of it. No support from models.

What steve sees is closer to what the extended eps are showing. low anomolies establishing over Europe and high ones to our north. That means the cold will back west. a broadbrush analysis and where the uk would sit in that remains unknown but your post isn't right. 

[Banbury]

Might please some

[stewfox]

14 minutes ago, swfc said:

Would seem that way and yes hes been a great help during his time on here.The models this morning esp the gfs 6z to my eye have later in the run the makings of a proper scan based easterly and more blocking moving into iceland.May be a slow process but imo thats where its heading 

The gfs 6z have only just started to run ?

[Nick F]

16 minutes ago, bluearmy said:

Not much to add to what nick and Stewart have said re the extended ens. Knocker would seem to have a slightly different view and I get where he is coming from a bit. Af the moment, the second bite at the cherry seems to be too Far East again but look so less likely that the blocking will sink away. seems to want to establish across w uk edging north over the next couple days and allowing the undercut from the Atlantic trough. The potential for this solution easily visible from the day 10 ECM op. the chances of an easterly flow looking better with each run and for once, no sign at the moment that the Euro low anomolies wil disappoint. however, we need to see this 12/15 day pattern of undercut get to day 10 when the eps lose their high resolution. 

looks like cold stays on the menu but the potential for the type of cold most in here are looking for is slowly increasing. 

I'm always uber wary of Atlantic troughing undercut of an Atlantic high, as it's been so rare in winters since 2010 and models, particularly ECM, are keen on the idea out at day 10 and beyond before backing off subsequently. However, with the PFJ undercutting the N Pacific block and tracking way south and strong over the U.S.A with deep cold sinking way south there, thus stronger likelihood that the PFJ energy will transfer under the block over the Atlantic than over. But not guaranteed. Hopefully the 12z suite will firm up on this idea or garden and path spring to mind.

Edited December 29, 2016 by Nick F

[Blessed Weather]

This morning's GEFS 500mb mean height anomalies support the story that the high to our NW will gradually move east to form a Scandi high, with low heights establishing over central Europe and an easterly flow developing into mid-January. Sequence shows 5th, 7th, 10th and 14th Jan:

   

[swfc]

8 minutes ago, stewfox said:

The gfs 6z have only just started to run ?

sorry 0z 

[Luke Attwood]

The way I see things developing is like this..we get the cold northerly around new years day probably lasting 2 or 3 days and with the threat of snow for some particularly in Scotland.as we approach midweek it turns milder with the high moving southeastward, a northwesterly wind.during the latter part of week we see a stronger ridge developing in the Atlantic initially pushing up to Greenland to allow another cold northerly to develop. What happens after this is crucial, we ideally want to see the high drift east then north, rather then east then south.I believe the latter will happen sadly which means the deep cold will escape us and Germany France and northern Spain may well see the bitter temperatures! So as I said where the high drifts later next week is crucial in terms of whether we see deep cold,or something just below average...I do hope I am wrong and we see the deep cold move westward towards us,we shall see. ☺

[winterof79]

14 minutes ago, Nick F said:

I'm always uber wary of Atlantic troughing undercut of an Atlantic high, as it's been so rare in winters since 2010 and models, particularly ECM, are keen on the idea out at day 10 and beyond before backing off subsequently. However, with the PFJ undercutting the N Pacific block and tracking way south and strong over the U.S.A with deep cold sinking way south there, thus stronger likelihood that the PFJ energy will transfer under the block over the Atlantic than over. But not guaranteed. Hopefully the 12z suite will firm up on this idea or garden and path spring to mind.

This ties in that the METO were seeing an increase in PC flows in their extended. Seems it is gathering momentum now.