And we begin.....

[Mitchel Volk]

It will take many more years of data to see how well the correlation works out. At this time I bet that the r2 is rather low. Overall it is an interesting theory.

[Mallow]

The anomalously low wave 1 amplitude in Oct suggests that tropospheric forcing on the stratosphere may be difficult to come by.  I don't think it should be looked at as a make or break year, though it is getting pretty clear that it isn't the big dog that perhaps we once thought it to be.

 

I was under the impression that the theory stated that wave number 1 wave activity into the stratosphere is supposed to be enhanced in November, not October.

 

EDIT: Yep. It's all about the anomalous wave 1 activity in November, not October. See 2009 vs. 1997 or 2006.

http://www.cpc.ncep.noaa.gov/products/stratosphere/strat-trop/

 

EDIT 2: It does look like there's a lot of noise, though, looking at other years.

[radarman]

I was under the impression that the theory stated that wave number 1 wave activity into the stratosphere is supposed to be enhanced in November, not October.

 

EDIT: Yep. It's all about the anomalous wave 1 activity in November, not October. See 2009 vs. 1997 or 2006.

http://www.cpc.ncep.noaa.gov/products/stratosphere/strat-trop/

 

EDIT 2: It does look like there's a lot of noise, though, looking at other years.

 

That link is my source too... There is an enhancement in November, but most years feature much more activity in late October as well. 

 

I don't believe it is a coincidence that 97 also featured low wave 1 amplitudes.  El Nino works to negate mountain torque... the southern hemisphere produces lower mean wave 1 amplitudes due (at least in part) to the lack of topography.   Wave 1 amplitudes are not a driver, more like a canary...  But it is thought that low amplitudes do mean less troposphere/stratosphere coupling.

[40/70 Benchmark]

I know the mathematics of it argue that we are a long way away from knowing how valuable it is, but you also have to drop the calculator, step away from the chalk board and acknowledge the fact that if this indicator fails miserably for a second consecutive year, then it will be paid much less mind next season.

Rightfully so.

If you want to wait 75 years to have a sufficiently large enough sample from which to draw your conclusions, cool...but in the mean time we have 74 outlooks to compose.

[griteater]

From Cohen...

 

"...So far this October, Siberian snow cover has advanced more rapidly than normal though not as fast as the two most recent Octobers. October Eurasian snow cover extent was above normal but within one standard deviation.  Another index that we compute the snow advance index was more strongly above normal, over one standard deviation."

 

...Also recently the snow cover across Eurasia has advanced more to the south across East Asia.  This has resulted in an even higher value for the snow advance index (SAI) value for October, since only snow cover equatorward of 60°N contributes to SAI values. Above normal Eurasian snow cover extent for the month of October favors a negative winter AO.  Also above normal snow cover favors more active energy transfer from the troposphere to the stratosphere in the six weeks from mid-November until the end of December, which often results in a weakening of the polar vortex in January.  Though if the current pattern persists, it will remain mostly hostile for the energy transfer to occur."

 

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

[Mallow]

From Cohen...

 

"...So far this October, Siberian snow cover has advanced more rapidly than normal though not as fast as the two most recent Octobers. October Eurasian snow cover extent was above normal but within one standard deviation.  Another index that we compute the snow advance index was more strongly above normal, over one standard deviation."

 

...Also recently the snow cover across Eurasia has advanced more to the south across East Asia.  This has resulted in an even higher value for the snow advance index (SAI) value for October, since only snow cover equatorward of 60°N contributes to SAI values. Above normal Eurasian snow cover extent for the month of October favors a negative winter AO.  Also above normal snow cover favors more active energy transfer from the troposphere to the stratosphere in the six weeks from mid-November until the end of December, which often results in a weakening of the polar vortex in January.  Though if the current pattern persists, it will remain mostly hostile for the energy transfer to occur."

 

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

 

Ya, that's what I thought.

[radarman]

Whereas the snow cover mechanism promotes the Siberian high, which in turn can intensify EP flux, the overall susceptibility of the stratosphere to tropospheric disturbances may be a function of the MT and AAM anomalies. FWIW I agree that the snowcover forced EP flux as well as wave 2 and wave 3 anomalies are not important until late November at the earliest... usually well into Dec in fact... but the weak wave 1 amplitude anomalies early on may indicate that non tropospheric sources will chiefly determine the state of the wintertime vortex...

[Amped]

Whereas the snow cover mechanism promotes the Siberian high, which in turn can intensify EP flux, the overall susceptibility of the stratosphere to tropospheric disturbances may be a function of the MT and AAM anomalies. FWIW I agree that the snowcover forced EP flux as well as wave 2 and wave 3 anomalies are not important until late November at the earliest... usually well into Dec in fact... but the weak wave 1 amplitude anomalies early on may indicate that non tropospheric sources will chiefly determine the state of the wintertime vortex...

HM said on twitter the stratosphere and QBO  don't favor blocking so far.

[40/70 Benchmark]

HM said on twitter the stratosphere and QBO  don't favor blocking so far.

Which confirms for the 537,482nd time that December will feature a +AO.

Keep us updated.

[radarman]

HM said on twitter the stratosphere and QBO don't favor blocking so far.

Yeah... stratosphere is cold, and QBO is positive. The latter will stay positive too... in every previous case that it flipped in the warm season the DJF average was significantly positive. Somewhat unclear just how much influence this has but the scatterplot does suggest that negative QBO is better for SSWs. This could be a contributing factor to what I believe may be a relative non-susceptibility of the stratosphere to tropospheric forcing this year.

