Cold hunt - models and chat

[Nath]

I have been watching every post over the last few weeks with avid interest.  Im an out and out coldie, but also my income depends on footie and rugby pitches being playable.  But if push comes to shove I would take a month of zero games for a big freeze up.  I thought we were on the cusp of that this morning, cant believe its gone pete tong .  :( 

[feb1991blizzard]

1 minute ago, CreweCold said:

Of course they can lol. There's nothing to stop a model predicting a polar low. Especially given the increased modelling resolution these days. 

I admit - i didn't go through a checklist though so i am not saying that it was definitely one - just looked like one.

[Kentish Snowman in Yorks]

11 minutes ago, CreweCold said:

They can't be predicted more than 24-48 hrs in advance with any degree of confidence... But they can show in a hypothetical N'ly on a FI chart. What mechanism would stop a model modelling a predicted polar low? 

People only say they can't be forecast in advance because of their spontaneous nature of development. Not because they CAN'T physically be shown in the modelling. 

Think the main ingredient for Polar Low formation is around -45c at 500mb level if I'm not mistaken?  Not often we get that around the UK to be fair but when it is forecast you could in theory predict in advance (a few days away) that such features forming are a possibility?

Certainly looks cold on the 18z GFS during week 2 with that chunk of the PV being ejected over the UK.

[MattStoke]

3 minutes ago, Johnp said:

The Mighty Navgem holding firm with the easterly

Really wish that wasn't a garbage model.

[Cheshire Freeze]

1 minute ago, feb1991blizzard said:

I admit - i didn't go through a checklist though so i am not saying that it was definitely one - just looked like one.

I have an image in my head of a weather model idling through its run, approaches a polar N'ly flow and goes 'oh crap I can't model that feature, drat. Damn polar low' 

[John Stevens]

7 minutes ago, Dancerwithwings said:

Via my desktop, phones okay also, 

Try deleting the internet history/ cache on the iPad. That normally resolves the issue. Sorry probably teaching granny to suck eggs.... But it's an issue that often crops up on staff iPads at work and this normally solves it....

[Ice Day]

Now fair play to the Para, that is remarkable run to run consistency at 240 (246)

18z  12z 

[Mokidugway]

Polar lows are a notoriously  difficult mesoscale system to predict ,almost up to the day 

[kold weather]

8 minutes ago, northwestsnow said:

So, the scene is set, finally...

Cold north westerly followed by a holding ridge- followed by the jet heading on a jolly into Europe and N Atlantic height rises to the holy Grail...

Thats how this is  going to pan out with a bit of luck..

Yep I think its actually a fairly solid and easy evolution, one I've personally seen come off in many different seasons. Singularity earlier on gives a good suggestion as to why its quite likely, we would have to be real unlucky in terms of where the upper troughing set-ups not to get a good spell out of it.

Anyway 18z is still solid, strong NW push around 216hrs (maybe some transient cold even before that though, both ECM+GFS bringing in a weaker NW airflow around 168hrs today) then that motion at 216hrs from the vortex is basically the code for open g the flood gates in terms of true northern blocking. 

[Cheshire Freeze]

1 minute ago, Mokidugway said:

Polar lows are a notoriously  difficult mesoscale system to predict ,almost up to the day 

Indeed, but in theory they can still be modelled. Even if they don't end up actually verifying on the same path or at all. 

[Ice Day]

And talking of consistency, GFS and GFSP at 276 both have us in an easterly, although the NH profile is very different.

 

Edit, and the Control as well

Edited January 19, 2019 by Ice Day

[NeilN]

I guess we're back in the game now? 

[snowking]

Just now, feb1991blizzard said:

They can surely be modelled at range though, if incorrectly??

