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Ladyofthestorm
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Posts posted by Ladyofthestorm
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How does the ECM compare to it's ensembles?
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10 hours ago, MattH said:
Hi.
I just wanted to create a post from an educational perspective and also be a point of reference regarding the importance of the GSDM and the AAM on the medium and long term. Hopefully, anyone who questions this should change their mind after reading the below. The reason it is worth doing this is because there is no better, clearer, example of the importance and connections between those upstream, Pacific developments and the downstream influence.
I'll attempt to highlight and stitch this together using some of the usual plots and charts which tell the story so very well indeed and it is this which, hopefully, helps people to at least better understand the influences of the GSDM and what to look for moving forward.
OVERVIEW: Firstly, we have just endured a very wet December, this comes as no surprise given what happened to the AAM in late November. Interestingly, seasonal models all pointed towards December being a +ve NAO month, in keeping with the long-term teleconnections with regard El Nino and a +IOD in early winter. The late Nov and early Dec cold spell can be linked back to the behaviour of the GSDM too, while what followed through much of December certainly can and what is happening now and looking ahead, most certainly is. Despite a weakened stratospheric polar vortex, it is the troposphere that is 'leading the dance' rather than the stratosphere for the most part even though it is lending a hand.
The late Nov/early Dec blocked pattern has links to the temporary rise in the AAM in mid-November, with the usual lag in place. We can see this first evolution in the below plots...
The second and more obvious evolution was then the more pronounced fall in AAM through late Nov as the MJO returned to the W Hem and westerly inertia was removed from the GSDM budget and, as usual, AAM fell along with a -FT (Frictional Torque) and -MT (Mountain Torque) event. The result was, as ever, propagation through the extra-tropics and then into the mid-latitudes of more westerly momentum, propped up by easterly momentum at circa 30-40N - Remember the inflated Azores high in the run-up to Christmas? - We can see how the +AAM anomalies, in particular, were distributed through the atmosphere within the usual window of approximately 14 days. No surprise we then saw an enhanced period of +AO and +NAO conditions just before mid-December onwards.
Lastly, comes the 'big event' within the last week or so in terms of the pronounced rise in AAM. Once again, in complete contrast to what happened through mid-November, with a lag of course, we can see how the marked rise in AAM has allowed the propagation through the sub-tropics and into the mid-latitudes of more easterly inertia (-AAM) very well indeed, this is particularly obvious on the relative AAM transports plot, as highlighted below. Once again, no surprises at all and of which has been documented by the usual few on the group we are now seeing a complete reversal of that +AO and +NAO period with an array of mid-latitude and, eventually, high latitude blocking patterns.
We can also see this visually on the zonal wind plots at 100hPa (top of the trop/bottom of the strat) too.
While like in many areas of meteorology, there is never often a usual "a+b=c evolution", but this is about as close to that as you can get. We have certainly had help from the stratosphere here mind because a robust stratospheric polar vortex that is downwelling westerly winds into the troposphere can often be the dominant player, overriding what has occurred over the last month. There is likely to be some 'help' here from the El Nino and eQBO combination this winter as the sPV continues to remain disorganised and far weaker than it can be at this point in the winter with far less influence on the troposphere too.
When it comes to the AAM it is crucial to be able to accept and acknowledge when there are other overriding influences and counterbalances. Tamara et al often talk about not taking the MJO at 'face value', it is similar with the AAM, but when you combine the usefulness of the GSDM and all it incorporates then, as I have perfectly examined here, nobody can ever say the likes of the GSDM and the AAM is "flawed or useless" when it comes to pre-empting NWP, at times, and also gauging how the broader patterns may evolve and shift.
As I mentioned at the start of the post, I wanted to put this one together because there is no better example of the usefulness of the GSDM than what has occurred over the last month or so. The evolution and 'story' of the atmosphere have been well played out in these plots.
