Model thread discussion - cold spell looming

[weathercold]

9 minutes ago, Catacol said:

Impacts of the SSW timed with pacific developments. All good.

But the tricky bit is going to be getting a proper nationwide snow event. It’s been a fabulous winter really, it just needs that major event to anchor it. Storm Darcy is only clipping the SE after looking initially like it might push further north. IMBY the 3rd narrow miss by about 40 miles. Shower streams will do well in some parts - but I really want everyone on this board to get their cut. My dad lives near Dundee - he confirms that this winter has seen more snow than they could possibly wish for up there. Meanwhile some parts of the south have remained green pretty much throughout. I’m hoping we can get this block aligned in order to create a Feb 91 style setup. But it may not happen. Truth is - the macro patterns have clicked well this season. For the south the micro ones have been a bit stingy.

On we go. Fingers crossed. At least mild and wet isn’t on the cards.

Could you explain for us amateurs how the block needs to align for a feb 91 style set up? The current projections look freezing but v dry with high pressure in charge post this week. Thanks 

[Johnp]

2 minutes ago, weathercold said:

Could you explain for us amateurs how the block needs to align for a feb 91 style set up? The current projections look freezing but v dry with high pressure in charge post this week. Thanks 

We're not a million miles away to be honest. Here's the Feb 91 chart

 

[Cold Winter Night]

4 minutes ago, weathercold said:

Could you explain for us amateurs how the block needs to align for a feb 91 style set up? The current projections look freezing but v dry with high pressure in charge post this week. Thanks 

I suppose for a Feb 1991 style set up it should align like Feb 1991

That would be like this:

GFS is not far from it.

[Howie]

19 minutes ago, Catacol said:

Impacts of the SSW timed with pacific developments. All good.

But the tricky bit is going to be getting a proper nationwide snow event. It’s been a fabulous winter really, it just needs that major event to anchor it. Storm Darcy is only clipping the SE after looking initially like it might push further north. IMBY the 3rd narrow miss by about 40 miles. Shower streams will do well in some parts - but I really want everyone on this board to get their cut. My dad lives near Dundee - he confirms that this winter has seen more snow than they could possibly wish for up there. Meanwhile some parts of the south have remained green pretty much throughout. I’m hoping we can get this block aligned in order to create a Feb 91 style setup. But it may not happen. Truth is - the macro patterns have clicked well this season. For the south the micro ones have been a bit stingy.

On we go. Fingers crossed. At least mild and wet isn’t on the cards.

Yess, seriously want that snow event for everyone 

[Mike Poole]

25 minutes ago, Howie said:

It sounds like an amazing spell of weather coming up. And oh I've been right there with everyone chasing it

It’s been quite a ride in terms of model watching.  Especially since we cant go on any actual rides!  probably beats 2018 now.  2018 was a huge model watching effort to see the preludes to the SSW, and then the fallout as it downwelled into march. But this year is more, to start with it’s earlier, so more of winter left.  But it also hasn’t been as simple downwelling, will it, won’t it?  Now it will!  We need no longer watch the stratosphere, the action is finally close to home, and will be for the next month, maybe month and a half, I would suggest.

[Methuselah]

4 minutes ago, CentralSouthernSnow said:

The charts don’t show snow though! 

As much as love snow, snow is the only reason I put up with cold... If it's nae going to snow, the cold weather had better just do one!

[Bricriu]

3 minutes ago, General Cluster said:

As much as love snow, snow is the only reason I put up with cold... If it's nae going to snow, the cold weather had better just do one!

If the High goes to Greenland, presuming it does not go too far west, the snow will come again.

[Mike Poole]

ECM mean T168:

Confident signal into scandi high now, T240:

Retrogression signal there too...I think that is the path folks, just need to count it down, meanwhile enjoy the snow those who have had it!

[Howie]

8 minutes ago, Mike Poole said:

It’s been quite a ride in terms of model watching.  Especially since we cant go on any actual rides!  probably beats 2018 now.  2018 was a huge model watching effort to see the preludes to the SSW, and then the fallout as it downwelled into march. But this year is more, to start with it’s earlier, so more of winter left.  But it also hasn’t been as simple downwelling, will it, won’t it?  Now it will!  We need no longer watch the stratosphere, the action is finally close to home, and will be for the next month, maybe month and a half, I would suggest.

