Model output discussion - winter proper underway

[Daniel*]

I don’t think the ensembles will be any of use for a while, not when higher res operationals are having immense challenge dealing with downstream impacts of Pacific ridge and it’s poleward movement it changes from run to run. Seems a bit of a guessing game currently. Very uncertain. It looks like the jet stream is going to be forced more south courtesy of amplification digging into the arctic, so that’s certainly what coldies want to see. Good that we’re also seeing the PV be much more tame and away from problematic areas, than what we have seen modelled. While not setting up the scene for classical cold outbreak yet, channel runners etc engaging with cold air - wintry surprises possible virtually anywhere. I feel less are interested in extreme cold (typically associated with a much drier air mass) than snow, I know I prefer the latter so I wouldn’t feel disheartened. 

Edited December 19, 2017 by Daniel*

[Captain Shortwave]

The outlook still looks mild and quite dry until Christmas with more changeable conditions developing around Christmas, but I must admit the chances of very wet and windy weather developing is decreasing as time goes on, mainly as we are probably not going to see that raging vortex to our north west thanks to the Pacific ridge punching through to the north Pole.

ECM/UKMO/GFS day 6

     

The ECM/UKMO still really going for this with the likely scenario of a strong Arctic high forming. I can see the ECM trying the same trick with the morning run, look for the Siberian lobe to try and make a break towards Scandinavia so it is down to where the high ends up, if it can land somewhere between Greenland and Norway it could disrupt low pressure exiting Canada and then suddenly we have a very different prospect as we head towards New Year.

I can't see raging zonality coming off going by the model trends, we could still see westerlies but much more subdued with shallower lows moving across, though as with the ECM we could end up with a UK based trough, but we could see something colder develop instead. Whilst the chages have been fairly small regarding that ridge, the fact that we are seeing this get right into the Arctic as opposed to reaching Alaska and then collasping has big implications further down the road, especially as I supect the troposphric vortex will come under intense strain as opposed to the typical EPO ridge which seems to feed a mass of purple over Canada/Greenland for which we have seen over the last couple of winters.

 

Edited December 19, 2017 by Captain Shortwave

[tight isobar]

'Again'...

Some sniffing around of AT-WAA around point tip greenland -via ec model.

And the eventualities, are paramount!!

Although' there are still longer yet feasible way for uk cold..  

The pc-ridge has the upper hand now ..so its how evo's- play out against/or for the ridge....

[knocker]

The ecm also going for the frontal wave 'bombing' between T132 and 156 bur also passing to the north west with the UK leaving the latter in quite strong  balmy south westerlies over the 25th  The front associated with the low initially impacts Scotland and N. Ireland by 00 Tuesday and it sweeps south east across the country during the day before the next low and associated front arrives over Ireland by 00 Wednesday ready to bring some more wet weather.

[northwestsnow]

 

Temps below average at 216 on EC-

Snow for northern hills perhaps?

cant post the image for some reason -

Edited December 19, 2017 by northwestsnow

[northwestsnow]

Well the EC snow depth charts for that run are really eye catching for large swathers of NW Britain inc Wales and the midlands!!

If thats anywhere near accurate there will be lots of happy people.

Think i will take that with a pinch of salt but i'd suggest taking a peak!

Edited December 19, 2017 by northwestsnow

[I remember Atlantic 252]

I'd be excited if I lived in the north, or Buxton etc, doubt low level snow on this EC, FI still yet though

[Hull snow]

Can anyone post ecm snow depth please

[northwestsnow]

1 minute ago, I remember Atlantic 252 said:

I'd be excited if I lived in the north, or Buxton etc, doubt low level snow on this EC, FI still yet though

Yes the action is 192 onwards on snow depth charts but i was very suorised how much was showing for Pennine areas.

Very snowy indeed for high parts of the Pennines / Peaks -

[johnholmes]

2 hours ago, Seasonality said:

Chalk and cheese. Much better run if colder weather is what you're after.

But the 12Z is similar to the 00z and both ,see my post earlier, have gradually moved to the set up shown on the 12z.

That is over the past 4-5 days, comparing like with like, it is far more reliable than watching every run and comparing at time scales beyond 144 maybe 168 at times.

[Tim Bland]

5 minutes ago, Hull snow said:

Can anyone post ecm snow depth please

 

[Ali1977]

10 minutes ago, ShortWaveHell said:

Aw well the MetO contingency planners latest update  is dire for anyone wanting lasting cold into Jan Feb March! And it’s seasonal output is mirrored by other global weather models (apparently) ! Pinch of salt I think 

Not quite as simple as saying it's dire, above normal temps more likely than below is what they say - you can have a deep freeze for 2 weeks and then a month of mild muck which would give above average temps!  Also, the wording suggests a cold spell in Jan isn't out the picture!!

[Weather-history]

26 minutes ago, northwestsnow said:

Well the EC snow depth charts for that run are really eye catching for large swathers of NW Britain inc Wales and the midlands!!

