Model discussion highlights

[Eagle Eye]

There's some chance that the MJO Phase 3 lag could build a Scandi high but imo the amplification won't be strong enough but I'm not ruling it out. I'm not dismissing early February but the cold chance is on the lower end of the scale there. I still think mid-late February may be the best chance given the teleconnection patterns.

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4797539

[Allseasons-Si]

The gefs mean at 150 is starting to show a kink in heights now,...good steps

12z 150 vs 06z 156.

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4797620

[Uncertainty]

Last night we were staring at a period of oblivion - and a very well signposted one at that. As I’ve stated before I’ve had U.K. high —> westerlies —> big block is the progression. But I expected the middle phase to last into the 2nd third of Feb. 

The ecm last night was just about as bad as it gets.

The 12z gfs op last night was completely and utterly on its own. A shining light of hope in an otherwise barren sea of desolate output. 

And yet, tonight, the gfs op (again), GEM and  EC Ops are suggesting an amplified U.K. high - and not one that looks like flattening quickly either. The ensembles aren’t there yet, but have trended in that direction. 

So why the shift? And will it be gone in the morning?

The mjo seems keener to stick in high amp phase 3, I’ve always found p4 promotes flat westerlies in winter. The Paul roundy regressions for Mid Feb are really really interesting, but don’t necessarily explain the present shift.

Could it be the strat? Perhaps - a bit early for a QTR. I don’t know. The strat pattern doesn’t scream exactly trop easterlies though. But what I do know is that if the zonal winds were v strong or strengthening, the block would be far less likely.

I’m very wary of this change. It is incredibly rare to go from this:

To this:

 

But what I do know is: I know which one I’d prefer!

 

 

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4797702

[Cold Winter Night]

Well, just when it seemed that winter chances were slipping away, the interest has returned.
EC at 240h follows a track that is a bit different from 0z and GFS/GEM, but still ends with blocking and a negative tilt on the Atlantic at Day 10.

Considering that these developments appeared on the high resolution runs, and that there was not much like this to be found in the extended EPS ensemble this morning, I doubt if this will be picked up by the EC46 tonight, since that starts off at Day 14 of the regular EPS.
Don't be too disappointed if the EC46 output is underwhelming compared to the 12z high resolution runs.

Could very well be an example of the operationals leading the ensembles.

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4797679

[Singularity]

3 hours ago, Battleground Snow said:

Perhaps this.... Strong amplitude mjo with a 10 day lag.

@Cold Winter Night has touted this already 

Nail on the head here IMO, I’ve been Tweeting along such lines for a few days.

With the usual cautionary notes of course. What we’re seeing is models increasingly resolving a tropically forced pattern that will do battle with the displaced stratospheric polar vortex.

If the former dominates then we likely see either a ‘Sceuro’ high (usually either mild or chilly in UK) or a Scandi high (usually chilly or cold).

If the latter does instead then something more akin to recent ensemble means is more likely although probably not as unsettled in southern UK.

Signals lead models and its in these situations that organisations like the Met Office have more of a propensity to slip up due to high reliance on what the models show as opposed to what the signals suggest they should be showing.

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4797727

[Nick F]

00z EPS Clusters out to day 10, for now. 6 clusters just for added uncertainty, control has more support than det T+192-240. On balance, zonal still looks the favourite, but there is definitely credible support for the scenario of ridge building N or NE over northern Europe in medium range which GFS picked up on yesterday.

Yesterday's NOAA CPC 8-14 day not really buying into the height rises over / near UK though

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4797496

[mushymanrob]

Well the current anomalies are clear.... Early February is looking very unsettled with a strong Westerly feed, unsettled and stormy is still the expected pattern and theres zero heights over Scandinavia.

Theres no sign of an Easterly here in fact these charts are about as far as they could be from allowing one.

It would be highly unusual for a FI GFS run to be more accurate than these.... but stranger things have happened.

