Stratosphere temperature watch - 2016/17

[blizzard81]

6 minutes ago, KyleHenry said:

Big tease. We can see why it is running with the split around the 7th November.

GFS is reading the current east based Rossby formation, followed by another large sigma event in sector 3,4 or 5 of the MJO and equating that with a PV split at the 10 hPa level. 

Possible but far too early.

One definite, is that this current Tropospheric  amplification phase will show a repeat cycle again within 21 days. 

Model thread to be sent barmy, with switches from extreme cold to mild and vice versa every 36 hours. 

 

 

Ha ha, well, we should be used to all that torture by now! 

[Interitus]

The split appeared largely a response to the handling of the current tropical storm 27w on the GFS 17/10/22 18z and especially the 17/10/22 12z, which after passing Japan as a typhoon, transitions into a powerful extratropical storm and helps to throw up a large arctic ridge splitting the tropospheric polar vortex -

 

[sebastiaan1973]

https://www.atmos-chem-phys.net/16/15529/2016/acp-16-15529-2016.pdf

""Based on the analysis of 108 years of QBO and climate
variables from reconstructions as well as 4×405 years of data
from climate model simulations, we came to the following
conclusions:
1. There is no evidence that the extended QBO reconstruc-
tion is out of phase with the true QBO, but further sup-
port for the reconstructions is clearly required.
2. The relation between the QBO and climate variables is
rather weak on average, but it is characterized by large
multidecadal fluctuations.
3. In boreal winter, there are links between the QBO and
the stratospheric polar vortex or between the QBO and
Berlin SAT, but the former relation is typically strong
when the latter is weak and vice versa (both in model
and observations). This suggests a climatic origin of the
decadal modulation (such as decadal latitudinal shifts
of circulation). The relation to a more broadly defined
Eurasian SAT index is more stable.
4. There is a weak but significant effect of the QBO on
deep convection over the Pacific warm pool, mainly in
boreal winter (an eastward shift of convection during
easterly QBO in the lowermost stratosphere). Though
significant, this change does not project strongly onto
the Pacific Walker Circulation or ENSO.
5. Our results are consistent with historical literature and
also with the sequence of discoveries of (quasi-)biennial
imprints in weather and climate, as expected for analy-
ses of small effects embedded within strong variability.""

[bluearmy]

Just saw some weatherbell content on a university of Arizona study into correlation between low solar/ weak nina/e QBO and MJO amplitude. seems there is one. should lead to more wave breaking with ssw potential. going to be an interesting season upcoming for sure - I wonder what variable will crush the hopes of the coldies this winter?  most likely our location! 

Incidentally, the upmcoming aleutian ridging is going to drive some wave 2 activity through the strat. Nothing of any notable amplitude but returning numbers higher than we saw last autumn when nearly all activity was wave 1 and that resulting displacement was easily overcome by the strengthening vortex once it eventually got going.  I'm beginning to get interested .............

Edited October 28, 2017 by bluearmy

[sebastiaan1973]

I suspect you mean this study https://ams.confex.com/ams/21Fluid19Middle/webprogram/Paper319446.html

[sebastiaan1973]

http://onlinelibrary.wiley.com/doi/10.1029/2007GL031354/full

Abstract

[1] The quasi-biennial oscillation (QBO) is important for understanding the dynamical and chemical variability of the global stratosphere. Currently available wind data from the equatorial stratosphere extend back to 1953. Here we present reconstructions of the QBO extending back to 1900 that can be used to constrain climate model simulations. The reconstructions are based on historical pilot balloon data as well as hourly sea-level pressure (SLP) data from Jakarta, Indonesia. The latter were used to extract the signal of the solar semi-diurnal tide in the middle atmosphere, which is modulated by the QBO. The reconstructions are in good agreement with the QBO signal extracted from historical total ozone data extending back to 1924. Further analyses suggest that the maximum phases of the QBO are captured relatively well after about 1910.

 

 

[bluearmy]

The 12z ec op stretches the upper vortex sufficiently to establish two centres at 10 and 30 hpa with a split almost evident at 50hpa. will be interesting to see the magnitude of the wave 2 on the Berlin charts derived from this run tomorrow morning. 

[Singularity]

Feeling more 'classic' this season with a near-average strength vortex that should resist warming events sufficiently for troposphere-stratosphere transfer to potentially (with enough supply) continue until the warming is large enough to have a more significant impact on the vortex, which is preferable to a dishevelled mess of a vortex that just gets displaced by even minor warming (the situation last Oct-Nov), messing up the troposphere-stratosphere transfer mechanisms, and can happily wait for support from the upper stratosphere to kick off big time (last Dec).

Overall this should translate to less of immediate/short-term interest but more during the winter itself. Whether sufficient warming will actually manifest, remains to be seen.

[Dennis]

some interessting could be in November (second part)

[booferking]

1 minute ago, Dennis said:

some interessting could be in November (second part)

Is that a spilt vortex we see??

[Dennis]

3 minutes ago, booferking said:

Is that a spilt vortex we see??

Its maybe a first start at higher lvl's .... it could go down to 30/10Hpa later

Edited October 30, 2017 by Dennis

[Interitus]

3 hours ago, Dennis said:

Its maybe a first start at higher lvl's .... it could go down to 30/10Hpa later

It starts at the lower levels from the troposphere and doesn't reach the levels above 10Hpa. There is no significant warming and the vortex quickly reorganises, it's a nothing really.

[sebastiaan1973]

http://www.aer.com/science-research/climate-weather/arctic-oscillation

Eurasian snow cover extent will finish above normal for the month of October.  It started the month with well above normal snow cover extent (SCE) but then had a fairly unusual stall where the snow cover extent nearly didn’t advance for two whole weeks. This was an unprecedented event in recent Octobers.  However, in the third week of October the snow cover extent picked up once again and October 2017 SCE will easily be above normal and given how the month began was never really in doubt.

