Model Output Discussion - Into Winter

[near northampton]

2 minutes ago, MATTWOLVES 3 said:

You know what I'm seriously thinking here folks.

This could be the  Winter when all is said and done that the teleconnections scratch there heads and say what the bloody hell just happened here!

I remember reading somewhere recently back in Summer from a climatological expert that there are so many variables coming into play right now that we are literally entering the unknown!

The moral of this story is do not be that suprised if you wake up some days and see that NWP as completely changed its direction.

The background drivers could well be overuled by overriding factors on occasion.

 What are the overriding factors?

[Lincs Observation]

2 minutes ago, MATTWOLVES 3 said:

You know what I'm seriously thinking here folks.

This could be the  Winter when all is said and done that the teleconnections scratch there heads and say what the bloody hell just happened here!

I remember reading somewhere recently back in Summer from a climatological expert that there are so many variables coming into play right now that we are literally entering the unknown!

The moral of this story is do not be that suprised if you wake up some days and see that NWP as completely changed its direction.

The background drivers could well be overuled by overriding factors on occasion.

Totally agree here, this has been an unusual year weather wise and I don’t see that changing anytime soon.

the El Niño is dealing out some quite dramatic weather globally that coupled with global warming is leading us into unknown territory.

looking at historic trends is not going to give us a clue this year at all in my opinion in the current climate 

[January Snowstorm]

The gfs control also upgrades the 850s for next few days. It's becoming quite the cold spell now and the depth of cold has been underestimated if gfs is right!!

Look at this over Ireland by next Tuesday, bitterly cold even still and evidence of home grown cold!!

Edited November 28, 2023 by January Snowstorm

[WYorksWeather]

I'm going to do a quick update on the SST stuff I went through a few days ago.

Today things are still looking fairly similar to last time:

At T+120/T+240/T+360, we have a similar trend to last time - gradual cooling around the UK, but probably looking closer to average now, whereas two days ago the charts were more bullish about cooling around the UK. Also, I would note the slight re-intensification of the anomalies in the Azores area.

 

I think this is part of the source of the huge spread we see on ensemble charts at the moment. Any cold pattern is likely to be as cold as you'd expect, or maybe a little colder, whereas a mild pattern is likely to be very mild indeed.

 Raging south-westerlies over SSTs 2-3C above average could give record-challenging temperatures as we go into December. I wouldn't even rule out the first 20C if we get perfect synoptics for it.

But if we stay with the cold and blocked pattern, the loss of the east coast SST modification will make a big difference to the chances of frontal snowfall if we do get an easterly. Basically, if it's cold you're looking for, you want it more easterly than northerly, because anything more towards the NW will be heavily modified.

Overall though, I think this has to count as a downgrade from a cold perspective.

[MATTWOLVES 3]

15 minutes ago, near northampton said:

 What are the overriding factors?

Variables that appear from warmer and colder sections of oceans which seem to be increasing,various degrees of Ice melt...changes in solar activities...larger amounts of emissions through pollutants and volcanic activities which seem to be on the rise. This is probably only a handful of other factors at play here.

Edited November 28, 2023 by MATTWOLVES 3

[Ladyofthestorm]

Hello everyone 

Just a few things to add,  any reintroduction of a Westerly regime will be brief.  This has been a very unusual El Nino year for us, with unexpected blocking. 

 

The block we are talking about is an Omega Block and it doesn't look ot it was will go away soon .

 

 

Another trend Ive noticed if that the Euro models  long range trended colder towards the actual month . The month of interest is December.

 

Current month ( November) prediction for December 

 

Octobers prediction for December

 

Septembers prediction for December 

 

 

Trend is your friend. Drivers. For blocking are surprisingly in place. 

[Sweatyman]

2 hours ago, Tim Bland said:

ECM has rain for most with snow on hills Sunday

wow. some cold spell this is!

[Derecho]

Whilst I'm anticipating a turn to milder conditions in the middle of next week, it's far from a done deal. 

The 18z GFS above briefly goes for a mid-latitude block and whilst it doesn't work out in this instance some small changes to this chart could easily send things off on a cold tangent for longer.

12z EC also goes for a brief ridge but this is coming from the SW and later the Atlantic fires back up.

The UKMO is poor at the same time.

Whilst I'm downbeat about the prospects of a memorable cold spell at this point in time the mild weather could easily get put back but we'd likely need to see the Scandi high signal re-emerge. This can either occur if a ridge moves across us from the SW or ideally a lobe of high pressure moves from Greenland and builds towards Svalbard. Some ensemble members show this:

A few more twists and turns over the next day or two before the T120-T144 period of uncertainty comes to an agreement. That will likely have a butterfly effect on what follows after.

Edited November 28, 2023 by Derecho

[Johnp]

A quick perusal of the GEFS at 192hrs shows a fair few going for renewed blocking and easterly winds. It’s not over yet!

