Model output discussion - mid January

[SMU]

For reference -3 @850 is the London ave -

so if we see -11c come through it’s the equiv of getting +5c from the south & 8 degrees below ave

The approx ave lapse rate is +10c in deepest winter -

so the -3c usually delivers 7c on ave at the surface- so when we see -10c being touted over +1 day then the second day is normally 0-1c at the surface...

 

best

s

[tight isobar]

16 minutes ago, Optimus Prime said:

You see though, that's the problem. Posting charts that are 7 & 10 days out is not rationale. And then go on and post a precip chart 10 days out!

Again they are just 850 hPa. -10 850 hPa from the NW will inheritably be different to one from the east. The surface cold from an easterly would not be there in a NW'ly. 

Those are not-850hpa upper charts there geo pots!!!

[Paul]

Just now, tight isobar said:

Those are not-850hpa upper charts there geo pots!!!

They're not tbh, they're 850's - says so on the title at the top of the chart  

[Snowjokes92]

23 minutes ago, Optimus Prime said:

You see though, that's the problem. Posting charts that are 7 & 10 days out is not rationale. And then go on and post a precip chart 10 days out!

Again they are just 850 hPa. -10 850 hPa from the NW will inheritably be different to one from the east. The surface cold from an easterly would not be there in a NW'ly. 

 No one has said anything about -10 850hPa temps from a NW'ly been different from an easterly. The point of the post was stating how rare it is to get it over in the uk! And there is the element of an easterly direction for us in the models. Look at the early stages of ecm ! Where do you think the cold air is been pulled from. Hardly from NW'ly is it...

Edited January 31, 2018 by Paul
No need to be so abrupt.

[snowice]

28 minutes ago, nick sussex said:

A pretty good ECM ensemble mean even at T240 hrs, displaced Azores high and low heights over Southern Europe.

Factor in the MJO and we could see further westwards corrections.

The mjo is due to impact in the next 48 hrs so we should see the  models adjust!

Edited January 31, 2018 by snowice

[Optimus Prime]

11 minutes ago, Snowjokes92 said:

 No one has said anything about -10 850hPa temps from a NW'ly been different from an easterly. The point of the post was stating how rare it is to get it over in the uk! And there is the element of an easterly direction for us in the models. Look at the early stages of ecm ! Where do you think the cold air is been pulled from. Hardly from NW'ly is it...

The point I was trying to make here was that rationale was being used as a counter argument but the content being displayed was model analysis well outside reliability. It just seemed a bit counterintuitive. I just wouldn't have used an example in that way myself.

But you're right the earlier ECM examples posted show some impressive cold over us from the east for a time. Looking at the way high pressure is orientated to the NE and how deep the cyclonic activity is bursting out of Greenland on the jet, facilitated by the contrast in very cold and warmer air I personally don't think an easterly is the most likely option, 

[Bottled Snow]

Very interesting charts today with some unusual synoptics suggesting cold and at times wintry weather for some. Here in Ireland we could do with the Pattern edging further west to bring us more in to the game. Not impossible by any means and it already happened in December when I had three days of lying snow after models adjusted pattern west a few days before the 10th Dec event which meant  snow rather than rain for my location ...either way much of the UK should do well if current charts verify so hopefully all you fellow snow geeks get your just rewards in the coming days and weeks ahead. Hopefully more upgrades to come starting with 18z later.

BTW pity to see such bickering here tonight on what is in general a fantastic forum with so many excellent posters . Be nice to each other peeps...its only the weather....

Signed : Bottled Snow (not BS) ?  

Edited January 31, 2018 by Bottled Snow

[Frosty.]

Well, I haven't posted for 15 days but after viewing this evening's Ecm 12z I couldn't keep quiet any longer!cold attack from the east followed by unusually cold air from the west / northwest..hardly bog standard is it?..good luck to us all, get the cold air in place (entrenched) and hopefully most of us will see snow ❄❄❄❄❄❄..speaking of snow, saturday could be a very interesting day across a large swathe of the uk..

[damianslaw]

Lots to discuss this evening an interesting set up, and different to much of the output we've had so far this winter - what is different? For the first time this season we have forecast some robust northern blocking to the north of scandi orientated in a position to pull in some notable cold uppers into scandi and n europe - something we haven't really had so far. This is important, we are in the depths of the winter season, and cold pooling in these conditions will result in a cold dense pool of surface air, which won't be easy to shift  even against a rampant atlantic. Alas whilst the models continue to show a fairly active atlantic -no surprise given how cold conditions are over NE Canada with a very tight temp gradient over NW atlantic, the block to the east in tandem with the azores high to the SW which continues to want to displace westwards - a sign that we are in still quite an amplified flow, will sink the upper atlantic trough on a more NW-SE aligned path - hence we look like having a pincer movement effect, cold to the east and very cold air to the west with trough disrupting over the UK, an interesting quite unusual set up. 