For those who want some winter weather after the last few weeks of very wet conditions then 'this is your time'. We approach mid-winter with such solid footing for cold synoptics that it should be a pleasure to watch the more unusual patterns being modelled in NWP and, interestingly, this continues to link in well with the majority if not all of the seasonal models with regards to how Jan and Feb and perhaps even Mar should progress. Winter is about to start...
With regards, Matt.
Matt best post
of the whole winter!
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11 minutes ago, LRD said:
Proper rant that. I've tried to use model evidence combined with the expert opinion of professionals to make you feel better and you've come at me with conjecture and a moan
If you don't care about what professionals say, that's your choice. I'll take more notice of them than someone whinging on the internet. I've seen them be right loads of times. The met office-bashing on here is extremely tedious
By the way, as I've said countless times, I'd like it to get cold but I ain't that invested in it so I'm looking at this quite coldly (pardon the pun) and neutrally. I rarely call cold. I'm calling it now
Anyway, I'll leave it there. Hope you cheer up soon
You are quite correct to call it cold.
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2 minutes ago, BLAST FROM THE PAST said:
18z looking to be monumental…..direct Arctic hit incoming
BFTP
It's onto something
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27 minutes ago, LRD said:
He'll need it this month and early next
Agreed!
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8 hours ago, Catacol said:
No. I wonder what went wrong. Good feed from Amy Butler yesterday reminding us all that SSWs are normally under modelled and that it is unclear what has caused the models to go over the top on this one. Recovery now looks likely and then we will have to see what transpires are we approach February. I'm not sure we have sufficient trop precursors going forward to suggest a SSW in Jan or first half of February. Wonder whether this will be one of those few eQBO/Nino seasons where we don't get one now.
Currently though winter is being saved by the pacific. Very high GLAAM and amplification signal, sufficient to make the most of the weakened vortex state perhaps. I might have to eat the words of my theory this year, that proper cold in the UK is no longer reliably achievable without a SSW. I would be delighted to do so by the way!
I've seen a few confident tweets mentioned in Amy Butler's feed about colder weather in Northern Hemisphere not requiring a SSW.
I think 2006 was the last time , cold dry Jan and Feb, after a really wet and stormy first half, March and April then was really snowy. It can and does happen.
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My suggestion is look towards the teleconnections for clues. That negative NAO is critical for where our best chances of colder weather is coming from. That Greenie High is the source of colder weather, not a technical SSW, ( that might happen later), It's been forecast to happen all winter! First on the longer ranges and now quite dramatically onto the GFS, ECM etc, as always the devils in the details for snow casting and it's pointless and fruitless exercise.
The settling down of the weather in January in my mind is a blessing in disguise, the trend is cooling which is also needed. The magic bullet snowy easterly , unlikely to bring snow. The major drivers are the high pressures which are mobile and dynamic this winter , big and high but moving around alot so not blocking anywhere for long. This situation won't last for much longer. Last night that was a huge Greenie high forecast , even moderated over time and model run, still high and big.
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1 minute ago, MATTWOLVES 3 said:
Bite ya tongue Scott? I've literally lost mine from putting the troops back in order
While we wait for the 12z ecm and more importantly the ext ens...which I feel was superb this morning...the 6z mogreps have the majority of clusters around cold territory!
We are slowly moving in the right direction...cold surface high with temps falling away by the Weekend...infact met only got 3c for here on Saturday....what comes next is how the high reacts..does it sink? I don't think so..Does it stay stationery for several days? Most likely. Does it retrogress North or North West? Going on those ens this morning I would say there's a good chance. And finally a rather subdued looking Atlantic for some time. Any inroads from that direction would certainly bring quite a high risk of wintry precipitation with time.
In a nutshell lots too keep an eye on.
Trend is the friend. Temps on way down.
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19 hours ago, MATTWOLVES 3 said:
I needed to jump out of semi retirement for this post..hope the mods don't mind.
