[Stratosphere and Polar Vortex Watch]

3 hours ago, johnholmes said:

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/

Anyone care to suggest what this may mean in terms of surface weather and how long before the effects, if any, are felt?

It was a serious request would anyone care to reply please?

This is the central theme of this entire thread. I think if you read back a couple of pages, you will find your question answered more than once. 

- The trop. response between SSWs differs between events. No guarantees given.

- The stratospheric vortex will likely be out of business for a while

- The standard time until the first trop. response is 10-14 days, but can be less, more, or the response may never come

- EC shows a modest signal for downwelling at +240, but nothing convincing yet

[Stratosphere and Polar Vortex Watch]

57 minutes ago, ArHu3 said:

Looking at the 3d vortex being modeled I understand why the models are struggling and average winds might not be very useful 

 

https://www.stratobserve.com/misc_vort3d

It's quite fascinating how the vortex shatters and basically ceases to exist at 10 hPa (GFS 12z FI). This translates to a pattern with relatively high geop. in the Canada/Greenland sector in the lower strat. Yet there is nothing (yet) to be seen in troposphere, not even a cute tiny baby polar high. 

[Stratosphere and Polar Vortex Watch]

8 minutes ago, Summer Sun said:

 

So there you have it, EC more or less adopts the GFS-scenario

[Stratosphere and Polar Vortex Watch]

Polar Stratospheric Clouds observed in the northern part of the Netherlands! Or?

Dutch/Belgian weather forum

[Stratosphere and Polar Vortex Watch]

4 minutes ago, Cloud 10 said:

SSW by day 7/8

 

 

That zonal wind at 1hpa used to be -40 in the previous runs though. But beggars can't be choosers

[Stratosphere and Polar Vortex Watch]

But is GFS truly that different? Showing a modest split at 10hpa. The bigger differences are at the top of the strat I think.

[Stratosphere and Polar Vortex Watch]

1 minute ago, sebastiaan1973 said:

Ruben you are right! Sorry folks. 100 hPa till 300 hPa.

 

So, where do we find the current NAM100-300?  

[Stratosphere and Polar Vortex Watch]

That's bad news bears. But please note that the paper mentions the NAM at 100-300 hPa, not 1000. 

[Stratosphere and Polar Vortex Watch]

22 minutes ago, Redbull165 said:

GFS06Z ensemble mean is seeing split vortex in the beginning of january, which is very important. The control one still doesnt see it, but in this kind of events ensembles  are probably the one we need to look at for an accurate forecast. 

 

 

Cheers on your first post!

For the record: the GEFS still shows a technical SSW but keeps pushing it back. Meanwhile, the hump in the short term is getting higher and higher (conform the operational runs). 

[‘Weather box’ vs shade]

Thanks for the great feedback. I will try to MacGyver my way out using a 5W solar panel! :)

[‘Weather box’ vs shade]

On 23/04/2018 at 14:34, Mapantz said:

I used an old adaptor that I had in a drawer. It has switches to choose from 3,6,9 and 12V. I just spiced the wires on it, and the fan, and joined them up and covered it up with heat shrink wrapping. The PC fans are designed to speed up and down via a higher or lower voltage, so it is perfectly safe. My sensor is attached to top of the box, which doubles as a lid. The fan is centered directly at the bottom to draw air up and over the sensor, and exhaust through the holes on the sides, and the ventilation around the top.

The fan hasn't missed a spin in 4 years!

Both my Davis and Netatmo sensors are attached to the same post, at the same height, out in the open.

Here's the Netatmo temp & graph:

  

Here's the Davis at the same time:

  

Quite happy with that.

So you take power from your Davis station? I'm sorry I do not quite understand. I'm building a diy version of a Stevenson screen and maybe I will add a fan (considering to use the Netatmo). What would be the best way to power the fan without having to run power cables into the yard?

[Model output discussion - Post SSW - Will it turn cold?]

The problem is the small low of the Norwegian coast shown here at +96. This prevents fusion between the two area's of high pressure. 

[Stratosphere and Polar Vortex Watch]

On 2/12/2018 at 12:44, KyleHenry said:

The ECM sees the reversal. It’s just not within the range of the 10 day model outputs of this past weekend.

My post was in reference to those that were  writing off the SSW effects by not seeing the tropospheric response showing an Easterly with every output. When the time table was always pointing towards 21st-25th Feb, if all proceeded as expected. 

Minor displacements in the Stratosphere give us a -AO, I expect the same and much more from this event.

I felt that if the ECMWF’s Stratosphere and Troposphere modelling were in sync, that it would show the formation of a significant-AO. That didnt happen and therein lays my sole criticism of the ECM. 

As for the GFS, it sees the signal, it just doesn’t know where and what date to proceed with the correct solution. 

Ive put a timetable of my expectations and upcoming events and expect to die on my sword for trying to be an SSW oracle. All good.

Right I read you  

Most model ensembles are now hinting with blocks, just a lot of variation in position and timing. 

It's an interesting idea to think to what extend the models perform with stratospheric configurations that are several sigma's away from normal conditions. To what extend are models calibrated to handle (or to what extend do we understand strat-trop coupling?) vortex remnants moving from east to west like in the coming 72 hours?