The trouble is they can be just a hundred miles or so in size and often have a lifespan of less than 48 hours (from formation to death), so when you think about that on a regular deterministic run, maybe somewhere between 3-6 pixels...now think about how much trouble we have seen trying to model something like the shortwaves (or whatever members would like to call such features) which are preventing the link up between our Atlantic and arctic ridges at present, which are probably easily 4-5 times the size of many polar lows. And what you’re essentially trying to do is model the ingredients for such a formation, and then use that to predict the formation and the track....so...

Add into the equation that in order to model uncertain situations such as the track of a polar low, you ideally want to use an ensemble suite, that’s exactly what ensembles are there for - to solve uncertainty. But of course the resolution of the ensemble runs is generally even lower, so they deal with such mesoscale features even more poorly (if they can pick up on them at all at those resolutions).

So you then generally want to wait for them to come into the range of models with resolution of far less than 10km....and those sorts of models are normally only run for fairly short periods ahead.

We’re probably in a much better position now given the upgrades to many global NWP’s in recent years, but then again we’ve not really had any UK centric polar lows to concentrate on for a long time, so it’s difficult to tell!

[northwestsnow]

2 minutes ago, Ice Day said:

And talking of consistency, GFS and GFSP at 276 both have us in an easterly, although the NH profile is very different.

 

Liking the look of that green circle over the Pole!!
I know people are sick of the P word but i honestly feel this time its going to happen, 144-192 the key timeframe for signs of the PV dropping SE and Atlantic height rises behind...

The next chase is beginning!!

[feb1991blizzard]

GEFS not quite as good as i imagined, not bad towards the end but the Graph further south id poorer than this NW graph.

EDIT - Thanks @snowking

 

Anyone got the ECM London Graph please?

Edited January 19, 2019 by feb1991blizzard

[Mike Poole]

10 minutes ago, CreweCold said:

Indeed, but in theory they can still be modelled. Even if they don't end up actually verifying on the same path or at all. 

What on earth does that mean, Crewe?  

The one a couple of years ago (can't remember when) was picked up on one model and was tracked on this thread, I remember.

Edited January 19, 2019 by Mike Poole

[Ice Day]

1 minute ago, feb1991blizzard said:

GEFS not quite as good as i imagined, not bad towards the end but the Graph further south id poorer than this NW graph.

Interesting mean at 264 though, shows the 'advertised' solution tonight could have legs!

[Mr Frost]

Great to see a happy/positive thread! 

GFS pub run has put me in a great mood - looking forward to what the morning runs bring! 

This sums up my current feeling.

Night all! 

 

 

[northwestsnow]

1 minute ago, feb1991blizzard said:

GEFS not quite as good as i imagined, not bad towards the end but the Graph further south id poorer than this NW graph.

certainly a strong signal for snow on the 22nd!

whats the exact location Feb?

[northwestsnow]

1 minute ago, Ice Day said:

Interesting mean at 264 though, shows the 'advertised' solution tonight could have legs!

PV nicely split caught my eye, as well as the jet digging south..

[feb1991blizzard]

1 minute ago, northwestsnow said:

certainly a strong signal for snow on the 22nd!

whats the exact location Feb?

Dont know but somewhere in NW England.

[Ice Day]

2 minutes ago, northwestsnow said:

Liking the look of that green circle over the Pole!!
I know people are sick of the P word but i honestly feel this time its going to happen, 144-192 the key timeframe for signs of the PV dropping SE and Atlantic height rises behind...

The next chase is beginning!!

2

Funny isn't it...... 12 hours ago we all felt a bit deflated, now we're back on the cold hunt express.  You've got to have stamina for this hobby.

 

[northwestsnow]

Just now, feb1991blizzard said:

Dont know but somewhere in NW England.

OK, thanks, APREGE still not interested in snow tues i might add even though GFS is certain..

[feb1991blizzard]

Got it now -

Rock Solid.

Edited January 19, 2019 by feb1991blizzard

[kold weather]

I'm amazed.

Man with Bread just put the 12z ECM clusters up...

100% agreement on -ve NAO solution for early Feb. That is a heck of signal!!