[Stratosphere and Polar Vortex Watch]

3 hours ago, feb1991blizzard said:

What about the op, is the current version or previous version better? are there actually any verification stats for the strat available?

There is not much hard data to compare the two as far as I know. There likely is data in existence, that was used during the development, testing and fine tuning phases for the new FV3. But those are probably mostly internal. At least I have not came across any comparison data.

On a general note, I kinda feel an anti-FV3 agenda in this thread. Not sure why, because FV3 is a very capable solver. It is actually appropriate for the strat, as a dynamic core. Has anyone noticed when looking at the strat charts, they look much more realistic? Especially the temperature forecast. You can actually get the feeling of fluidity, even at 1° resolution. You can actually see the eddies in the surf zone, and energy and waves in the forecast. That is not due to resolution, but due to the capability of the FV3. Below is a comparison of GEFS and FV3, both on a 0.5°grid. Now you tell me, where can you see the actual fluid dynamics?   You really get the feeling that you are looking at water motion, when you look at the GFS with the FV3 core. And that is pretty much what this is. It is like motion of water, combined with waves and circulation.

 

This does not automatically mean a better forecast, but as far as I am looking by eye, it is not bad at all! It has the same bias as the old one, trending towards a weaker vortex into FI. But all those biases go out the window and are not important when SSW dynamics start.<-Those are mainly influenced by the trop activity, so any error in the trop forecast will reflect in the strat forecast too. Besides, when a stratospheric warming trend starts in the FI, it can swing the warming air mass 1000-3000km left or right with each run, making big differences from run to run. But the forecast is still a success, because it has seen the developing warming for example, which materializes. 

So to me, the FV3 is quite a capable strat solver. Forget the old GFS, it is gone anyways. So far it seems that FV3 is doing a good job. More time will be needed to make proper actual comparisons.

[Stratosphere and Polar Vortex Watch]

8 hours ago, feb1991blizzard said:

Meteociel - Cartes Ensemble GFS (ENS/GEFS)

WWW.METEOCIEL.FR

---

meteociel propose des rubriques météo temps réel, forums, modeles...

 

Legacy is the GEFS v10 version. As it says on the site, it is the pre-December (v11) version. That means it is the pre-upgrade version.

It has 42 vertical levels and model top at 2mb. The v11 version (december 2015-present) has 64 vertical levels and model top at 0.2mb.

So the legacy version is underqualfied to be a useful strat forecasting tool. At least in the modern times.

[Stratosphere and Polar Vortex Watch]

Just a side note: The GFS//GEFS suite is running without the Aura Ozone Monitoring Instrument (OMI) data in the inputs since 15th 06z run. I have seen a warm bias in the FI before when this dataset was not in the initials. Not saying that is why we are seeing the warming. The warming is likely legit, and already seems good on the 12z as well. I am just adding a note that there is a lack of ozone data in the initials for future reference.

[Stratosphere and Polar Vortex Watch]

For all that watch the zonal winds. Let me urge you to look at the geopotential heights more. At least as far as weakening/strengthening trends go. Because as the polar vortex cries for help, you might gonna see an increase in zonal winds, or at least no weakening, while the vortex is actually starting to lose the battle. It was seen on many occasions. This goes for GFS and GEFS. As the vortex goes under heavy load, via wave 1 or 2, it gets contracted, so one side of the vortex can get "compressed" which can amplify the wind speed as the pressure gradients tighten. If one looks at a 60N lat U/U-wind line graphs, one can say that the weakening has stopped and that the power of the night jet is stable. While in reality it is perhaps just shining its last powerful brightness. Like a light bulb shines brightest before going out. At least the old ones, not the new LED technology.

Here is the latest 384 forecast from GFS. I added a 60N latitude circle. We can see the heavy warming in the surf zone. You can also see that there are still mostly zonal wind components on the 60N circle.

Looking more directly, here is the actual zonal component at 10mb. It is obvious that this is very far from the optimal for this time of year. The night jet is displaced on the pacific side, but it is the Eurasian part of the jet that is raising the values of the GFS on the zonal mean zonal wind graphs. Looking at the picture above again, we can see the vortex in a pretty bad spot, which tells us much more than one single line on a graph. 

The actual wind speeds show the story too. The Eurasian part of the jet is directly on the 60N lat line, keeping the zonal wind components up on the graphs. In reality, the vortex is getting contracted and is in trouble if that warming really escalates. Still no direct SSW on sight, but this could be the beginning of the end if it persists. 

I write updates on another site, where I was saying over a week ago that given the tropospheric pattern, more warming phases should be on the way. So this is kinda it.

*Stratosphere warming watch* A powerful new warming phase is building for early December. Stratospheric temperatures likely to raise over 30°C above normal, affecting the already weakened vortex! » Severe Weather Europe

WWW.SEVERE-WEATHER.EU

---

-spread the word- The polar vortex is slowly but steadily losing its power. While the pressure waves are “attacking” the polar vortex, a new temperature wave is building for early December, that should...

