Model discussion - hunt for cold - Christmas countdown

[Malarky]

4 minutes ago, That ECM said:

There is north easterlies and then there is north easterlies.

 

Im more intrigued to how we can get to a settled ne and a se draw. 

The pressure difference in the Atlantic low at 6 days away is quite something.

[SqueakheartLW]

Just now, Staffmoorlands said:

And the GFS is just wet and wild. 

As some like to say on here

BIN IT !!!

[nick sussex]

Still no agreement !

For those that were around in the morning US forecasters highlighted the unusual uncertainty at short range for the weekend .

The issue is what happens in the east USA which impacts downstream the troughing to the west of the UK.

The set up over the UK is very sensitive to small changes upstream and as you can see this is being played out with the models so far !

[Kasim Awan]

Just now, goosey007 said:

 very similar to what Gem was showing overnight so does have support ..........this is just madness more flips and flops than the olympic high jump!

55/45 for colder solutuion atm - 

[BarometerCat]

GFS 12z 25th midday 

Cold air not far away, nothing drastic. Slight changes early on from this morning.  compare again with 18z later and then the dreaded hangover 0z tomorrow...

[Battleground Snow]

Mean is a fairly big  correction south in one run too,

 

 

[Kasim Awan]

Gfs mean - few more ens supporting sharper trough disruption at 84h.

[Eagle Eye]

Here's what's going to happen for the rest of Winter

25-27th - Snow showers

28-30th - Blocking high occurs into Greenland

31-3rd January - Quick easterly occurs with strong snow drifts

4-11th - Another blocking high moves on with cold undercutting it

11-15th - Snow showers once again

15-20th - A strong blocking high similar to that of 2018 occurs moving north east

21-23rd - An easterly begins moving in, snow piles up on hills 

24th - Blizzards and snow piles up on my birthday 

25-31 - The easterly slowly dissipates and the Polar Vortex returns back to normal 

1-8th February- A SSW begins setting up

8-20th- Large SSW brings hefty snow and snow showers 

20th onwards - Early Spring begins 

It's going to happen like this exactly isn't it's?

 

[Ali1977]

2 minutes ago, Kasim Awan said:

Gfs mean - few more ens supporting sharper trough disruption at 84h.

Yeah 4/5 ENS with snow back down Towards the M4 - could in trend further south again on the pub run I wonder !! The control corrects south, just like the mean 

Edited December 22, 2021 by Ali1977

[That ECM]

2 minutes ago, Kasim Awan said:

Gfs mean - few more ens supporting sharper trough disruption at 84h.

 

[alexisj9]

13 minutes ago, Kasim Awan said:

GFS tries to pull in a NErly.

That's at 138, low will probably get smaller, GFS may well be doing it's normal blow up stuff.

[Staffmoorlands]

Big warm up for New Year on the GFS tonight which Marco Petagna hinted at last night  

 

[caistor top]

3 minutes ago, Eagle Eye said:

Here's what's going to happen for the rest of Winter

25-27th - Snow showers

28-30th - Blocking high occurs into Greenland

31-3rd January - Quick easterly occurs with strong snow drifts

4-11th - Another blocking high moves on with cold undercutting it

11-15th - Snow showers once again

15-20th - A strong blocking high similar to that of 2018 occurs moving north east

21-23rd - An easterly begins moving in, snow piles up on hills 

24th - Blizzards and snow piles up on my birthday 

25-31 - The easterly slowly dissipates and the Polar Vortex returns back to normal 

1-8th February- A SSW begins setting up

8-20th- Large SSW brings hefty snow and snow showers 

20th onwards - Early Spring begins 

It's going to happen like this exactly isn't it's?

 

Then your alarm clock went off

[Don]

1 minute ago, Staffmoorlands said:

Big warm up for New Year on the GFS tonight which Marco Petagna hinted at last night  

 

Good for outdoor New Years eve parties!!  However, nothing like this is being hinted in the Metoffice outlook?!

Edited December 22, 2021 by Don

[Kasim Awan]

1 minute ago, That ECM said:

 

We need to see the isobars connecting to our east as opposed to curving back towards Iberia - that is the barometric requirement for an optimal slide. A good increase in the number doing that on 12z.

