Model discussion: Hunt for cold - into mid-January

[warrenb]

1 hour ago, IDO said:

The NH is in a quasi-blocked static state where the blocks have left the UK close to a HP. There is plenty of cold to mid-lats but the three waves send the cold too far from our little island:

D8-16 T850s> 

It is amazing to see the next 16 days how each wave of cold circulating the vortices managing to miss the UK! This underlying pattern dictates that result so to be expected and Jan looks tough for any snow as things stand. Can this cycle continue in February and finish winter or is a sea-change coming? 

It is because the jet has gone north rather than south of us, the steering therefore is for depressions to go north along with their warm sectors.

 

[Northwest NI]

9 hours ago, Cold Winter Night said:

A chart like the one above shows two variables:

1) The surface pressure, expressed in hPa and made visible with the white isobars.
2) The height of the level where the air pressure is equal to 500 hPa. This is expressed in decameters (dam) and made visible with the colours. See the legend at the bottom of the chart.

The last variable is what we refer to when talking about "heights".
Higher values (higher heights) mean that the 500hPa level is found higher up, and therefore there is 'more air' below it, it's a thicker layer of air (usually warmer too). The more yellow and orange, the higher the heights.
Lower heights are represented by the blues and purples. In those places the layer of air is thinner (usually colder) and therefore the 500 hPa level is already found at a lower height.

On average this 500 hPa surface is higher as you go further South towards the equator (obvious on charts), because warmer air has a lower density and takes up more space than cold, dense air.

The tricky thing is that often low pressure systems at the surface are associated with a "low height" of the 500hPa level, but not always.
And high surface pressure is often associated with a "high height" of the 500hPa level, but not always.

If they go together, they are more powerful. If they don't they are weaker features.
For example, a "wedge" is an area of higher surface pressure that does not have a really high 500 hPa level. It is weaker than a real High, because it is not backed up by that thick layer of air, so to speak.

Hope this helps!

 

I’m going to hazard a guess that Cold Winter Night is/ was once, in the teaching profession. Such an excellent explanatory post with just the right amount of words used, and not for the first time.

[Staffmoorlands]

A little cold ramp from our Met Office Marco 

 

 

[TSNWK]

We know this.. though and thats the frustration it's all so near yet so far..

The only thing to go on that is if there is a carrot bring dangled with the word currently......

Edited January 13, 2022 by TSNWK

[That ECM]

6 minutes ago, Staffmoorlands said:

A little cold ramp from our Met Office Marco 

 

 

Ramp? Cold air not over us is likely to stay not over us. This is coming is a ramp.

Edited January 13, 2022 by That ECM

[Northwest NI]

4 minutes ago, That ECM said:

Ramp? Cold air not over us is likely to stay not over us.

That’s what qualifies as a ramp these days so the original post is accurate

[Ali1977]

15 minutes ago, Staffmoorlands said:

A little cold ramp from our Met Office Marco 

 

 

Interesting, I don’t think he would mention if not a decent chance of being correct. If you look at the UKMO at 144 vs the latest GFS it’s clear to see the cold is much more likely with the trigger low being much further west, and WAA therefore being stronger and further west also. One to watch for in the ENS.

Beyond 144 there is a strong WAA event, so hold back the Atlantic slightly and we could be in a much better position!! 

Edited January 13, 2022 by Ali1977

[Northwest NI]

Just now, Ali1977 said:

Interesting, I don’t think he would mention if not a decent chance of being correct. If you look at the UKMO at 144 vs the latest GFS it’s clear to see the cold is much more likely with the trigger low being much further west, and WAA therefore being stronger and further west also. One to watch for in the ENS.

Don’t do it to yourself!

[FENDER.]

I would have thought that the type of pattern that we currently  have would be fairly straightforward  for the models to deal with.  So I think its unlikely that anything cold of snowy is suddenly  going to appear in the medium time frame.  The last week of January  seems the earliest for any major change

[mb018538]

1 hour ago, minus10 said:

Yes amazing that there is so much hp now for all of Jan it seems

Also it has been a crystal clear night...no fog...and the temp has barely got down to zero. Quite amazing really for a long night in January. Are well.... least the sunshine is nice..

It was the same here - crystal clear and only just below 0c. Upper air is very mild, so a very cold night not as easy to achieve. Usually with very warm upper air we don't get clear highs as they tend to get a load of muck trapped underneath. 