[Stratosphere and Polar Vortex Watch]

11 hours ago, KyleHenry said:

 

 

So it stands to reason that in reality it does not know that it’s coming. As seen on the 10 Day model forecasts of this weekend.

 

I do not quite see what you mean here. Surely, EC sees the reversal coming as it is output from the exact same model we look at in Berlin's Strat. plots vs. tropospheric output on meteociel. Perhaps, our current understanding of strat-trop dynamics limits our ability to accurately model responses to SSW events, but that's something different. And there is a possibility that the response is not as we all expect it (i.e. quick response, AO-), right? Not what we all hope for, but a possibility none the less.

[Stratosphere and Polar Vortex Watch]

2 hours ago, Interitus said:

Check out the SSW compendium for a full list of dates from reanalyses - https://www.esrl.noaa.gov/csd/groups/csd8/sswcompendium/majorevents.html

Since 1958 there have been 5 with 1981 perhaps most well known - winter 1981/2 was famously cold for the UK.

FWIW this forecast event is very similar to 1998.

edit: pipped to the post, lol

Would I be correct in stating this would also be a Canadian Warming? I.e. anomalies in early winter in the Canadian sector are Canadian Warmings, but only some of these also classify as a full-SSW?

[Stratosphere and Polar Vortex Watch]

Still rather impressive output this morning (GFS 06z in FI). Does anyone have any info on December SSWs? I believe there are rare and FU Berlin reports such events only in '87, '98, and 2001. These were not exactly impressive winters...

[Stratosphere and Polar Vortex Watch]

22 minutes ago, ArHu3 said:

Oh and these winds are @ 65 degrees, not 60 where they need to reverse for a true ssw

This is the WMO definition, yes. However, there is no real difference between using 60 and 65N when it comes to classifying SSW events. See: http://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-13-00173.1

"Poleward of 60°N, the local and coherent reversal requirements yield nearly identical numbers of SSWs; anywhere in this region, if the wind reverses from westerly to easterly at one latitude, it is also almost certain that the wind is reversing everywhere poleward of that latitude."

This is also why Attard plots 65N and not 60N.

[Stratosphere and Polar Vortex Watch]

I believe this is the first true reversal forecasted this season. The GEFS supports this to some degree, but we all know the model has the tendency to be too progressive.

[Stratosphere and Polar Vortex Watch]

Nope, not here

 

[Stratosphere and Polar Vortex Watch]

25 minutes ago, feb1991blizzard said:

Reversal of zonal mean winds between from 70N to the pole quite a long way up into the stratosphere.

- From about 7mb almost right the way down to the tropopause.

 

EDIT : I did think it was an SSW when I first looked (I was looking at the 70N) and realised it couldn't have been when viewing the10mb height chart. Still mighty impressive D10 forecast considering time of year and temps are running well below average right now over the pole now.

FYI: we are talking about the graph below? You may have uploaded the wrong image because the one in your post is very unexciting

 

[Stratosphere temperature watch - 2016/17]

I was going to write that y'all are a bit too enthousiastic: I do not see it as abnormal to have some minor dents in the vortex before the season starts. (Remember last year's quiet start, followed by an unleashed vortex the rest of the season.) But after today's 12z one eye is officially open:

 

[Stratosphere temperature watch - 2016/17]

Poof!

[Stratosphere temperature watch - 2016/17]

First nacreous clouds spotted near Tromsø, Norway. Very spectacular sunset here in Oslo yesterday, also due to the cold stratosphere (although I personally did not observe any "classic" pearly clouds). All signs that the vortex is indeed displaced. 

Picture source is the twitter account of Yr.no, a collaboration between the Meteorlogical Institute and state broadcast NRK. 

 

Edit: picture I took from the sunset here yesterday

[Stratosphere temperature watch - 2016/17]

1 hour ago, Gael_Force said:

I cannot see any of your images but agree wholeheartedly with the text part.

Weird... But glad you agree haha

[Stratosphere temperature watch - 2016/17]

I've been absent for a while now due to winter weather in early November (totally awesome!) and dark and mild "mørketid" weather (I hate it) for the last week or so. But, here's my two cents on the whole thing.

After the initial dip in zonal winds related to the - I am quite sure it is one - Canadian warming this November, we see a strong uptick in zonal wind speed forecast. Or I should say, recovery to seasonally mean zonal wind speeds - note the very large spread in wind speeds around the average. The brief(!) reversal of zonal wind (at 65N at least) and the positioning of the whole thing makes this a CW for me. 

 

 

Yet, soon after the recovery of zonal wind speeds, we see a new area of higher geopotentials (and significant warming btw) in the GFS FI. This has been modelled consistently in the last consecutive runs, including todays 06z. It would be great if this develops further and could punch the vortex in the face once again. A '62-63/'76-'77/'80-81/'00-'01 scenario with a CW followed by a proper SSW would be the bees knees for stratonerds  

 

Regarding the effects of this CW event on lower levels, I think the displacement of the vortex and axis of "southward flow" could be very important. I think a pattern where the direction of this flow is parallel to the 0° meridional (or even 30° W) would generally favour a trough bringing cold air to Western Europe, whereas allignment with the 30° E meridional could trigger the Atlantic? Please correct me if I'm wrong (or my English terminology is crappy haha). 

So this is good regarding tropospheric responses, I would say. 

 

Edit: can's seem to get rid of the last image, shouldn't be there