Stratosphere and Polar Vortex Watch

[Mattias]

Some more pictures about the downward propagation/reflection of the wave 1 pattern that's been discussed above.

By filtering out only the wave 1 component of the geopotential height field and plotting for 30 and 100 hpa in the same picture (see below) the predicted phase shift from westerly to easterly by height can be clearly seen, indicating a shift from upward to downward propagation. Contours showing 30 hPa and filled contours 300 hPa (note: scale not the same for 300 and 30 hPa, but amplitude not very important here since the phase tilt is what is meant to be shown).

The shift from upward to downward propagation can also be seen by looking at a cross section for the wave activity flux. In the first figure below, showing the forecast for 22^st of December (some day before the wave 1 pattern in the stratosphere culminates) there is upward flux from the troposphere to the stratosphere. A couple of days later there is instead downward directed EP-flux in the lower stratosphere (from around 60N and northwards).

When the direction of the wave activity flux changes the stratospheric vortex can recover while the zonal winds in the troposphere is decelerating which is shown in the last image below showing the zonal mean zonal winds from GEFS at 10 and 300 hPa.   

[Interitus]

Excellent charts Mattias, displays the concept perfectly.

[Dennis]

10Hpa and 50Hpa chart

[bluearmy]

Not much doubt that the upper vortex is returning closer to its home, likely to end up  ne Greenland towards Svalbard 

Ecm now forecasting the 60N U wind picking up to approx 40 m/s although I expect we will see renewed trop waves from the hemispheric amplifications having an effect some days later and already signs of a reflective wave 1 high up as ineritus mused yesterday.  

 

[northwestsnow]

32 minutes ago, bluearmy said:

Not much doubt that the upper vortex is returning closer to its home, likely to end up  ne Greenland towards Svalbard 

Ecm now forecasting the 60N U wind picking up to approx 40 m/s although I expect we will see renewed trop waves from the hemispheric amplifications having an effect some days later and already signs of a reflective wave 1 high up as ineritus mused yesterday.  

 

We're in deep trouble again Blue.(from a cold perspective).

At this stage a euro high (inversion cold) is about the best we can hope for into Jan-

Doesn't look like we are going to get much help from the strat ...

 

Edited December 20, 2017 by northwestsnow

[bluearmy]

25 minutes ago, northwestsnow said:

We're in deep trouble again Blue.(from a cold perspective).

At this stage a euro high (inversion cold) is about the best we can hope for into Jan-

Doesn't look like we are going to get much help from the strat ...

 

I don’t see it as a ‘done deal’. There is no guarantee that an increased zonal flow will downwell to the trop. And as the vortex returns to its more traditional place and potentially stretches, it could be prone to a wave 2 attack. However, time will be ticking on and aside from a quick trop response which isn’t a given, it could just lead to a cold spring as last seasons beg Feb trop slowdown likely did.

[knocker]

 

[fromey]

And then you have this

[ArHu3]

2 hours ago, knocker said:

 

@fromey

 

Maybe he is working with old data or he has the very latest but since this morning both EC and gfs are seeing an increase again of wafz after an initial decrease 

[fromey]

27 minutes ago, ArHu3 said:

@fromey

 

Maybe he is working with old data or he has the very latest but since this morning both EC and gfs are seeing an increase again of wafz after an initial decrease 

Thanks for that, still learning.

fromey

[bluearmy]

27 minutes ago, ArHu3 said:

@fromey

 

Maybe he is working with old data or he has the very latest but since this morning both EC and gfs are seeing an increase again of wafz after an initial decrease 

Well he is working off the cfs for five weeks time so .........

[bluearmy]

30 minutes ago, ArHu3 said:

@fromey

 

Maybe he is working with old data or he has the very latest but since this morning both EC and gfs are seeing an increase again of wafz after an initial decrease 

But gefs is definitely returning the vortex to the pole in week 2 (consistently ) and ecm op looks to be headed In roughly a similar direction until we see what wave activity may do towards the end of week 2.

[jules216]

Can I ask Stratospheric experts why is tropospheric Aleutian Low and SIberian High  combination good for cold weather going forward for us, what favorable mechanisms are in play then, is it because it causes EAMT events caused by Rossby waves that penetrate towards Stratosphere or something else? 

Also is Aleutian anticyclone good for pertubering stratosheric polar vortex through generating gravity waves?