Besides SCE an alternative snow index that I have proposed and utilize in subseasonal to seasonal forecasts is the snow advance index (SAI).  The SAI does not measure the areal extent of snow cover but rather the rate at which the snow cover advances over the course of the month and the area measured is limited to equatorward or south of 60°N.  A relatively rapid advance of snow cover would be comparable to extensive snow cover and an indication for a weak polar vortex (PV), a negative AO first in the stratosphere followed by a negative AO in the troposphere and relatively cold weather across the Northern Hemisphere (NH) mid-latitudes.  Given the long stall in snow cover advance in mid-October, the SAI will likely be negative this October.  This is a forecast of a strong PV, a positive AO in both the stratosphere and troposphere and a relatively mild winter across the NH. 

The SAI index is in contrast to the SCE index that indicates just the opposite.  This is a similar situation to 2013 when the SCE was strongly positive and the SAI was negative.  This adds complexity and decreases my confidence in the winter forecast.  I have come to believe that the SAI is most useful as an indicator of the timing of when we might expect a weakening the stratospheric PV.  When the SAI is positive then we can expect a stratospheric PV weakening earlier in the season and when the SAI is negative then we can expect any weakening of the stratospheric PV to take place later in the season.  In 2009 and 2016 when the highest SAI values have been observed since daily snow cover extent has been available, stratospheric PV weakenings were observed even before the winter began with an unprecedently early PV split observed at the end of October and early November last year.  There are so far no signs of a robust stratospheric PV weakening and indications are even for a relatively strong stratospheric PV for much of the month of November.  Similarly in fall and early winter 2013/14 the stratospheric PV was strong but eventually troposphere-stratosphere coupling became active that did not result in a strong PV weakening (no major mid-winter warmings were observed that winter) but did stretch or repeatedly elongated the stratospheric PV that contributed to a cold winter in the Eastern US.

The relatively quiet WAFz, the strengthening stratospheric PV and the positive stratospheric AO suggest that in the coming weeks the circulation pattern in the stratosphere could couple to the troposphere leading to a period of a positive tropospheric AO, mostly zonal flow and relatively mild conditions across the NH mid-latitude continents.  I consider this the most likely stratospheric-tropospheric coupling in the next 30-days.  The PCH plot does suggest the tropospheric PCHs will warm in mid-November, signaling a turn to colder weather across the continents most likely across Eurasia.  This could also set up more active poleward heat flux and a weakening of the stratospheric PV.  I am skeptical of the timing of this scenario as suggested by the GFS PCH forecast, however I do expect this set of events to occur if not in November then in December.

[knocker]

 

[Dennis]

16 hours ago, Interitus said:

It starts at the lower levels from the troposphere and doesn't reach the levels above 10Hpa. There is no significant warming and the vortex quickly reorganises, it's a nothing really.

True not ssw but some to watch

[sebastiaan1973]

An interesting read http://ionlyusethegfs.blogspot.nl/2012/04/qbo-aleutian-high-relationship.html?m=1

[knocker]

 

[DAVID SNOW]

15 minutes ago, knocker said:

 

Thanks Amy, we don't tend to rely on the GFS here in the UK, because as you inferred , it really is , and always  has been "All over the map"

Knocker seems to like your posts/tweets or whatever they are though, so that's nice.

[northwestsnow]

1 hour ago, DAVID SNOW said:

Thanks Amy, we don't tend to rely on the GFS here in the UK, because as you inferred , it really is , and always  has been "All over the map"

Knocker seems to like your posts/tweets or whatever they are though, so that's nice.

Dont like the look of that graph!! Suggests a very strong vortex come December.

[joggs]

The above graph front Amy.It always seems to super dupere(rhymes with hight) on us in winter lol.

Roll on a crap summer 

After 12 weeks of abysmal toss through Dec and Jan.

[bluearmy]

As we entry November, tomorrow will see the first issue of the graphical representation of the strat data on the Berlin website. 

Are we going to have a new strat thread for this season or continue this one ?

[Bullseye]

Maybe something that ties in with this forum, forecast for upcoming winter based covering all things winter including stratosphere warmings and how this interacts with QBO/solar plus analogs to upcoming winter. Thanks.

https://twitter.com/RaleighWx/status/925010393092755458

[chris55]

On 01/11/2017 at 06:49, bluearmy said:

As we entry November, tomorrow will see the first issue of the graphical representation of the strat data on the Berlin website. 

Are we going to have a new strat thread for this season or continue this one ?

New thread for the upcoming winter is a good idea nick   

Edited November 2, 2017 by chris55

[Catacol]

On 01/11/2017 at 18:47, Bullseye said:

Maybe something that ties in with this forum, forecast for upcoming winter based covering all things winter including stratosphere warmings and how this interacts with QBO/solar plus analogs to upcoming winter. Thanks.

https://twitter.com/RaleighWx/status/925010393092755458

Well - that made for a very good read. His top 2 analog years? 62/63 (particularly if the PDO were to trend negative) and 95/96. Very well laid out. I’d take either of those winters in a heartbeat. -AO in the second half of winter with a signal for Greenland blocking. Ideal. Pity his forecast bust last year!!

[sebastiaan1973]

 

https://www.americanwx.com/bb/topic/50432-griteaters-winter-outlook-17-18/

IMO an excellent read. The author says we get an EP La Nina, based on ENSO of this autumn and this research https://link.springer.com/content/pdf/10.1007%2Fs00382-014-2155-z.pdf