Hunt For Cold: Model Discussion - Heading Into Christmas

[lorenzo]

Yesterday or perhaps the day before there were maybe two or three runs flirting with High Pressure over Greenland..

Today it looks like this... definitely a trend developing..

[Dancerwithwings]

I can’t recall now who posted these wise words, “Don’t bother with the op, keep an eye on the gefs for indications of SSW down dwelling and it’s affects” well looks like and hopefully them wise words maybe wright.

[bluearmy]

Eps clusters are a pretty well a 20% set through extended ......... not really any help

there are some sceuro trough options throughout but also more flatter ones than recent suites ......greeny doesn’t look a strong bet for a ridge end week 2 but tbh, I wouldn’t be placing much behind these clusters at the moment .......

nice gefs ......... the models seem keen to put the split trop vortex back together post day 10 ...... this is what fires back the Atlantic and kills any greeny ridge sustaining ......they could easily be wrong on that ........

[MR EXTREMES]

1 hour ago, Ali1977 said:

WHATS GOING ON GEFS

Things may have taken a good turn 

Check out the day 9 mean - that’s v v good 

Remember back in 2010 the gefs model was emphatically dominant on an idea similar to this.

This time I'd be a little more encouraged as that data from back then could be good data used for this similar situation.

But of course I'm not an expert but it's a case of wait and see.

 

[Premiere Neige]

30 minutes ago, legritter said:

Good morning gang , I am certainly looking forward to the next 9 weeks of meteorological winter and also March .just wondering when the main models really latched on to the cold weather last winter ,Feb March etc .I can remember a big night when HEY Presto we all went crackers . Keep the faith gang ,I have noticed as usuall ecm days 8 9 10 all over the place , STELLAS all round .

 

You beat me to it. Was just going to ask the same thing. I seem to remember it being pretty late on...

[Selliso]

45 minutes ago, Ali1977 said:

Best set of the season so far, prolonged -3/-5 is good. 

Very nice, same profile in my location, although it seems to sniff out a slightly higher snow risk... 

[Methuselah]

Despite the ensembles looking positive, the FV3 clearly does not look overly great...YET! The prospect of another sixteen days' anticyclonic dross, quite frankly, does my 'ed in!

[summer blizzard]

1 hour ago, Djdazzle said:

Good. We need to see if the 12z suite continues this. How good are the ensembles at sniffing out trends?

The further one goes out, the more accurate the ensemble means are in relative terms (operationals by their nature will bounce around).

In the 2017 hurricane season the Euro ensemble was so statistically accurate at day 5 that it even outperformed the NOAA's specialised tropical consensus models. In their discussions (Nick occasionally posts them) for US weather, they go with the Euro ensemble mean a significant proportion of the time. 

 

[summer blizzard]

2 hours ago, MR EXTREMES said:

good post.

i also see the siberian ridge returning as our side vortex segment drops down into europe and eastern europe,

in turn becoming unsettled into the mediterranean area with more free movement of ridges getting dominant to our west northwest or directly north.

Despite a lack of amplitude i have to say that the day 10 Euro mean was actually quite similar to the MJO anomoly for phase 6.

Here is where that may lead..

[Methuselah]

4 minutes ago, summer blizzard said:

The further one goes out, the more accurate the ensemble means are in relative terms (operationals by their nature will bounce around).

In the 2017 hurricane season the Euro ensemble was so statistically accurate at day 5 that it even outperformed the NOAA's specialised tropical consensus models. In their discussions (Nick occasionally posts them) for US weather, they go with the Euro ensemble mean a significant proportion of the time. 

I couldn't agree more SB! Which is why I cannae see much point in posting individual ensemble members; not only do they flap around, just as the Ops do, they are fed with 'duff' data, to start with?

[Blessed Weather]

1 hour ago, Borei said:

It ends with no northern or even mid lat blocking in sight, and a seemingly increasingly well formed polar vortex.

This is the exact opposite of what the tele-connections brigade have been forecasting for a seeming eternity.

That's a very negative post. Just in case there's any confusion, here's what a well organised stratospheric polar vortex (SPV) at 10hPa 60N looks like. Example from Nov 2011:

And here's what the SPV is forecast to look like by 14th January 2019. Disorganised and split after the SSW:

The tropospheric polar vortex at 500hPa is a different beast to the SPV and if you read the posts from knowledgeable people on here, there have been plenty of informed discussions around whether the SPV SSW will "downwell" and "couple" with the troposphere to give the synoptic patterns that the Hunt for Cold thread is looking for. This doesn't always happen, but here's what the Met Office say:

".....a cold snap follows more often than not, so the SSW greatly increases the risk of wintry weather."