Actually, the EPS by feb 10 is very similar to previous EPS charts we had before the recent cold spell.. so IMHO if theres any chance of a cold spell, then itll be a repeat performance of the recent, with low dropping over us and ridging building to our West. However in early January the TPV wasnt as strong as it is now.. As i see it, theres no chance of an Easterly , if we get another cold spell itll come via the North as the last one did.

edit...i see Nick has posted whilst i was composing...

 

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4797498

[Kirkcaldy Weather]

More on the MJO in phase 3, phases 2 + 3 are the Indian Ocean segments and as the MJO moves through these phases that indicates an increasingly active weather setup across the Indian Ocean such as tropical waves + cyclones. Right on cue 

Live tracking of Cheneso here 

TROPICAL CYCLONE CHENESO Tracker | Cyclocane

WWW.CYCLOCANE.COM

More really fun modelling commencing as the phase 3 input becomes clearer

 

 

 

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4797705

[Mike Poole]

Clusters still pretty intermittent whether we get them or not.  No chart for T120 to T240, but the extended T264+ is available:

So - the scandi high signal then.  Clusters 2 and 5 have promise, so that’s 10+6=16 members.  Cluster 4 wouldn’t take much of an adjustment either, another 6.  So there is now a reasonable and growing, but still minority, signal for building a high through the UK into scandi somewhere.

Note, that this is not the straight link up over the arctic with the pacific ridge from Wednesday’s GFS 12z - that was rightly dismissed as being highly unlikely, and is not on the table, but a less specific build of heights to our NE very much is on the table.

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4797895

[Cold Winter Night]

1 hour ago, Mike Poole said:

Clusters still pretty intermittent whether we get them or not.  No chart for T120 to T240, but the extended T264+ is available:

So - the scandi high signal then.  Clusters 2 and 5 have promise, so that’s 10+6=16 members.  Cluster 4 wouldn’t take much of an adjustment either, another 6.  So there is now a reasonable and growing, but still minority, signal for building a high through the UK into scandi somewhere.

Note, that this is not the straight link up over the arctic with the pacific ridge from Wednesday’s GFS 12z - that was rightly dismissed as being highly unlikely, and is not on the table, but a less specific build of heights to our NE very much is on the table.

The EPS 192-240h cluster charts are available now.

The UK-Scandi High clusters (2,3,4) contain 30 members on that range, a majority therefore, up from 23 on yesterday's 12z (ensembles are not a democracy though).
Cluster 5, although flat, is not the worst outcome, as it drives the NW-SE deep into SE-Europe, leaving some possibilities for modest Pm shots and Scandi height developments later on.

The De Bilt 2m plume has cooled a bit in the 9-15 day range, more members with frost due to those heights nearby. Generally near average.

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4797909

[Catacol]

28 minutes ago, bluearmy said:

The end of the gfs run has a downwelling  reversal wave signature and the timing is more in line with what might be expected following current events in the upper strat 

Now to look out for eps members  playing with this pattern and timing … 

Yep - outer edges of GFS is likely to be the best place to look for cold at the moment because I don't see much other than westerly dominated weather over the next 2 weeks at least. I'm going to hunker down and get through to the first round of the Six Nations and launch my consciousness at the one week's holiday coming to me in the middle of February and try and switch off from the weather for a bit. Even in our best winters (bar 62/63) we know westerlies dominate numerically and are never far away - so while it is disappointing to see a flattish spell it goes with the territory for us. Strat disruption has not fallen kindly (and precursor pattern has gone), pacific drivers not helping, ENSO/QBO/Solar from a seasonal perspective not in the right zone either. AAM now firmly heading negative too, a sign of reducing amplification

Anomaly chart remains solidly westerly

If anything changes, I'll be back.... 

Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4797917

[johnholmes]

EE, even I am not that daft.

I have a hazy idea of 15-25 days being the time scale?

Original post: https://community.netweather.tv/topic/98326-model-output-discussion-into-february/?do=findComment&comment=4798303

[Eagle Eye]

1 hour ago, feb1991blizzard said:

here we go - round 2, wonder if this is caused by an E.Asian mountain torque event - response to MJO phase 3?.

