Model Output Discussion - Snow for some, but what else is in store?

[Griff]

This is messy but getting colder over Europe //

[I remember Atlantic 252]

Another GFS run that goes mild/wrong Sun/Mon 24th/25th, don't think it can be discounted, key 00Z's tomorrow

 

 

[IDO]

2 minutes ago, sub zero said:

Really surprised that no one has mentioned the blizzard showing across most of the country at 108, if this was to come off...

WOW....

Buxton might get a top up:

The usual suspects...

[Vikos]

1 minute ago, IDO said:

No real change in the signature pattern by d7, but changes per run as to timing, phasing and disruption of the features, mini-waves and troughs.

This I was to write about, even further in mid-term changes aren't so signicantly.

This is rather unusual, mostly for winter time. Is there a (big) disturbance or a signal in the background forcing the models to miscalculate or be misled?

Hmmm....

[chris55]

2 minutes ago, Frosty Winter said:

Parallel run is still showing a potential snow event next weekend.

Its in my diary lol...... Snow event for the middle section of the UK next weekend. It'll be news worthy.

Im expecting snowman pics from Cheltenham, Swindon, Hereford, Oxford, MiltonKeynes as a guide  

[Tim Bland]

Possible ridge going up? Northerly at the end?

[Feb2009London]

Small signals emerging in some of the latest output of an organised snow event Wednesday night further S/SE. One to watch!

[Don]

9 minutes ago, sheikhy said:

Im afraid to say ukmo is the outlier here!!!!we will find out on the 00zs!!!if the other models move towards it in the morning then bingo we are heading to a more snowy period!!!if not then the search goes on!!im saying ukmo is the outlier right now!!

Well, the UKMO has often been the party pooper in the past when the ECM/GFS have got carried away with snowmageddon charts, so I just hope it's on to something this time!

[Tim Bland]

Wow at the UKV ...that’s a big shift south! Similar to GEM.  GFSp much further west / north still. 

Edited January 16, 2021 by Tim Bland

[mountain shadow]

So its UKMO v The Rest of the world.

Will the 0zs finally give us a consensus?

[IDO]

3 minutes ago, Vikos said:

This I was to write about, even further in mid-term changes aren't so signicantly.

This is rather unusual, mostly for winter time. Is there a (big) disturbance or a signal in the background forcing the models to miscalculate or be misled?

Hmmm....

I thought it was to do with the way the blocking pattern sets up at d8, best illustrated with the anomaly NH profile:

The Atlantic sector surrounded by blocking highs and little opportunity for us to escape this log jam quickly. Post d12 it seems to relax so we will see if that can change for us?

 

[Allseasons-Si]

That is certainly a cold northerly albeit in fl...

some of the ext EPS show this scenario esp cluster three.

 

[Vikos]

Just now, IDO said:

I thought it was to do with the way the blocking pattern sets up at d8, best illustrated with the anomaly NH profile:

The Atlantic sector surrounded by blocking highs and little opportunity for us to escape this log jam quickly. Post d12 it seems to relax so we will see if that can change for us?

 

The cold air is no longer retained at the North Pole, it flows out to lower latitudes and fires up low pressure production (cyclogenesis) in N-Atlantic. 2 comments at this point.

First: In the Scandinavian area, the cold air from the open sea southeast of Spitsbergen is softened. This is not the case in Canada - the breeding ground for the Atlantic lows - where it encounters ice and snow. These are the northernmost land masses on earth.

And secondly, there is an easterly current on the north side of the lows, with which the Siberian cold air is carried past the southern tip of Greenland to northern Canada and the Labrador Sea, in turn into the nutrient zone of the Atlantic lows

The whole thing even with a negative NAO, because on the north side of the Atlantic lows near Iceland there is a slight high pressure tendency and the lows tend to influence the Azores, no contradiction.

2 plus points for the Atlantic against the Siberian cold air.

Thats our problem.

[Man With Beard]

1 hour ago, chris55 said:

I'd be interested for the experts to add a bit more information  on the single cluster scenario from ECM.

It has shown this a few times in the last few days.

My understanding is the the spread is so wide within a smaller envelope, that the clusters just say 51 members agree?

While this may be more useful on an entire NH perspective, its essentially useless when trying to decipher a boundary line over the UK when the jet is tracking south. 

Essentially, its not a very useful forecast tool in the current set up? Right or wrong?

 

Wouldn't call myself an expert, but I do analyse the ECM individual ensembles a lot - in the D8-D10 period, about 60% are the same = low to our NW, heights brushing Iberia, the result being the return to an Atlantic flow. So to answer your question ... when there is one cluster beyond D6, I don't usually find the ensembles are tight enough to eliminate other possibilities, nor are they so random that patterns can't be found. The clusters are useful but not always a completely authoritative guide to the ensembles imo.

