Model output discussion - into the last third of January

[XtremeUKWeather]

11 minutes ago, Beano said:

Aperge looks inline with the radar

Seems like Aprege is behind as well with the front and the angle it’s at 

 

[winterof79]

Clearly moved further North before pushing west 

 

[Tim Bland]

Icon for tomorrow 

[Andrew snow hope]

Looking at the meto vid forecast,  this band comes from north - gets to Wales and then tracks south with more showers coming from the south west direction merging. Should be a good day for the South and south east later in the day. 

[Uncertainty]

Good evening
 

It is quite bizarre that with this anomaly:

It is still questionable whether we will end up with a ‘colder than average’ classification for this winter! I mean come on! Perhaps not quite enough red over Greenland / Iceland but still, one would expect a pretty cold CET with that 500mb analysis...

The final classification for this winter (both in the statistical sense and the judgement of many of the readers of this forum) depends upon the evolution of the pattern into the early part of Feb, which I feel and have felt for quite some time, holds the best chance for a nationwide, highly notable cold spell this winter. But I am still yet to see a convincing evolution amongst the models.

 
A few concerns on this afternoons runs that I hope are rectified ASAP:

- The para has backed off from its wedgey snowy output and pushes the cold well back (gets there eventually but the cold uppers are washed out of Europe by repeated AH incursions and we’re back to square one)

- The 12z GEFS are iffier for big time blocking and cold, with many members getting there but like the para, disappointingly late in the run. 

- The EPS, whilst not short of blocking, still offer little guidance on the expected pattern beyond day 10 and overall, the weather still seems to be coming from the west on most members, though there will be some snowy undercuts in there too.

 

- Other ensembles, such as the NAEFS and GEPs are fence sitting also

So the wait for clarity in the extended range goes on. 
 

A promising development in an earlier timeframe is noted on the EPS for next Saturday:

Last night’s 192

Tonight’s 168

More evidence of a wedge and the low now moves across S U.K. and would bring a risk of snow on the northern side. Remember this is a mean chart so it’s noteworthy.

The 144 UKMO is also toying with a wedge after clearing the low but it looks a little out of place compared to the other models, as it often has at that range this winter, so I’ll note it down in my log as pending 0z inspection.

Finally the 8-14 NOAA chart now has the low anomaly slightly east of the UK,  more snowy chances you would guess, but not a powerhouse Easterly or Northerly.

This has been an frustratingly fascinating winter that has promised so much and sort of delivered. Many parts of the S will get their snow fix tomorrow and there are plenty of chances for winter weather in the short, medium and long term. It just doesn’t feel like it’s truly ‘kicked off’ and, if February fails to deliver the goods big time, it will surely be remembered as a ‘teaser’ winter rather than a classic. 

[stodge]

Evening all

A glorious winter's day here in downtown East London and the question du soir is whether I will see falling snow tomorrow. 

I'm sure that's being debated elsewhere so I'll look further ahead and a milder spell coming from Tuesday lasting, well, that's the thing. Last evening, both GFS and ECM were looking at changes at T+240 which suggested the return of something cool if not cold and certainly not epic cold. There was plenty of that on the far FI charts from both GFS OP (via Greenland) and Control (via Scandinavia). 

On then to tonight's melange or should that be blancmange?

12Z GEM: T+120 takes us to Thursday January 28th. A shallow LP is clearing the north east coast with a strong W'ly flow to its south but a brief ridge upstream with another LP developing to the west in the circulation of a shallow but extensive mid-Atlantic trough centred to the SE of Greenland. Heights persist over Iberia while a residual trough lingers over the Baltic States and Eastern Europe. Mild air with 850s of +4 covers most of the British Isles with only lightly negative uppers in the far north and north-east. From there, the second LP crosses through centre parts while a new LP deepens from the south west and moves first NE and then east crossing Wales by T+180. The British Isles is in a cyclonic flow at that time with tentative heights building into Scandinavia. Mild air persists for most but again the far north remains under negative uppers. Moving on and the LP clears away east but slows to the south of Denmark as the next shallow LP follows it across the south of Britain. Meanwhile, heights are building over Scandinavia and to the north and by T+240 most of northern and central Britain is north of the trough and under an E'ly flow while the trough extends from Northern Germany through the Low Countries to Southern Britain and north west towards Greenland. A sharp temperature gradient across the British Isles by this time with positive uppers confined to the far south west while 850s of below -8  are across most northern and north eastern parts and Shetland is basking in -12 uppers. 

February starts as a real battleground according to GEM with the south remaining mild under the trough and the north turning much colder.

