Model Output Discussion - Snow for some, but what else is in store?

[Cloud 10]

10 minutes ago, Tim Bland said:

GFSp is the most appetizing for the south this weekend with 10cm in a few spots. Unlikely but not impossible 

 

I'll raise your 10cm......

 

[IDO]

5 minutes ago, Battleground Snow said:

Hi @IDO

Did you see the composite when it was filtered for a  - NAO regime

 

No, did not see that. Looks a bit more interesting, a bit of tweaking and it would not be a bad synoptic. However the AO and NAO indices are not heading in the right direction as we head into Feb:

 

[Battleground Snow]

1 minute ago, IDO said:

No, did not see that. Looks a bit more interesting, a bit of tweaking and it would not be a bad synoptic. However the AO and NAO indices are not heading in the right direction as we head into Feb:

 

Indeed, it's heading towards neutral, but that's a fair way out, 

[Froze were the Days]

Might as well throw a coin up in the air with GFS regarding medium to longer term...it certainly chops from one scenario to another.

[A Frayed Knot]

16 minutes ago, That ECM said:

This is the only way the south coast is going to get anything. liking the ukmo in all seriousness.

Looks OK if you are standing on your head.

[feb1991blizzard]

18 minutes ago, Battleground Snow said:

Hi @IDO

Did you see the composite when it was filtered for a  - NAO regime

 

The NAO is a reflective teleconnection, not a driver, combine any other teleconnection with a -NAO and it will give you erm erm, well, a -NAO, in other words Northern blocking.

Edited January 18, 2021 by feb1991blizzard

[Methuselah]

1 minute ago, Froze were the Days said:

Might as well throw a coin up in the air with GFS regarding medium to longer term...it certainly chops from one scenario to another.

And 'ditto' for all the models -- should they go out that far?

[Phil Blake]

For all the people worried about nao becoming positive. A nice scandi high could still produce a +Nao. 

[Anthony Burden]

All up for grabs regarding Thursday onwards cold spell temperatures and longevity 

still in the balance.Low pressure systems and orientation will decide who is on the Arctic side

or Atlantic,good watching.

[swfc]

10 minutes ago, Froze were the Days said:

Might as well throw a coin up in the air with GFS regarding medium to longer term...it certainly chops from one scenario to another.

Yes I agree. There's nothing in the mo or nhp to suggest anything wintry which will dig in and hang about. You can call fi 144 hrs or whatever but I'm not seeing anything substantial. The move towards a cold wintry February has a ring to it has in the past it can stretch to march. A bit of negativety but that's not a bad thing going forward 

[IDO]

13 minutes ago, feb1991blizzard said:

The NAO is a reflective teleconnection, not a driver, combine any other teleconnection with a -NAO and it will give you erm erm, well, a -NAO, in other words Northern blocking.

Of course, but the discussion was on the MJO signal and the composites. The MJO phase 6 El Nino does not necessarily mean HLB'ing (-NAO) when it begins. The composites were for -NAO and not, the latter shows a MLB over the UK! @Battleground Snow highlighted the -NAO composite which I assume would have to be in place for that composite to be valid in Feb? The current NAO is forecast to be neutral, though moving from negative so if it is a neutral NAO or +NAO when the MJO phase 6 pattern emerges we would not look at a -NAO composite for instruction?

[chris55]

Thats one hell of a shortwave on Saturday from UKMO day 5. Definitely a much stronger feature, when does a shortwave become long wave lol!

Snow event somewhere in the middle of the UK this weekend is still in my diary!

 

[Don]

1 hour ago, Tim Bland said:

GFSp is the most appetizing for the south this weekend with 10cm in a few spots. Unlikely but not impossible 

I'm just about in the sweet spot on that chart.  Have I not told you the GFSP is the most accurate for snow depths at 6 days out?!! 

[Dorsetbred]

1 hour ago, Tim Bland said:

GFSp is the most appetizing for the south this weekend with 10cm in a few spots. Unlikely but not impossible 

I suspect given the current model ups and downs, this is probably a better synopsis of the chart..

[Lord Grogon]

Hello, first time I have ventured onto this thread so please be gentle.

Last year I recall there was a fair bit of chatter about the GFSp having a cold bias. I've no idea how this would work in practice but I do recall it tending to through out colder solutions more often that average.

Was that ever verified/resolved. Or was it just random internet speculation? Would be good to know as every time somebody posts a good run from this model it pops into my thoughts.

