Possible Snow Gradient Explanation

[usedtobe]

The -QBO's effect on the Brewer-Dobson Circulation starts in the autumn and it takes roughly 3-6 months for that ozone to make it to the North Pole; but in a year like this one, this isn't going to work out so well. The QBO affects the polar vortex through planetary wave behavior more so than the convection. There is more to how the BDC/NAM/PV behave than what the QBO state dictates and the same can be said about tropical forcing. Yes, the theory is that -QBO increases equatorial convection with a higher than normal tropopause, particularly in the western Pacific. However, this doesn't necessarily mean MJO waves either and this entire process is always augmented by ENSO. Don't forget, the sun also plays a role in tropical convection through changes in incoming radiation and temperature.

But this thread's main point was to discuss how the tropical Pacific may affect the z-circulations which would affect the Aleutian High. These relationships cannot be applied to tropical convection because many things can cause a MJO wave. For example, the late stratospheric warming of intense magnitude this year displaced cooler air into the equatorial regions and caused big time MJO waves to develop (along with warming ENSO). In fact, we have been riding those harmonics ever since in a much weakened state. As of right now, the +QBO is in full control of the lower stratosphere and has generally been keeping tropical forcing weak, in terms of waves, but enhancing areas off the equator for sure. This would likely continue through the autumn season, except that off-equatorial convection would gradually weaken with time. A heavily ENSO-dominated period would likely be in the end-result along with a more expanded than normal Hadley Cell.

Thanks for the reply. Then am I wrong in thinking this year we have a pretty good chance that we have half the winter with a negative ao/nao? I'd certainly feel more confident with low sun, easterly qbo and a nino rather than a nina? I guess I don't really understand the processes that much.

[HM]

Thanks for the reply. Then am I wrong in thinking this year we have a pretty good chance that we have half the winter with a negative ao/nao? I'd certainly feel more confident with low sun, easterly qbo and a nino rather than a nina? I guess I don't really understand the processes that much.

Well, I wasn't trying to say one thing would happen over the other and I do think you have a good understanding. I was just saying that you can't equate -QBO with dateline convection or MJO waves. I think we see blocking this winter for sure and I agree with you that it seems to make sense to be about half of it.

If things can work out correctly, we could benefit from the developing -QBO wave producing a warming while the lingering low level +QBO wave could help bring us a more poleward Aleutian High. Could be quite the cold recipe. However, should the +QBO weaken quickly, then I think this winter will have a very stern Southeast Ridge, despite the stratospheric warming, overall.

[usedtobe]

Well, I wasn't trying to say one thing would happen over the other and I do think you have a good understanding. I was just saying that you can't equate -QBO with dateline convection or MJO waves. I think we see blocking this winter for sure and I agree with you that it seems to make sense to be about half of it.

If things can work out correctly, we could benefit from the developing -QBO wave producing a warming while the lingering low level +QBO wave could help bring us a more poleward Aleutian High. Could be quite the cold recipe. However, should the +QBO weaken quickly, then I think this winter will have a very stern Southeast Ridge, despite the stratospheric warming, overall.

Thanks again for the reply, I'm still basically a short to medium range guy and nowdays, I don't have that much interest until winter.

[Typhoon Tip]

Thanks for the reply. Then am I wrong in thinking this year we have a pretty good chance that we have half the winter with a negative ao/nao? I'd certainly feel more confident with low sun, easterly qbo and a nino rather than a nina? I guess I don't really understand the processes that much.

How do you perceive the multi-decadal NAO sign going negative in all this? -just curious. Whatever the cause, that is the case and it seems to have worked out as we've have -NAO more than 60% of the time since the sign flipped negative.

[Typhoon Tip]

I haven't run anything statistical between the MJO and WPO but I would imagine that the WPO variability is caused by the MJO and not the other way around. Although, like anything in weather, there is always a way something can affect something the other way too. And I do agree that there is a feedback between the mid latitudes and the MJO as well as the poles/stratosphere too. The positive WPO phase is a classic poleward shifted Hadley Cell, typical of a MJO progression from Indonesia through the Tropical Pacific (like phase 4-7).

Interesting... my imagination takes me elsewhere The WPO is one of those pesky cross domain spatial regions; similar to the NAO, they are predisposed to transitory events that may augment them temporarily away from any on-going baser phase state. If there are background physics - large scale - driving a given WPO phase, those may not include the MJO frequency/magnitudes. Since the WPO will oscillate independent of the MJO, it is logical to assume there is only a weak dependency there. The MJO may certainly damp or enhance the WPO's negative or positive phase depending on spatial-temporal events, but that would have to be transitory in nature.