[Bricriu]

34 minutes ago, Met4Cast said:

Becoming rather difficult to keep up the rhetoric for a continuation of cold beyond the first week of December now, MOGREPS showing a clear trend towards less cold air moving in across the UK, in agreement with the GEFS & EPS.

Hopefully we can squeeze as much snow out of this week as we can!

Less cold for a few days seems inevitable now, but whether it becomes a lot milder, and for how long it lasts,  is far from certain. There is not much sign of raging zonality for weeks on end as of yet

[Dennis]

well see this now UK

Edited November 28, 2023 by Dennis

[WYorksWeather]

I wouldn't worry overly much about a return to mild conditions showing on the models beyond day 7. I mean just look at this mess - around day 9 and we're already showing nearly a 20C range to the 850hPa temperatures. That's not a milder trend, or a colder trend, it's a nobody-has-a-clue trend!

It'll probably get even more ridiculous as it runs out to the end...

[Johnp]

Zoom in and see for yourselves. 

 

Edited November 28, 2023 by Johnp

[Mcconnor8]

6 minutes ago, WYorksWeather said:

I wouldn't worry overly much about a return to mild conditions showing on the models beyond day 7. I mean just look at this mess - around day 9 and we're already showing nearly a 20C range to the 850hPa temperatures. That's not a milder trend, or a colder trend, it's a nobody-has-a-clue trend!

It'll probably get even more ridiculous as it runs out to the end...

Looks like the mean delays the return to mild by a day or so compared to the 12z ensemble, so looks like a decent extension on this 18z ensemble.

[pages]

4 minutes ago, WYorksWeather said:

I wouldn't worry overly much about a return to mild conditions showing on the models beyond day 7. I mean just look at this mess - around day 9 and we're already showing nearly a 20C range to the 850hPa temperatures. That's not a milder trend, or a colder trend, it's a nobody-has-a-clue trend!

It'll probably get even more ridiculous as it runs out to the end...

Last sentence definitely true, watching the ensembles roll out think they might need to rescale that above chart in a couple of frames time for ensemble 21 minus 16 uppers might make it.

[minus10]

Interesting to see the higher thickness anomalies return accross the pole further on into December on the gfs18z. Although fi, this is what needs to be looked for on subsequent runs and other models to tie in with the  bigger driver developments such as MJO and AAM previously detailed..as i understand it....

[WYorksWeather]

Just now, Mcconnor8 said:

Looks like the mean delays the return to mild by a day or so compared to the 12z ensemble, so looks like a decent extension on this 18z ensemble.

Yep, crosses the mean line at the 8th December in London. But I would say that that's not a mild signal, even if the mean verified it would only be average conditions for the time of year. We're not talking about raging south-westerlies and temperatures into the mid teens by day! And as I highlighted earlier, the uncertainty range is immense.

In short, I'd say cold for the next 5 days pretty much certain, 7 days quite likely, and as we approach day 10 less certainty, but no clear signal for mild.

[Mcconnor8]

2 minutes ago, WYorksWeather said:

Yep, crosses the mean line at the 8th December in London. But I would say that that's not a mild signal, even if the mean verified it would only be average conditions for the time of year. We're not talking about raging south-westerlies and temperatures into the mid teens by day! And as I highlighted earlier, the uncertainty range is immense.

In short, I'd say cold for the next 5 days pretty much certain, 7 days quite likely, and as we approach day 10 less certainty, but no clear signal for mild.

Interesting that the ECM ensemble seems much keener to start to increase 850s from Sunday onwards compared to the GFS which takes until Wednesday/Thursday.

Edited November 28, 2023 by Mcconnor8

[lorenzo]

EC doing it's king model thing vs an adventurous 12z GFS, the NATL Ec Anom plot at D10 pretty much as expected via other drivers. Enjoy this cold spell, look ahead to 13th Dec progressions coming around.

[Allseasons-Si]

The latest gefs dew points in the ext'd tells me there is some continental air to tap into,there is a minority that stay below the 0c isotherm if i am reading that correctly

plenty of undercuts and a smattering of easterlies in those members...

[booferking]

The block still trying to hold on in 18z ens we see what tomorrow brings.

[pages]

Just for fun, how cold would this be minus 12/13 uppers in slack north easterly with snow on the ground.

[feb1991blizzard]

a few more corkers in this GEFS suite - if by the end of the whole suite, the 12z op was superimposed on the 18z uppers graph, ive got a feeling it wouldn't be an outlier

[ScottSnow]

3 minutes ago, feb1991blizzard said:

a few more corkers in this GEFS suite - if by the end of the whole suite, the 12z op was superimposed on the 18z uppers graph, ive got a feeling it wouldn't be an outlier

Yeah I’ve just had a quick look through and I would say at least a third went down the Scandy high route.

[Battleground Snow]

7 minutes ago, feb1991blizzard said:

a few more corkers in this GEFS suite - if by the end of the whole suite, the 12z op was superimposed on the 18z uppers graph, ive got a feeling it wouldn't be an outlier

A Few approaching -15, definitely interesting model watching, just hoping the moving parts fall into place pre Xmas for once