Model Output Discussion - cold spell to end Autumn

[shaky]

4 minutes ago, bluearmy said:

I think I just found the reason for ecm 12z having the snow line as far south as the n Home Counties 

a discreet little low at the extension of the trough at 9am Sunday 

Thats the feature i mentioned earlier to you mate!!!and gfs 18z looks like it might do the same thing!!

[chionomaniac]

A few posts have been hidden following a misleading post.

 

Please keep on topic

[bluearmy]

6 minutes ago, shaky said:

Thats the feature i mentioned earlier to you mate!!!and gfs 18z looks like it might do the same thing!!

It didn't 

only way we see if Exeter are thinking the same is if ec does the same in the morning and the T36 fax shows it.  

[damianslaw]

Northern hemispheric base state remains the same for the foreseeable - so expecting u-turns over the weekend back to the predominantly cold outlook with the atlantic never breaking through fully - a temporary westerly mid week, before cold returns later in the week.

Models as they often do probably overreacting to the incoming westerly feed, powering up the jet.

I'm still seeing a signal for height rises to our NE as we approach christmas.

[shaky]

Hirlam 18z model goes crazy on the snow totals!!25cms across the midlands and into east anglia!!

[Ice Day]

Out to 120 and the theme remains cold, brisk north westerly winds with snow to the high ground in the north.  Ridging up towards Greenland slightly stronger on this run as well

[Delka]

Just now, shaky said:

Hirlam 18z model goes crazy on the snow totals!!25cms across the midlands and into east anglia!!

links?

[feb1991blizzard]

3 minutes ago, shaky said:

Hirlam 18z model goes crazy on the snow totals!!25cms across the midlands and into east anglia!!

Id take that with a pinch of salt, look how much it has over Ireland.

[Nick F]

GFS edging a little further south with Sunday's low with each subsequent run today.

ECM 00z & 12z fairly similar in track with Sunday's low, though Monday's deep low affecting S England a little further north, while 18z GFS has trended further south with Monday's low compared to 12z. Be interesting to see if GFS trends further south still with Sunday's low on 00z.

 

 

[Derecho]

Good 18z so far, shame about that mild sector on Wednesday but it quickly turns cold again on Thursday, maybe an easier path to Scandi later for the Azores high?



If we get a slack flow developing with an incoming ridge this run could turn very cold.

Edited December 8, 2017 by Quicksilver1989

[Man With Beard]

Re: Monday's "snow" - most output apart from ECM seems to be backing away from a major snow event, as far as I can see: GFS 18z, gem, ARGEPE, nnm all not making so much of it now.

[Weegaz]

Hopefully the slider stalls over Ireland, further north the better, while it decides on which route it will follow 

At this time frame it’s still causing head scratching it seems

[Ice Day]

I think we've seen so many great charts over the last few weeks maybe we're getting a little worn down!  This at 144 is another cracker....just think of the doom last December!!!

And decent uppers compared to 12z at 150

Edited December 8, 2017 by Ice Day

[bluearmy]

2 minutes ago, Man With Beard said:

Re: Monday's "snow" - most output apart from ECM seems to be backing away from a major snow event, as far as I can see: GFS 18z, gem, ARGEPE, nnm all not making so much of it now.

Not wanting to be imby but I'm intrigued that most of the high res modelling we get to see seems to want to keep the snow line further south (apart from euro4) 

[SMU]

18 minutes ago, bluearmy said:

Not wanting to be imby but I'm intrigued that most of the high res modelling we get to see seems to want to keep the snow line further south (apart from euro4) 

ECM - as you highlighted in the pic is doing what I tried to describe earlier - elongating the trough so that the cold air doesnt filter as far NE..

late in the day but still corrections happening- however if theres to be any snow south of the water then the 18z jog south needs to be followed up with another 2 jogs south 00z & 06z...

S

Edited December 8, 2017 by Steve Murr

[Nick F]

8 minutes ago, Quicksilver1989 said:

Good 18z so far, shame about that mild sector on Wednesday but it quickly turns cold again on Thursday, maybe an easier path to Scandi later?



If we get a slack flow developing with an incoming ridge this run could turn very cold.