I'm actually more interested in the QBO in all this. Some 10 years ago there was a lot more "intuitive" speculation on that, but now it seems there are more statistical analysis showing various correlations. I still think though that the QBO is just another teleconnector, with perhaps a longer residence for concern then the ones we more typically work with - it seems right that it is better applied to seasonal vs intraseasonal timescales as you and others have alluded.

[usedtobe]

How do you perceive the multi-decadal NAO sign going negative in all this? -just curious. Whatever the cause, that is the case and it seems to have worked out as we've have -NAO more than 60% of the time since the sign flipped negative.

It certainly is part of the equation but even last year the NAO was strongly negative in Dec and Jan but positive in Feb, Mar and April. A negative summer NAO does correlate weakly to a negative nao during winter. Still, I don't expect the NAO will be negative throughout the winter but even if it only is negative for half the winter, it has a good chance of averaging in the negative territory during the dec-March period.

[Typhoon Tip]

It certainly is part of the equation but even last year the NAO was strongly negative in Dec and Jan but positive in Feb, Mar and April. A negative summer NAO does correlate weakly to a negative nao during winter. Still, I don't expect the NAO will be negative throughout the winter but even if it only is negative for half the winter, it has a good chance of averaging in the negative territory during the dec-March period.

This is a hugely good point in this discussion! Take last year... we had a slippage of the AO into negative (whether the NAO was in its shared domain on the same page at any given time, notwithstanding - and the two can at times part company though rare), and up in NE there was 40-60" of snow in just 40 days in repeating coastals with intervening cold. There was 35" on the level and rivaled the mega-pack of 1995-1996 by early February... Point being, all of last winter was really about 40 to 50 days up this way. Interesting how the statistics work out that way.

[Ginx snewx]

It certainly is part of the equation but even last year the NAO was strongly negative in Dec and Jan but positive in Feb, Mar and April. A negative summer NAO does correlate weakly to a negative nao during winter. Still, I don't expect the NAO will be negative throughout the winter but even if it only is negative for half the winter, it has a good chance of averaging in the negative territory during the dec-March period.

The correlation with AO is pretty high especially in the MA though.

[usedtobe]

The correlation with AO is pretty high especially in the MA though.

Yes, but lower than that for the NAO if I remember correctly. even that correlation (R=.3) and it's square (.09) only explains a small part of the variance of the temperatures during winter. Still, it may argue against a torch if the ao does end up being negative. I suspect this winter will have an extended cold period along with a torch or two across the mid atlantic region but that's only a WAG as it's still pretty early to make any forecast.

[Ginx snewx]

Yes, but lower than that for the NAO if I remember correctly. even that correlation (R=.3) and it's square (.09) only explains a small part of the variance of the temperatures during winter. Still, it may argue against a torch if the ao does end up being negative. I suspect this winter will have an extended cold period along with a torch or two across the mid atlantic region but that's only a WAG as it's still pretty early to make any forecast.

I like your suspicions, they usually are dead on. Seems pretty certain we end up with a big thermal gradient which at the very least keeps it from being a boring winter.

[HM]

Interesting... my imagination takes me elsewhere The WPO is one of those pesky cross domain spatial regions; similar to the NAO, they are predisposed to transitory events that may augment them temporarily away from any on-going baser phase state. If there are background physics - large scale - driving a given WPO phase, those may not include the MJO frequency/magnitudes. Since the WPO will oscillate independent of the MJO, it is logical to assume there is only a weak dependency there. The MJO may certainly damp or enhance the WPO's negative or positive phase depending on spatial-temporal events, but that would have to be transitory in nature.

I'm actually more interested in the QBO in all this. Some 10 years ago there was a lot more "intuitive" speculation on that, but now it seems there are more statistical analysis showing various correlations. I still think though that the QBO is just another teleconnector, with perhaps a longer residence for concern then the ones we more typically work with - it seems right that it is better applied to seasonal vs intraseasonal timescales as you and others have alluded.

I feel like the WPO is kind of a joke in the whole teleconnections world and it is like a conglomeration of other forcings/patterns. I think making any connection with it is meaningless and it is better to just skip to the source (whatever that may be)...aka red herring. The WPO seems like a classic -AAM response all-around to tropical forcing

[usedtobe]

I like your suspicions, they usually are dead on. Seems pretty certain we end up with a big thermal gradient which at the very least keeps it from being a boring winter.