The trop pattern forecast does look supportive to perhaps finish the blow towards mid December. But the real question is what will happen if we get an SSW? Who will benefit from it, and who will have to wait for another one? It is way too soon to look into downwelling, since we need to have a clear idea how the trop pattern looks like at that time. So since there is no SSW yet on the medium range forecasts, that will have to wait for now. First we need to get to an actual SSW, and we will deal with propagations later.

Cheers

[Stratosphere and Polar Vortex Watch]

Of course. Trop-Strat coupling is not such an easy matter for the medium range, harder for the extended range, and very hard for the seasonal range.

[Stratosphere and Polar Vortex Watch]

9 hours ago, Steve Murr said:

Glosea is a high top model & will be able to factor in the SSWs into the seasonal forecast however its only in the last week or so this has become more visible in the models - based on that the next seasonal run of the models in particular Met office & ECMWF will be very interesting...

Well, I can share the fresh ECMWF seasonals for strat, which I just made. It does see the warming, and even escalates it towards January!

For December it has the wave 2 pattern, with the warming we are seeing now in the FI GFS.

  

January tho, it drops the bomb. Not sure it has an actual SSW, but this is definitely a weak vortex event. Not much recovery is seen in February, but that is a long lead time.

   

UKMO Glosea5, is quite different as far as geopotential heights go. It does not have an obvious weak vortex event. These are monthly averages, but the ECM forecast is an obvious weak vortex compared to the UKMO forecast. This is the same averaging/members as the official forecast on the UKMO website.

December looks kinda on track with the pressure waves surrounding the vortex. But in January its nothing special.

  

Temperature anomalies do indicate a weaker core temperature wise, but nothing spectacular.

 

 

These are seasonal monthly averages, but ECMWF has an obvious attempt at a weaker vortex event, even if perhaps not a proper major SSW. The problem is that it does raise heights over the pole, and breaks up the tropospheric vortex, but the residual lobes end up in Pacific, Atlantic and India/Himalayas. So essentially we end up with a +NAOish type pattern.

[Stratosphere and Polar Vortex Watch]

Yes, I was aware of early 3D animations, which served as a great guideline. I was not aware of this specific paper (which has great looking 3D plots), but all I ever found, was in research papers. Which is why, as I said above, I consider to be one of the first (not necessarily THE first), that did it on an operational/forecast basis, rather than research-case study examples.  

 

[Stratosphere and Polar Vortex Watch]

Well, any type of copyright would not be very scientific.  Besides, the data is not mine, and also the software is not mine, so its not really possible to copyright just the method, even if I would want to.

On a side note, I just noticed that after the last upgrade of the GFS to the dynamical core FV3, the model levels in the output grids got an addition of the 0.4mb level. Not a lot of forecasting power in it, but t will be interesting to see where the "lid" of the warming is. The graphic I made shows the 16-day change in temperature, a zonal mean. The warming is obvious and anomalous, but the core itself is cooling seasonally. There you can see addition of the top level.

[Stratosphere and Polar Vortex Watch]

14 hours ago, bluearmy said:

Not at all nws .... just wondering whether these supa dupa ‘new things’ were infact done by someone on here quite a while ago ??.

Well, I did extensive research back then, and true 3D simulations of the polar vortex were nowhere to be found. There were images of a 3D polar vortex, but in a 2D (cartoonish) style, and specific to research papers individually. That was the very reason I decided to research this field (3D simulation), and essentially (by my knowledge at least) being among the first (if not the first) to create operational 3D simulations of the polar vortex in 3 (4) dimensions (time) from operational model forecast data and reanalysis data (ECMWF ERA-Interim, NASA MERRA-2). That was already in 2013 I think, so Mr. Ventrice is almost 6 years late.  

[Stratosphere and Polar Vortex Watch]

As I also stated in my article on another site, as long as the pattern configuration with the Siberian high/Aleutian low persits, there should be more of this on the way, increasing the potential for a proper SSW by the end of the year.

On a seasonal note, I was in a hurry, but managed to make the 10mb temperature anomaly charts for december, from ECM and Glosea5, from October runs. Will be interesting to see the November runs. Its amazing how different they are despite pushing a similar tropospheric agenda. Tho these maps have no practical use in forecasting, it is interesting to see what is the stratospheric idea behind the tropospheric forecast.

[Stratosphere and Polar Vortex Watch]

The circulation pattern overall is supportive for further wave activity in the stratosphere. At least if one trusts the likes of weekly CFS and JMA ensemble models. The Siberian high is a good sight to see for now, if we can also get decent lows in the North Pacific.

 

I have gathered more thoughts in another place.

An unusually strong early attack on the Polar Vortex expected! Sudden Stratospheric Warming event is not excluded in the next 30-60 days – Severe Weather Europe

WWW.SEVERE-WEATHER.EU

---

-spread the word- We often hear the term “polar vortex” as we head closer to winter. But this season, we will talk about it earlier than expected. We recommend you read our tutorial article, on what is the polar...