[Battleground Snow]

Gem, almost a direct eastlerly feed by Xmas day

UNBELIEVABLE

[Trom]

34 minutes ago, Catacol said:

Yep - the hemispheric graphs are clear. An even clearer representation of the ebb and flow of this would be here, showing the skill over mainland USA. It is a pity there doesn't appear to be a rating anywhere (at least not that I can find) for the UK or regions close.

However skill is not the same across all regions and for all measurements. Take this graph here from an article back in 2014. Skill over the pole for T2 temps significantly better in the summer.

And then you could pull skills graphs to try and spot what is happening more regionally - available now at ECM. The top one is the one month skill graph for sea level pressure for May forecasting the summer and the bottom one November forecasting the winter.

Not a lot of difference in our corner of the world, though a lot of the winter accuracy reflected in the smoothed hemispheric model verification stats for pressure would appear to be lodged in the arctic....running somewhat at odds to the T2m temps graph from Jung's 2014 article. 

But whether you want to look at smoothed averages or regional differences we hit a bit of a brick wall when looking for verification data up against regime type. As I said initially - when a +NAO is underway with a well formed vortex then the winter models do indeed get very accurate and many of our winters broadly pan out this way. But when the regime type becomes more problematic due to amplification and/or disrupted vortex then I will stand by my feeling (based on observation and not based upon being qualified on the subject) that verification takes a dive and forecasting becomes much more sensitive to tiny changes. And I also maintain that the impacts on the ground are more acutely felt in the winter. In the summer if the model gets temps wrong by 5 degrees and a 26 degree max temp becomes a 21 degree max temp then to be honest we don't blink. But if a snowy forecast of 1 degree becomes a cold rain forecast of 6 degrees then that error is perceptively greater and snow hopers snarl.

 

Interesting post.  The RMSE clearly shows the models are better in summer and worse in winter.  Low RMSE meaning a good match between forecast and actual and higher being poorer.

I wasn't sure I was interpreting the anomaly correlations correctly.  The UK appears to be in a grey zone indicating -0.2 to 0.2.  Those correlations look woeful but I wondered if I was missing something.  It appears the models are great at the equator and reasonable at the poles but horrible in the mid latitudes.  Is this the correct interpretation?

[Jason M]

34 minutes ago, georgiedre said:

Such a tease there but it's nice to have your insight Into hopefully a happier and colder new year. I've been wondering where the meto have had info into continental winds .. I personally can see some heavy snow around in the next 2 weeks mostly by systems brushing the sw corner.. hope this is what you also see. Hope your keeping well too

Yep, Tamara is a valuable contributor to the forum. Quite why every post has to feature a load of digs at the rest of the community is a mystery to me though as it just detracts from the otherwise excellent content. 

[goosey007]

1 minute ago, Staffmoorlands said:

Big warm up for New Year on the GFS tonight which Marco Petagna hinted at last night  

 

this will  likely be watered down as we move forward.... cant even sort t72 out ! ......Marco Pategna also said last week the Thursday 23rd the fun begins with low pressure into cold air.......

[supernova]

3 minutes ago, Battleground Snow said:

Gem, almost a direct eastlerly feed by Xmas day

UNBELIEVABLE

Yup

[That ECM]

3 minutes ago, Kasim Awan said:

We need to see the isobars connecting to our east as opposed to curving back towards Iberia - that is the barometric requirement for an optimal slide. A good increase in the number doing that on 12z.

Not loads but some.

[sheikhy]

Just a thing to add here from me!!ecm 06z earlier had a stronger wedge of heights across iceland at 72 hours compared to the gfs for the same time!!!not saying it will happen but ecm COULD look even better than the gfs on the 12z!!

[Mariescb]

2 minutes ago, Staffmoorlands said:

Big warm up for New Year on the GFS tonight which Marco Petagna hinted at last night  

 

That chart is 8 days away. So we're supposed to believe a chart that far ahead when things are so up in the air at a fraction of that timescale? Maybe you have some insights as to why you're confident of this? Thanks

[Ali1977]

GEM is a gem fir the south 

[The Northern Ramper]

39 minutes ago, SqueakheartLW said:

So far

ICON - No

Arpeege - Yes

UKMO - Yes

GFS - Not sure

Icon - No for what/who?