I hope that's true as I still want to write stuff for CWG. I don't have much faith in making any long range call this year even though I think we will have a decent period with a negative ao and probably nao but claim no skill at longer range forecasting.

[ptb127]

It's interesting to see how the statistics and indices set up overall as a whole, like all have given in this thread. What's interesting, for a weather weenie like myself(even though when it was happening I was upset about it), was the sharp cutoff for heavy snowfall especially in the interior regions. We definitely had our share of snow (I want to say the seasonal total was somewhere around 60" when the avg here is 50") but it came in a shorter window then you mentioned... as some of the storms that hit the PHL-NYC/NJ corridor essentially missed the interior regions when you compare it. What's interesting to me is studying and reading about how the indicies set up and the reasons why the storm behaved the way it did. I am definitely learning a lot in this thread and it definitely helps out a lot.

This is a hugely good point in this discussion! Take last year... we had a slippage of the AO into negative (whether the NAO was in its shared domain on the same page at any given time, notwithstanding - and the two can at times part company though rare), and up in NE there was 40-60" of snow in just 40 days in repeating coastals with intervening cold. There was 35" on the level and rivaled the mega-pack of 1995-1996 by early February... Point being, all of last winter was really about 40 to 50 days up this way. Interesting how the statistics work out that way.

[WinterWxLuvr]

The knowledge regularly displayed on this board is staggering. Thanks to all the mets and non mets who contribute this stuff so that those of us who know very little can see the depths of the science involved. Keep it coming. You guys are amazing.

[Gibbsfreeenergy]

Yeah I agree they feed off one another. Which one is most responsible for forcing the other can be debated endlessly and probably is pointless since each can be the "driver" in certain circumstances, but it does seem that once both are established, it's tough to break. You can see it easily by separating nina winters by NAO phase (this doesn't even include some recent winters since I made these long ago).

Nina / -NAO

Nina / +NAO

just make a bearing sea index! that should be the be all end all!

[HM]

Based on what we have so far for September, it appears the state of the 30 and 50mb zonal winds will be quite similar to August. This will have an effect on the Brewer-Dobson Circulation, too, with a lower flux of ozone to the North Pole. However, not all is lost yet with that (very early in the game). Despite ozone being well below normal across most of the polar regions now, some influx from the enhanced W PAC convection and oncoming -QBO may still make it in by late autumn.

[usedtobe]

Based on what we have so far for September, it appears the state of the 30 and 50mb zonal winds will be quite similar to August. This will have an effect on the Brewer-Dobson Circulation, too, with a lower flux of ozone to the North Pole. However, not all is lost yet with that (very early in the game). Despite ozone being well below normal across most of the polar regions now, some influx from the enhanced W PAC convection and oncoming -QBO may still make it in by late autumn.

Does that mean we are more likely to start out the winter with a stronger polar vortex than normal? I note the zonal winds near the poles are above normal. What is the possible impact of the 50 mb winds still being westerly when looking towards Nov and Dec?

[HM]

Does that mean we are more likely to start out the winter with a stronger polar vortex than normal? I note the zonal winds near the poles are above normal. What is the possible impact of the 50 mb winds still being westerly when looking towards Nov and Dec?

I think we are going to follow the trend of the last few winters and get a tropical-induced cold pattern November into early December. I think everyone and their mothers is calling for that, so deep down I hope it fails for the sake of monotony. The westerly zonal winds will likely help produce a more poleward Aleutian high which will help keep the NAO from going too positive as well. Also factor in that there will likely be an upper level easterly anomaly somewhere in the 30-60N belt in the stratosphere from the lower solar component.

But there is no denying that the polar vortex is coming on strong, like it did last year. In fact, the PV last year was the coldest I ever saw it and that clearly didn't seem to matter for 6 weeks during the winter. So, with that logic, the state of the QBO/PV may not be all that detrimental. I think December will look more like the +QBO composites I made than the -QBO composites. If the PV ends up being very consolidated over western Canada, despite the blocking, it may allow for a warmer picture across most of the CONUS...something like 67' or 56' .... but my gut says that won't happen given the state of the sun. Perhaps it will briefly mid-decemberish when the AAM spikes.

[usedtobe]

I think we are going to follow the trend of the last few winters and get a tropical-induced cold pattern November into early December. I think everyone and their mothers is calling for that, so deep down I hope it fails for the sake of monotony. The westerly zonal winds will likely help produce a more poleward Aleutian high which will help keep the NAO from going too positive as well. Also factor in that there will likely be an upper level easterly anomaly somewhere in the 30-60N belt in the stratosphere from the lower solar component.

