Model Output Discussion - Into Winter

[northwestsnow]

1 hour ago, MJB said:

Hmmmmm NWS, that isn't strictly true, both show HP to the West of the UK, so a similarity is there, just a difference in orientation..........surely. And at that range, it's not worth looking at the tiniest detail , the fact that we have a HP near us gives a chance of retrogression down the line.

Sorry mate ,I meant conditions for the UK are chalk and cheese, and compare   surface temps on both runs ( which I do).

[johncam]

Current sea temps are very warm to west and north and with very little sea ice around Svalbard and Barents a northerly wouldn't pack the usual punch 

[northwestsnow]

1 hour ago, bluearmy said:

The gefs 06z hangs back a high anomoly from the Atlantic around T300 in line with the general direction of travel at this timescale. it’s a struggle to get the drop in euro heights backed far enough west in the 12/14 day period 

atm, the momentum is definitely with a mlb across the U.K. extended from the Atlantic high approaching Xmas weekend 

beginning to see a definitive trend to the Siberian ridge and western American ridging loosely meeting across the polar field - potentially assisted by the Arctic high which usually defaults to exiting the Arctic by one of these routes. That aligns the NH profile in its traditional west - east profile and makes it tougher for the Atlantic ridge to gain the traction we want to see. The 06z gefs certinainly a poor suite for Greenland heights post T300 with the Canadian vortex extending well across that region.  
 

to illustrate my point comparing yesterdays 06z with todays for Xmas eve 

    

Well not many people will like that trend but its basically what I've been saying since the 00z runs.

Of course my posts are referring to the pre Xmas period,who knows beyond Xmas.

Edited December 9, 2023 by northwestsnow

[feb1991blizzard]

no panic yet, another week of poor output needed yet to worry, target date for anything is and always has been post xmas into Jan.

Although yes its boring!

Edited December 9, 2023 by feb1991blizzard

[phil nw.]

Given time lags of a week or two(we can never be precise on this)of mjo phases it may be nearer to Christmas before nwp factor in the cold phases.

Current ens guidance for week 2 suggests more of a retrogression of a mid latitude Atlantic high rather than any amplification at this stage.

We may squeeze a colder north westerly out of this.

I think if we are to get the main course(Arctic cold) from there it will be likely post Christmas

As ever it's a waiting game and following the trends in the ensemble suites is usually the way to keep expectations grounded.

[MJB]

26 minutes ago, johncam said:

It does have the best stats but this far out they will all be wrong when we get to day 0

Best stats at 22 days out hmmmmmmmmmmmmmmm I doubt there are any to verify that ......are there?

[Scandinavian High.]

4 hours ago, Catacol said:

There's no change in the signals this morning - a few of our US weather passionate cousins are wailing and gnashing their teeth over a very mild and flat forecast pattern for them - but this is gravy on the turkey for us. Once we get into the interesting final third of the month we can chalk off concerns over cold US air helping locally to enhance low pressure development. And in that old simple minded maxim - if arctic air isnt flooding the US then the same air is up for grabs to flood somewhere else!

For a few more days - unless the signals change - the best thing to do is stick to ensemble runs in the extended. Here is GEFS for a few days before Xmas.

Nothing here to concern UK snow hunters - and this is the position before we get the knock on impacts of developments upstream. 

Look at the size and depth of that north pacific trough signal. Wow. HP downstream of the Rockies too. Expect to see some major US torque and warm air firing up into the strat. SSW for early January has to be considered as more than just a possibility now. We want a split if we are to stand a chance of something more than the Blankety Blank Chequebook and Pen....

We’ll there is no concerns from CATACOL this morning unless there as been massive swing.

[Midlands Ice Age]

12 minutes ago, johncam said:

Current sea temps are very warm to west and north and with very little sea ice around Svalbard and Barents a northerly wouldn't pack the usual punch 

Johncam..

No problems with the Barents sea ice this year it is second highest in the last 5 years,

MIA

[LRD]

43 minutes ago, CameronWS said:

Why so many negative when the MJO signal isn’t even being factored in yet to the models? Surely when that becomes apparent the blocking showing up is likely to increase.

Well, it's not negative - people are just commenting on what we can all see on the models. No point deluding ourselves and misleading others and looking for positives that aren't there. Having said that, there is little point in analysing every op run and nothing cold was expected as a result of the MJO cycle until Xmas Day IIRC (and that might have now been put back until New Year (surprise, surprise - mild is hardly ever delayed is it?!))

Speaking of the MJO - it and other teleconnections are important drivers of our weather, of course, but they do not guarantee anything this far out (if we're talking about a cold Xmas week, for example). I think some are putting an awful lot of their eggs in the MJO basket when it's just another forecast at the moment with absolutely no guarantees

Edited December 9, 2023 by LRD

[Notty]

26 minutes ago, johncam said:

Current sea temps are very warm to west and north and with very little sea ice around Svalbard and Barents a northerly wouldn't pack the usual punch 

What are the anomalies comparing to? Some weird stuff going on in the Atlantic between the UK and Canada

[Dennis]

ill take this one 

Edited December 9, 2023 by Dennis

[TSNWK]

9 minutes ago, Dennis said:

ill take this one 

Nooooo has the Christmas cold spell fallen off the tracks so far that we are wheeling out nasa model.  

[Cambrian]

That’s quite a difference at day 11 and 12 between the 0z and 6z GEFS. Much better orientation and build of heights towards Iceland in the latest run, the link-up through eastern Greenland rather than through the Norwegian Sea. 

Day 11 0z, 6z

 

Day 12 0z, 6z

 

This allows the development of a better defined Scandinavia - Europe trough, around 6 dam lower on the contours at the northernmost part of the Baltic Sea. The trough is further west too. 

