Model Output Discussion - Spring Has Sprung

[Dennis]

its just some snow idea that could happen ....alot is first to be done between 3-5 febr

6 or 7 is to watch on the MJO these days

 

 

London chart 

 

 

Edited January 27 by Dennis

[Purga]

Promising at least this morning from GFS

 

[winterof79]

  @Lukesluckybunch at last the NWP starting to prog the relocation of the PV to a very favourable spot come mid Feb and the Met may bring forward the timescale in their extended

[offerman]

  @damianslaw nice post, Damien, I do agree that 5 6 day timeframe starts to become more semi reliable timeframe, but as we know, even that can be subject to change during this time, but at least five or six days out is more of a guide. It’s better to be cautious, and at the moment, take it with a pinch of salt, and any further out than that with regards to a cold spell as we’ve seen so much already shots and forecast flip-flop on a daily basis. Because the Arctic has been in such a mess with no large sustained, weather patter to be the guider of a More, certain outcome. The weather patterns are much harder to predict and what I have found looking this winter, as there has been so many more smaller areas and pockets of disruption, and all you need is one of those in the wrong place to disrupt the whole colder potential. 
that’s one thing, I’ve noticed that’s changed over the recent years, whereas before I remember you may have a large north, Atlantic, mid Atlantic high extending up Linking into a Greenland high driving down, Nally went straight from the Arctic all the way through the UK down into France. 
when you look how far any colder air reaches it struggles to get down over the whole of the UK, but it has made it on occasion this winter, but there was always seems to have been southern blocking, or the orientation of any highs have not been sustained, but have contained more mobility to them so you have a brief northerly blast with usual coastal wintry showers East West and North, but there’s been no chance of topers because the high has been forced in across and then passed us allowing one Southwest lease to come back in . The weather patterns are very mobile. This winter has lacked static structured patterns to them. 
 

what will February bring? Let’s wait-and-see, but at this conjuncture. I’d say it’s too far out and as you rightly pointed out five or six day is when we can, then start taking it more seriously and bring it into the semi reliable timeframe

 

 

[winterof79]

The trend is your friend and there's definitely one showing

[chris55]

Coldest set of GFS ensembles in the longer term that I have seen since the last cold spell.

(Gloucestershire)

[bluearmy]

ATM it’s not clear if the back end of week 2 is becoming 850 cold off the back of cold zonality or cold cyclonic. And you certainly wouldn’t  discount a varied solution at this time either with the Atlantic ridge closer to the U.K.   

It’s a waiting game - whilst  the nwp begins to evolve we just have to buckle in and those in the south U.K. hope for some very cold solutions given that we’re headed towards mid feb. 

[Mike Poole]

9 hours ago, Uncertainty said:

On top of and related to all of this is the frankly ferocious +EAMT burst we’re presently seeing. Some of the +MT is from the rockies but even more of it is East Asian. Along with the tropical progression, It does all feel a bit 2018 but we’ve been burned before this winter and I’m still not fully convinced.

A couple have people have made the connection to 2018 - where has this come from all of a sudden?  I can’t see the similarity at all, apart from the time of year.  2018 was defined by a pretty much optimal split SSW with a very quick and striking trop response, it’s not just that we’re not in the same ballpark this year, we aren’t even in the same city!  

I’m optimistic we might see one final chase for the last period of winter, but am remaining cautious for now.  A lot depends on the MJO, so almost by definition a lot can go wrong!

[Mike Poole]

Extended clusters this morning have slightly less of a signal for a well placed block:

Cluster 2 is where the signal lies, perhaps (putting faith in the teleconnections), and while it has more members (20) than yesterday’s similar cluster, it is a less well positioned high and weaker (on the representative member at any rate).  Cluster 1 shows a -NAO but poorly aligned.  Cluster 3 reverts to Atlantic driven.  

 

[sebastiaan1973]

  @Mike Poole Indeed, 2018 was an extreme event, a combination with SSW and very strong MJO. 

[Purga]

The ECM ENS are showing a lot of spread but a significant cluster of cold runs in he later period

[Jacob]

The GFS 6z has the PV ever so slightly east and has stronger heights to our south

[Blessed Weather]

29 minutes ago, sebastiaan1973 said:

Indeed, 2018 was an extreme event, a combination with SSW and very strong MJO. 

The 2018 SSW makes a good case study with the MJO playing a 'trigger' role. Extracts:

Mechanisms and predictability of sudden stratospheric warming in winter 2018
We investigate the role of the tropospheric forcing in the occurrence of the SSW, its predictability and teleconnection with the Madden–Julian oscillation (MJO) by analysing the European Centre for Medium-Range Weather Forecasts (ECMWF) ensemble forecast. The SSW was preceded by significant synoptic wave activity over the Pacific and Atlantic basins, which led to the upward propagation of wave packets and resulted in the amplification of a stratospheric wavenumber 2 planetary wave.
......a composite analysis suggests that teleconnections associated with the record-breaking MJO phase 6 observed in late January 2018 likely played a role in triggering this SSW event.

Full paper: https://wcd.copernicus.org/articles/1/657/2020/

Latest MJO, nicely into Phase 6 atm at reasonable amplitude. ECM and GFS ensembles:

Source: https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/clivar_wh.shtml

 

[northwestsnow]

EC det looks a milf outlier 

[fromey]

  @northwestsnow Milf!!!???

[northwestsnow]

  @fromey Mild , stupid phone !!

[Lukesluckybunch]

The pv looks to be transferring eastward at 144..but there seems to be a few troublesome lows upstream..that will probably prevent any hlb!

Edited January 27 by Lukesluckybunch
Spelling

[Lukesluckybunch]

It's starting too look interesting at 186!

[LRD]

21 minutes ago, northwestsnow said:

EC det looks a milf outlier 

Now I AM interested! 

Ahem, MOGREPS still showing remarkable warmth late next week/weekend. Possibility of a quick down turn after that

Edited January 27 by LRD

[bluearmy]

11 minutes ago, Lukesluckybunch said:

The pv looks to be transferring eastward at 144..but there seems to be a few troublesome lows upstream..that will probably prevent any hlb!

If the east usa trough doesn’t detatch from the vortex then I think any amplification in the Atlantic is less notable in the 9/11 day period 

it’s good to see runs that vary this because it shows how wide the envelope remains 

[Lukesluckybunch]

9 minutes ago, bluearmy said:

the east usa trough doesn’t detatch from the vortex then I think any amplification in the Atlantic is less notable in the 9/11 day period 

it’s good to see runs that vary this because it shows how wide the envelope remains 

That's a good point..it's looking likely we could be in dreamland by day 10!cut off greenland hp at day 10?

Edited January 27 by Lukesluckybunch
Adding

[TSNWK]

  @Lukesluckybunch got a chart please? 

[Lukesluckybunch]

1 minute ago, TSNWK said:

got a chart please? 

 

[Ali1977]

Chase about to start again, and the signal is moving closer too so we aren’t chasing from T300+ as we do sometimes!! 
day 10 looks good - ENS hopefully supporting too 

[northwestsnow]

I'd take 6z right now!!