 

[Stratosphere and Polar Vortex Watch]

My new animation sequence, showing the nice wave2 pressure from GFS in late terms, which are strongly tropospheric forced, by the Alaskan and Atlantic ridges.

 

[Stratosphere and Polar Vortex Watch]

I think it should be around 10-12th, and similar for UKMO. 

[Stratosphere and Polar Vortex Watch]

Great job Lorenzo!

If I can make a suggestion: Reduce the amount of lon/lat lines to 90x30 interval, since for this type of data it is not as important and can sometimes even be a distraction. 

Also, you have an important flaw in the color scaling. You dont have zero centered colour scale, which is critical when plotting anomalies. That means that the colour scaling is centered on zero, so all negatives are on one side and positives on the other. Basically you must have 0 value in the white middle. One plot has colour bar from -80 to 60 for example, which means that the zero lands in the red colour so you get more red colour on the plot than there should be. When plotting anomalies you need to have mirrored values in the colour bar, like -80/80, or -40/40, so you get zero in the middle and colours represent proper anomaly values. 

[Stratosphere and Polar Vortex Watch]

21 hours ago, Interitus said:

Are these CFS plots ever right?

Not really.

The configurations and systematics of the CFSv2 model, are not really that appropriate for stratospheric forecasting beyond the normal operational range (15-16 days).

Anything beyond that should be ensemble (breeding) only.

[Stratosphere and Polar Vortex Watch]

Yes its relative vorticity, but I am not sure about the value, I think around 18? Since it was done on the fly...

Tho for SSW reanalysis from ECMWF ERA data, I rather use absolute vorticity. Its much more clean and gives a better impression. But the new ERA-5 data only has relative vorticity for now, so I will try that out since it has really nice resolution for a reanalysis model.

[Stratosphere and Polar Vortex Watch]

I dusted off my 3D plotter today and did a first new season test of the 3D vortex structure, from todays 00z GFS data, for 384h forecast. This is the whole vortex core 1mb-150mb, so you can track how the whole vortex is tilted and where it connects to the troposphere. It is just to show how the GFS develops the core and links it downward, since this is deep FI, and beyond 240h nothing is really used as a forecasting tool. 

 

[Stratosphere and Polar Vortex Watch]

Here is my updated plot with SSW markers included. The SSW markers on top are colour coded by their respective ENSO phase. 

 

[Stratosphere and Polar Vortex Watch]

Not to be a party breaker, but 5K is like a normal core oscillation. Can hardly call it a warming event really, let alone count on it to bring colder trop weather. And this is a 50mb level, so its even less significant. 

[Stratosphere and Polar Vortex Watch]

Thank you for your work Lorenzo. I am tho a bit confused with the first plot. The enso regime from 1990 to 2001 seems quite off, being all in negative? 

I did one a while ago, I guess I should update it and add SSW dates. Black line is ENSO.

[Stratosphere and Polar Vortex Watch]

5 hours ago, Interitus said:

 

And to further elaborate, below is my own version of this graphic from @Interitus , after I apply my "Recretos' 30-second full-HD optimisation procedure".   It really is that quick once you know what to do.   Colour is of course just a matter of taste. 

             

 

[Stratosphere and Polar Vortex Watch]

Yes, the monthly mean of 50-members at a 3-5 month lead time is diluted enough to show near climatological pattern to the untrained eye. Anomalies are needed to reveal actual forecasted deviation, which must be calculated from the model hindcast climatology.

Panoply is a great tool. It needs some getting used to, but its a great begginners tool. I use it on a daily basis for all kinds of plots. It takes some basic trial-and-error, to learn how to optimize the graphics and to create strat-specific plots. Tho it is not for mass production of maps.

I use a whole different beast for that, which is slightly more technically demanding, but enables 3D/4D plotting.

[Stratosphere and Polar Vortex Watch]

As far as the stratosphete goes, the Atlantic has not gone wild because there is nothing wild in the strat to begin with. 25m/s is a good start, but in mid winter that speed would be considered a weak/very weak vortex. The vortex core 10mb pressure height dropped below 3000dm just a few days ago, so its not yet that wild beast that we all know and love. Or hate, for that matter. 

In the near future the trop. Atlantic wave will help to push the core around a bit, keeping a lot of the vortex' core energy away from the Atlantic sector, pushing it more into the Siberian region.

[Stratosphere and Polar Vortex Watch]

As promised, I finally managed to complete the website with ECMWF seasonal forecasts, including the stratosphere. I will add Glosea5 around its November update, so it will be fresh when it goes live.

http://www.severe-weather.eu/ecmwf/

[Stratosphere and Polar Vortex Watch]

I noticed talks of QBO, and decided to look at it via GFS, and it is in the positive values already, so October mean might end up near or at positive values. I made one HD graphic of QBO progress at 10mb and 30mb from GFS data.