Model Output Discussion - cold spell to end Autumn

[Had Worse]

1 minute ago, Mokidugway said:

Quick question for the professionals , does the IPA effect  change the model output ?? 

It makes the isobars more wavy and adds the appearance of polar lows.

The model output for the northerly already shows that to be the case.

[Mokidugway]

2 minutes ago, karlos1983 said:

Yes, you need a vodka and then go home 

Lol, thought it was Guinness entropy 

[MattStoke]

4 minutes ago, Don said:

They were showing 13C for the south on Thursday so no snow event here!  Fair play though, they can't go into much detail at this stage and I agree overall it looks promising ATM.

That's the day's max temperature. Probably ahead of the front.

[andymusic]

2 minutes ago, Snowy L said:

Not a good run this. No back edge snow, the low to our east is further away so we are not getting those sharp curves in the isobars that bring precipitation. Rain followed by a cold and dry northerly except for the usual exposed areas.

details like that impossible to work out this far ahead - that'll be a radar out the window set up for the day

[markw2680]

4 minutes ago, I remember Atlantic 252 said:

18Z! looks good, surely not wishbone as winds look NNW'ly, Cheshire streamer

They look like a streamer set up to me

[Midlands Ice Age]

8 minutes ago, Don said:

They were showing 13C for the south on Thursday so no snow event here!  Fair play though, they can't go into much detail at this stage and I agree overall it looks promising ATM.

After seeing the BBC weather..

The difference is that the BBC has deepened and slowed down the incoming low compared to the GFS and ECM model output just published above. It therefore slows down the cold air and allows a large burst of warm air over most of England (and even southern Scotland ) before the cold sweeps thru on Thursday night and Friday morning. He did suggest there could be some back-edge snow on Friday before it is all swept away to the east.

Compare it to the charts above where the cold is all the way down to the south coast on Thursday on the latest GFs charts.

Which one will be correct?

I pray it will be the GFS/ ECM combination

MIA 

Edited December 2, 2017 by Midlands Ice Age

[northwestsnow]

5 minutes ago, I remember Atlantic 252 said:

18Z! looks good, surely not wishbone as winds look NNW'ly, Cheshire streamer

Looks fabulous mate happy days 

[Had Worse]

I wouldnt worry too much about the lack of back edge snow on the 18z.

The models will consolidate the fine detail as we get closer to T+0 so probably the final position will be better.

[I remember Atlantic 252]

Back edge snow never really on anyway, the northerly is what we want, cold air knocking on the door of my region 3pm Thursday, it clears the front by 9am

[northwestsnow]

6 minutes ago, bluearmy said:

Gfs finally loses any back edge snow on the cold front - wouldn't expect it to return away from elevation in the north

Surely there is going to be trough in the flow blue

[Weathizard]

Pretty consistent from the GFS, anything past that's just conjecture. (Interesting all the same)

Lots of posts not related to the models tonight though, naughty people! 

Edited December 2, 2017 by Weathizard

[bluearmy]

I'm sure it won't be there on the next run but the 18z finds and little chunk of discarded vortex and passes it along the edge of the northerly flow - heavily modified by the time it reaches nw Britain but fun to watch 

[Mokidugway]

2 minutes ago, northwestsnow said:

Surely there is going to be trough in the flow blue

Are you thinking polar low ??

[bluearmy]

1 minute ago, northwestsnow said:

Surely there is going to be trough in the flow blue

I'm sure there is mate - it's just the back of the cold front which I doubt will bring anything notable 

[Snowy L]

Weird one, over the UK its moved eastwards compared to the 12z, but further north over Greenland it is a shift to the west. Dont know what that will mean later in the run.

[Ice Day]

You really have to ignore the final details of where snow falls, that comes within 36 hours.  However, we are only 6 days away from this (or something very close to it), tremendous stufff. Right, time to repeat the well worn Netweather phrase, altogether now, 'get the cold in first......'

  

[Derecho]

Like the 12z we are getting some serious trough disruption

Could this buffer up the Greenland block?



As for the snow event later on in the week... don't forget evaporate cooling and things will change from run to run given its borderline nature.

Troughs will emerge in a northerly flow given the uppers are pretty cold.

Edited December 2, 2017 by Quicksilver1989

[Winter Hill]

2 minutes ago, Snowy L said:

Weird one, over the UK its moved eastwards compared to the 12z, but further north over Greenland it is a shift to the west. Dont know what that will mean later in the run.

Hence the pub run 

[Frosty.]

4 minutes ago, northwestsnow said:

Surely there is going to be trough in the flow blue

Unstable Northerly, I'm sure the fax charts will show trough lines swinging south in the arctic flow..how great is it to be talking about arctic air instead of the usual mild zonal mush!

[Freezing-Point]

15 minutes ago, Snowy L said:

Not a good run this. No back edge snow, the low to our east is further away so we are not getting those sharp curves in the isobars that bring precipitation. Rain followed by a cold and dry northerly except for the usual exposed areas.

Perfection

[karlos1983]

6 minutes ago, northwestsnow said:

Surely there is going to be trough in the flow blue

If it plays out as modelled I can’t see there not being troughs!  

[Allseasons-Si]

1 minute ago, Had Worse said:

I wouldnt worry too much about the lack of back edge snow on the 18z.

The models will consolidate the fine detail as we get closer to T+0 so probably the final position will be better.

Very true

and i just want to make a point about amplification->it is very difficult to forecast  the weather in an ampified setup more than 4-5 days out,sometimes less than that,whereas a zonal flow is easier to forecast 6-7 days out

yes we look to have a northerly by next thu's but after that all options are on the table.

[Jason Edwards]

I can smell an Easterly coming ......Atlantic dead in the water ...defaintely a chart loaded with potential from here on out..

 

prolonged cold spell looming perhaps 

[Met4Cast]

Low pressure systems seem to be able to absolutely blast their way through blocks to ruin cold weather, but when a potential slide could bring snowfall to the UK, the weakest, most pathetic slither of high pressure stops the low in it's tracks.

Weird looking chart that one. 

The back edge for Thursdays snow is gone which isn't a huge surprise given the lack of interest by EC/UKMO, though more changes are likely, I'd be surprised if somewhere didn't see something.

[John Badrick]

6 minutes ago, Ice Day said:

You really have to ignore the final details of where snow falls, that comes within 36 hours.  However, we are only 6 days away from this (or something very close to it), tremendous stufff. Right, time to repeat the well worn Netweather phrase, altogether now, 'get the cold in first......'

  

Rember it can all go pete tong even 48 hours out, don't forget the infamous "That ECM" back in 2012