Short-term Saturday looks interesting, with low pressure developing over the UK as the trough sinks into cold air - a surprise snowfall for some possibly, with the front turned back on itself, with cold air both in front an behind it, a nowcast event. Into next week, ECM is showing cold surface air over the UK and any frontal attacks from the west would most likely give snow, indeed the cold air to the west catches up with any warm sector and instead we have occluded front with no warm sector at all - outcome a possible very snowy scene.

Expect further twists and turns.

Model watching has got interesting again after a 10 day lull..

 

Edited January 31, 2018 by damianslaw

[geordiekev]

30 minutes ago, Frosty. said:

Well, I haven't posted for 15 days but after viewing this evening's Ecm 12z I couldn't keep quiet any longer!cold attack from the east followed by unusually cold air from the west / northwest..hardly bog standard is it?..good luck to us all, get the cold air in place (entrenched) and hopefully most of us will see snow ❄❄❄❄❄❄..speaking of snow, saturday could be a very interesting day across a large swathe of the uk..

We are all wondering where you've been Karl, I'm wondering if you finally found the magical controls to the charts. There's no place like home... Good to see you back posting again ? I think you may need to stock up on your blue/purple crayons ❄

Edited January 31, 2018 by geordiekev

[Catacol]

I've been very busy and consequently rather absent the last couple of weeks... but events are catching my eye now again. Late Jan was a fail unless you like north westerlies... no doubt about that. Nina won out. We are now approaching the next cycle of torques and the crucial discussion of MJO phase 7/8 and things are looking eye catching.

Let's start with this:

Pulled this off twitter earlier, and we can see the highest amplitude MJO wave forecast to occur in the modern record. That is above expectation (obviously...) All season long we have hoped for the MJO to break through the dominant Nina pattern and apart from a brief flirtation early season it has failed and we have been stuck in a low GLAAM state with little sign of westerly injection in the pacific equator to hammer the Nina forcing onto the back foot. But this current MJO wave means business, and forecasts from a week or so ago that looked promising (but we viewed with a pinch of salt in the context of the overall season) look like they may actually come to pass and in fact exceed expectation. The filtered VP200 image available on Ventrice's site shows the impressive amplitude quite clearly - bright colours both east and west of the maritimes

Consequently global AAM is on the up, and this graph clearly shows a steady and swift return to neutral today

From here, bearing in mind the amplitude of the MJO forecast, there is only one direction this is going to head - further up as it hits phase 7. February composites for phase 7 over at JMA are clear: height rises over the NE with a gentle low anomaly to our south. Continental feed of some description.

@Tamara understands far more than me about the global impact of a GWO orbit passing through a 5 - 6 - 7 - 8 orbit.... but suffice to say this is a Nino style setup with falling momentum budgets at our latitude and a signal for a much more meridional pattern

NWP isnt quite seeing it yet - perhaps slightly too far out. This is a scenario where teleconnections come into their own perhaps, and our reading of the signals can lead the models. Currently EPS at 240 looks pretty non descript

but I would expect this to change now and for mid Feb to see a stronger signal building for blocking to the NE. Whether this leads to snow laden battlegrounds and streamers off strong easterly breezes, or a calm slack easterly with mirk and frost is way too early to tell yet: but I for one will be glad to see the back of our westerly rainy pattern and see at least some time with something seasonal once again. It really has been a grim winter once again in the SW so far.

Fingers crossed this isnt a case of thrice burned. So far Nina has had this winter in its back pocket, and the NE pacific ridge (perhaps reinforced by low sea ice north of Alaska) has controlled events across the pond with consequent impacts on us. Can we break nina's gripjust for a short while? I hope, before Spring gets too close, that lowland areas of the south can catch a bit of the white stuff that polar north westerlies have delivered to favoured spots further north. Model output over the next week should certainly be an interesting watch.

 

 

[supernova]

42 minutes ago, Frosty. said:

Well, I haven't posted for 15 days but after viewing this evening's Ecm 12z I couldn't keep quiet any longer!cold attack from the east followed by unusually cold air from the west / northwest..hardly bog standard is it?..good luck to us all, get the cold air in place (entrenched) and hopefully most of us will see snow ❄❄❄❄❄❄..speaking of snow, saturday could be a very interesting day across a large swathe of the uk..