I am a bit confused as to what is the ideal pattern for us and Europe re.cold weather prospect in relation to area around Aleutians within both Stratosphere and Troposfere.

Would appreciate a reasonably simplistic explanation if there is such a thing re. these complicated teleconections.lol.

Thanks

[bluearmy]

browsing the runs as they come out each 6 hours, it seems there is a drift to take the vortex back towards the Asian side as week two progresses. not quite as displaced as it has been. whilst the wave 1 is waning in the mid strat, it seems to be coming back quite strongly higher up according to past couple berlin runs. question is how much will the strong zonal flow downwell in the meantime

[Blessed Weather]

So we appear to have an interesting variance in forecasts for January. GloSea output a week or so back switched to saying no to a SSW in Jan, but now we have the latest CFS output saying yes.

Today's Weatheriscool chart shows the CFS (pink and green plots) forecasting negative Zonal Mean u-wind at 10hPa 60N, meaning a reversal:

And today's GEFS output right at the end of the forecast period (6th - 7th Jan) is not without interest, showing Wave 1 activity returning. All out in the unreliable at the mo, but something to watch.

Charts from http://weatheriscool.com/

 

[bluearmy]

The predicted rate of increase in the zonal winds around 60N high up are as rapid as I have ever seen. certainly between 1 and 10hpa. the core of the zonal flow will certainly be 50/60N rather than the 40/50N that we have seen thus far.  just as rapid decelerations leave a legacy of wave breaking down from the strat into the trop over a period of months, does the same apply to rapid accelerations in what has been a generally benign environment thus far?  I always feel that big changes in quick time such as we are about to see must have ramifications - that doesn't discount an SSW btw. what goes up etc etc 

[bluearmy]

Just a note that latest Berlin chart day 10 hints at the core of the vortex heading back towards 50N. That would be better although the residual surge of flow down through the strat is still to manifest itself on the trop output end week 2 and into week 3. 

[Singularity]

High amplitude warming at 10hPa on the morning GFS runs and starting up near day 10... strongest indication of SSW potential I’ve seen so far this season and ties in with the CFSv2 trend.

Potential perhaps for Jan 2018 to be a month of two halves...?

[northwestsnow]

2 hours ago, Singularity said:

High amplitude warming at 10hPa on the morning GFS runs and starting up near day 10... strongest indication of SSW potential I’ve seen so far this season and ties in with the CFSv2 trend.

Potential perhaps for Jan 2018 to be a month of two halves...?

GFs going for a displacement towards the end of the run on 6z- (10 hPa)

Not suggesting a split but surely if this verified we would see core vortex moving towards Scandy ?

[Singularity]

9 minutes ago, northwestsnow said:

GFs going for a displacement towards the end of the run on 6z- (10 hPa)

Not suggesting a split but surely if this verified we would see core vortex moving towards Scandy ?

Depends on the extent of strat-trop coupling but it could see us trending back toward the late Nov to early Dec setups... but only if the MJO also plays ball. Both that and the warming in the first place are too far out to depend upon at this stage. All we can really do for now is wait and hope.

[bluearmy]

Gfs strat is stretching the vortex late on and gefs shows a lobe at both ends 

[Paul_1978]

6 hours ago, northwestsnow said:

GFs going for a displacement towards the end of the run on 6z- (10 hPa)

Not suggesting a split but surely if this verified we would see core vortex moving towards Scandy ?

T+384 charts never verify. Ain’t gonna happen! When we start seeing these within T+200 then there will be much more interest.

[feb1991blizzard]

5 hours ago, bluearmy said:

Gfs strat is stretching the vortex late on and gefs shows a lobe at both ends 

Even more so on the 18z.

[Allseasons-Si]

1 hour ago, feb1991blizzard said:

Even more so on the 18z.

Looks like it has been put on the Asian ropes(forcasted)with maybe a wave two,but i would like to see more oranges and reds circa -20 to 0 instead of -24,lets see where we go from there

[feb1991blizzard]

4 hours ago, Allseasons-si said:

Looks like it has been put on the Asian ropes(forcasted)with maybe a wave two,but i would like to see more oranges and reds circa -20 to 0 instead of -24,lets see where we go from there

Check the 10mb chart here

http://www.instantweathermaps.com/GFS-php/showmap-strat.php?run=2017122418&var=HGT&lev=10mb&hour=384

Although 0z not as good.