Model Output Discussion - Into Winter

[Met4Cast]

One thing of note; 

Any snow that does fall & accumulate from back edge snowfall of the cold front around the 6th or wintriness from the E/NE before the high builds in could be on the ground for upwards of 10+ days. 

Details of course but worth mentioning. Likely a case of a cold high & cold pooling deepening in situ, when weather fronts return that could be very interesting (assuming we don’t see the currently unlikely solution of a sinking high)

[Met4Cast]

2 minutes ago, Harsh Climate said:

Terrific piece there, no mention of Mountain Torque or Angular Momentum straight to the point! Not endless waffle leading to the road to nowhere!

Just because you don’t understand something or don’t want to take the time to learn, it doesn’t make it “waffle”  

The GSDM is firmly based in science & is a diagnostic tool to understand the drivers and subsequent atmospheric response, those that follow the GSDM have been flagging this cold period far longer than NWP modelling has. 

Edited December 31, 2023 by Met4Cast

[The Enforcer]

9 minutes ago, Met4Cast said:

Just because you don’t understand something or don’t want to take the time to learn, it doesn’t make it “waffle”  

The GSDM is firmly based in science & is a diagnostic tool to understand the drivers and subsequent atmospheric response, those that follow the GSDM have been flagging this cold period far longer than NWP modelling has. 

I am sure GSDM is a useful forecasting tool, but there hasn't been a cold period yet.

[Cambrian]

Another fascinating year of studying the models comes to an end with another complete turnabout on the cards, but to be fair, a step forward from the usual “will it turn cold?” to “just how cold will it turn?”, which all in all, is not a bad place to be if you like that kind of thing  

Here on the 0z ECM ensemble mean, the transformation between day 4 and day 7, the second half of the coming week is astounding. How far north the high will ultimately sit by next weekend is still to be resolved. If this is right, it will be cold enough, but mainly dry, a very welcome anticyclonic period. 

 

Thereafter, it’s best just to look at the overall evolution at this stage. For hints about that, the 0z ECM control closely shadows the mean for pressure, a rise to 1030mb+ by around day 9, followed by a fall as the high sinks southeast, but doing so only to make way for a good chunk of the Siberian lobe of the PV to drop into Northern Europe. 

Day 8-15

 

Notably, not once in the T850 animation is there any flow from the west, Arctic air from the northwest at times, but no Atlantic sourced air. 

The core evolution surrounds a generally cold outlook with a trend towards even colder as January progresses. 

(If I may:

It’s not anything I ever expected but I proudly accepted the offer of a role with the forum team as despite one or two rough edges that we all know we collectively have, I genuinely believe in the forum, its purpose, uniqueness and integrity. 

Already I see the challenge. Please help by staying on topic. Please try and avoid too many one liners, try and post a chart or at least refer to one, be as clear as you can in specifying details of model runs that you’re speaking of, avoid knee jerk posts that you just know afterwards you should have thought about a bit more before clicking submit. Don’t get wound up, report nonsense. If you have any questions or concerns, approach the team. I never realised how much work is done.

Most of all, on a human level, please be kind. There is so much crap going on in the world, and we in our common interest, friendship and care are such a hell of a lot better than all of that.

In addition to helping with the tremendous team effort of moderation, I will endeavour to maintain the same posting and reaction “presence” and try and make a good contribution to what we collectively enjoy so much.)

Blwyddyn Newydd Dda i bawb, Happy New Year to everyone.   Have a brilliant 2024.

[Met4Cast]

2 minutes ago, The Enforcer said:

I am sure GSDM is a useful forecasting tool, but there hasn't been a cold period yet.

It’s well advertised across all ensemble suites, regardless of details on snow we are going to be entering a prolonged period of below average temperatures, continuing to cool as time progresses. That much is clear. 

[Ali1977]

4 minutes ago, Met4Cast said:

It’s well advertised across all ensemble suites, regardless of details on snow we are going to be entering a prolonged period of below average temperatures, continuing to cool as time progresses. That much is clear. 