If thats anywhere near accurate there will be lots of happy people.

Think i will take that with a pinch of salt but i'd suggest taking a peak!

GFS ensembles are not devoid of snow depth spikes

Here's for Cheadle Heath

http://www.wetterzentrale.de/en/show_diagrams.php?geoid=51342&model=gfs&var=26&run=12&lid=ENS&bw=

[chris55]

48 minutes ago, tight isobar said:

'Again'...

Some sniffing around of AT-WAA around point tip greenland -via ec model.

And the eventualities, are paramount!!

Although' there are still longer yet feasible way for uk cold..  

The pc-ridge has the upper hand now ..so its how evo's- play out against/or for the ridge....

Since when did you start consistently talking in riddles with lots of full stops...... I can't grasp your posts. Plain English is actually quite effective lol

[Paul_1978]

29 minutes ago, ShortWaveHell said:

Aw well the MetO contingency planners latest update  is dire for anyone wanting lasting cold into Jan Feb March! And it’s seasonal output is mirrored by other global weather models (apparently) ! Pinch of salt I think 

It's actually not that different to the last update. Cold and snow not ruled out but milder weather more likely on balance. 

I'll take that if we get another Feb 1991!

[Summer Sun]

UKMO extended looking increasingly wet and windy this evening

[shaky]

2 hours ago, fromey said:

Surely that could be good for us, slow down the jet stream etc? 

Yes it will!!need the jet stream further south!!

[northwestsnow]

2 minutes ago, Summer Sun said:

UKMO extended looking increasingly wet and windy this evening

Looks like quite a bit of energy on a SE trajectory to me..

[Man With Beard]

ECM mean T240: low pressure and westerly dominated, but original source is far North Atlantic rather than mid Atlantic = fairly cold. 

Spreads suggest some runs with low pressure quite far south into Europe. We'll see the detail later

[damianslaw]

In projected mobile periods always worth keeping an eye on the jetstream, and the latest forecasts are for it to trend south next week, so whilst unsettled looks the theme it could be a cold unsettled spell, at least in the north increasing chances of some wintry precipitation to low levels at times with frost, further south more average conditions. Indeed secondary low, and sudden trough development looks likely to happen, making forecasting each day ahead quite difficult, timing of fronts and low pressure and path not easy to forecast. I too am not expecting a particularly stormy spell, windy yes, but nothing remarkable, jet will have some oomph but the wind will be taken out of it so to speak.

Until Christmas Day - one of those miserable murky grey descents into christmas, that has plagued the UK for the seventh year in a row now, maybe next year will bring something different, very very uninspiring, but at least nothing to interfere with pre-christmas travels. 

ECM showing a arctic high developing next week thanks to pacific ridging, UKMO going for a more NW influence for christmas day, and GFS trending colder once we get to christmas day.

 

[northwestsnow]

You have to say if your elevated and in NW Britain you could be snowed in between chistmas and new year...

The higher pennines and peaks could get plenty..

[BLAST FROM THE PAST]

4 hours ago, Devonshire said:

I am not sure where you are getting a 'strong solar wind' hit from - there are 2 small coronal holes on Earth side of Sun - certainly nothing out of the ordinary to my eyes, especially in light of much larger ones that trundle round periodically (days, not weeks). I will keep an eye on the jet though in case it exhibits any extraordinary short-notice behaviour - same with LPs, though my (limited!) understanding is that flares/CMEs are more implicated than solar wind in affecting strength/track of storm systems.

To appease mods: if there is a sudden effect on the Jet I guess we can look at sudden (actual) departures from modelled jet track /LPs in very short term - as well as any sudden large shifts in models' track of jet/LPs, wrt timing of solar wind inpacts .... maybe. It would be great to think that Solar teleconnections could be included in (public) models - or at least included (mechanistically) by those who are switched on to teleconnections. I suspect this conversation is for another place though ...

As between 7-10 the precip and snow was more than standard forecasts.  I expect more deviation to occur.  In fairness it could mean even stronger HP buffering the Atlantic which infers more jet stream interference.  Caveat is that GFS has shown extreme storm.....that is a caveat.

 

BFTP

[feb1991blizzard]

Ext eps are even crapper than the overnight run.

[stodge]

Evening all

As is often the case with winter, hints and whispers on the edges.

The problem for me looking at the post-Christmas evolution is both ECM and GEM send the HP back into Europe re-tilting the trough positive and sending back milder SW winds.

If that can be halted or reduced and the Azores HP kept suppressed far to the SW, it looks more interesting for cold as the negatively-tilted trough and the southerly tracking jet offer plenty of opportunities for those to the north and with altitude.

I've probably had my snow for the winter here in lowland East London - or have I ?

[frosty ground]

7 minutes ago, feb1991blizzard said:

Ext eps are even crapper than the overnight run.

Which will change again in the morning....