You might wish to read their full blog here: https://www.metoffice.gov.uk/learning/wind/sudden-stratospheric-warming

And this morning we've read that some of the GEFS pertubations are starting to show more encouraging patterns, maybe starting to sniff out what's happening higher up in the stratosphere? For example, Pert 17 looking very interesting.

[Frosty.]

Enjoy this weeks cold with frosts and fog..at least it will feel like winter for a change!!..looking ahead, the GEFS is yet again indicating increasing potential for wintry weather, perhaps even severe!..the second half / last third of January could be special!

Edited December 31, 2018 by Frosty.

[Duane S.]

I have to say, this morning as poor as I’ve seen on this forum. And that’s saying something. I genuinely think if people insist on only following every suite religiously and then are unable to control their frustration through one liner gloomy posts, give it (and others) a break for a few days.

Anyway, the GEFS continue to smell the coffee in a big way.

And as for this not moving forward. Day10 means... (Euro charts to highlight improvement in Atlantic ridging).

12z

18z

00z

And the 06z...

[Purga]

As has been rightly alluded to, the GEFS are trending in the right direction.

Notice the shift in the mean & colder runs from yesterday's 18z thru' 06z today.

METO / GLOSEA are still 'on song' btw.

 

Edited December 31, 2018 by Purga

[bluearmy]

3 minutes ago, lassie23 said:

It will be snowing somewhere soon

It always is .............

the only consistency in recent days is the sceuro low anomoly end week 2 .......it’s what happens in the Atlantic and to our nw which is varying ..........

given the polar field responding to the downwelling wave(s), inconsistencies here, run to run, aren’t helping the ops. 

[karyo]

6 minutes ago, lassie23 said:

It will be snowing somewhere soon

It is: https://www.skylinewebcams.com/en/webcam/ellada/evrytania/agrafa/granitsa.html

[Minnizi]

1 hour ago, Dancerwithwings said:

I can’t recall now who posted these wise words, “Don’t bother with the op, keep an eye on the gefs for indications of SSW down dwelling and it’s affects” well looks like and hopefully them wise words maybe wright.

Think the chap your thinking of is david? Not sure of his profile name

[matt111]

4 minutes ago, Minnizi said:

Think the chap your thinking of is david? Not sure of his profile name

Not sure if it was him but you’re thinking of @Bring Back1962-63

[Selliso]

13 minutes ago, karyo said:

It is: https://www.skylinewebcams.com/en/webcam/ellada/evrytania/agrafa/granitsa.html

Only c.900m elevation too, so doing well already! A little on the cool side for Greece at T96

[Guest]

1 hour ago, Blessed Weather said:

That's a very negative post. Just in case there's any confusion, here's what a well organised stratospheric polar vortex (SPV) at 10hPa 60N looks like. Example from Nov 2011:

And here's what the SPV is forecast to look like by 14th January 2019. Disorganised and split after the SSW:

The tropospheric polar vortex at 500hPa is a different beast to the SPV and if you read the posts from knowledgeable people on here, there have been plenty of informed discussions around whether the SPV SSW will "downwell" and "couple" with the troposphere to give the synoptic patterns that the Hunt for Cold thread is looking for. This doesn't always happen, but here's what the Met Office say:

".....a cold snap follows more often than not, so the SSW greatly increases the risk of wintry weather."

You might wish to read their full blog here: https://www.metoffice.gov.uk/learning/wind/sudden-stratospheric-warming

And this morning we've read that some of the GEFS pertubations are starting to show more encouraging patterns, maybe starting to sniff out what's happening higher up in the stratosphere? For example, Pert 17 looking very interesting.

SNIPPED

 

Thanks for this excellent post Malcolm. This is just a very brief comment from me.  As some have said the GFS op run continues to be a big outlier and the 6z was an extreme example of this. Almost all the GEFS ensemble members show HP building close to or over the pole.  Let's look at one of the key periods - the day 10, T+240 "mean" chart:

Several others have already "cherry picked" some of the perturbations showing a full reversal and a split right down to the surface.  The "mean" shows that most members are well on their merry way to this - the later output is likely to adjust (some already looks great) "if" day 10 is anywhere near right (it may be too conservative or there might be a further delay). Contrary to what some of the most impatient members have been saying - the timing issues have hardly changed all the way through this long build up.  We've spent some weeks watching the strat with interest.  The timing of the SSW (when the warming occurs up there - not the surface impacts) was mostly expected from around Xmas or shortly afterwards. A few models were forecasting it for slightly earlier than that and a few for around the New Year.  It "has" happened and now we await whether we shall see a full split of the SPV or a displaced one.  The vortex is still under attack and if they're needed another shot of planetary waves will be sent up by the very +ve EAMT event which is now well underway (time lagged response of a few days to a further hit).  Yes we have issues over downward propagation and this is where the tropical forcing can really help.  I've posted on this a number of times and that is all going in the right direction.  In fact, even without an SSW, the current +ve momentum and torques and their interaction with the MJO would deliver a decent colder spell in any event.  This current HP is starting to amplify. The strong HP and ridging over the UK, Europe and northern Asia is making the surface very conducive to at least some blocking and assuming that we get that final propagation to the surface (which I believe will occur due to the tropical forcing, existing blocking and +ve torques) the surface pattern looks great for producing HLB setting up in a very favourable position. 

