Model Output Discussion - Into Winter

[Tamara]

1 hour ago, Singularity said:

Overall the modelling has drifted from a Nino like MJO phase 4-5-6 response (ridging W Europe to Siberia) toward a neutral ENSO one (Atlantic ridge, attempts to dig a trough into Scandi), but GFS more so than GEFS and still more so than ECM & it’s ensemble. A key matter that needs resolving.

That is to be permed with the GWO to provide the full wind-flow budget response from both tropics & extra tropics.

The GWO is struggling with amplitude in Phase 4 but surely a matter of time before a kick to the Nino attractor phases occurs. The extra tropical responses to the Pacific wavetrain continue to be modelled by NWP less buoyantly than expected. The current modelling wants to try to repeat the sequence of a few weeks back of Atlantic ridging replacing the trough A low angular momentum signature.. Based on the progression of tropical forcing through the Pacific & associated rise in momentum tendency, this more Nina-esque synoptical response seems counter intuitive on any sustainable basis.

So this mornings ECM makes more sense than the US modelling - retaining an element of height rises across mainland and NE Europe & the trough resetting to the NW. This would be a precursor to split flow/sub tropical flow returning and attempting to send the jet stream south of the UK and a thermal gradient setting up. Anomalously warm, moist & humid for my part of the world, cold dense air making inroads from NE Europe towards UK and the rest of NW Europe.

With that in mind I remain sceptical about the lack of sub tropical forcing which has flirted with thinking about interacting more with the blocking this past week. This momentum response cannot remain AWOL too long based on the upcoming tropical > extra tropical forcing. So a large mid Atlantic/mid latitude ridge and heights falling over Scandinavia is not intuitive to stick around like the GFS is modelling. Unless something rather unexpected happens across the tropics to derail the wavetrain and the angular momentum response, again, somehow falls short..

[That ECM]

8 minutes ago, Tamara said:

cold dense air making inroads from NE Europe towards UK and the rest of NW Europe.

That bit I understand. 

[bluearmy]

Looking through the eps ens in two weeks says that we are very likely to see amplification but whether that’s to the west over us or to our east remains the question. note the gfs op again heads towards the same broadscale solution as yesterdays 12z and 18z

[Ali1977]

GEFS at day 9 look much more interesting this morning, several more with blocking attempts to our N/NE  - hopefully even better further down the line.

If we are heading much more favourable with global influences by mid month, I expect the ENS and ops will flip colder in the next few days as they work all that out. I think we’ll be dinging out the winter Woolley’s again by 16/17th!! 

Edited December 5, 2023 by Ali1977

[Mike Poole]

27 minutes ago, bluearmy said:

Looking through the eps ens in two weeks says that we are very likely to see amplification but whether that’s to the west over us or to our east remains the question. note the gfs op again heads towards the same broadscale solution as yesterdays 12z and 18z

Yes, not much interest up to day 10, not expected really, but beyond that the EPS seem to favour any blocking to the NE, here are the extended clusters:

Clearly favouring the Scandi block (red border) regime over the others.  Cluster 3 looks very good, one to watch.

[TEITS]

Overall a disappointing set of model runs. A rather unsettled spell of weather until at last mid Dec looks on the cards. Beyond and a hint we may see much colder weather via N,ly towards Xmas. However as per usual the GFS does tend to produce incredible cold synoptics at +384.

Sorry for being a misery but my normal methods of looking for signs of a cold spell are at the moment disappointing. The Iceland SLP mean does not suggest any blocking in that area with the mean dropping to 995mb.

Even the likes of Helsinki & Oslo have a 850hpa mean of only -5C. This suggests the mobile W,ly pattern will affect even these areas.

[PiscesStar]

1 hour ago, fromey said:

A little bit of warming beginning to show now

Is that the Canadian one? 

[Ali1977]

3 minutes ago, Mike Poole said:

Yes, not much interest up to day 10, not expected really, but beyond that the EPS seem to favour any blocking to the NE, here are the extended clusters:

Clearly favouring the Scandi block (red border) regime over the others.  Cluster 3 looks very good, one to watch.

That’s a huge amount of blocking on cluster 3 and 5, I’ll order those please

[Downburst]

The ECM MJO for Day 10, the mean line is now above the COD area for phase 6, whereas yesterday and a few days before it flirted with below. So phase 6 period is adjusting and it it continues we might see more towards the end of the GFS runs at least and perhaps shortly the 10 day ECM. Remember the higher the amplitude the more skill the forecast has historically, so maybe once the next 5 days finish we might get more consistency. 