6-8c below normal in places - ice days 

[The Enforcer]

5 minutes ago, Met4Cast said:

It’s well advertised across all ensemble suites, regardless of details on snow we are going to be entering a prolonged period of below average temperatures, continuing to cool as time progresses. That much is clear. 

Ah yes, another 10 day+ chart. However, I could be persuaded after a further 20-something runs.

[Met4Cast]

1 minute ago, The Enforcer said:

Ah yes, another 10 day+ chart. However, I could be persuaded after a further 20-something runs.

Temperatures fall below average at day 5. The broader picture from there is clearer, HP dominating with temperatures continuing to fall before a possible re-amplification attempt. 

Nothing in the outlook suggests a quick return to mild or above average temperatures so we can be pretty confident about a protracted below average period. 

[Nick2373]

Just now, The Enforcer said:

Ah yes, another 10 day+ chart. However, I could be persuaded after a further 20-something runs.

Yes that keeps getting pushed back abate the cold, the teleconnections in my opinion aren’t the best in predicting cold nirvana runs, they are good in pushing them back through 

[northwestsnow]

Seems quite a few are underwhelmed this morning..

Let's look at this from a different angle -

It's rained for weeks and weeks since early Dec ,we are now looking at a period of seasonal weather with the potential for frost fog and even some snow showers as winds switch NE for a short period ..

There is room for upgrades IMHO -

 

 

[Nick2373]

Just now, Met4Cast said:

Temperatures fall below average at day 5. The broader picture from there is clearer, HP dominating with temperatures continuing to fall before a possible re-amplification attempt. 

Nothing in the outlook suggests a quick return to mild or above average temperatures so we can be pretty confident about a protracted below average period. 

That’s not really precise if the high collapses and the new high fails to build after next weekend it will be normal service resumed, highs eventually decline there are so many factors in play. 7 days out is Fantasy Island as you know there is no guarantee prolonged spell being shown as of yet. 

[Rob 79812010]

Tamara, could you resend the post from yesterday?? Thanks so much

[MJB]

3 minutes ago, northwestsnow said:

Seems quite a few are underwhelmed this morning..

Let's look at this from a different angle -

It's rained for weeks and weeks since early Dec ,we are now looking at a period of seasonal weather with the potential for frost fog and even some snow showers as winds switch NE for a short period ..

There is room for upgrades IMHO -

 

 

Yes, very true.

Get the HP over us, Ice days are a possibility with fog and frost around.

With all that cold setting up to the NE and into Europe we are always in with a shout.

And ......And if there was encroachment from the Atlantic a snowy breakdown of the cold could be in the offing.

[Ali1977]

The METO forecast still seems on point with this mornings runs.

[Purga]

P26 looks half decent - LOL

[MJB]

2 minutes ago, Ali1977 said:

The METO forecast still seems on point with this mornings runs.

Today's update shouldn't change, I don't see why it would. 

[Ali1977]

1 minute ago, MJB said:

Today's update shouldn't change, I don't see why it would. 

I hope the longer range changes to “ the chance of severe cold Is extremely likely” - although that’s extremely unlikely!!

[northwestsnow]

Meto app finally picking up the change ..

Colder as we head through next weekend and temps locally dropping below zero sat night..

And so it begins

[northwestsnow]

Obviously we are all entitled to our opinions but I'm personally a firm believer in telecommunications- 9 times out of 10 from my POV,if telecommunications are not supportive of a UK cold spell it  won't happen.

I freely admit a lot goes over my head but the above I believe to be true.

Edited December 31, 2023 by northwestsnow

[MJB]

7 minutes ago, Ali1977 said:

I hope the longer range changes to “ the chance of severe cold Is extremely likely” - although that’s extremely unlikely!!

That WILL happen one day, that I have no doubt. We experience extremes, be it Summer or Winter.

Let's hope it's soon

[Paul]

Locking this one now, as it's a bit long. New thread:

 

Edited December 31, 2023 by Paul