We should be looking for the split over the next few days to firm up on that and particularly the timing. Then watching for the downward propagation and then the blocking patterns setting up. I would say that the time range might be any time from Jan 10th to 20th and perhaps most likely around mid month.  If it takes a little longer, so be it.  This is all happening now and during early January not after Easter!  Last week some of us (including myself) were saying that we would start to see the models beginning to sniff out these changes from around or just after Xmas and that is precisely what has been happening. While anticyclonic gloom seems to be prevailing both outside and here on this thread both types of gloom are totally uncalled for.  Some arctic air is about to be injected and this will clear the gloom and producing some brighter and frosty weather (but with some fog too).  Meanwhile, as we await the changes, this is a totally fascinating period meteorologically - why not start to understand, embrace and accept that and consider how unusual the set up is both high up in the strat and down here on the surface?  Watch the models trying to factor all this in and accept that we'll see some more ups and downs for at least several more days.  Then if we are to see the full SSW impacts, there may well be a transition period with several days of more unsettled "Atlantic" weather.  This period has been steadily shortening and it's possible that the HP will hold on and link up to the HLB as it develops.

Overall there is so much to be excited about right now.  David      

EDIT:  Whilst writing this post I see that @Dancerwithwings is wondering if I wrote a post referencing the GEFS rather than the op run. - a bit like I did just now!  Well, not for any other reason than to show that many of the ens were showing what I said we should be looking out for. Here's the link to that post so that you can see exactly what I said.  D

https://www.netweather.tv/forum/topic/91032-hunt-for-cold-model-discussion-heading-into-christmas/?do=findComment&comment=3947020

 

Edited December 31, 2018 by Guest
check charts, correct typos and add a comment

[karyo]

3 minutes ago, Selliso said:

Only c.900m elevation too, so doing well already! A little on the cool side for Greece at T96

Yes Selliso, a good spell of snow later this week and intense cold in northern counties. My hometown (Serres) which is notorious for its dry continental winters is also likely to see a covering by Thursday morning.

[phil nw.]

21 minutes ago, bluearmy said:

It always is .............

the only consistency in recent days is the sceuro low anomoly end week 2 .......it’s what happens in the Atlantic and to our nw which is varying ..........

given the polar field responding to the downwelling wave(s), inconsistencies here, run to run, aren’t helping the ops. 

Looking at the day 10 eps clusters Blue there is a reasonable chance of a cold northerly. It is down to getting better ridging than currently shown on the means. 

Once part of the jigsaw seems consistent though wrt that Scand/Euro trough. 

[Frosty.]

1 hour ago, Dancerwithwings said:

I can’t recall now who posted these wise words, “Don’t bother with the op, keep an eye on the gefs for indications of SSW down dwelling and it’s affects” well looks like and hopefully them wise words maybe wright.

I hope the GEFS continues trending the way it is right now because there is a lot for snow starved / cold starved coldies to look forward to if it does..and we still have exeter with their potential much colder signal which is very important. 

Edited December 31, 2018 by Frosty.

[bluearmy]

1 minute ago, phil nw. said:

Looking at the day 10 eps clusters Blue there is a reasonable chance of a cold northerly. It is down to getting better ridging than currently shown on the means. 

Once part of the jigsaw seems consistent though wrt that Scand/Euro trough. 

Agree Phil - the higher sharper ridge is certainly an option and wouldn’t be surprised to see the op jump there later ......from that point at day 10, could get interesting sooner ......

[Duane S.]

Another great update this morning. SSW, as has been the case for quite a few days now, on course for lift off tomorrow (possibly even technically later tonight).

It’s a fairly simplistic chart and of course many nuances within, but to have a mid strat reversal that continues for 16 days+ (one solitary member bounces back to positive, and even that is after two weeks!) at this time of year is incredible. Albeit, I wouldn’t be surprised to see that end up being pegged back a bit. Still, it’s impressive.

There will be repercussions, cold will exit the Arctic down to the mid lats. Stay patient, we would have to consider ourselves to be unlucky to miss out on a decent cold spell from this. Might well end up doing but NOBODY knows yet,  save your stress until then and in the meantime, enjoy!