Possible Snow Gradient Explanation

[HM]

The QBO is a multilayer phenomenon and it can get tedious labeling a certain winter westerly or easterly. I think this is part of the reason why many forecasters sometimes throw the QBO out the door when it comes to preparing seasonal outlooks. Different layers' zonal wind has different effects on the pattern. Most of the time, the situation is more complicated than we think.

Below is the data. Keep in mind, labeling something cold in terms of ENSO is a bit subjective. I cross-checked borderline years that failed to reach the official 3.4 definition and decided if they were worthy contenders based on the MEI, SST and forcing.

A deep-layer -QBO during any cold ENSO event:

56-57

62-63

70-71

74-75

89-90

96-97

00-01 **technically the 50mb QBO was neutral transitioning to -QBO from NOV-MAR: -0.50 -0.72 -1.88 -2.30 -2.31

05-06

07-08

A deep-layer +QBO during any cold ENSO event:

55-56

61-62

64-65

66-67

71-72

75-76

85-86

99-00

08-09

10-11

Now, here are the rejected years because the QBO was not firmly in one camp: 67-68, 83-84, 84-85, 88-89, 95-96, 98-99, 01-02

In 67-68, there was a solid -QBO wave at 30mb but it was westerly in the lower levels.

In 83-84, there was a solid -QBO wave at 30mb but the lower levels were still transitioning from positive to negative

In 84-85, there was a transitioning -QBO to +QBO at 30mb and a -QBO at 50mb

In 88-89, there was a weak -QBO at 30mb and a strong +QBO wave at 50mb

In 95-96, there was a weak but strengthening -QBO at 30mb and a solid +QBO at 50mb

In 98-99, there was a -QBO to +QBO transition at 30mb with a solid -QBO at 50mb

In 01-02, there was a weak but strengthening +QBO at 30mb with a -QBO to +QBO at 50mb.

While some of these years are actually good fits for the upcoming winter's QBO progression, we'll leave these out for the time being.

Now for the 500mb composites:

Cold ENSO DJFM during a solid -QBO

Cold ENSO DJFM during a solid +QBO

The +QBO years tend to have a more poleward and stronger Aleutian High in comparison to the -QBO years where the high was more to the southeast and weaker. This seems counter-intuitive because one would think the -QBO years would favor more polar blocking and therefore a more poleward high. So, the -QBO years would favor more of a Southeast Ridge and temperature gradient, while the +QBO years have a weaker temp gradient.

Perhaps you were wondering if this relationship holds if we manipulate the years further. Let's get rid of the +PDO years and see if that matters (there aren't many):

Cold ENSO with solid -QBO/PDO

Cold ENSO with solid +QBO/PDO

All this seemed to do was strengthen the idea further.

The next set of images is only for true 3.4 La Niña events during their respective QBO phases:

La Niña with solid -QBO

La Niña with solid +QBO

While the NAO sees some differences along with polar vortex strength, the North Pacific still sees the same relationship. Also, the height gradient remains stronger in the -QBO years.

For the +QBO/-PDO years, lets get rid of 2010-11 just in case that was poisoning the composite:

It still seems to have the same look. Let's lose the neutral years from this composite.

Only difference is the blocking gets reduced somewhat on the Atlantic-side but the Aleutian High is still there.

Here are the -PDO/-QBO years without the neutral years:

The gradient is still there and so is the concept.

It appears that a -QBO combined with a cold ENSO event flattens the Aleutian High southward, strengthening the Southeast Ridge and increasing the height gradient across the East. This is especially true when the NAO is negative. It appears this could be the large-scale setup that favors a more intense snow gradient.

This year may actually end up being more in the "not so clear cut camp" with a lingering +QBO in the lower levels and a strengthening -QBO at 30mb. Throw in the extreme warm pool in the North Pacific and suddenly we have a case for a strong Aleutian High. If the 50mb QBO heads negative, we'll probably look more like the -QBO composites, seasonally-speaking.

[CoastalWx]

Dude, great stuff. Nice breakdown of the pattern.

I guess my question is....what would cause the shift in the placement of the Aleutian ridge from a forcing standpoint. IOW, what forcing from a -QBO standpoint causes the ridge to shift vs a +QBO? Is there any correlation to Hadley cell displacement and/or tropopause heights with each phase causing the difference in the ridging over the NPAC?

[HM]

Dude, great stuff. Nice breakdown of the pattern.

I guess my question is....what would cause the shift in the placement of the Aleutian ridge from a forcing standpoint. IOW, what forcing from a -QBO standpoint causes the ridge to shift vs a +QBO? Is there any correlation to Hadley cell displacement and/or tropopause heights with each phase causing the difference in the ridging over the NPAC?

I can't post maps at this time but I'll elaborate.