When I joined this forum nearly 5 years ago I was sceptical of back ground drivers as I didn't really understand them..so I just played ignorant to it all....but I never disrespected any of the posters who shared this knowledge! As the years have rolled by the likes of Tamara..catacol...met4cast...chio..matt H.. eagle eye...(I could go on with this list as there's more of you) have completely changed my attitude to such a wonderful science,and the amount of work that goes into this subject with there posts is unreal! Do keep in mind many of the above are not professional! Yes you would think they were...they are that good at it,they simply have a gr8 passion for the subject and spend a hell of a lot of time studying,and then they pass this information on to us giving us the chance to learn something new!
I for one know for a fact some of them in the past have come close to stopping posting due to non stop criticism...and I've actually talked one of them out of it privately on more than one occasion!
Where do you think the Met get there long range forecasts from! A clairvoyant!! The tea leafs! It's all based on drivers around the globe and much of it is inputted into those monthly text updates.. yet when they're talking up cold and snow,everyone loves em! When they get it wrong they're useless! Get my point here!
Let's all dismiss those drivers and base our forecasts on 4 gfs runs a day! One run shows Greenland blocking...the next a bartlett high! Exactly!!! Its not quite that simple.
So I say to all of those that spend so much time bringing us these amazing insights with the teleconnections to please keep at it...most of us on this Forum want to keep learning from it.
Keep the peace folks...no point in dismissing something you either don't understand,or are simply not willing to try and understand.
Hi Matt I'm just catching up , a huge thankyou for posting this up, I very much agree with all that you say. When I read Tamara, Eagle Eyes and Catacols posts, to name but a few.I dont sometimes understand it , but catch glimpses of what I do understand. The big atmospheric drivers in our part of the world will definitely play significant roles... We live at the end of a conveyor belt of a rather large ( thinking energy) duck pond.
Tamaras post from a few days ago struck a cord when she mentioned the colder air could be as a result of pressure building to west and north rather than an SSW zonal wind reversal. I suppose we should be looking at negative NAOs for this. I have had my hunch on this for a while too, but I am no expert.
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I have my rising suspicions now that colder weather for UK will come from a negative NAO with Greene high, blocking the Atlantic machine rather than an SSW reversing the zonal winds. The warming about to take place looks like it will stretch the PV , rather than displace it .it's a pretty fragmented /messy PV anyway. All change for January I think. A later SSW will be a technical SSW and this will reverse the winds. I would actually look at the GFS for these clues long term as it's resolution 6 days and less isn't brilliant. But it can
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Ok A reversal of the zonal winds looks unlikely , this time around, but the experts are bullish about a negative NAO in Jan.
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I was under the impression from the models that a SSW is going to happen , it's just unlikely to have any significant impact on the troposphere therefore zonal winds.... yet.
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I think it's too easy to get wrapped up in individual runs of models when it comes to SSWs , patience it's coming and when it does it will be a cracker
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6 hours ago, Daniel* said:
This is one of very last frames from EPS, Jan 10th, it’s noteworthy at such an advanced lead to see greens in Benelux near 5C below normals evidence there is a lot of appetite already to roll some decidedly cold air west. There is evidently an already a strong signal for a significant cold outbreak in western Russia near 10C below normal, on mean at day 16 is crazy. This looks to be where there will be a fragment of polar vortex. I can’t see us complaining about shortage of cold to east. I would expect us to see more beast style synoptics in future whether they verify I don’t know but the possibility is clearly much higher than normal.
Agreed,
Trends are always friends and the ensemble models are actually in very strong agreement, pressure rising to the North, and decreasing to the south
This ties in with this temp chart above and with what is beginning to unfold on the stratosphere front.
Indeed on the longer range models you can see the effects of zonal wind reversal happening.
I am very hopeful of something colder and more seasonal in January. Though I am sure it will come come from the North and NE this time not continental/ Siberia, true beast from the east.
The west of Scotland is definitely having a true el Nino winter so far, still waiting on the NLy blast , it is not far away.