I'm definitely enjoying it .  And you wouldn't think I would seeing as I was born in Jamaica

Edited February 7, 2021 by Howie

[Battleground Snow]

Definitely scope for the high to get further  north on future runs, we don't want it too far north though,

You can see why getting -18 to ours shores is so difficult and rare, everything has to align perfectly.

Edited February 7, 2021 by Battleground Snow

[Bricriu]

5 minutes ago, Mike Poole said:

ECM mean T168:

Confident signal into scandi high now, T240:

Retrogression signal there too...I think that is the path folks, just need to count it down, meanwhile enjoy the snow those who have had it!

Do you think this is due to the MJO  going to phase 8? Also is there a danger the high goes too far west , if that's the case?

[Howie]

2 minutes ago, Battleground Snow said:

Definitely scope for the high to get further  north on future runs, we don't want to too far north through,

You can see why getting -18 to ours shores is so difficult and rare, everything has to align perfectly.

Wow that's a huge spread

[geordiekev]

5 minutes ago, Bricriu said:

Do you think this is due to the MJO  going to phase 8? Also is there a danger the high goes too far west , if that's the case?

If it goes west there's chance of a blocked Atlantic in strong Arctic flow, as per gfs 0z output today.

As posted further up Dec 2010 was even farther centered over Greenland.

That's the beauty of these outputs, they are all variations of a prolonging cold theme

Edited February 7, 2021 by geordiekev

[Man With Beard]

A real time model related question, can NE folks help?

Which is right? - the radar 

or the models?

 

 

 

[Bricriu]

2 minutes ago, geordiekev said:

If it goes west there's chance of a blocked Atlantic in strong Arctic flow, as per gfs 0z output today.

As posted further up Dec 2010 was even farther centered over Greenland

So almost 2010 redux?? Stop my beating heart. That would be brilliant if it came off!

[Mike Poole]

Just now, Bricriu said:

Do you think this is due to the MJO  going to phase 8? Also is there a danger the high goes too far west , if that's the case?

No I don’t think that is a problem at the moment, MJO in Phase 7:

I take it you are thinking about the first BFTE in 2018 when the high looked like sticking around and then scooted off west without so much as a wave goodbye?  Don’t think it will happen this time.  

MJO is not the whole picture, AAM forecast above average for the next two weeks, so get all of that together, then there are background signals for a more amplified jet in our vicinity for a while yet, so plenty of scope for the weather to follow the imprint down here of the SSW events earlier.  AAM plot:

While I am about it, North Sea SSTs above average still, should help with all those streamers....

Colder out west, not bad either, but i doubt the weather will be coming from there for a fair while

[geordiekev]

6 minutes ago, Man Without Beard said:

A real time model related question, can NE folks help?

Which is right? - the radar 

or the models?

 

 

 

Believe me after years of narrowly missed White Christmas bets, the naked eye is sometimes the only best bet, though the bookies use radar to settle rather than someone on a roof with a hand out on triple time. Something i discovered haggling with Corals but my screenshot of the pink stuff over Boulmer was enough to pay me

Edited February 7, 2021 by geordiekev

[geordiekev]

6 minutes ago, Bricriu said:

So almost 2010 redux?? Stop my beating heart. That would be brilliant if it came off!

Yep this was the blocked Dec 2010 outlook and a bit of Amplification & retrogression would make it plausible.

Dec 2010

[SqueakheartLW]

Give me GFS 12z Member 11. Keeps the cold in for the longest of all

Coldest point of GFS 12z Member 11

If not GFS 12z Member 11 then I'll take either of these runs from the GEM 12z. GEM 12z Member 15 or Member 7

GEM 12z Member 15 - Coldest point

GEM 12z Member 7 - Coldest point

Between all 3 of those runs the GEM 12z Member 7 I feel is the best one as it is the coldest of all of the featured runs and is the only one that keeps things cold right out to 384 hours away

Other fantasy cold charts from both GFS 12z and GEM 12z

[bluearmy]

Plenty of encouragement from the eps clusters ..... no strongly favoured options but no way is anyone taking a few days off from here over the next week ! 