The +QBO does two things:

1. Strengthens the polar night jet

2. Shifts and tightens the Mid-Latitude easterly jet (because of the westerly wind at the Equator)

This forces the Aleutian High circulation to intensify and becomes enhanced in the La Nina/-PDO circulation.

During the -QBO, the easterlies are enhanced in the Subtropics/equatorial regions and again near the pole. This weakens the Aleutian High.

The Hadley Cell looks ideal in +QBO years and how you would draw one for any La Nina year. The stratospheric setup becomes harmonious with the troposphere, making a perfect latitudinal circulation between 180-160W. During the -QBO years, the cell shifts east and widens between 160W-120W.

[HM]

The major circulations from the N PAC into N. America shift east and south between the +QBO years and -QBO years. So the gradient will naturally strengthen in the -QBO years. Also, with the further east and south N PAC high, the SE ridge pumps up a bit more.

My list is a bit different from Will's original list so I am looking forward to some of the results of the "New England snow gradient."

[OKpowdah]

Good stuff HM. One big distinction I see is the location of the PV. In the -QBO winters, the PV is centered in southern Manitoba and North Dakota, while in the +QBO winters, the PV is located much further northwest into western Canada. This actually looks like threateningly warm pattern, with +EPO look, despite subtle differences that we see over the southeast US.

Looking at tropical forcing, the largest -OLR anomalies are further east, closer to the dateline in the -QBO years versus the +QBO years, and actually exhibits a stronger Nino-esque subtropical jet extending into Mexico. I could try to attribute the forcing differences to stronger trade winds focused further east over the E Pac, converging further east, closer to the dateline, and enhanced by higher tropopause height over the equator. As a result of the forcing differences, the North Pacific ridge is shifted east in the -QBO years, also shifting the PV east. The whole pattern is rotated cyclonically, with North Atlantic blocking further west, forcing the PV also southward.

[HM]

Good stuff HM. One big distinction I see is the location of the PV. In the -QBO winters, the PV is centered in southern Manitoba and North Dakota, while in the +QBO winters, the PV is located much further northwest into western Canada. This actually looks like threateningly warm pattern, with +EPO look, despite subtle differences that we see over the southeast US.

Looking at tropical forcing, the largest -OLR anomalies are further east, closer to the dateline in the -QBO years versus the +QBO years, and actually exhibits a stronger Nino-esque subtropical jet extending into Mexico. I could try to attribute the forcing differences to stronger trade winds focused further east over the E Pac, converging further east, closer to the dateline, and enhanced by higher tropopause height over the equator. As a result of the forcing differences, the North Pacific ridge is shifted east in the -QBO years, also shifting the PV east. The whole pattern is rotated cyclonically, with North Atlantic blocking further west, forcing the PV also southward.

Yes, definitely; excellent post. Therefore, the potential gradient over the East Coast is enhanced during the -QBO years and this is likely the culprit for the potential enhanced snowfall gradient too. It seems like if you can get the NAO to tank in the +QBO years, a larger area of the country may potentially be influenced and the gradient across the East wouldn't be as tight. The -QBO years could host some impressive cyclones given the findings here but it could also become annoying for anyone south of the gradient in the Mid Atlantic.

[OKpowdah]

Yes, definitely; excellent post. Therefore, the potential gradient over the East Coast is enhanced during the -QBO years and this is likely the culprit for the potential enhanced snowfall gradient too. It seems like if you can get the NAO to tank in the +QBO years, a larger area of the country may potentially be influenced and the gradient across the East wouldn't be as tight. The -QBO years could host some impressive cyclones given the findings here but it could also become annoying for anyone south of the gradient in the Mid Atlantic.

Sounds good! This actually seemed to play out pretty well just comparing 07-08 and 08-09

[weatherwiz]

This is excellent stuff! Awesome job breaking things down and explaining everything...very clear and easy to understand.

[CoastalWx]

I can't post maps at this time but I'll elaborate.

The +QBO does two things:

1. Strengthens the polar night jet

2. Shifts and tightens the Mid-Latitude easterly jet (because of the westerly wind at the Equator)

This forces the Aleutian High circulation to intensify and becomes enhanced in the La Nina/-PDO circulation.

During the -QBO, the easterlies are enhanced in the Subtropics/equatorial regions and again near the pole. This weakens the Aleutian High.

The Hadley Cell looks ideal in +QBO years and how you would draw one for any La Nina year. The stratospheric setup becomes harmonious with the troposphere, making a perfect latitudinal circulation between 180-160W. During the -QBO years, the cell shifts east and widens between 160W-120W.

Good stuff HM. One big distinction I see is the location of the PV. In the -QBO winters, the PV is centered in southern Manitoba and North Dakota, while in the +QBO winters, the PV is located much further northwest into western Canada. This actually looks like threateningly warm pattern, with +EPO look, despite subtle differences that we see over the southeast US.