But there is no denying that the polar vortex is coming on strong, like it did last year. In fact, the PV last year was the coldest I ever saw it and that clearly didn't seem to matter for 6 weeks during the winter. So, with that logic, the state of the QBO/PV may not be all that detrimental. I think December will look more like the +QBO composites I made than the -QBO composites. If the PV ends up being very consolidated over western Canada, despite the blocking, it may allow for a warmer picture across most of the CONUS...something like 67' or 56' .... but my gut says that won't happen given the state of the sun. Perhaps it will briefly mid-decemberish when the AAM spikes.

Just looking at the cold enso and negative qbo years monthy temp anomalies and dec is the coldest month relative to normal for the dc area with Jan and Feb both averaging above normal. Too bad, forecasting isn't that simple. Not sure how we yet cycle in the solar factor except as to which months would be warmer. The QBO would argue for any ssw event being during the first half of the winter rather than later. However, except for 2009-2010, I've never had much luck with monthly temps prior to the latter half of Nov. Even then, I thought March 2010 March would start out cold.

[HM]

Just looking at the cold enso and negative qbo years monthy temp anomalies and dec is the coldest month relative to normal for the dc area with Jan and Feb both averaging above normal. Too bad, forecasting isn't that simple. Not sure how we yet cycle in the solar factor except as to which months would be warmer. The QBO would argue for any ssw event being during the first half of the winter rather than later. However, except for 2009-2010, I've never had much luck with monthly temps prior to the latter half of winter. Even then, I thought March 2010 March would start out cold.

How are you determining negative QBO years? I would imagine you took the 30mb number? What happens if the 50mb is positive?

[usedtobe]

How are you determining negative QBO years? I would imagine you took the 30mb number? What happens if the 50mb is positive?

I did it even lazier than that. I just used the years that you noted in the first post. Not scientific at all. Oops, not saying that you weren't scientific just that I was lazy so I used your years.

[HM]

I did it even lazier than that. I just used you years that you noted in the first post. Not scientific at all.

Wes, it seems like the -QBO allows for that obvious block to form from the North Atlantic into Siberia. So, even though the N PAC high ends up more displaced south, it ends up acting like a PNA ridge but more to the west. This, in tandem with the -AO/NAO, allows more of the eastern two thirds to experience a cold December.

Unfortunately, this December is not clear cut in one camp with the +QBO likely continuing in the lower levels and -QBO strengthening in the upper levels.

[usedtobe]

Wes, it seems like the -QBO allows for that obvious block to form from the North Atlantic into Siberia. So, even though the N PAC high ends up more displaced south, it ends up acting like a PNA ridge but more to the west. This, in tandem with the -AO/NAO, allows more of the eastern two thirds to experience a cold December.

Unfortunately, this December is not clear cut in one camp with the +QBO likely continuing in the lower levels and -QBO strengthening in the upper levels.

I think that is what I'm trying to understand and am worried about. To me, this year is another really tough one to call for this area. What I'm worried about is when we have a negative nao it could be quite cold especially for the plains but probably also into the east at times but when the NAO goes positive, I could see us having some Ji suicide type temps.

[tacoman25]

Any thoughts on the possibility that the descending QBO and different placement of -ENSO forcing this year could lead to the second half of winter being colder in the East than the first half? This is actually the way I leaned in my winter outlook, though I think December (especially early) still has a chance to be cold, especially in the Northeast.

[BethesdaWX]

Any thoughts on the possibility that the descending QBO and different placement of -ENSO forcing this year could lead to the second half of winter being colder in the East than the first half? This is actually the way I leaned in my winter outlook, though I think December (especially early) still has a chance to be cold, especially in the Northeast.

I'm no expert but I think the timing of when and/or if the QBO 50mb index does negative could have consequences to many winter forecasts, I'm actually leaning opposite to you there, I have a hunch much of the U.S. blowtorches in Febuary, unscentifically for the time being.

[HM]

I think that is what I'm trying to understand and am worried about. To me, this year is another really tough one to call for this area. What I'm worried about is when we have a negative nao it could be quite cold especially for the plains but probably also into the east at times but when the NAO goes positive, I could see us having some Ji suicide type temps.