[cragonmore]

48 minutes ago, Man Without Beard said:

A real time model related question, can NE folks help?

Which is right? - the radar 

or the models?

 

 

 

MWB I’m just north of Dundee and can confirm your first 2 pictures/charts (radar) are most accurate to what’s happening right now. 

[Mike Poole]

7 minutes ago, bluearmy said:

Plenty of encouragement from the eps clusters ..... no strongly favoured options but no way is anyone taking a few days off from here over the next week ! 

Struggling to download the clusters, to post them, that usually means they are X rated, try again at 9pm...

Do you know, I think when ECMWF made all this data available, they might not have considered the fact that lots of people might have wanted to look at it.  The likes of netweather and meteociel seem to have this fixed!  

Edited February 7, 2021 by Mike Poole

[stodge]

Evening all

A memorable snow day for a few, a disappointment for some. Here in lowland East London, a bleak overcast day with occasional rain, sleet and snow and temperatures falling back close to freezing. I don't know if we'll get more snow overnight or tomorrow - that's a discussion for a regional thread.

Looking further ahead, some excellent model output yesterday evening hinted at an extension of the cold spell into next weekend and perhaps beyond but a variety of evolutions - so much depended on the Scandinavian HP "behaving itself", remaining in situ and heading WNW rather than sinking south or retreating east.

T+120 takes us to Friday 12th, T+240 to the 17th, T+312 to the 20th and T+384 to the 23rd February.

12Z GEM: at T+120 and intense HP (1045MB) sits over central southern Norway with a ridge north west toward Iceland. A large LP sits positively aligned in mid Atlantic but well to the west and north west of Ireland. Another LP sits over the Ukraine. A SSE'ly air flow covers the British Isles at this time. Milder air with positive uppers has reached Cornwall and south-west Ireland but uppers remain -4 to --8 over most of the British Isles with pockets below -8 over northern England.  From there, the Atlantic trough tries to move in to the British Isles but is held at bay and by T+180 has withdrawn north-west towards southern Greenland. The anticyclone persists over Scandinavia with further heights re-enforcing from the south. Winds remain from the south or south east over most of the British Isles and this has drawn in less cold air with uppers generally either ide of zero by T+180.  From there, the anticyclone gradually sinks into Europe and by T+240 is centred over the Czech Republic but a ridge extends back over the south of Britain as the Atlantic LP starts to try to move NE round the top of the HP towards the north of Scandinavia. Uppers remain either side of zero generally with the mildest air in the south and the coldest in the north.

A disappointing start to the evening from GEM which largely follows the ECM evolution from last evening and suggests the HP won't retrogress but will eventually collapse south allowing the trough to in time move round to the north.

12Z GFS OP - by T+120 a large HP (1040 MB) is centred over south western Norway and Denmark and a strong SE'ly air flow covers most of the British Isles with any Atlantic influence confined to the far west of Ireland with an intense Atlantic trough to the south west of Iceland. Uppers remain below -8 over most northern and eastern parts with less cold air just getting into the far south west of Britain and Ireland by this time. From there, the Scandinavian HP intensifies further and re-orients to a classic SW-NE pattern over north-central Scandinavia. The Atlantic LP starts to align negatively as it tries to approach the British Isles and the SE'ly air flow persists over most parts. The brief push of milder air is halted and reversed so that by T+180 much colder air is back over most parts with uppers generally -4 to -8 and below that in eastern areas.  From there, the fun and games really starts - the Scandinavian HP pushes an increasingly cold air mass over the British Isles but then itself starts to move NW to be just to the east of Iceland by T+240. The Atlantic trough has been forced south east by the block and one part of that energy has passed to the south of the British Isles and is centred over the Gulf of Genoa. Meanwhile, another storm system from lower latitudes has phased with the colder trough and formed an intense storm system which at T+240 is far to the south west of the British Isles. A brief flirtation with -16 uppers notwithstanding, it remains cold over much of the British Isles though slightly less cold in the far south and uppers below -8 confined to northern Britain.

