Model Output Discussion - cold spell to end Autumn

[Duane S.]

9 minutes ago, blizzard81 said:

I mentioned this about the ecm op tonight. Much stronger pv over north east Canada. The gfs 18z has followed suit. Not good news at all. 

The vortex ramping up over NE Canada is a plausible, if not fairly likely scenario but as long as we get the projected strong Eastern Pacific ridging, this will mean it has hardly had time to put its first tent pegs into the ground before it is being drawn back westwards into central Canada and start spitting of shards of energy south eastwards.

That is far from set in stone of course but we have a ticket to the raffle in that the atmospheric state is conducive.

Edited December 3, 2017 by s4lancia

[ICE COLD]

This forum makes me die sometimes. We have brilliant charts showing for a change and in the reliable for once ? 

 

And people are are still banging on it's a toppler it's only 2 days bla bla bla . Yes it may turn briefly milder again but when you have charts like these coming out on FI there is definitely something brewing . It is especially strange that the GFS keeps showing these as it usually has low after low heading towards us and all it shows at the min is northern blocking . Something is afoot . 

Edited December 3, 2017 by ICE COLD
Typo

[SMU]

25 minutes ago, blizzard81 said:

I mentioned this about the ecm op tonight. Much stronger pv over north east Canada. The gfs 18z has followed suit. Not good news at all. Some bargaining on the positive pna but if that trend of growing pv over NE Canada carries on then things will change very quickly in the long term  modelling. And not a nice change for coldies. 

I think you need to be careful with just assuming a lobe of the vortex over Canada is going to have the same impacts as the entire vortex setting up in the same locale, especially when there is so much opposing force coming back at it out of Russia ... 

[Tracy Flick]

The JMA is slider after slider after slider, some colder than others.

[Frosty.]

Some peachy wintry 18z charts for my coldie netweather  friends..

[Met4Cast]

Yeah. 

Vortex ripped apart and deader than the dodo in FI, snow moving Southwards across the country in the form of troughs, but because the high sinks (edit: actually, it doesn't even sink, it just allows a low pressure system to temporarily break through before the block reloads) and for a couple of days we get some slightly less cold air, people in here are throwing their toys out of the pram 

Just a quick reminder of the weather last year

Look at the raging Polar Vortex to the North of us. Now look at the projected pattern for next week

Back to last year. Now back to this year. Back to last year one more time, now back to the here and now.

We are in an incredible position, background signals all favour blocking and cold across W Europe and the UK. I feel those getting "let down" because the GFS Precip charts don't show snow in their locality 5/6/7 days out need to realise how useless those precip charts actually are, and how useless the models often are at picking up shortwaves and troughs this far out. 

Relax. The cold is coming, the snow will follow. 

Edited December 3, 2017 by Danny*

[karlos1983]

1 minute ago, meh said:

The JMA is slider after slider after slider, some colder than others.

That is your perfect slider scenario right there, winds from se straight off the continent, we can dream

[phil nw.]

15 minutes ago, nick sussex said:

Some very unusual and welcome synoptics showing up.

Great to see these trends in early December and very happy with tonights outputs. The PV blob has no chance as long as you get that re-load of the positive PNA as that pulls the PV lobe towards Canada and helps to separate the low tracking se from the PV mothership.

Then positive heights to the ne can build sw.

 

Agree Nick.

A classic route to a more prolonged cold spell.As long as the upstream pattern holds then sooner or later the jet will be steered se by a segment off the Canadian vortex.The key is then to see the heights to the ne build/.Even if they are delayed then we still have the cold north/north westerly setup.

The main thing is we continue to see the retention of the euro trough and the Atlantic ridge in the extended ens.

[northwestsnow]

While the euro low remains locked in we should remain generally on the right side of the jet...

Hopefully some corrections south of the weekend slider

[karlos1983]

Nice control run

Edited December 3, 2017 by karlos1983

[SMU]

GFS control @168

Standard toppler ...

[nick sussex]

4 minutes ago, phil nw. said:

Agree Nick.

A classic route to a more prolonged cold spell.As long as the upstream pattern holds then sooner or later the jet will be steered se by a segment off the Canadian vortex.The key is then to see the heights to the ne build/.Even if they are delayed then we still have the cold north/north westerly setup.

The main thing is we continue to see the retention of the euro trough and the Atlantic ridge in the extended ens.

Yes I'd be less confident if the signal to re-load that positive PNA was inconsistent but its appeared for days now on every run.

It's not often you see that and currently it looks like a very strong signal.