Yeah I am not so sure on how cold the anomalies will be in December. I could see something very strange where the East Coast is at / below normal (perhaps upper Midwest/Great Lakes) but much of the western states are above normal down into the Plains/Gulf States. I am fairly confident that the Siberian Snow will come in above normal this October and will begin triggering a stratospheric/tropospheric coupling response by mid November. A deep freeze will be likely when this occurs, especially when a possible MJO wave comes through Indonesia. It wouldn't shock me if most places see accumulating snow in the Northeast Corridor, including major cities, before December 1st this year.

The MJO will get into the El Niño phases as we move into December; but by this point, the wavelengths should be long enough to allow the PNA pattern to continue. In early November and October, this same thing would have meant warmth. As the forcing becomes more unfavorable for cold deeper into December, we will have to rely on the NAO to pick up the slack. If the NAO fails, then the rest of December will be quite warm. Last year, it came through for us but that was with an extreme setup solar-wise, coupled with the +QBO Aleutian High aiding in sustaining the -AO/NAO. Will these circumstances repeat?

[ORH_wxman]

Yeah I am not so sure on how cold the anomalies will be in December. I could see something very strange where the East Coast is at / below normal (perhaps upper Midwest/Great Lakes) but much of the western states are above normal down into the Plains/Gulf States. I am fairly confident that the Siberian Snow will come in above normal this October and will begin triggering a stratospheric/tropospheric coupling response by mid November. A deep freeze will be likely when this occurs, especially when a possible MJO wave comes through Indonesia. It wouldn't shock me if most places see accumulating snow in the Northeast Corridor, including major cities, before December 1st this year.

The MJO will get into the El Niño phases as we move into December; but by this point, the wavelengths should be long enough to allow the PNA pattern to continue. In early November and October, this same thing would have meant warmth. As the forcing becomes more unfavorable for cold deeper into December, we will have to rely on the NAO to pick up the slack. If the NAO fails, then the rest of December will be quite warm. Last year, it came through for us but that was with an extreme setup solar-wise, coupled with the +QBO Aleutian High aiding in sustaining the -AO/NAO. Will these circumstances repeat?

Almost seems like you are leaning at a Nov 2002 and early Dec 2002 type evolution for the beginning if things work out like you are thinking, but then breaking down (as is probably expected in a Nina since +PNA is hard to sustain) and then leaving things up to the NAO if the colder pattern continues through New Years.

MJO should be interesting to follow this winter. Wes produced the paper that showed it does better in -QBO winters....but in -qbo AND La Nina winters recently it hasn't done so well in getting into Nino territories. But the caveat is that the QBO this year isn't necessarily negative in the same sense that those '07-'08, '05-'06 type years were when it was full blown through the whole layer.

[HM]

Almost seems like you are leaning at a Nov 2002 and early Dec 2002 type evolution for the beginning if things work out like you are thinking, but then breaking down (as is probably expected in a Nina since +PNA is hard to sustain) and then leaving things up to the NAO if the colder pattern continues through New Years.

MJO should be interesting to follow this winter. Wes produced the paper that showed it does better in -QBO winters....but in -qbo AND La Nina winters recently it hasn't done so well in getting into Nino territories. But the caveat is that the QBO this year isn't necessarily negative in the same sense that those '07-'08, '05-'06 type years were when it was full blown through the whole layer.

You could almost consider the QBO element a draw in terms of tropical forcing. Currently, the behavior is very very much like a +QBO with how the Walker Cell is behaving / E. Hemisphere uplift. The ozone is also lacking etc. But, this will continue to weaken through the cool season; however, I do think those westerly zonal wind anomalies will linger in the lower equatorial stratosphere.

Last year, I tried to end the NAO block too fast. This year I may try again.

[HM]

Actually, Will, I could see a December 2008 like NAO behavior except that round 2 is not quite as negative. So there will be a secondary response into New Years but it won' t be quite as intense as the first round. Meanwhile, I think the late January-early February shot this year will be more negative than the 2008-09 shot.

[ORH_wxman]

Actually, Will, I could see a December 2008 like NAO behavior except that round 2 is not quite as negative. So there will be a secondary response into New Years but it won' t be quite as intense as the first round. Meanwhile, I think the late January-early February shot this year will be more negative than the 2008-09 shot.

Yeah we had a pretty extreme block right around Dec 30-New Years in '08-'09...but then a weaker one at the end of January '09 after a very favorable Pacific in between the -NAO stints (huge MJO wave really bolstered that).

A lot of forecasts have been smoked by the MJO in the past two Ninas in January ('09 and last winter)....how do you feel about it this year?