Welcome back Frosty. Few of us on here been wondering where you'd got to. Good to have you back cheering the cold in. 

Edited January 31, 2018 by supernova

[ANYWEATHER]

I've been on this forum for eleven years I've never seen such winter charts from both west and east such cold but subject to change ....

[philglossop]

Really interesting charts and certainly heading towards a 2010 event after many years of dross.

interesting to see that so called warm sector on Mon/Tuesday admittedly only -7 here in the South West . I’m mindful that the last 3 snow events here in South Devon 1985/1987 and 1994 all came in early to mid February and this appears to be more towards a 1985/1994 event as 87 came from a blocked easterly month. Heck even in 2010 in that December was only marginal here. Do others see this the same way?? Perhaps these comments that February are too late haven’t seen the events we get here in February  

On a personal level I’m driving from London to Plymouth on Sunday I’m just hoping it’ll be ok to be fair!! 

[supernova]

@fergieweather on Twitter.  No surprises but no cold water either, no pun intended.

[SMU]

Updated 18z shows a stronger Scandi high at 72 with no shortwave blocker in the North Sea - -10 to -12c should be odds on

[damianslaw]

15 minutes ago, philglossop said:

Really interesting charts and certainly heading towards a 2010 event after many years of dross.

interesting to see that so called warm sector on Mon/Tuesday admittedly only -7 here in the South West . I’m mindful that the last 3 snow events here in South Devon 1985/1987 and 1994 all came in early to mid February and this appears to be more towards a 1985/1994 event as 87 came from a blocked easterly month. Heck even in 2010 in that December was only marginal here. Do others see this the same way?? Perhaps these comments that February are too late haven’t seen the events we get here in February  

On a personal level I’m driving from London to Plymouth on Sunday I’m just hoping it’ll be ok to be fair!! 

I don't have the stats, but for lowland SW England at least I think February on average is every bit as snowy as January, indeed slightly colder as well. Certainly February isn't too late for heavy snow, indeed more chance of snow in late Feb than much of December. Yes the increasing strength of the sun, makes it more difficult to sustain snow cover during the midday; but other factors often override its effects, including SST's being lower now, and continental cold pooling and arctic cold pooling being at there greatest in depth.

Feb is the equivalent of August - and no-one says no chance of heatwaves in August, so absolutely no reason to discount snow chances in Feb. Our two heaviest snowfalls of the last 30 years have come in February, and one came in March. Indeed March has been snowier than January in many a recent year! Alot of winter left still - only at half way stage.

Edited January 31, 2018 by damianslaw

[tight isobar]

Southern track feature should aid in closing the warm sector..

and as again start to introduce eastwards cold spillage....

With intro of azhp to tighten things for a more continental flow!!

Edited January 31, 2018 by tight isobar

[comet]

I for one have for some time been calling end of Jan and then on into Feb for cold weather with the strat and MJO playing ball with east / north easterly airflow. As late as early yesterday was thinking this was a poor call with mediocre upper temps and similar wet snow, slushy fest away from high ground. The last 24 hours has seen a fairly substantial  upgrade although not sure if ecm is over doing it a tad.

Whether we stay locked into a cold pattern as the ecm is starting to suggest or there will be a temporarily relaxation one thing I do known if the warming and split that the gefs have been modelling comes off ( There is every likelihood that it will) then what we may see in the second half of February could be the like of which we have not seen since Feb 91 or Jan 87 both in terms of snow and depth of cold. That is a long way off for now though and plenty to keep us entertained in the meantime.

Happy days.

[Allseasons-Si]

1 hour ago, blizzard81 said:

Ecm op a marked cold outlier for London. We may need to temper expectations with regards to what exactly comes our way from the east early next week. 

I was looking at the mean of which is cold anyway

[supernova]

Cold advecting Eastwards faster. Deep continental cold now diving SE instead of South in this timeframe (straight for the UK). Could be an upgrade this. 0100 Sunday 12z vs 18z.

Edited January 31, 2018 by supernova

[SMU]

GFS now aligned to the ECM @96 with snow showers moving into the SE corner in SUB -10c air...

stella tastic

[Matthew.]

I don’t know if anyone saw this earlier but the uppers are quite something heading in from the ECM

[Ice Day]

-10's nudging into the east coast just 96 hours away...and plenty more where that come from.  This run is looking very nice so far.

  

[tinybill]

just watched  bbc news 24  weather  they saying its going  to be cold for the next 2 weeks   with sleet and snow at times