12Z GFS OP - at T+120 not hugely different to GEM except in the immediate vicinity of the British Isles. GFS OP has three shallow areas of LP with once crossing out of eastern Scotland and two approaching from the west. The main Atlantic feature looks shallower than on GEM and perhaps more hint of height rises around Iceland. Mild air covers all the British Isles by this time with +4 uppers over the south west. From there, a series of shallow LP cross the British Isles with the last clearing into the North Sea by T+180 with a ridge upstream from the HP which has eased west towards the Azores. Weak heights also extend south from Iceland and a NNE'ly covers the north of the British Isles with more of a NNW'ly component further south. The milder air mass has been replaced by 850s of zero to -4 by T+180 with uppers of -4 to -8 further north. Moving on, the LP which has come up from lower latitudes extends a lobe of energy east across southern Britain. An attempt to build a wedge of heights from Iceland south fails and by T+240 the Atlantic trough sits to the west with a new LP coming out of the eastern seaboard and a residual trough and some very cold air over Scandinavia. Strangely, the 850s profile ends very similar to GEM with positive uppers over the south west and much of Ireland but with -8 uppers over eastern England and much of Scotland.

 

GFS OP ends less favourable than GEM but I note the colder air mass over Scandinavia and perhaps more heights over Greenland which was the theme of last evening - mid-Atlantic ridge in far FI?

12Z Parallel - we have a Parallel run tonight which is nice. At T+120 less sign of disruption over the UK than on GFS OP or GEM with the lobes of energy ejected more to the NE so the LP is close to the Hebrides at this theme but the core Atlantic trough also seems closer and hints of further secondary disturbances in the flow to the south west. Mild air with positive uppers for most of the British Isles at this time. From there an unsettled couple of days with small areas of LP crossing southern Britain bringing further rain but by T+180 a clean break in the trough with a wedge of heights upstream and a N'ly over the British Isles.  Uppers of -4 to -8 over much of the British Isles but colder air still moving south through Scotland. The N'ly is transient but the heights sink south first as a ridge and then move into Europe as a new HP while the next Atlantic trough is positively aligned to the northwest and by T+240 a flow of SW'ly TM air has been re-established with positive 850s for the whole of the British Isles.

Basically, Parallel ends very poor for cold fans with the SW'ly pattern re-establishing thanks to the infusion of heights into Europe from the north west.

12Z ECM - a very different Atlantic profile than Parallel at T+120. Heights to the east and north east of Iceland have forced the Atlantic trough to align negatively and any lobes of energy are sent more ESE across the British Isles rather the NE as on Parallel. The trough now extends across the British Isles and phases with the residual trough over Scandinavia.  Milder air has reached most of the British Isles but it remains cold with -8 uppers to the far north east. From there, weak heights to the north but they have the effect of aligning the trough negatively so LP are taking a more southerly track crossing the British Isles with the Iberian HP relaxing a smidgen further south. Slack pressure over Scandinavia as well. Milder air has been pushed back to the west with -8 uppers over the furthest eastern counties at T+192. From there, the trough remains close to the south west of the British Isles and by T+240 a new area of LP is approaching Cornwall on an ESE trajectory with a notable nose of HP into Scandinavia by this time. Milder air has pushed back into southern and western areas but it remains cold to the north and east if you are looking for your snowfields (!)

ECM joins GEM and GFS OP in positing a battleground at T+240 and we all know how marginal these can be. Parallel is alone in keeping it mild for all.

Looking further ahead, OP and Parallel at T+312 and T+384 respectively.

The curious thing with far FI output is how often it drags you in - I'd have bet my money (and very nice money it is too) on the OP going cold and Parallel staying mild but the reverse happens. OP snatches mild from what looked an inevitable cold set up while Parallel creates a wintry nirvana (with poor 850s admittedly) from nothing. Control look similar to Parallel but is if anything even more spectacular for coldies by the end of its run. 

Conclusion: - Parallel is the one model keeping it mildest for longest (Control not too different) but the other models are all sniffing around changes within the T+240 window so a shorter lived milder interlude of 3-7 days. GEM tonight is the most favourable T+240 for coldies but both GFS OP and ECM are suggesting synoptic changes which could head down a much colder evolution. In the short term, milder air marches back in during Tuesday and it may even feel a little spring-like by Thursday but it could well be a false dawn - let's hope.

Edited January 23, 2021 by stodge

[bluearmy]

gfs 18z for tomorrow’s snow 


though meteociel has a more downbeat assessment of the snowcover 

Edited January 23, 2021 by bluearmy

[northwestsnow]

BBC long ranger following the EC det

'Staying unsettled through next weekend but pulling in cold air '...

[Mike Poole]

20 minutes ago, Uncertainy said:

This has been an frustratingly fascinating winter that has promised so much and sort of delivered. Many parts of the S will get their snow fix tomorrow and there are plenty of chances for winter weather in the short, medium and long term. It just doesn’t feel like it’s truly ‘kicked off’ and, if February fails to deliver the goods big time, it will surely be remembered as a ‘teaser’ winter rather than a classic. 

The thing with long chases, and this is definitely one, we’ve been on it since weeks before the SSW on 5/1/21, for me, is that they are great fun -provided they deliver in the end.  March 2018 was the classic example of one that did.  Despite having seen nothing but a few polystyrene balls of graupel this year, I am still fully committed to this chase and think it will deliver.  Hope to see snow tomorrow!

