Model Output Discussion 29th December - Into mid-Winter.

[Duane S.]

4 minutes ago, Singularity said:

I believe teleconnections are a means of seeing which day the dice is weighted, meaning we can get a sense of what's more likely, but not be able to rule out the less likely options until the short range.

Some years there's so much supportive forcing that factors such as the MJO are to do with how good things will get. Others, like this one, are about whether we can overcome the odds at least for a short time in the season.

Exactly my take. Had the cold spell in I.e. 09 not occurred we could have considered ourselves unlucky as so much was going for it. Others, perhaps Jan'87? you could say was very much against the odds.

It all comes down to the drivers. Which are 'primary', when they are, which drivers drive which other drivers, under what circumstances and to what degree. Their interactions with each other are so impossibly complex that you very soon realise no computer will EVER EVER be able to get a handle on that. Chaos.

[Man With Beard]

Looking closely at Friday - there is a chance of an almost nationwide snow event. The disturbance that crosses the country originates from Greenland, if you study the track. There's likely to be a moderate amount of precipitation involved. Mid-January, little daytime heating ... It's possible that 75% of the country will see something white on the ground by the end of the day.

[karyo]

The 6z at 150 hours toys with the slider idea but doesn't make it as the Atlantic ridge eases.

[northwestsnow]

2 minutes ago, Man With Beard said:

Looking closely at Friday - there is a chance of an almost nationwide snow event. The disturbance that crosses the country originates from Greenland, if you study the track. There's likely to be a moderate amount of precipitation involved. Mid-January, little daytime heating ... It's possible that 75% of the country will see something white on the ground by the end of the day.

Yes i agree on 6z at least more southrrn parts of the UK in the game.

[bluearmy]

10 minutes ago, Man With Beard said:

Looking closely at Friday - there is a chance of an almost nationwide snow event. The disturbance that crosses the country originates from Greenland, if you study the track. There's likely to be a moderate amount of precipitation involved. Mid-January, little daytime heating ... It's possible that 75% of the country will see something white on the ground by the end of the day.

DId you mean wet?

[Banbury]

3 minutes ago, bluearmy said:

DId you mean wet?

White would be good

[KyleHenry]

1 minute ago, s4lancia said:

Exactly my take. Had the cold spell in I.e. 09 not occurred we could have considered ourselves unlucky as so much was going for it. Others, perhaps Jan'87? you could say was very much against the odds.

It all comes down to the drivers. Which are 'primary', when they are, which drivers drive which other drivers, under what circumstances and to what degree. Their interactions with each other are so impossibly complex that you very soon realise no computer will EVER EVER be able to get a handle on that. Chaos.

Agreed. For the UK there is one very important teleconection especially in La Niña years, the EPO/WPO. Models can get a good downstream read on this pattern.

Its the models reading of Tropispheric PV lobe placement which leads to failure. 

 

North Pacific high pressure will always dictate MLB for the UK. 

 

The ECMWF now shows wholesale change with HP replaced with LP. 

That allows inhanced SSW opportunity in East Asia. 

He who can program the correct algorithms for Trop PV movement will be king predictor.

 

[northwestsnow]

6 minutes ago, bluearmy said:

DId you mean wet?

Altitude will play a part next week Blue, Thursday looks potentially very snowy in the north west..

[Ali1977]

-6 uppers from the NW, anywhere could see snow but precip during Fri and Sat night may have more chance of lying. Doesn't look like it will stay cold beyond next weekend but when have those charts been correct lately - lets hope the cold weekend is nailed , and we all see something white.

[Man With Beard]

14 minutes ago, bluearmy said:

DId you mean wet?

Funny, my GFS chart had snow on Friday - like Banbury's (Edit - I was going by charts earlier in the day which were all snow).

Though rather than just use the GFS charts, I think logically the origin of the air would suggest a higher risk of snow than usual.

Edited January 7, 2017 by Man With Beard

[chris55]

19 minutes ago, Man With Beard said:

Looking closely at Friday - there is a chance of an almost nationwide snow event. The disturbance that crosses the country originates from Greenland, if you study the track. There's likely to be a moderate amount of precipitation involved. Mid-January, little daytime heating ... It's possible that 75% of the country will see something white on the ground by the end of the day.

This little wave on Thursday  has been trending south on every run, the 0c isotherm was over Scotland yesterday, now its over the channel! This will help in dragging the cold air in ahead of Fridays feature.