Looks to be linked with the vertical drive of thermal Eddy's linked with the UK-Scandi Rossby pattern. GIven the circulation of the Earth and time it will likely take to transport that mass through Brewer-Dobson Circulation in the Stratosphere generally making distribution of planetary Waves including Wave breaking fairly slow. So quick response between Mid Trop and Upper Trop followed by a slow rise from the lower Strat to the upper Strat.

Original post: https://community.netweather.tv/topic/98326-model-output-discussion-into-february/?do=findComment&comment=4798464

[bluearmy]

looking at the at zonal flow today through the whole NH atmosphere from top to bottom 

I’ve drawn some stuff on the right image to help people understand what the chart shows. Blue/purple  is neg and green, yellow,red is pos. 

of course this shows the nett flow around the whole NH which means you still need to refer to the output to see where the troughs and ridges are. Whilst we don’t have an east to west flow at 60N 10 hpa, (marked with ssw ring) , we do at a higher latitude (hatched) 

Whilst we don’t have a tech ssw, we will see consequences in the trop from this reversal of flow over the next month -  even if it’s the perpetuation of stronger flow at our latitude. I would be looking at the polar high currently establishing from the big ridge n of Alaska as being the most obvious consequence for the time being 

     

Original post: https://community.netweather.tv/topic/98326-model-output-discussion-into-february/?do=findComment&comment=4798582

[bluearmy]

9 minutes ago, Purga said:

Ueber Vortex

Looks like there will be no SSW in february tbh. To achieve that you need mean zonal winds at 60N to reverse and no model indicates this despite the warming at 10hPa.

There are indications that we could see another effort approaching mid month. Repeated gfs runs are also showing that the recovery of the spv will not be as strong as looked likely with n scandi displacement (again) as week two progresses. However, the mid to lower strat 55/70N continues to look stronger than average with the weaker upper vortex having forced the westerlies down. 
 

I would bookmark around 14 days if the scandi ridge is to see a meandering cold pool reach us.  The odds as high as  20% imo, 

note that the developing polar high has prevented the behemoth Canadian tpv that looked likely to occur. hence we see a split signature continue as has been the case for most of the winter.  The upstream tpv is still way too strong to allow any HLB to establish west of the meridian for the next ten days at least.  mid lat high seems a safe bet to see out the first week at least of feb.

the extended clusters have inevitably broken down from the 12z binary appearance with more nuances on the Sandi/sceuro ridges 

Original post: https://community.netweather.tv/topic/98326-model-output-discussion-into-february/?do=findComment&comment=4798575

[mushymanrob]

45 minutes ago, ANYWEATHER said:

Just would like anybodies thoughts on the projected stormy period,  which really does look like not happening? 

Yeah, it keeps getting put back... IMHO the anomalies had suggested it turn stormy and i posted charts (EPS) to support that. But high pressure to our near South is now looking more dominant, and despite some EPS charts suggesting low pressure and very mobile conditions nearer to mid month, these havnt gained support and the high looks like hanging on.

The more reliable NOAA do suggest a mobile pattern, but with a positive height anomaly over the Country doesnt suggest to me stormy. This chart suggests mainly dry and on the milder side of average, with the Atlantic systems tracking North of the UK.

Original post: https://community.netweather.tv/topic/98326-model-output-discussion-into-february/?do=findComment&comment=4798595

[Cambrian]

The problem with looking for a period of influence from a Scandinavian high this winter is that we’re very likely being teased. Fair enough, we’ll occasionally see a sustained build of heights centred over Denmark, sometimes a bit further north, but this is part of a continuous belt of heights stretching from the eastern half of North America, all the way to Siberia…

 

and with a healthy lobe of PV centred between Baffin Island and Greenland, this only translates into a gentle Azores influenced pattern, the resilient high there to our southwest is looking very happy with itself on the day 10 0z ECM (above) and 6z GFS ensemble means.