That said, with the air not mixing and the high just sitting there again today, tonight looks colder than last night:

[That ECM]

21 minutes ago, FENDER. said:

I would have thought that the type of pattern that we currently  have would be fairly straightforward  for the models to deal with.  So I think its unlikely that anything cold of snowy is suddenly  going to appear in the medium time frame.  The last week of January  seems the earliest for any major change

Agreed. 

Edited January 13, 2022 by That ECM

[TSNWK]

8 minutes ago, That ECM said:

Agreed. 

Yep.. model consistency at day 9/10 when we don't want it..

[That ECM]

Now to Tplus 300.  

[Andy Bown]

21 minutes ago, mb018538 said:

It was the same here - crystal clear and only just below 0c. Upper air is very mild, so a very cold night not as easy to achieve. Usually with very warm upper air we don't get clear highs as they tend to get a load of muck trapped underneath. 

That said, with the air not mixing and the high just sitting there again today, tonight looks colder than last night:

The opposite of summer when daytime temperatures creep up day on day under an intense HIGH.

[joggs]

8 minutes ago, That ECM said:

Now to Tplus 300.  

Why can't we have this set up in summer over us

[mb018538]

1 minute ago, TSNWK said:

Yep.. model consistency at day 9/10 when we don't want it..

Always the way @TSNWK. When it's high pressure just parked over the UK, no collywobbles from the NWP. Just every model agreeing with each other. Great for forecast certainty, but not overly interesting! As soon as any cold appears (like the phantom cold xmas we just saw vanish) then all hell breaks loose!

[northwestsnow]

That damn Vortex is so durable.

The consolation is we stay mainly dry ,great set up for SE Europe though.

 

Edited January 13, 2022 by northwestsnow

[mb018538]

6 minutes ago, Andy Bown said:

The opposite of summer when daytime temperatures creep up day on day under an intense HIGH.

Very much so - the opposite effect. With nearly 16 hours of darkness a day at the moment then the cold quickly develops. As you say....in high summer with 16.5 hours of daylight and only 7.5 hours of darkness then any hot air doesn't get enough chance to radiate away, especially with high pressure trapping it.

[NewEra21]

All I know is that SE Europe cold lovers, love a high over the UK. While the frustration goes on and on for us!

[Chesil View]

Interesting that although the prongged high pressure set up is not great for snow.  It wouldn't need that much amplification to make it more interesting.  

[damianslaw]

No comment on GFS 6z.. not surprised it shows a high of 1040mb today and it's still there overhead end of the run..

Can't recall a GFS run ever doing this... normally brings in the Atlantic at some point.. and its mid winter. Need to something to shake this static state.. its blocked but the blocking not setting up in a position for anything especially cold and certainly not wintry..  but neither mild either.. 

[northwestsnow]

I suppose if you are after snow ,the outlook doesn't come much worse .

If you want dry weather ,you are in luck.

Some days milder ,some days cooler as the block meanders. 

Truth is with the vortex as is it's going to be a long slog to get any true cold uppers near our shores. 

[Froze were the Days]

Pretty poor operational runs this morning, yes some inversion cold at times and by the looks of it fairly dry for the foreseeable but for snow chances for the rest of the month it looks a write-off in my opinion! Another blank January (IMBY) looks like passing!

If we're in this locked pattern come the start of Feb it will be interesting where we go from there...I for one would be surprised to see a kick start from the Atlantic though these shores. 

Edited January 13, 2022 by Froze were the Days

[johnholmes]

1 hour ago, Ali1977 said:

Interesting, I don’t think he would mention if not a decent chance of being correct. If you look at the UKMO at 144 vs the latest GFS it’s clear to see the cold is much more likely with the trigger low being much further west, and WAA therefore being stronger and further west also. One to watch for in the ENS.

Beyond 144 there is a strong WAA event, so hold back the Atlantic slightly and we could be in a much better position!! 

Just what do you mean by 'trigger low' please?

thanks

[Penrith Snow]

47 minutes ago, NewEra21 said:

All I know is that SE Europe cold lovers, love a high over the UK. While the frustration goes on and on for us!

Yes expect an Athens Snowfall Special some time in the next 10 days just to rub salt into our festering wounds  

As for our high pressure experience tells us it will eventually sink, having said that if it holds on to late January a northward movement as the PV undergoes its seasonal weakenening can not be ruled out. In the meantime the Boredomometer is as high as the pressure!

Andy