 

[radiohead]

Same problem as the 0Z. Too much spoiler energy spilling over the top at the southern tip of Greenland. I fear this will be the trend now that it's creeping closer to the reliable time-frame. 

[Polar Maritime]

Yes altitude will also help for the end of the week, But with such fine /margins/instability at this range its hardly worth splitting hairs over... Into the run a cool/cold Pm/rPm pattern from the N/W continues, With again plenty of scope for Snow especially at elevation.

All in all a wintry run.

 

Edited January 7, 2017 by Polar Maritime

[Ali1977]

CFS I know but this could give us a cold spell weeks 3-4.

[blizzard81]

7 minutes ago, Ali1977 said:

CFS I know but this could give us a cold spell weeks 3-4.

The cfs weekly charts have been as bad as the ec46 all winter. 

[alexisj9]

37 minutes ago, karyo said:

The 6z at 150 hours toys with the slider idea but doesn't make it as the Atlantic ridge eases.

The good thing at the moment is, there's still plenty of time for something at 150 to upgrade, especially if it's a new idea being toyed with. Something to watch perhaps. Let's see if the idea is still there in the 12z.

[Dennis]

watch out next week.....

[joggs]

A good chart from a coldie pov for a few days but my worry is that all the energy over the top will be modeled to catch up with the low to our east and give us more of a westerly drift.

Hope I'm wrong.

My excitement is gearing up for later Jan and early Feb.

Not time atm but I shall explain later after ive been to watch my beloved Bradford city.

[Day 10]

This chart from matt hugo's twitter just sums up our general luck in Winter!

[blizzard81]

1 minute ago, Day 10 said:

This chart from matt hugo's twitter just sums up our general luck in Winter!

And just about every winter for that matter. 

[Scandinavian High.]

 Unfortunately we heading in a mobile pattern lows to the north west high to the south west as the lows pass through the  far  north of uk they will bring short lived colder interludes and at times cold enough for some wintery showers in the north and west maybe the odd wintery shower pusheing south at times so yes looking very mobile next two weeks or so I'm looking north east for a long lasting cold spell maybe later part of January in to February. but all could change.

[nick sussex]

Once again today the GFS flat bias is showing up. You'll see upstream the 00hrs had a flat shortwave running east across the USA around T144hrs. The GFS 06hrs now slowly backtracking towards the Euros with that more amplified wave.

 GFS 00hrs run to T144hrs                            GFS 06hrs run to T138hrs

 

 

The stand out model today for those hoping for the easterly is the UKMO with the most amplified upstream shortwave. Looking at its T168hrs output Atlantic view you can see a different shortwave running se'wards this is the trigger for any possible easterly. The UKMO has this the furthest west of any of the outputs.

Its not just what happens to the east with the Russian ridge but the critical area is upstream with the pattern in the eastern USA, the more amplified the pattern is there at that crucial timeframe the higher chances of that easterly. If for arguments sake the UKMO verified at T168hrs it would have the coldest solution past that point and would likely bring in an easterly.

I think at the moment there looks a bit too much energy in the northern arm of the jet with the odds more in favour of you guessed it the coldest air heading towards south/se Europe but theres still uncertainty with how much amplitude there will be over the USA and Canada.

Regardless of that any amplitude upstream will help back the pattern further west.

 

 

 

[Gustywind]

7 minutes ago, Day 10 said:

This chart from matt hugo's twitter just sums up our general luck in Winter!

Got to admit this chart has made me chuckle, it's like a mild force field is in place around the UK, deflecting cold to every other country in Europe!

 

[karyo]

3 minutes ago, nick sussex said:

Once again today the GFS flat bias is showing up. You'll see upstream the 00hrs had a flat shortwave running east across the USA around T144hrs. The GFS 06hrs now slowly backtracking towards the Euros with that more amplified wave.

 GFS 00hrs run to T144hrs                            GFS 06hrs run to T138hrs

 

 

The stand out model today for those hoping for the easterly is the UKMO with the most amplified upstream shortwave. Looking at its T168hrs output Atlantic view you can see a different shortwave running se'wards this is the trigger for any possible easterly. The UKMO has this the furthest west of any of the outputs.

 

 

 

 

Nick, that's the most promising chart I have seen from the UKMO in a long time.                                                                                                                                    The 12z ECM also has some kind of slider and the 6z gfs flirts with the idea but then flattens quickly.

[stratty]

Just now, Gustywind said:

Got to admit this chart has made me chuckle, it's like a mild force field is in place around the UK, deflecting cold to every other country in Europe!

 

...or just our particular climate?