And then I look for what is next, and I think the SSW has not gone away, has yet to impact fully and we not be done with warmings yet either, here zonal winds plot:

The MJO may help to get the blocking we want in the trop.  The NAM plot shows the downwelling from the SSW and the hiatus that has so far prevented the blocking patterns developing, but that may be about to change (note GFS 0z forecast);

If the combination of the 5/1/21 SSW and the MJO now contrive to get blocking in the right place, then any further strat warming events may reinforce the pattern.

Meanwhile the ECM T240 mean has a wedges and sliders look about it, a displaced Azores high, and trough into Europe.  So the big picture is all good.

 

[Don]

17 minutes ago, bluearmy said:

gfs 18z for tomorrow’s snow 


though meteociel has a more downbeat assessment of the snowcover 

Bloody Midlands event again!

[Griff]

A bit more amplified down the pub

[bluearmy]

1 minute ago, Don said:

Bloody Midlands event again!

no models will be totally right on this ......

[Don]

2 minutes ago, bluearmy said:

no models will be totally right on this ......

No, will be a case of radar watching and looking out the window, or if you're silly like me, agree to go for a walk at 6.30am and look up at the sky lol!

Edited January 23, 2021 by Don

[MATTWOLVES 3]

4 minutes ago, Don said:

Bloody Midlands event again!

Lol Don, I sense a touch of resentment for us Midlanders...let's not forget it was you that got that big snowfall in 2019..Dont rule out further surprises tomorrow and perhaps on Monday,could becoming colder next weekend also..

 

 

[Mike Poole]

HARMONIE 18z take:

Radar check about 10pm:

Not bad, and there is more significant precipitation to the south of that band than the north, so the onward evolution looks consistent to me.

Edited January 23, 2021 by Mike Poole

[Bricriu]

I think if we were going to get a beast from the east type scenario in February the models would be firming up on it by now.  Still we don't need a beast from the east to get snowy weather. A case in point is the 5cm I had tonight from an Atlantic trough. I think February will be quite snowy at time due to systems sliding under wedges of High Pressure , but no deep cold.

[Don]

1 minute ago, MATTWOLVES said:

Lol Don, I sense a touch of resentment for us Midlanders...let's not forget it was you that got that big snowfall in 2019..Dont rule out further surprises tomorrow and perhaps on Monday,could becoming colder next weekend also..

 

 

Lol Matt!  Not really, just frustrating that I have yet to see any snow (i.e. more than a few flakes) so far this winter and it looked like us southerners were finally going to get our share, without looking at day 10 charts!  Still may  do well tomorrow, but nothing's ever straightforward in this game!

[sheikhy]

2 minutes ago, Mike Poole said:

HARMONIE 18 take:

Radar check about 10pm:

Not bad, and there is more significant precipitation to the south of that band than the north, so the onward evolution looks consistent to me.

Current radar is further north and east and an hour earlier at that aswell!!makes a huge difference in the end i think!

[Mike Poole]

1 minute ago, sheikhy said:

Current radar is further north and east and an hour earlier at that aswell!!makes a huge difference in the end i think!

Nope same time, Meteociel is 1 hr ahead mate!

[saintkip]

1 minute ago, sheikhy said:

Current radar is further north and east and an hour earlier at that aswell!!makes a huge difference in the end i think!

Imbyism It’s gonna pivot over the Basingstoke plateau 

[Griff]

Just for fun on a Saturday nighty, the parallel might provide some entertainment 

[Don]

3 minutes ago, Bricriu said:

I think if we were going to get a beast from the east type scenario in February the models would be firming up on it by now.  Still we don't need a beast from the east to get snowy weather. A case in point is the 5cm I had tonight from an Atlantic trough. I think February will be quite snowy at time due to systems sliding under wedges of High Pressure , but no deep cold.

The models currently don't go far into February and the GFS has already toyed with the idea of a beast from the east.  The GFS sometimes picks up on a trend, drops it and then returns to it.  I don't think deep cold can be ruled out for February just yet.

[Updated_Weather]

9 minutes ago, Mike Poole said:

HARMONIE 18z take:

Radar check about 10pm:

Not bad, and there is more significant precipitation to the south of that band than the north, so the onward evolution looks consistent to me.

Seems very similar to AROME 18z to me

[Bricriu]

Just now, Don said:

The models currently don't go far into February and the GFS has already toyed with the idea of a beast from the east.  The GFS sometimes picks up on a trend, drops it and then returns to it.  I don't think deep cold can be ruled out for February just yet.

I hope so Don. The CFS is still very much suggesting it anyway.

[Don]

3 minutes ago, Updated_Weather said:

Seems very similar to AROME 18z to me

Looks to be quite close to the Metoffice forecast tomorrow.

Edited January 23, 2021 by Don