 

Whether it’s the jet-fuelled fast road into northern Scandinavia, or the slow road under the pan-Atlantic heights to our part of the world, things are only going to head west-east. 

The feed into the middle of the UK and Ireland at day 10 can be traced back to the eastern United States. Throughout this winter, we have experienced relatively short periods of this “warm” Atlantic mean feed, just a few days at a time at the periphery of an anticyclone to our south, - invariably “failed Scandinavian highs”! 

True to form, by day 15 we see the feed bending back north, originating from the Canadian Arctic, supported by the GFS too at day 16.

  

Previously this winter, as the North Atlantic trough has moved west, this has then often progressed first to a mean feed from Greenland, and we’ve been fortunate this year with the Siberian lobe of the PV offering support by dropping troughs down the Norwegian Sea, pulling the Atlantic trough east and giving us spells of more northerly cold. 

There is no such definite support on offer this time at day 15/16. However, the 6z GFS mean is beginning to draw lower heights back over the top of Svalbard towards the Kara Sea. There is of course a huge problem in residence by then though in the form of the European high, 1010-1025 mb the order of the day for the UK and Ireland. 

 

Looking for chances of colder weather, this might appear grim, indeed very grim. On the face of it, we’re in the worst possible place - teased by WAA into Scandinavia, looking for a build in heights there (that would be great to see deliver, but won’t) - these heights will much more likely instead flatten south into a European high, paradoxically being framed by cold air reaching out of China to the Caucuses and the “wasted” cold air pushing south into the Atlantic. 

Three slightly more positive observations. It hasn’t really been a season of extended European highs; it’s nowhere near the same strength of high pressure that we were looking at last January; and when the models have changed tack before now this winter, the change has tended to appear “suddenly” at day 8 - 10. 

I’d be very surprised if the models were this flat by next weekend. Though there is no great evidence of any PV help from Siberia soon, there is just a hint of lower heights re-forming all the way along the north of Eurasia by day 16, and quite a change on the means and anomalies from day 10. The low heights over Greenland at day 10 have pushed south into the Atlantic, broken the pan-Atlantic heights and are beginning to bear down on the European heights, pushing them southeast. 

A progression of this trend could well see a degree of recovery of the Siberian lobe of the PV and a link up with the Atlantic trough as it pushes into Europe. With the lobe of PV over Greenland easing somewhat, another spell from the north by mid-month, or very soon after, might well be a decent possibility.

Original post: https://community.netweather.tv/topic/98326-model-output-discussion-into-february/?do=findComment&comment=4798692

[Cold Winter Night]

2 minutes ago, LRD said:

Feb 1991 just goes to show you can have a strong PV over Greenland and still get cold

Not just February 1991.

Nearly all great cold spells (Scandi-type) start off with a strong PV over Greenland, because that PV drives the powerful WAA a solid High over Scandinavia needs. It's usually what happens over the European continent what makes the difference (CAA or flattening).

Here are just a few snapshots from 1942, 1947 and Dec 1962 (not coincidentally the 20th century winter Top 3).

Just looking at Greenland they all seem ominous.

(Note: I am NOT saying we will see anything like this...)

Original post: https://community.netweather.tv/topic/98326-model-output-discussion-into-february/?do=findComment&comment=4799215

[Mike Poole]

ECM clusters show a dramatic improvement tonight.  Maybe expected given ECM and GEM - UKMO looked very good too, so maybe there is something in this idea of evolution to a scandi high.

T120-168:

The ridge very strongly supported at T168, variations on a theme, op in cluster 1.

T192-T240:

Full house of red borders here, op is in cluster 3 but cluster 2 also very good.

T264+:

Orientation and position of the high are of course to be determined, cluster 1 looks excellent with 22 members, cluster 2 also good.  Cluster 3 is the +NAO one, that’s down to 13 members.  