Thanks

[Don]

56 minutes ago, IDO said:

No, did not see that. Looks a bit more interesting, a bit of tweaking and it would not be a bad synoptic. However the AO and NAO indices are not heading in the right direction as we head into Feb:

 

Always a bit concerning to see those ticking up at the end with all members heading upwards.  This would be frustrating but as others have said a long way off still.

Edited January 18, 2021 by Don

[Tim Bland]

Last 3 GFSp runs at the end...

[Don]

41 minutes ago, Phil Blake said:

For all the people worried about nao becoming positive. A nice scandi high could still produce a +Nao. 

Indeed, February 1991!  Would still prefer the AO/NAO to remain negative though!

Edited January 18, 2021 by Don

[IDO]

1 minute ago, Don said:

Always a bit concerning to see those ticking up at the end and would be frustrating but as others have said a long way off still.

Yes, as @feb1991blizzard said they are only indices, so those NAO charts are a reflection of what the ens are showing. Hopefully that will change before Feb arrives!

The gefs at d12 are trending the wrong way and I can see why the NAO is heading in that direction:

The mean 850's and spread, all rather underwhelming:

Usual caveats for d12, but with the general x-model and inter-model consensus, and no obvious signal for anything to disrupt the pattern, they have some validity?

[Severe Siberian icy blast]

6 minutes ago, Tim Bland said:

Last 3 GFSp runs at the end...

An asian/Russian high or the home of the vortex, high pressure than normal over southern Greenland or the home of the vortex!? 

I rest my case, no point in even doing the study 

[Vikos]

1 hour ago, IDO said:

No, did not see that. Looks a bit more interesting, a bit of tweaking and it would not be a bad synoptic. However the AO and NAO indices are not heading in the right direction as we head into Feb:

 

NAO and AO are direct outputs of GFS main runs. As we now, those are swinging like a donkeys tail... don't even bother about those is my hint.

FU Berlin is what one should look at, I did post the charts in the morning, the DISPLACED Vortex is changing its axis into a more favourable condition...

Edited January 18, 2021 by Vikos

[feb1991blizzard]

3 minutes ago, IDO said:

Yes, as @feb1991blizzard said they are only indices, so those NAO charts are a reflection of what the ens are showing. Hopefully that will change before Feb arrives!

The gefs at d12 are trending the wrong way and I can see why the NAO is heading in that direction:

The mean 850's and spread, all rather underwhelming:

Usual caveats for d12, but with the general x-model and inter-model consensus, and no obvious signal for anything to disrupt the pattern, they have some validity?

Getting better a few frames further on though.

[Mike Poole]

12 minutes ago, Lord Grogon said:

Hello, first time I have ventured onto this thread so please be gentle.

Last year I recall there was a fair bit of chatter about the GFSp having a cold bias. I've no idea how this would work in practice but I do recall it tending to through out colder solutions more often that average.

Was that ever verified/resolved. Or was it just random internet speculation? Would be good to know as every time somebody posts a good run from this model it pops into my thoughts.

Thanks

Welcome.  I think the GFS // at that time was what is now the GFS, with the new FV3 core, there was some talk of a cold bias, but don’t know how that panned out.  This new GFS // is a new one been running for a couple of months, which will eventually replace the GFS again in February, I think.  The big enhancement in this one is the increased vertical resolution, which may help with its modelling of the SSW and fallout.  So that is why people are giving it credence over the current GFS at this time.  Hope that helps.

[Timmytour]

A new little-publicised feature of GFS this winter is the insertion of a heart within its charts over the UK when there is a 24 hour period about to start which may produce snow.

It can be clearly seen here  on the T36 of today's 12z run where the favoured spots for snow are those parts of the UK within the heart.....  

 

[IDO]

11 minutes ago, Vikos said:

NAO and AO are direclty outs of GFS main runs. As we now, those are swinging like a donkeys tail... don't even bother about those is my hint.

FU Berlin is what one should look at, I did post the charts in the morning, the DISPLACED Vortex is changing its axis into a more favourable condition...

Yes, I did mention that in a latter post, we are assuming the gfs is right in what it sees in the next two weeks? I am up to about d12 before FI starts!

10 minutes ago, feb1991blizzard said:

Getting better a few frames further on though.

Glad you posted that, I would be in big trouble if I did! A Scandi/Euro trough would be okay and as a BFTE has not really been a probability this winter, maybe our best option?