Lots of fun and games before and after that, though! The majority of ECM ensembles still have a snow event pushing through the country over next weekend (on a line somewhere between the M4 and Sheffield particularly favoured). Northern areas may see snow before the weekend in any case. Then after D10, the ensembles generally think we'll see another trough dipping south and further snow in many places. Some of snow levels are astronomical for northern inland areas by D15.

However, pulses of heights to the south keep popping up on most ensembles, which makes it hard to see a more persistent cold spell taking hold before February. Unless the SSW has something spunky up its sleeve

Edited January 16, 2021 by Man Without Beard

[Allseasons-Si]

Now can we gain some traction on this northerly at around 300 hrs,yes i know and you can laugh and i laugh at myself but the gfs and gfs/p have it at that said timescale.

[danthetan]

Updated UKMO fax charts updated show things marginally further south against GFS 18Z which is crucial here as you can see @65N roughly the flow is  heading east. The further south the block in the greenland vicinity will push the low exiting the Newfoundland disrupting it and keeping it in the westerly flow going south of the UK instead of travelling north and hitting the easterly flow and blowing up. in the first few frames of the 18Z you can there is sufficient forcing of the block to disrupt the first low exiting newfoundland sending the low into the base of the trough NE of the UK. 

[Matt H]

Just now, Allseasons-si said:

Now can we gain some traction on this northerly at around 300 hrs,yes i know and you can laugh and i laugh at myself but the gfs and gfs/p have it at that said timescale.

No doubt we will reel it into t168 with full ensemble support, only to watch it collapse at the last hurdle like most of the other attempts recently.

[Allseasons-Si]

7 minutes ago, Frosty Winter said:

No doubt we will reel it into t168 with full ensemble support, only to watch it collapse at the last hurdle like most of the other attempts recently.

With the MJO passing into phase 6/7 by the end of the month i see no reason why this wouldn't gain strength but other factors are at play here so who knows

Edited January 16, 2021 by Allseasons-si
typo

[Vikos]

16 minutes ago, Don said:

How potentially unlucky are we this winter?!

Right now, 10 out of 10

That's why I am waiting for that massive low as a gamechanger (hopefully) which can break up those structures. Hope and keep the faith

 

 

[Frosty_wsm]

40 minutes ago, sub zero said:

Really surprised that no one has mentioned the blizzard showing across most of the country at 108, if this was to come off...

WOW....

Nothing 'wow' about those charts for here, every time I see the phrase 'most of the country' with regards to snowfall I know  exactly what the charts will look like before I even see them lol

This current pattern is so damn annoying for the far south, need to get that jet running further south but that doesn't look likely 

[Kentspur]

35 minutes ago, Feb2009London said:

Small signals emerging in some of the latest output of an organised snow event Wednesday night further S/SE. One to watch!

Interesting to see if UKV sticks to showing sleet and snow over virtutally the entire SE 1/3 of the country as this morning it consistently forecast rain/sleet only for a number of places (blue shades) which proved right its my go to model now along with Icon 

Edited January 16, 2021 by Kentspur

[bluearmy]

6 minutes ago, Allseasons-si said:

With the MJO passing into phase 6/7 by the end of the month i see no reason why this wouldn't gain strength but other factors are at play here so who knows

How far into phase 7 is the question (if it actually makes it)

 

[Allseasons-Si]

7 minutes ago, bluearmy said:

How far into phase 7 is the question (if it actually makes it)

 

That is a good question Nick(it is Nick isn't it?)

gefs and ecm

they have been hogging the COD for most of this season now and they are finally on the move,hopefully,...a pattern change maybe?

Edited January 16, 2021 by Allseasons-si

[Bullseye]

6 minutes ago, Allseasons-si said:

That is a good question Nick(it is Nick isn't it?)

gefs and ecm

they have been hogging the COD for most of this season now and they are finally on the move,hopefully,...a pattern change maybe?

I have just posted a tweet from Masiello into the tweet thread which relates to MJO phases and how the SSW may have temporarily paused the progress of the MJO. They seem to hinting over on Twitter of MJO into more favourable phases for blocking around late Jan. 

Edited January 16, 2021 by Bullseye

[Don]

16 minutes ago, Smartie said:

Nothing 'wow' about those charts for here, every time I see the phrase 'most of the country' with regards to snowfall I know  exactly what the charts will look like before I even see them lol

This current pattern is so damn annoying for the far south, need to get that jet running further south but that doesn't look likely 

As I alluded to earlier, if we didn't have those pesky heights to the south, the outlook would be pretty good with more southerly tracking lows!