Decent - very decent - in fact bloody brilliant if you are a cold fan and a snow fan for parts of the south with a Beast Reload for the early part of the week after mid month and a brief taste of -16 uppers which we've not seen for a fair while.

12Z Control - as might be expected, at T+120, Control follows the OP closely. On to T+180 and while the Scandinavian profile remains the same, the Atlantic profile is different with a intense LP in mid ocean after one storm passes from south to north well to the west of Ireland. The colder air is marching back in from the east with uppers below -8 over eastern and south eastern England and 850s just negative further west. Unlike the OP,  the more intense storm does push the block back a little and the block starts to move NNW out of Scandinavia which in turn blocks the cold flow from the east and allows another push of milder SW'ly air into western areas. Uppers are largely below negative but the coldest air is now over northern and north eastern parts with milder air approaching from the south west.

Control is let down by this monster mid-Atlantic storm which is strong enough to dislodge the block and break the cold flow from the east. 

12Z ECM - this was the disappointment of last evening sinking the Scandinavian HP early and allowing the mild air back rather quickly. Let's see if it can do better this evening.  I suspect not.  By T+120, the stand off is in place with the HP over south west Norway and the positively aligned Atlantic trough far to the west. Uppers remain below -8 over eastern Britain but milder air has already arrive din the far west of Ireland with positive uppers returning. From there, the evolution looks a whole lost better than last evening with the Scandinavian HP growing in intensity and the Atlantic trough disrupting completely with a small residue of energy to the far south west as a new storm emerges at T+192 from the eastern seaboard. The HP extends across to the north east of the British Isles with a chill ESE'ly flow, strongest over southern and western Britain by this time. Uppers are negative elsewhere with the coldest air (850s below -8) over eastern and south-eastern England.  Moving on and the HP remains firmly in charge and by T+240 it is centred over the Faeroes looking lie it will retrogress to Greenland. A cold ESE'ly continues across the south with a weak LP over Iberia and a negatively aligned Atlantic feature far to the west.  A final push of cold has been mitigated somewhat by T+240 as the air is now being sourced from south east Europe rather than points further east.

ECM actually ends less cold (surprisingly) vet hardly mild, It's not quite as good an evolution as GFS OP but still decent.

Looking further ahead, T+312 and T+384 from OP and Control to end proceedings for the evening:

Both interesting and neither what you'd expect for mid to late February in a "normal" winter. 

Conclusion: the Scandinavian HP is going to play a big part in the evolution from the end of the coming week onward. GEM and to an extent GFS Control are a little disappointing but both ECM and especially GFS OP use it to maintain a cold pattern for several more days especially for eastern areas. Indeed, we could get a second "bite" of the cold cherry in a few days but this will be more about cold and less about snow I suspect. GEM and Control hint at a more traditional breakdown but it could be something less common such as a "different" E'ly or indeed no breakdown at all. I don't rule out a brief milder incursion into western areas at the end of the coming week but as the HP takes over the cold might well return from the east albeit not as we are seeing now but a drier cold. We've come a long way since Tuesday with ever ynight showing incremental extensions to the cold spell. It's been quite a ride.

[Scott Ingham]

1 hour ago, Mike Poole said:

ECM mean T168:

Confident signal into scandi high now, T240:

Retrogression signal there too...I think that is the path folks, just need to count it down, meanwhile enjoy the snow those who have had it!

I agree this pattern fits perfectly with my thinking as well. Still think theres scope to get that 168 chart further north west when it comes under the t-120 range. Tuesday 12z is the next big day in my head for upgrades

[Mike Poole]

Wheyhay, I got the clusters T192-T240:

Pick the bones out of that!  

Seriously, look at that low in the Atlantic, on most of them it just doesn’t budge, feeding WAA, that is all.  This is just 6 ways of saying we’ve got a long period of high latitude blocking and cold weather.  Eastern promise...

Edited February 7, 2021 by Mike Poole