This is a high risk evolution in my view, but it has happened in the past as @Cold Winter Night has posted, so we’re right back in the game with something exciting to watch on the models!!

Original post: https://community.netweather.tv/topic/98326-model-output-discussion-into-february/?do=findComment&comment=4799232

[Cold Winter Night]

With this EC 240h chart there is hope after all, with decent support from the other models.
Developments are not unlike February 1991, with that Scandi High not super strong and the low heights in SE Europe:

 

Original post: https://community.netweather.tv/topic/98326-model-output-discussion-into-february/?do=findComment&comment=4799194

[Cheshire Freeze]

2 minutes ago, RainAllNight said:

Interesting wall running through us!

I'm going to go for broke here - is the 'stratospheric final warming' also the reason for northerly and easterly winds at the surface being more prevalent in April and May than in any other months?

It's part of it yes.

If you can get an early enough final warming, the cold that has 'bottled up' throughout winter has to drain somewhere into the mid latitudes. Obviously this is moderated by surface heating (more and more the further into spring we go) but we can still get some falls of snow and some notable cold comparable to the time of year.

Original post: https://community.netweather.tv/topic/98326-model-output-discussion-into-february/?do=findComment&comment=4799313

[feb1991blizzard]

Strat is burning, charts are turning,

Merry Easter every one,

we're gonna have a party tonight.

Original post: https://community.netweather.tv/topic/98326-model-output-discussion-into-february/?do=findComment&comment=4799411

[nick sussex]

There are still early differences between the models .

The GFS has a trigger shortwave and at the same time takes that low south Greenland ne and this becomes absorbed .

You can see that here . 

Day 4 low pressure is heading ne , shortwave energy is about to be ejected se.

Day 5 that low has become absorbed , the trigger shortwave is ejected se.

The ECM handles this differently .

Day 4 you can see that low pressure south Greenland , this is moving east .

Day 5 that low has moved east .

We don’t want a middle ground solution here .

So either an early trigger shortwave or the low clearing east with decent clearance between that and the upstream troughing .

Original post: https://community.netweather.tv/topic/98326-model-output-discussion-into-february/?do=findComment&comment=4799437

[Cold Winter Night]

Very interesting times in model output land.
There is cross model agreement that these potential Euro-Scandinavian heights will be located at a higher latitude than foreseen just a couple of days ago.

Compare the EPS clusters from last Saturday's 0z to today's 0z for Friday, February 10 (then Day13, now Day 10):
Positive height anomalies are located further North and Northeast now, and the trough into Eastern Europe has 'curved back' much more to form Low heights in SE-Europe.

These new developments may make it difficult for coldies to contain their enthusiasm, this thread is alive again, but do keep in mind that at this moment the very cold runs and ensemble members we get to see do not represent the majority yet.

A good sign is the wind direction chart for De Bilt, where the South winds that were associated with a High at lower latitude have been replaced by NE/E/SE winds, due to the higher latitude of the High. They now build an ensemble majority around Day 10:

The deepest cold, bringing ice days to Holland does not convincingly make it this far West yet; the Op is clearly one of the coldest on the De Bilt T2m plume:

The mean around Feb 6/7 is down 5 degrees from just 3 days ago, so that's good.

We're heading in the right direction for cold, the Operationals are tasty, but I'd still like to see upgrades in the ensembles as well.

Original post: https://community.netweather.tv/topic/98326-model-output-discussion-into-february/?do=findComment&comment=4799545

[johnholmes]

I was just thinking of the post I made some days ago about rapid T rises on the 30 mb pole chart. 15-25 days was what I seem to remember for cold weather to develop over the UK, SOMETIMES;  Just a thought. The 500 mb charts at the moment do show a developing ridge east of the UK, bit far south, but the last 8-14 day did give a SLIGHT slight suggestion of a nnw-nne trend. No more than 25% I would say at the moment but it is there.

Original post: https://community.netweather.tv/topic/98326-model-output-discussion-into-february/?do=findComment&comment=4799669