[Isotherm]

Whereas the snow cover mechanism promotes the Siberian high, which in turn can intensify EP flux, the overall susceptibility of the stratosphere to tropospheric disturbances may be a function of the MT and AAM anomalies. FWIW I agree that the snowcover forced EP flux as well as wave 2 and wave 3 anomalies are not important until late November at the earliest... usually well into Dec in fact... but the weak wave 1 amplitude anomalies early on may indicate that non tropospheric sources will chiefly determine the state of the wintertime vortex...

 

 

Do you have an updated AAM data website? The PSD one that I utilized is dead:

 

http://www.esrl.noaa.gov/psd/map/clim/aam.90day.seascyc.shtml

[radarman]

Do you have an updated AAM data website? The PSD one that I utilized is dead:

 

http://www.esrl.noaa.gov/psd/map/clim/aam.90day.seascyc.shtml

 

 

http://www.gfz-potsdam.de/en/section/earthsystemmodelling/services/eam/

[radarman]

That link above is good for raw data. 

 

For better maps to make use of, WDT has decided to take over for ESRL producing this stuff and is offering free access.  Very helpful and appreciated.

 

http://wdtinc.com/product-service/futures/

[radarman]

So AAM is currently significantly positive, as one would expect with an El Nino of this strength... however the singular global number (the zonal averages of all levels of the atmosphere) is being driven by the QBO. The tropospheric contribution is only weakly positive and fading. Relative AAM tendency is negative, which corresponds to an enhanced STJ and systems in the southwest US.... exactly what we are seeing. Negative frictional torque is the apparent cause of the declining aam down low.

Meanwhile, in a bit of a surprise, global mountain torque has averaged above normal through Oct This was driven mostly by mountains in the Americas, and the tropics. Asian MT had been slightly BN, but recently has spiked even as the others have fallen. This may be consistent with ridging beginning to form on the west side of the Himalayas in Eurasia, boosted by the +snowcover anomalies. Hopefully we see wave 1 activity start to respond.

FWIW it would not surprise me to see the relative AAM tendency begin to rise in response to possibly rising MT, which may result in a pattern change to a pineapple express or something similar... Cali getting some snow now and could use a lot more, mudslides or not.

[mitchnick]

Radarman, you sure sound like HM. He's the only one I ever read talking about MT with authority before you.

[radarman]

Radarman, you sure sound like HM. He's the only one I ever read talking about MT with authority before you.

 

Take this as a compliment.  I have always appreciated his analysis.

[billgwx]

Eurasia Week 44 Snow Cover Extent per Rutgers is 19.08 million sq km...second in the last 48 years only to 1976. Last year 17.75 msk. Lack of SAI (Snow Advance Index) data (for the rate of growth south of 60N in weeks 40-44) is driving me nuts. Ideas anyone?

 

As for QBO: my understanding over the past few years has been that the trend is more important than its actual value, as far as high latitude blocking a la -NAO is concerned? Neither its October value or trend (13.38 and rising) are promising at all for wintertime -NAO, and fly in the face of other correlating factors (North Pacific October mean MSLP which argues for -NAO). Not sure what that will mean for late winter though, especially if El Nino weakens as forecast.

[ORH_wxman]

Eurasia Week 44 Snow Cover Extent per Rutgers is 19.08 million sq km...second in the last 48 years only to 1976. Last year 17.75 msk. Lack of SAI (Snow Advance Index) data (for the rate of growth south of 60N in weeks 40-44) is driving me nuts. Ideas anyone?

 

As for QBO: my understanding over the past few years has been that the trend is more important than its actual value, as far as high latitude blocking a la -NAO is concerned? Neither its October value or trend (13.38 and rising) are promising at all for wintertime -NAO, and fly in the face of other correlating factors (North Pacific October mean SST which argues for -NAO). Not sure what that will mean for late winter though, especially if El Nino weakens as forecast.

 

 

We don't have the exact number, but Cohen did mention that is was over 1 SD above normal in his latest update which was yesterday.

 

 

So far this October, Siberian snow cover has advanced more rapidly than normal though not as fast as the two most recent Octobers. October Eurasian snow cover extent was above normal but within one standard deviation.  Another index that we compute the snow advance index was more strongly above normal, over one standard deviation.

 

 

 

 

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

[Isotherm]

That link above is good for raw data. 

 

For better maps to make use of, WDT has decided to take over for ESRL producing this stuff and is offering free access.  Very helpful and appreciated.

 

http://wdtinc.com/product-service/futures/

 

 

http://www.gfz-potsdam.de/en/section/earthsystemmodelling/services/eam/

 

 

Thanks radarman!

[Absolute Humidity]

I'd say this is pretty spectacular considering all the hoopla over last year's values.

[Absolute Humidity]

Although one of these is off by 4ml sq km

[DaculaWeather]

[nzucker]

Looks better in eastern Russia and Kazakhstan than last year. Canada shaping up too, but particularly noticeable in the SE Siberian Plateau.

[Huffwx]

eurasian snow cover.jpg

 

 

Doesn't really seem to be a connection to colder/snowier winters when you look in the mid atlantic or maybe closer to my area. Two of our better winters 8182 and 7980 are in the bottom few. 

[40/70 Benchmark]

Doesn't really seem to be a connection to colder/snowier winters when you look in the mid atlantic or maybe closer to my area. Two of our better winters 8182 and 7980 are in the bottom few.

I think your correlation would be lower because all you need is one good storm on a lousy SAI year to skew things.