Model output discussion - Closing in on Christmas

[Battleground Snow]

5 minutes ago, Updated_Weather said:

Doesn't seem that much difference so far on ICON 12z

Slightly better heights around Iceland, due to the low to our SW... Need that low over Greenland to stay further west for a better sustained heights though.....

[Battleground Snow]

It does just stay far enough west! Can't complain about this for xmas day in my opinion... Can't wait for the Ukmo shortly

 

[Updated_Weather]

ICON 12z is full GIF glory!

[Howie]

Are those euro heights I'm seeing on the icon?

[ITSY]

Keep an eye out for the low pressure as it spins out of the UK on xmas eve. The 06z spawned a secondary low that was marginally a rain event for southern central England but it's not impossible for significant snow if it passes 100 miles or two further south (and there's ample time for movement at this range). I suspect the northerly movement of the initial low, which  is in keeping with the pattern of the last day or so, makes this shift unlikely but you never know! Tis the season to be cheerful

Edited December 17, 2020 by ITSY

[SMU]

GFS 12z finally worked it out - no more catastrophic 18z scenarios....

Edited December 17, 2020 by Steve Murr

[rug]

4 minutes ago, Steve Murr said:

GFS 12z finally worked it out - no more catastrophic 18z scenarios....

Welcome back Steve.

 

5 minutes ago, Steve Murr said:

GFS 12z finally worked it out - no more catastrophic 18z scenarios....

 

[Ultima Thule]

12z GFS has high slightly better oriented at 132.

[That ECM]

Nice looking Ukmo at T144 

[Battleground Snow]

*insert randy marsh computer gif* 

Ukmo Looks even better than the icon at 144!

 

[snowking]

re: the MJO question - it's best to think of all the factors which get mentioned on here (e.g. QBO, SSW's, AAM state etc.) as singular parts of a great big machine. The more of these you have in your favour for cold, the higher the chance of cold there is. However, no one  single factor is definitely going to drive us towards another 2010. By having each one in your favour it's essentially like buying lottery tickets - theoretically the more you buy, the better the chances are that you will win, but there is no guarantee.

So having the MJO in an amplified, particular phase in a particular season certainly gives you a better shot of particular longwave pressure patterns (in the case of winter, as a very rough guide, something somewhere between phases 6-1 gives you a shot of something more amplified), but there is no one size fits all answer to the equation which is the weather. What I'm cautioning against here is assuming that what can be a driver of global longwave patterns will definitely deliver cold to the UK is a dangerous game to play (e.g. La Nina or MJO phase 6 = early winter atlantic amplification)

[Zak M]

Has anyone seen this mornings GFS parallel?

   

[A Frayed Knot]

11 minutes ago, Steve Murr said:

GFS 12z finally worked it out - no more catastrophic 18z scenarios....

Nice to see you contributing again in here with you knowledgeable experience on this up and coming cold snap and your fantastic post's.

[TSNWK]

1 minute ago, snowking said:

re: the MJO question - it's best to think of all the factors which get mentioned on here (e.g. QBO, SSW's, AAM state etc.) as singular parts of a great big machine. The more of these you have in your favour for cold, the higher the chance of cold there is. However, no one  single factor is definitely going to drive us towards another 2010. By having each one in your favour it's essentially like buying lottery tickets - theoretically the more you buy, the better the chances are that you will win, but there is no guarantee.

So having the MJO in an amplified, particular phase in a particular season certainly gives you a better shot of particular longwave pressure patterns (in the case of winter, as a very rough guide, something somewhere between phases 6-1 gives you a shot of something more amplified), but there is no one size fits all answer to the equation which is the weather. What I'm cautioning against here is assuming that what can be a driver of global longwave patterns will definitely deliver cold to the UK is a dangerous game to play (e.g. La Nina or MJO phase 6 = early winter atlantic amplification)

And by the same token can we assume that when mjo is a COD phase which I understand is not good for coldies that we are still able to get cold..

[That ECM]

Long way to go but interesting little feature.

[Allseasons-Si]

It's laughable really,the different between the gfs and UKMO at 144!

the gfs want's to send the LP NE with pos snow in the north whereas the UKMO sends it packing to the Azores

 

[frosty ground]

Has to be a serious risk of Snow on the North Western flank of that low, been model regularly now, so should be an interesting watch


Cold air needs to dig in more thou
 

[mountain shadow]

Just now, TSNWK said:

And by the same token can we assume that when mjo is a COD phase which I understand is not good for coldies that we are still able to get cold..

Yes. By the same token, there are amplified phases of the MJO which are unfavourable for Winter cold, so if it's in the COD we won't be unduly influenced. Other factors can become more relevant, such as SSTs etc..

[snowking]

1 minute ago, TSNWK said:

And by the same token can we assume that when mjo is a COD phase which I understand is not good for coldies that we are still able to get cold..

Absolutely - I think we can all be guilty about religiously following the MJO forecast charts, or looking at the 10mb temperature charts looking for an SSW, but as we have seen with some of the recent output (whether it proves to be correct or not), sometimes you can just get something cold spring up out of seemingly nowhere.

I guess it's what keeps us all nerdily interested in the weather - if it was entirely predictable what would be the point

[Mike Poole]

GFS and UKMO at T144:

Both good, GFS the slightly more amplified at this point, could go on to be decent.

[WxHerts]

1 minute ago, Allseasons-si said:

It's laughable really,the different between the gfs and UKMO at 144!

the gfs want's to send the LP NE with pos snow in the north whereas the UKMO sends it packing to the Azores

 

I think what's most important is what's going on to our west and really they look quite similar in that regard!

 

[frosty ground]

Not massively different to the 18z

[Howie]

The pv is reforming over Greenland, not good

[Allseasons-Si]

3 minutes ago, WxHerts said:

I think what's most important is what's going on to our west and really they look quite similar in that regard!

 

I am just highlight the uncertainty with this low as this will determine what will happen down the line

on the gfs ,the low phases with a trough coming down from Iceland,on the UKMO it doesn't.

[Tom Jarvis]

7 minutes ago, Allseasons-si said:

It's laughable really,the different between the gfs and UKMO at 144!

the gfs want's to send the LP NE with pos snow in the north whereas the UKMO sends it packing to the Azores

 

UKMO could be charter the day today the only way I can see it going from there is the low near Greenland becoming negatively tilted. That then ejects energy southeast and links with the low in the Azores which then basically traps the high to the north and then allows lows to go into Europe giving us an easterly. @Steve Murr the UKMO 168 chart might give us an idea even though it only shows you a tiny bit. Just my 2 pennies worth but if the more seasoned posters think I’m a bit mad thinking that pls say why as wanting to learn.