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1 hour ago, That ECM said:
Disagreement in the output, can’t work out how we are going to go cold.
For me seeing ecm bought the biggest smile. T120 shows the start of pressure rise.
Yep T120.
we are a long way from seeing small details but that can wait.
To be honest , Scotland and North England is already there. Ragged and already fragmented PV . It really isnt going to take too much.
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On 20/12/2023 at 23:52, Norrance said:
They need very cold air very high up in the stratosphere and the clouds have very small ice particles. I have read that under-78C is needed so most associated with the far North in Winter. Some say they precede a cold snap but I not sure if there is any association with an SSW.
Also known as mother of pearl clouds and sometimes rainbow clouds.Given the incredible amount of Nacreous cloud I saw a few days ago, It's has to be at least -85C in the stratosphere ( non polar regions) the now.
And yes 1984, 1995, 2009, 2010, 2013 , and now this year are pretty good markers .
Some say we will see them more die to climate change, not surprising as the polar stratosphere becomes unstable, and ragged and more likely to leak it's colder "air" to sub polar and mid latitude regions .
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11 hours ago, MATTWOLVES 3 said:
I see some of you are a tad stressed over the ECM and gfs solutions.. GFS seems to be king at smelling the coffee before ECM.
I think the buzzword is it trends colder,and certainly colder than recent days.
The zonal winds still looking toasty.
Now get ya marshmallows roasted on an open fire and hit the mulled wine. Go on ya deserve it.
As always the trend is your friend . Its on the way down , temps and Zonal reversal, I note the increase first before it reverses, significant aspect of this SSW coming up and note that it doesn't fully recover and is significantly weakened .
The GFS nearly always sniffs the trend out first . It feels like its got better longer term resolution than the ECM. That shouldn't be surprising as it's runs are longer. I noticed last night the 18z dropped colder weather signal into the new year and flattened the heights in the Atlantic, this morning it's back again ( to stay)
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We live, allegedly, right on the middle of the the mid Atlantic drift. Subject to the brunt of the Atlantic wrath... Isle of Lewis
Right now a WARM front is straddling our island and it's 1C with sleety precipitation.
This is not normal or typical conditions. 10C yes not 1C
Big Shouty Letters
It not NOT MILD
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I keep ending up back here and how similar this December setup is to December 1983 set up.
The euro slug with empowered Jetstream , and then bang , the high pressure are over Iberia shifts westwards .
Letting a flood of NLy break out in January
Something to bear in mind , I really don't think synoptically we are far away from this set up.
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2 minutes ago, January Snowstorm said:
Those who think this is a normal zonal type pattern/chart need to look again. It's full of potential and ripe for development to cold! Somethings afoot, and ok it's not going to save Christmas but it could well come to fruition this side of new year!!
Agreed!
We have a very fragmented almost Split PV.
The wintry weather will come in from the North or NW. To be honest I s the the direction that is significant but it's origin.
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Personally, I think now is the time to actually stop model watching for the Christmas period as there are still huge number uncertainties to be ironed out.
The ensembles for the major models are basically showing up as mild outliers on the operational.
We should wait about 48 hrs for better agreement ( though the models agree to be all mild outliers around Christmas. ). Look at those green lines , as all models assume the high pressure over Atlantic flattens bringing in a warm front. The NLy all but a brief cold snap just before Christmas. Not confident on that one either. Nearly every run of the model colder than the operational. ( Especially true for the ECM)
Is this the classic GFS picked up a wintry signal , drops it days 8 to 10 then picks it up again?
Source : Wetterzendrale
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Model Output Discussion - Into 2024
in Forecast Model Discussion
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More experienced model watchers will be pretty happy with the way these models are churning out colder weather prospects.
Remember the mantra the trend is your friend. All roads lead to cold and very cold.
Enjoy this week. The colder weather is coming in from the North end of week , late January looks interesting.
Who remembers the doom and gloom from last week when the SSW wasnt quite what they expected. Look what's happened , it's even better!
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