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December 2019 Discussion


Torch Tiger
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18 minutes ago, Damage In Tolland said:

Didn’t Ray say the threat on the 15-16th was real? Still on?

Yea, threat is there, but doesn't have to work out...not looking like the SSW is going to succeed, which is why NAO pulse is absent. It can still work out, but confidence sinks a bit.

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6 minutes ago, 40/70 Benchmark said:

Yea, threat is there, but doesn't have to work out...not looking like the SSW is going to succeed, which is why NAO pulse is absent. It can still work out, but confidence sinks a bit.

Are you suggesting immediate effects of the SSW? It looks to me like the vortex at 50mb starts to get punched around a bit at the end of the EPS, so more than likely maybe January something happens. I don't understand why twitter mets will all abuzz of a SSW in December. At least to me, I didn't see evidence of it. The latest talk from fraud Judah was how he is using the polar vortex (not even the tropospheric version) on the GFS to help determine cold shots. I don't understand how that is a good metric for this. There is no immediate response, because you cannot permeate what is virtually a physical boundary between the stratosphere and troposphere. 

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24 minutes ago, CoastalWx said:

Are you suggesting immediate effects of the SSW? It looks to me like the vortex at 50mb starts to get punched around a bit at the end of the EPS, so more than likely maybe January something happens. I don't understand why twitter mets will all abuzz of a SSW in December. At least to me, I didn't see evidence of it. The latest talk from fraud Judah was how he is using the polar vortex (not even the tropospheric version) on the GFS to help determine cold shots. I don't understand how that is a good metric for this. There is no immediate response, because you cannot permeate what is virtually a physical boundary between the stratosphere and troposphere. 

You are right, there is no immediate response with respect to the coupling of the stratosphere and troposphere, which takes a good 3 weeks to a month for propagation and such. However as referenced in my blog, there is a tendency for a successful SSW to excite the MJO response, which I was tentatively progged at extended leads to be in phase 7 or 8 come mid December. Last season, the MJO was entering a la nina like phase at the time of the SSW, which accentuated deconstructive interference of an el Nino that had already been struggling to couple with the atmosphere. This also created an environment even more hostile to blocking during the subsequent recovery of the PV.

Anyway, I will not be suprised to see it fail because I only expected minor attacks on the PV early this season, from which it will be able to recover. However some guidance suggested that a SSW would indeed take place a week or two back.

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13 minutes ago, 40/70 Benchmark said:

You are right, there is no immediate response with respect to the coupling of the stratosphere and troposphere, which takes a good 3 weeks to a month for propagation and such. However as referenced in my blog, there is a tendency for a successful SSW to excite the MJO reaponse, which I was tentatively progged at extended leads to be in phase 7 or 8 come mid December. Last season, the MJO was entering a la nina like phase at the time of the SSW, which accentuated deconstructive interference of a an el Nino that had already been struggling to couple with the atmosphere.

Anyway, I will not be suprised to see it fail because I didn't expect I only expected minor attacks on the PV early this season, from which it will be able to recover. However some guidance suggested that a SSW would indeed take place a week or two back.

Ahh ok. I see what you mean. 

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29 minutes ago, 40/70 Benchmark said:

You are right, there is no immediate response with respect to the coupling of the stratosphere and troposphere, which takes a good 3 weeks to a month for propagation and such. However as referenced in my blog, there is a tendency for a successful SSW to excite the MJO response, which I was tentatively progged at extended leads to be in phase 7 or 8 come mid December. Last season, the MJO was entering a la nina like phase at the time of the SSW, which accentuated deconstructive interference of an el Nino that had already been struggling to couple with the atmosphere. This also created an environment even more hostile to blocking during the subsequent recovery of the PV.

Anyway, I will not be suprised to see it fail because I only expected minor attacks on the PV early this season, from which it will be able to recover. However some guidance suggested that a SSW would indeed take place a week or two back.

Don't mean to bombard, but you are correct. There is actually a paper out that shows evidence that when you get a rather robust phase 3 mjo that propagates around, like we had last year that it does lead to a SSW if the conditions are favorable. With how weak the PV got in late nov I wonder if we had a more robust mjo signal through phase 3  would it of initiated anything. Though, we really didn't get a strong wave 2 hit on the pv after the wave 1 displacement which is needed usually. 

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2012GL053144

 

mjossw.png.b2d81e08f982f378a23967f353eeb3fa.png

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2 minutes ago, tombo82685 said:

Don't mean to bombard, but you are correct. There is actually a paper out that shows evidence that when you get a rather robust phase 3 mjo that propagates around, like we had last year that it does lead to a SSW if the conditions are favorable. With how weak the PV got in late nov I wonder if we had a more robust mjo signal through phase 3  would it of initiated anything. Though, we really didn't get a strong wave 2 hit on the pv after the wave 1 displacement which is needed usually. 

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2012GL053144

 

mjossw.png.b2d81e08f982f378a23967f353eeb3fa.png

Chicken or egg, I guess...as my understanding was that the SSW amplified the MJO, not that the amplified MJO induced the SSW...but like I said, frontier concept and I'm all ears...

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3 minutes ago, 40/70 Benchmark said:

Scott, there was support for a SSW....moreso probably from GFS. But again, no issue with it ultimately not succeeding...

There probably will be one, I just did not see it this early. In any case, whatever happens this week, it looks fairly active after the 15th too.

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7 minutes ago, CoastalWx said:

There probably will be one, I just did not see it this early. In any case, whatever happens this week, it looks fairly active after the 15th too.

My position in the outlook was that there would be only minor disruptions in Dec, and the pv would be resilient....a SSW in January would fit with my theme of second half blocking. However if the SSW had succeeded in mid Dec, I feel we would have had a big NAO dip, transient as it may be...

December going as planned with an active, variable pattern and any NAO transient. Should be PAC driven. Second half NAO driven with less Pacifc.

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