[Nick F]

Nice southerly tracking jet in 18z GFS FI, courtesy of high latitude blocking over Russia and Barents Sea extending across Greenland eventually and forcing the jet south.

The extended EC/GFS ENS and GFS operational runs to day 15/16 over recent days have shown a distinct lack of interest in strengthening and shifting the tropospheric PV to its normal home over Greenland. Rather, instead, shown +ve heights over the pole, created by the +PNA ridge and a little help later on from +ve heights over Russian too, keeping the amplified status quo with the trop PV fragmented into H5 vortices over N America, Europe and E Asia. Which is encouraging for longer term cold patterns re-occurring or persisting through December. 

In the meantime, 18z shows an interesting little disturbance running S/SE early Friday, unlikely to verify as this track or timing this far out, but goes to show there will be troughs in the flow of the northerly, which could mean its not the just the usual coastal suspects benefitting from the wishbone effect, but chances of some snow getting inland too.

Also fax charts updated today have feature running down the west

 

Edited December 3, 2017 by Nick F

[Duane S.]

5 minutes ago, Frosty. said:

Some peachy wintry 18z charts for my coldie netweather  friends..

Well, I can give you a cast iron guarantee this one WILL occur just like this...

I

It misses my house by about a mile!

 

[feb1991blizzard]

1 minute ago, Steve Murr said:

GFS control @168

Standard toppler ...

'Standard toppler' also backed up by a 20 ensemble member mean as well.

[phil nw.]

Mentions of a toppler after the northerly i read somewhere-see the jet pattern.

Heading se not straight across to our north so we remain on the cold side of the jet.I would guess too that at that range time for GFS bias to ease that back a little further west too.

[shaky]

7 minutes ago, Steve Murr said:

GFS control @168

Standard toppler ...

Hopefully the op run can follow the control route tomorrow morning!!need ecm to be ever so slightly further west aswell!!

[SMU]

What date was the Ian Brown infamous WTF - that was a similar slider event..

[feb1991blizzard]

1 minute ago, Steve Murr said:

What date was the Ian Brown infamous WTF - that was a similar slider event..

early jan 13 - cant remember exact date - guessing 6th = 10th ish

[SMU]

18 minutes ago, shaky said:

Hopefully the op run can follow the control route tomorrow morning!!need ecm to be ever so slightly further west aswell!!

Yes snow for the south, snow for the extreme North & deep deep surface cold wedged in the middle !

[SMU]

19 minutes ago, feb1991blizzard said:

early jan 13 - cant remember exact date - guessing 6th = 10th ish

Cheers

proof on the chart below that a small system can get through the block & slide SE

[Malcolm Edwards]

11 minutes ago, Nick F said:

Nice southerly tracking jet in 18z GFS FI, courtesy of high latitude blocking over Russia and Barents Sea extending across Greenland eventually and forcing the jet south.

The extended EC/GFS ENS and GFS operational runs to day 15/16 over recent days have shown a distinct lack of interest in strengthening and shifting the tropospheric PV to its normal home over Greenland. Rather, instead, shown +ve heights over the pole, created by the +PNA ridge and a little help later on from +ve heights over Russian too, keeping the amplified status quo with the trop PV fragmented into H5 vortices over N America, Europe and E Asia. Which is encouraging for longer term cold patterns re-occurring or persisting through December. 

In the meantime, 18z shows an interesting little disturbance running S/SE early Friday, unlikely to verify as this track or timing this far out, but goes to show there will be troughs in the flow of the northerly, which could mean its not the just the usual coastal suspects benefitting from the wishbone effect, but chances of some snow getting inland too.

Also fax charts updated today have feature running down the west

 

OOOh 528 line clears south coast...fingers crossed for us here in Marazion then.

[karlos1983]

Ens London 

Ecm whilst no outlier, does taker one of the more milder routes from around the 10th. 

My mind still says it will back west with the slider low. 

 

Edited December 3, 2017 by karlos1983

[Tracy Flick]

Not what people care about right now I know, but the last few FI GEFS runs have suggested some nasty vortices spewed into the mid-Atlantic.

Starting to look like an irresistible force meeting an immovable object... who will win?

 

Hopefully the lows will lose else the south-west could be in the firing-line:

Or maybe the tune will completely change in due course.

 

[Frosty.]

What an amazing day, plenty of fabulous output for the majority. Hope for more of this..or better tomorrow as the models fine tune the wintry developments later in the week..fingers crossed the cold becomes entrenched!..night all.