Model output discussion - cold spell approaching?

[sheikhy]

Ukmo looks good!!few slider snow events!!one between 48 and 72 hours and then one between 120 and 144 hours!!especially if we can back that scandi ridge west a bit more!!

[Matt H]

This has made me realise how much of my lockdown afternoons have been dedicated to the GFS runs recently. Feel slightly lost at the moment.

[MattStoke]

4 minutes ago, Kasim Awan said:

Yeah, depends on what you mean is "nailed on". Within 20 hours for a hi res trough / volatile front, within 100 hours for the macro placement of lows, within 140 hours for the overall synoptic pattern.

Nothing is ever ‘nailed on’ with weather prediction. That’s why it’s a prediction and not a promise. It’s based on probabilities.

Edited January 11, 2021 by MattStoke

[Griff]

2 minutes ago, Paul said:

GFS still delayed, this the latest from NCEP

 

I totally relate, sometimes my ipad refuses to connect to the WiFi

[Weathizard]

GFS (6z) and UKM both keen on lower heights to our south than the ECM which got there in the end but flirted with danger in that 144-192 range.

I keep harping on about that piece of vortex over E Canada but it still concerns me, it’s very rare to get a sustainable GH with that amount of energy there

[Kasim Awan]

11 minutes ago, MattStoke said:

Nothing is ever ‘nailed on’ with the weather.

It depends how well defined what you described "nailed on" to be. In broadly speaking & broadly defined terms, a lot is certain. For example, "it will snow in parts of Northern England on Thursday" is largely "nailed on" - meaning the confidence is over 95%.

However, calling 9.5cm of snow "nailed on" is not possible as it is to narrowly defined. This is important. 

Edited January 11, 2021 by Kasim Awan

[nick sussex]

The day 5 UKMO could bring another round of frontal snow . Depends how much of a se undercut occurs .

Not sure I’m feeling the love though for the day 6 chart . The low near the Azores is far too close to phasing with the low near the UK.

[Battleground Snow]

1 minute ago, Weathizard said:

GFS (6z) and UKM both keen on lower heights to our south than the ECM which got there in the end but flirted with danger in that 144-192 range.

I keep harping on about that piece of vortex over E Canada but it still concerns me, it’s very rare to get a sustainable GH with that amount of energy there

It's just far enough west atm, but needs watching, along with about 5 other things that need to go right for us.

[Tim Bland]

8 minutes ago, phil nw. said:

Could be something in that Nick.

Thursdays fax  

showing that wave development along the front.Coming back west with a cold undercut-something to watch for.

It’s also similar to what the ECM was showing yesterday morning....

[Cold Winter Night]

UKMO 144 yesterday and 120 today.

This timeframe is far from resolved yet.

Scandi heights more pronounced, getting pinched more, lower heights in Eastern Europe.
The Azores/Iberian High more West than yesterday.

[Battleground Snow]

6 minutes ago, nick sussex said:

The day 5 UKMO could bring another round of frontal snow . Depends how much of a se undercut occurs .

Not sure I’m feeling the love though for the day 6 chart . The low near the Azores is far too close to phasing with the low near the UK.

Looks quite a decent distance to me? But I take your point after what the icon did

Edited January 11, 2021 by Battleground Snow

[Singularity]

3 minutes ago, nick sussex said:

The day 5 UKMO could bring another round of frontal snow . Depends how much of a se undercut occurs .

Not sure I’m feeling the love though for the day 6 chart . The low near the Azores is far too close to phasing with the low near the UK.

That low would likely split as illustrated and run into the base of the trough moving eastward through the UK.

Could be a bit messy but some snow potential on the northern flank. Not that such detail is worth worrying about given the huge variation between runs at the mo.

Main positive for me about this run is that it has a decent alignment to the ridge that's north of that cut-off low.

[Guest]

Well we can blame the dodgy connection should the GFS run a stinker later 

[sheikhy]

1 minute ago, Cold Winter Night said:

UKMO 144 yesterday and 120 today.

This timeframe is far from resolved yet.

Scandi heights more pronounced, getting pinched more, lower heights in Eastern Europe.
The Azores/Iberian High more West than yesterday.

Big difference stronger scandi high and low sliding across the uk!!if this continues there will be a heavy snow event widely across the uk saturday!!and thats after the snow on thursday!!

[nick sussex]

Just now, Battleground Snow said:

Looks quite a decent distance to me? But I take your point after that icon did

The problem is as the flow amplifies upstream if you get an early phasing that could then see too much ne track and a delay to the cold heading se , or worst case scenario  trapped on the wrong side with the cold heading sw to the west of the UK.

So a clear separation of the UK low and the one near the Azores is needed. 

[Tim Bland]

Somewhere like East Anglia and East mids probably the prime spot on Sat going by the UKMO.

[Griff]

2 minutes ago, sheikhy said:

Big difference stronger scandi high and low sliding across the uk!!if this continues there will be a heavy snow event widely across the uk saturday!!and thats after the snow on thursday!!

Better watch the gem trickle out then, just to feed the habit.. 

Edited January 11, 2021 by Griff

[Allseasons-Si]

Check out the ICON in motion...

[XtremeUKWeather]

we wait and we wait and wait

[Matt H]

GEM 12z goes for a decent amount of frontal snow this Thursday/Friday...

Edited January 11, 2021 by Frosty Winter

[Tim Bland]

GEM shows snow for Scotland and eastern areas sat. Probably turning briefly to snow in the south east in the next few frames before clearing. Not too dissimilar to Aperge. Be interesting to see ECM take later 

Edited January 11, 2021 by Tim Bland

[ALL ABOARD]

Has the scandi high got legs? 

Much stronger on GEM at just 78 hours?? 

 

[Man With Beard]

Well here's something to enjoy for Eastern England - ARPEGE 12Z is out for France, showing a sizeable snowfall across most of this area by the end of the week 

 

[Battleground Snow]

2 minutes ago, Griff said:

Better watch the gem trickle out then, just to feed the habit.. 

Gem going to get some good airtime this evening.

Top tip: it rolls out in wetter slightly faster.

Low cuts off at 114

[northwestsnow]

UKMO 144 looks good to me ..