Model Output Discussion - Winter arrives

[Ali1977]

A few ENS from T336 - we have a few days of nothing even at day 10 on the ECM looking at this. Everyone just needs to look beyond that for now!! 

[Ali1977]

P5 would be nice in the run up to Xmas 

 

[Cold Winter Night]

Little has changed this morning in the big picture model output.

In the short to midterm we see an ongoing battle between Atlantic influences and a more Eastern European based 'block' that proves to be more resilient and extending towards Scandinavia more than models anticipated, but is far from powerful enough to speak of a Scandi High.

The 120h-168h is in the NAO+ camp, but that classification, which is focused on the Atlantic and Europe, does no justice to the ever growing height to the East and Northeast.

It should not come as a surprise therefore that the red bordered BLO+ regime makes its appearance as one of the clusters in the 192h-240h range. Last week we saw its presence in the extended and over the weekend, it moved into the end of the 10 day range.
It is accompanied by two clusters that are still NAO+, but also have those NE height anomalies.

In the extended 264h-360h range, the positive blocking regime becomes dominant, with heights all around us. Or not really, mainly North, Northeast, East, or right over us. Not South of us, that's a good thing. Even all the NAO+ clustster members don't seem to get continuous mild SSW-lies going a la 2015.

Lovers of cold and snow have to remember that blocking to the NE does not guarantee cold and snow at all though.
For now, we don't see real winter cold in the output yet, but those blocks do put us in the game. It's better to have them, with potential for more, than to just have to hope and wait for them.

Add to that the insecurity about what exactly will happen in the interaction between Atlantic and block, which is far from resolved, making what follows less reliable.
The run up to Christmas is going to be interesting from a coldies' point of view.

[damianslaw]

39 minutes ago, Ali1977 said:

A few ENS from T336 - we have a few days of nothing even at day 10 on the ECM looking at this. Everyone just needs to look beyond that for now!! 

Agree a case of watching and waiting to see where the building heights to our south end up in the run up to Christmas. Ensembles, anomalies, long range forecasts all on the same page in their pattern of anticyclonic conditions holding sway from some point next week.. the signals are heights will build through the UK, and then either merge with heights to the NE or move further north and west.. either way a transition to colder likely whether that be from surface cold or northerly/ easterly influences..  to get there though a milder southerly outlook is needed.. many precursors to cold are preceded by milder southerly influences.. December 2021 could end up our most varied December for a long time with a bit of everything...

Edited December 6, 2021 by damianslaw

[tight isobar]

So - the latest on la- Nina structure.. is in brief showing sst becoming below average @ gaing and the equitiriol state in situ... But now annomily departures are likely rolling with the nxt mjo proposed phase!!!! — the pac basin is the if- maybe atm.. everything is looking in tandem going forwards!!.. .. some great in depth discussion via cpc.. so it now appears the MJO, is the maker/breaker, but chasing slightly lagged ssts, data!- so in short great for going further into winter.. and still even mid/late December. So in basic raw modelling- expect to see a further rounding of the jet @pacific side.. and heights punching through on the Russian/Eurasia quadrant.. and also a defined shift latter, of pv migration- even complete separation through the pole!!- as we gain. It’s not ALWAYS about layer warmth @ssw..

Edited December 6, 2021 by tight isobar

[alexisj9]

On 06/12/2021 at 10:43, Midlands Ice Age said:

Probably an even better illustration -

This is what is causing the lows to compress and to move slightly more southeastwards over the tip of Greenland,

The effect in our locality is the sudden plunge to the south as the lows lose their intensity and start to be pushed more by the jet.

MIA

That does explain a lot. So perhaps GFS is right then, however why does ECM not see this high, does it have that layer?

Edited December 6, 2021 by alexisj9

[mushymanrob]

1 hour ago, Ed Stone said:

True. Even the famous winter of 1963 had a less-cold week in February. And December 1969 was mild until a couple of days after Christmas, when cold air came westward out of mainland Europe. At least, this winter, there's cold air where it's meant to be?

Many of us have already had more snow than we have had in many winters...

[sebastiaan1973]

35 minutes ago, tight isobar said:

So - the latest on la- Nina structure.. is in brief showing sst becoming below average @ gaing and the equitiriol state in situ... But now annomily departures are likely rolling with the nxt mjo proposed phase!!!! — the pac basin is the if- maybe atm.. everything is looking in tandem going forwards!!.. .. some great in depth discussion via cpc.. so it now appears the MJO, is the maker/breaker, but chasing slightly lagged ssts, data!- so in short great for going further into winter.. and still even mid/late December. So in basic raw modelling- expect to see a further rounding of the jet @pacific side.. and heights punching through on the Russian/Eurasia quadrant.. and also a defined shift latter, of pv migration- even complete separation through the pole!!- as we gain. It’s not ALWAYS about layer warmth @ssw..

For those for care to read it: https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf

[Methuselah]

Clearly there's plenty of variation in today's GEFS 06Z ensembles. Not only in Blighty, but in Moscow too! Is winter biding its time?

    

    

[tight isobar]

On 06/12/2021 at 13:49, sebastiaan1973 said:

For those for care to read it: https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf

Tar- I should have posted @link

[mb018538]

Looks like we've got a problem around day 10 in the models...

Ensembles splitting into low pressure continuing or strong high pressure building.



