Stratosphere Thread

[HM]

As you all know, the stratosphere can play a huge role in the state of the Arctic Oscillation. So far, the PV has been stronger than normal with u-anomaly winds being exceptionally positive and the temperatures being colder than normal. Potential disturbances to the PV can originate from many sources, but today we'll key in on East-Asia.

A notorious place for genesis of these warming events is the Himalayas. Notice that these warm anomalies start in eastern portions of Asia, build northward into the N PAC and ultimately N. America/Atlantic.

As you can see by the following graph, these warming events seem to initiate right around the time of an East-Asian mountain torque (MT) response.

With the higher than normal pressures across the North Pacific, from the recent frictional dissipation I discussed in the last update, vector anomalies are mainly negative when interacting with Asia (below normal pressures across Siberia). Also, North America, during the +EA_MT, was negative because of the below normal SLP across the eastern two thirds of the CONUS. In typical fashion, the N. America sign will reverse, following this response, as higher than normal pressures build southward. Anyway, because the Earth spins the other way, these -u anomalies at the surface can become sources for +AAM.

Model projections now show the lower stratospheric disturbance from East Asia disturbing the PV in 5 - 10 days...first as a stretching of the potential vorticity fields and then finally a split, depending upon which layer. While I don't expect a full-fledged PV breakdown, it will be interesting to see how this interacts with the tropospheric -NAO pattern already in place.

Time sensitive--> ECMWF PV anomalies out through 240h. Watch how the higher PV anomalies split: http://wekuw.met.fu-...ast=all&lng=eng

[Yes_Probably_Maybe_No]

Thanks for the update.

Is the GFS also on board? Based on that image of the ECM it looks like the statospheric pattern will remain unfavorable in the E Pac. I guess it's a wait and see as to whether or not we get this split (if not, displacement is acceptable) and where the "pieces" set-up.

[HM]

Thanks for the update.

Is the GFS also on board? Based on that image of the ECM it looks like the statospheric pattern will remain unfavorable in the E Pac. I guess it's a wait and see as to whether or not we get this split (if not, displacement is acceptable) and where the "pieces" set-up.

The GFS is on board as well. This polar vortex split is related to a couple of things:

1. The -NAO/EPO in the troposphere putting the squeeze play on the vortex from both sides in the lowest layers of the stratosphere

2. The 50-10mb warming that will be squeezed into the northern latitudes from the recent Asian response.

I picked the 600K potential temperature layer figuring it was high enough to show the impact these tropospheric disturbances will have. I am not sure if the vortex will completely fall apart but my gut says that it doesn't. I think it will get polarized, split temporarily and then potentially reconfigure down the road.

I thought this was noteworthy, however, given the +QBO/healthy La Niña in place that has been helping the PV stay strong.

Anyone notice, too, that the solar factor has really picked up lately? I know I keep repeating myself but there are some folks here who believe we are still in some extended minimum. While I agree the solar flux / parameters are pathetically low still for where we are in the cycle (I mean hell, we are still trying to keep up with the Dalton Min!!), the solar wind recently spiked to 800 km/s and the sunspot groups continue to become more complex/numerous.

[usedtobe]

Intersting post, I almost missed looking at it because my senses get overwhelmed by the new skin. lol

[HM]

Intersting post, I almost missed looking at it because my senses get overwhelmed by the new skin. lol

I was wondering where your post was. After the initial shock of the skin, adjustment has begun on my eyes. Although, a white background is dangerous, no matter what, if you are trying to avoid blinding posters. Anyway, new ECMWF basically splits the vortex into 2 at 144h now but then congeals them back together, almost completely, by day 10. Just goes to show how powerful the force is going to have to be this year to disturb the vortex. Your simple mountain torque+tropospheric upwelling, even under ideal blocking from both the EPO and NAO, doesn't seem like it will be enough to offset the other factors. I will say though, it is early. And as research shows, +QBO years take longer to disturb. Perhaps several more of these will tire the old vortex out sometime later in the winter.

[Srain]

Great thread, guys. Should be pinned, IMO. Hopefully donsoutherland1 will opine in the days ahead as well.

[Yes_Probably_Maybe_No]

I was wondering where your post was. After the initial shock of the skin, adjustment has begun on my eyes. Although, a white background is dangerous, no matter what, if you are trying to avoid blinding posters. Anyway, new ECMWF basically splits the vortex into 2 at 144h now but then congeals them back together, almost completely, by day 10. Just goes to show how powerful the force is going to have to be this year to disturb the vortex. Your simple mountain torque+tropospheric upwelling, even under ideal blocking from both the EPO and NAO, doesn't seem like it will be enough to offset the other factors. I will say though, it is early. And as research shows, +QBO years take longer to disturb. Perhaps several more of these will tire the old vortex out sometime later in the winter.

And just like that, it appears EA will try to give it another go with increased warmth, albeit this time the MT has transitioned from positive to neutral, so delayed propagation/upwelling?

[Yes_Probably_Maybe_No]

Interesting placement by the Euro of the increased potential vorticity.

MT torque in Asia is remaining near neutral, so much of the building warmth at 10 hPa is not being transported toward the poles and is just dying out, unless we see another rapid spike....which we probably won't given the position of the vortex.

GFS Day 10

Still seeing that very fast flow across the U.S and your generic weakening -NAO signal.

ECM Day 10

The -NAO signal is there, albeit much weaker than its current state, but more west based than the GFS. The position of the PV actually isn't half bad, with Europe under its direct influence and NE Canada/W Greenland having room for increased heights. However, if you were to take a look at the PV chart up above, you would think that there's probably little to no chance of any -NAO formation from D10 onward.

On that note...the second half of December doesn't look so good

I'm not the most knowledgable of persons, but it looks like to me that any -NAO formation will have to occur from the troposphere and force its way up once we hit the wall mid-December.

[Ed Lizard]

For the amateurs, ie, me, we care about stratospheric warm anamolies near the Pole because they sometimes precede building cold over the polar region that can eventually be displaced towards the US and my house?

Edit to add, decent description from Wiki, and this page http://www.appmath.columbia.edu/ssws/ but nothing on Google about sensible weather in the Lower 48 and stratospheric warming.

[Ed Lizard]

Speaking of sensible weather related to stratospheric warming, JB's afternoon update yesterday referenced the QBO and stratospheric warming, and has over half the nation snow covered by Christmas. Not sure if that includes Alaska, as Alaska alone would skew that significantly.

BTW, it would seem JB either reads American or he and HM think more alike than HM would probably want...

[Yes_Probably_Maybe_No]

Speaking of sensible weather related to stratospheric warming, JB's afternoon update yesterday referenced the QBO and stratospheric warming, and has over half the nation snow covered by Christmas. Not sure if that includes Alaska, as Alaska alone would skew that significantly.

BTW, it would seem JB either reads American or he and HM think more alike than HM would probably want...

If by half the nation he means from Cali ENE right through Michigan then he could very well be right.

The only warming of significance that I see is near Alaska. Could that somehow translate to a -EPO way down the road? Perhaps, but I would think we would need to see some more sustained warming. The NAO in itself has little chance of sustaining itself past mid-December (at least the way I see it).