In saying all this, I am thinking, at least at the surface, that Canadian (+10c and corresponding Siberian -10 c temp anomaly this week is so strong, one has to wonder surely that will have more effect than anything else? 

 

Also, over the last few days the 10hpa anomaly over the pole has really strengthened each run for 1st week of January. Although I won't hazard a guess (mini ice age end of January ) how and when that might effect us, especially so far out from even happening, but that's a strong signal all the same.

 

[Dennis]

next week ... with love from scandi (maybe)

.

but this could  be a hammer from 20th

[fromey]

37 minutes ago, PiscesStar said:

Is that the Canadian one? 

I believe it is

[bluearmy]

Ec seasonal update referenced on the winter thread 

[Jacob]

There's somewhat of a cluster, just below -5 after mid December which may suggest a colder period at this time 

[Nick2373]

The trend continues from the 14th onward for something dryer, close to average temps one to watch. 

[Ali1977]

A blocked Jan and Feb according to the ECM - I’d take that after a cold Xmas and new year!! 

[sebastiaan1973]

A good update from ECMWF.

[bluearmy]

9 minutes ago, Ali1977 said:

A blocked Jan and Feb according to the ECM - I’d take that after a cold Xmas and new year!! 

We have to wait for the copernicus charts in a week for publicly accessible monthly breakdowns as opposed to the three monthly ones you’ve posted above 

[Catacol]

1 hour ago, Ali1977 said:

A blocked Jan and Feb according to the ECM - I’d take that after a cold Xmas and new year!! 

It would be quite hard to paint a better anomaly picture than that for snow potential. If folks hoping for wintry conditions aren't happy with this run they never will be.

[Premiere Neige]

3 hours ago, Downburst said:

The ECM MJO for Day 10, the mean line is now above the COD area for phase 6, whereas yesterday and a few days before it flirted with below. So phase 6 period is adjusting and it it continues we might see more towards the end of the GFS runs at least and perhaps shortly the 10 day ECM. Remember the higher the amplitude the more skill the forecast has historically, so maybe once the next 5 days finish we might get more consistency. 

In saying all this, I am thinking, at least at the surface, that Canadian (+10c and corresponding Siberian -10 c temp anomaly this week is so strong, one has to wonder surely that will have more effect than anything else? 

 

Also, over the last few days the 10hpa anomaly over the pole has really strengthened each run for 1st week of January. Although I won't hazard a guess (mini ice age end of January ) how and when that might effect us, especially so far out from even happening, but that's a strong signal all the same.

 

I know that 3 weeks is usually quoted as the lag time for the effects of an SSW to be felt.......trouble is, we can't tell if we reach SSW (+50°c) on those charts. 

[Downburst]

Would like a take on this, from ECM site and the long range. 

2M Temp Area average Northern Europe, to show where this is, a map

 

A very large drop (Purple) in 2m temp compared to climate (Grey) for December showing there, purple box the middle tercile. This is opposite of the prediction last month which had December positive..

https://charts.ecmwf.int/products/seasonal_system5_climagrams_2mt?base_time=202312010000&index_type=Northern Europe

 

And NOA negative for each of the 3 months to come. Although it has been negative nearly all year. But near -3 for February, which fits into expctations.

[Vikos]

To be honest, December never was a fully winter’y month (at least the last years), more an extension of fall… so glad to see that January and onwards looks to be cold…

[DavidS]

Icon 12z keeping things generally unsettled in the next week.

Is it though looking to build an Atlantic ridge from T+168 or would it likely flatten?

[northwestsnow]

14 minutes ago, DavidS said:

Icon 12z keeping things generally unsettled in the next week.

Is it though looking to build an Atlantic ridge from T+168 or would it likely flatten?

I'm more interested in a huge Siberian High to the NE..

[Rob 79812010]

1 hour ago, Catacol said:

It would be quite hard to paint a better anomaly picture than that for snow potential. If folks hoping for wintry conditions aren't happy with this run they never will be.

I hope you're right. And unless there are any big surprises this month, it looks like December will pan out at average or just below temp wise

[frosty ground]

2 minutes ago, northwestsnow said:

I'm more interested in a huge Siberian High to the NE..

It looks like it’s in retreat thou, but it is an eye catching feature