Been earmarked by the models for a while for some amplification in the H500 flow tail end of next week, with a NLy reload, it's whether or not subsequently the trop PV over NE Canada can hold back and not drift east to flatten the flow out again and allow a block to form over the GIN corridor - which is being highlighted by the 12z runs. Very deep low modeled by 12z and 18z heading towards Davis Strait straight may help reinforce ridging downstream to the east of Greenland.

Edited December 8, 2017 by Nick F

[norfolksnow]

Just now, Nick F said:

GFS edging a little further south with Sunday's low with each subsequent run today.

ECM 00z & 12z fairly similar in track with Sunday's low, though Monday's deep low affecting S England a little further north, while 18z GFS has trended further south with Monday's low compared to 12z. Be interesting to see if GFS trends further south still with Sunday's low on 00z.

 

 

Hi well as a senior forcaster, what would be your opinion? instead of commenting on a run!

Thanks Jason

[Met4Cast]

3 minutes ago, norfolksnow said:

Hi well as a senior forcaster, what would be your opinion? instead of commenting on a run!

Thanks Jason

Yes, how dare Nick as a senior forecaster comment on a run instead of giving an actual forecast! Lets all tut in unison. 

Lots to be happy about tonight, good trends for the mid-range term with Westerlies being constantly pushed back/downgraded. It seems a "less cold" spell is likely at some point but mild it definitely wont be! 

EURO4 18z will be interesting to see if that too shifts Sundays snowline further South, I'd imagine it will, it's the furthest North of any of the models now.

[blizzard81]

The big impression I am getting from the models tonight is that there is going to be some very cold stagnant air over Scandinavia next weekend. This can be a crucial ingredient in the development of a scandi high appearing seemingly out of nowhere. I will say no more. 

[markw2680]

Just now, blizzard81 said:

The big impression I am getting from the models tonight is that there is going to be some very cold stagnant air over Scandinavia next weekend. This can be a crucial ingredient in the development of a scandi high appearing seemingly out of nowhere. I will say no more. 

Iv been thinking the same thing tbh, they do just seem to appear out of nowhere 

[blizzard81]

Just now, markw2680 said:

Iv been thinking the same thing tbh, they do just seem to appear out of nowhere 

Especially in tandem with trough disruption in our vicinity which is exactly what we are seeing at the moment in the modelling. 

[Nick F]

6 minutes ago, norfolksnow said:

Hi well as a senior forcaster, what would be your opinion? instead of commenting on a run!

Thanks Jason

For Sunday I would go for the general consensus of snowline north of the M4 and north of Greater London, where it settles more of gamble, but parts of Wales and Midlands and southern parts of N England esp. The Peaks look to stay all snow. I don't think there will be anymore nudges north in track more likely south if there is anymore changes. As for Monday's low, more difficult as the centre and the precipitation circulating around it may end up missing SE UK altogether!

[Derecho]

12 minutes ago, Nick F said:

Been earmarked by the models for a while for some amplification in the H500 flow tail end of next week, with a NLy reload, it's whether or not subsequently the trop PV over NE Canada can hold back and not drift east to flatten the flow out again and allow a block to form over the GIN corridor - which is being highlighted by the 12z runs. Very deep low modeled by 12z and 18z heading towards Davis Strait straight may help reinforce ridging downstream to the east of Greenland.

Yup it doesn't quite work out later on with the Atlantic looking like it may wake up again



Though it's all fine margins and it could easily change for the better. I hope that deep low hangs back over NE Canada so we don't have energy spilled into the North Atlantic.

It wouldn't surprise me if we got another northerly reload... they seem to occur every week at some point now 

[norfolksnow]

Just now, Nick F said:

For Sunday I would go for the general consensus of snowline north of the M4 and north of Greater London, where it settles more of gamble, but parts of Wales and Midlands and southern parts of N England esp. The Peaks look to stay all snow. I don't think there will be anymore nudges north in track more likely south if there is anymore changes. As for Monday's low, more difficult as the centre and the precipitation circulating around it may end up missing SE UK altogether!

Thank you Nick

 

[CanadaAl]

7 minutes ago, blizzard81 said:

The big impression I am getting from the models tonight is that there is going to be some very cold stagnant air over Scandinavia next weekend. This can be a crucial ingredient in the development of a scandi high appearing seemingly out of nowhere. I will say no more. 

Yeah i'm fairly certain a lot of them don't appear until 5/6 days before, anyways. You could be on to something, we won't know until probably middle of next week. I imagine.