The models seem to be working these run-to-run variations around the core theme of where the EC46 has the weekly means for the 18th to 25th and the following week, between Christmas and the New Year. 

 

We could perhaps be looking at more of a northwesterly flow as the Atlantic high draws west, before it then builds heights north as the trough consolidates over Scandinavia, straightening to a flow more directly from the north for the holiday period for the UK and Ireland.

With the models consistently toying with these patterns for durations of weeks rather than days ahead, the run-to-run differences should perhaps be taken in the context of there being clearly plenty of scope for a very seasonal end to the year.

Edited December 9, 2023 by Cambrian

[Dennis]

25 minutes ago, TSNWK said:

Nooooo has the Christmas cold spell fallen off the tracks so far that we are wheeling out nasa model.  

hi this is allready late next week.....before 20th 

GFS looks ok between 20-24th now , but at christmas (dont look)6z

 

Edited December 9, 2023 by Dennis

[bluearmy]

6 minutes ago, Cambrian said:

That’s quite a difference at day 11 and 12 between the 0z and 6z GEFS. Much better orientation and build of heights towards Iceland in the latest run, the link-up through eastern Greenland rather than through the Norwegian Sea. 

Day 11 0z, 6z

Day 12 0z, 6z

 

This allows the development of a better defined Scandinavia - Europe trough, around 6 dam lower on the contours at the northernmost part of the Baltic Sea. The trough is further west too. 

The models seem to be working these run-to-run variations around the core theme of where the EC46 has the weekly means for the 18th to 25th and the following week, between Christmas and the New Year. 

 

We could perhaps be looking at more of a northwesterly flow as the Atlantic high draws west, before it then builds heights north as the trough consolidates over Scandinavia, straightening to a flow more directly from the north for the holiday period for the UK and Ireland.

With the models consistently toying with these patterns for durations of weeks rather than days ahead, the run-to-run differences should perhaps be taken in the context of there being clearly plenty of scope for a very seasonal end to the year.

That’s true at a moment in time as you’ve shown day 11/12 but that ridging is flattened on the mean quite soon afterwards 

[AO-]

1 hour ago, johncam said:

Current sea temps are very warm to west and north and with very little sea ice around Svalbard and Barents a northerly wouldn't pack the usual punch 

Perhaps the sea temperatures are higher when compared to the climate mean, but when looking at the sea ice extent in the Baltic sea, it hasn't been this high for over a decade. 2010 Was the last winter with a complete coverage of ice in the Baltic sea. And we might expect it to increase as Scandinavia consolidates it's cold status. Remarkable for mee hoe easy the cold is maintained in the North. That has been different over the past years. 

[Dennis]

interesting weekend ahead

MJO EC 

 

[Derecho]

That's an incredibly mild December chart from the GFS. I mentioned a few pages back that if the high doesn't ridge north out of France or Spain then retrogression and a northerly will be on shaky ground. The EC and UKMO were never really backing a scenario of the high ridging north to give us some cold anticyclonic weather unfortunately and the GFS is moving into line.

The MJO still going into phase 8 according to the BOM mean but just look at that spread...

 

 

Definitely glass half empty output for coldies today. Wouldn't be surprised if the December CET ended up above average to end the month if a northerly doesn't come off.

I'd much rather have good synoptics at present then poor synoptics with potentially interesting background signals. We've been in the latter position far too much in recent winters and before you know it weeks have gone by.

Either way some real dogs dinner charts at day 7 with later next weekend potentially being exceptionally mild.

The GFS 06z ens are interesting at least but it all looks on shaky ground to me.

Edited December 9, 2023 by Derecho

[AO-]

12 minutes ago, Dennis said:

interesting weekend ahead

MJO EC 

 

Does anybody know why EC misses the amplitude in phase 8 that other models do calculate? What is the main driver? Is there any bias . No good synoptics are to be expected for phase 7 as only a temporary increase in surface pressure over Scandinavia is seen around the 14th (reflected in the small amplitude in the MJO?). After that phase 8 has to come to fruition, but according to EC we might end up with MLB ending up in cloudy weather lacking cold. That would be the worst case scenario imo.

[damianslaw]

GFS often gets the jitters as pattern changes begin to enter the semi-reliable only to then revert back to what their longer term outlook was showing all the time, as the pattern change enters the reliable. I still rate it over the ECM for spotting upstream developments i.e. developments to our NW and eastern USA seaboard.

Today appears to be one of those days that throws up confusion and doubt, all par the course when a change is still outside semi-reliable. 

[sebastiaan1973]

21 minutes ago, Derecho said:

 

 

 

 

HI, this is a chart from 7 of december.

Dennis, we see the MJO with little amplitude through phase 6,7. In phase 8 it gets better. But that is over almost a week when it comes there. 

[Alexis]

1 hour ago, johncam said:

Current sea temps are very warm to west and north and with very little sea ice around Svalbard and Barents a northerly wouldn't pack the usual punch 

The colour scale is a bit deceptive. Yellow isn't 'very warm' really.

[Derecho]

5 minutes ago, sebastiaan1973 said:

HI, this is a chart from 7 of december.

Dennis, we see the MJO with little amplitude through phase 6,7. In phase 8 it gets better. But that is over almost a week when it comes there. 

Indeed but it's the more optimistic of the MJO plots...

Edited December 9, 2023 by Derecho

[Premiere Neige]

2 hours ago, johncam said:

Current sea temps are very warm to west and north and with very little sea ice around Svalbard and Barents a northerly wouldn't pack the usual punch 

Seem to remember you saying that prior to the recent cold spell and yet many of us had snow and frost...

[Dennis]

AO forecast after 15th to neg value to most members

Edited December 9, 2023 by Dennis