ECM/GEM/GFS 6z below showing this split in  settled/unsettled forecasts well. If the unsettled weather prevails it could be a longer wait for a pattern change:

 

[Midlands Ice Age]

2 hours ago, alexisj9 said:

That does explain a lot. So perhaps GFS is right then, however why does ECM not see this high, does it have that layer?

Not sure ..

I am not an expert in weather forecasting, and came across this when I was trawling through the data for my reports in the N Hem Snow and ice blog.

I have not come across this type of chart in the 'normal' weather forecasts, although I have seen Jet-stream charts, though perhaps not in this much detail before.

It must be known about/used by the experts who post to the 'strat' thread?

I found it on Climate Reanalyser and initially just thought it was 'odd' , but then I realized that this high level Jet-stream was what was probably pushing the depressions in our part of the world, and could be the reason as to why we currently are seeing our weather.

I looked back - but there is no archive facility on CR for the Jetstream  (aka 250hpa) to check it out. (when it started and where did it come from?, etc). 

My interest in this area is spiked by the current ' waves' of ozone which seem to be breaking through the Northern Hem at the moment, and it could be significant that currently there is an Ozone 'hole'  exactly 'over' the area were this block is shown.               . 

This height is quite a little way up into the Stratosphere, so it would be expected to see  the troposphere wave breaking from 'down below', which would then cause Ozone to show up. However, this may be the opposite and be causing the stratosphere to discharge its  colder heavier air into the troposphere, hence causing the blocking to occur??

Most of the charts currently being shown on the 'infant' Vortex seem to show the values at 1HPa down to 50hpa,  so this level (250hpa) is not shown much.  

Perhaps it can 'steer' events in the troposphere?

MIA

 

 

Edited December 6, 2021 by Midlands Ice Age

[Mucka]

11 hours ago, weathermadbarnsleylad said:

@Muckanever a dull moment model watching. Let's see what ECM says later. 

Well this mornings  ECM run was the opposite of what I hoped and the final nail in coffin it seems of any upstream amplification,, especially since all models are now accelerating the demise of the block though it hung much longer than originally modelled.

Shame upstream has been so fast and flat although Southerly jet kept us in the game a little while.

Mild, wet and windy looks the order of the day with typical zonal conditions and high pressure to our South becoming established before mid month.

That is going to stick around a while so we are going to need some help from background signals before we see the next chase for cold and snow.

Will it come in time for Xmas?

Plenty of time isn't there and the hour before dawn is the darkest as they say.

[Notty]

5 hours ago, Met4Cast said:

Does Tamara not post on the forum anymore? I never used to have a clue what she was saying but I feel like I understand the background signals etc and the things she talks about far better now, would be nice to see what she's thinking.

I always wondered whether Tamara is short for Jam Tamara ?

[Battleground Snow]

Nothing of interest over the next 10 days from the GFS for UK cold

The vortex is not happy at 240 though

[sheikhy]

As i mentioned earlier this morning if you dont have ecm on board we will never be comfortable!!just saying it how it is and how situations like these have played out before!both ukmo and gfs edge towards ecm on this evenings 12zs!!

[johnholmes]

3 hours ago, mushymanrob said:

Many of us have already had more snow than we have had in many winters...

lucky folk

[Updated_Weather]

A lot can and most likely will change once we've gone through this storm as their are still disagreements on path and depending on what path it takes can produce big changes.. 
We will see though.

[johnholmes]

Just now, Updated_Weather said:

A lot can and most likely will change once we've gone through this storm as their are still disagreements on path and depending on what path it takes can produce big changes.. 
We will see though.

that was said prior to the last storm, unless the 500 mb anomaly charts are very wrong then there is little prospect 6-10 days from now and probably to ta least 14 days (as far as these charts go, of any marked pattern change.

[sundog]

Its been shown up time and again for hp to take control once we get into the second half of the month.  

[SLEETY]

Some of the coldest winters in history have had mild and stormy weather in December,so not worth getting too frustrated over the next couple of weeks,standard fare for December

[Staffmoorlands]

8 minutes ago, johnholmes said:

that was said prior to the last storm, unless the 500 mb anomaly charts are very wrong then there is little prospect 6-10 days from now and probably to ta least 14 days (as far as these charts go, of any marked pattern change.

Completely agree. Classic zonal spell coming up on tonights UKMO & GFS. Flooding looks an increasing risk

[frosty ground]

On 06/12/2021 at 16:56, Staffmoorlands said:

Completely agree. Classic zonal spell coming up on tonights UKMO & GFS. Flooding looks an increasing risk

Classic zonal charts in FI

 

we could look at Day ten that once again shows another plunge into Europe.

 

the signs of a mobile spell of weather has been there for a while and for almost as long as a spell of settled weather beyond days 9/10 

[LRD]

3 minutes ago, sundog said:

Its been shown up time and again for hp to take control once we get into the second half of the month.  

Completely agree

If the modelled settled spell does follow what is going to be a rainy and windy next 10 days, then the models have done remarkably well in picking this up and the consistency they have shown (the Met Office deserve credit too)

If the GFS12z run is correct, it will, initially, be mild and dry (the most tedious weather in winter for my tastes) but will eventually probably become quite cold at the surface with fog and frost if it is a clean high with clear skies

This won't be mild:

And signs of wanting to go further north too. One frame's meaningless at this stage but something to keep an eye on to see if it trends and moves closer in time

[weathercold]

No dressing up the current runs, aside from some brief wintry showers this week for the northern hills it’s looking grim.

If current charts are to materialise it’s a long way back from there to cold potential.

Grim