Looking at tropical forcing, the largest -OLR anomalies are further east, closer to the dateline in the -QBO years versus the +QBO years, and actually exhibits a stronger Nino-esque subtropical jet extending into Mexico. I could try to attribute the forcing differences to stronger trade winds focused further east over the E Pac, converging further east, closer to the dateline, and enhanced by higher tropopause height over the equator. As a result of the forcing differences, the North Pacific ridge is shifted east in the -QBO years, also shifting the PV east. The whole pattern is rotated cyclonically, with North Atlantic blocking further west, forcing the PV also southward.

Thanks guys....cool. Just getting up and reading this, but I think it makes sense.

Sam funny you mention that position of the PV in NW Canada, because I was thinking even though overall heights are lower in the northeast, it's precarious to a torch position. If the flow is right, you probably could have lower heights, but temps near or above normal...especially in the later winter months when the sun angle increases. Lets hope for some blocking this winter.

[Damage In Tolland]

Wait until Will and Ray see this..Full frontal nudity with laptops in midair

[Ginx snewx]

Great stuff HM, AWT 70-71 big big interior winter incoming.

[Typhoon Tip]

The QBO is a multilayer phenomenon and it can get tedious labeling a certain winter westerly or easterly. I think this is part of the reason why many forecasters sometimes throw the QBO out the door when it comes to preparing seasonal outlooks. Different layers' zonal wind has different effects on the pattern. Most of the time, the situation is more complicated than we think.

Below is the data. Keep in mind, labeling something cold in terms of ENSO is a bit subjective. I cross-checked borderline years that failed to reach the official 3.4 definition and decided if they were worthy contenders based on the MEI, SST and forcing.

A deep-layer -QBO during any cold ENSO event:

56-57

62-63

70-71

74-75

89-90

96-97

00-01 **technically the 50mb QBO was neutral transitioning to -QBO from NOV-MAR: -0.50 -0.72 -1.88 -2.30 -2.31

05-06

07-08

A deep-layer +QBO during any cold ENSO event:

55-56

61-62

64-65

66-67

71-72

75-76

85-86

99-00

08-09

10-11

Now, here are the rejected years because the QBO was not firmly in one camp: 67-68, 83-84, 84-85, 88-89, 95-96, 98-99, 01-02

In 67-68, there was a solid -QBO wave at 30mb but it was westerly in the lower levels.

In 83-84, there was a solid -QBO wave at 30mb but the lower levels were still transitioning from positive to negative

In 84-85, there was a transitioning -QBO to +QBO at 30mb and a -QBO at 50mb

In 88-89, there was a weak -QBO at 30mb and a strong +QBO wave at 50mb

In 95-96, there was a weak but strengthening -QBO at 30mb and a solid +QBO at 50mb

In 98-99, there was a -QBO to +QBO transition at 30mb with a solid -QBO at 50mb

In 01-02, there was a weak but strengthening +QBO at 30mb with a -QBO to +QBO at 50mb.

While some of these years are actually good fits for the upcoming winter's QBO progression, we'll leave these out for the time being.

Now for the 500mb composites:

Cold ENSO DJFM during a solid -QBO

..

Cold ENSO DJFM during a solid +QBO

..

The +QBO years tend to have a more poleward and stronger Aleutian High in comparison to the -QBO years where the high was more to the southeast and weaker. This seems counter-intuitive because one would think the -QBO years would favor more polar blocking and therefore a more poleward high. So, the -QBO years would favor more of a Southeast Ridge and temperature gradient, while the +QBO years have a weaker temp gradient.

Perhaps you were wondering if this relationship holds if we manipulate the years further. Let's get rid of the +PDO years and see if that matters (there aren't many):

Cold ENSO with solid -QBO/PDO

..

Cold ENSO with solid +QBO/PDO

..

All this seemed to do was strengthen the idea further.

The next set of images is only for true 3.4 La Niña events during their respective QBO phases:

La Niña with solid -QBO

..

La Niña with solid +QBO

..

While the NAO sees some differences along with polar vortex strength, the North Pacific still sees the same relationship. Also, the height gradient remains stronger in the -QBO years.

For the +QBO/-PDO years, lets get rid of 2010-11 just in case that was poisoning the composite:

..

It still seems to have the same look. Let's lose the neutral years from this composite.

..

Only difference is the blocking gets reduced somewhat on the Atlantic-side but the Aleutian High is still there.

Here are the -PDO/-QBO years without the neutral years:

..

The gradient is still there and so is the concept.

It appears that a -QBO combined with a cold ENSO event flattens the Aleutian High southward, strengthening the Southeast Ridge and increasing the height gradient across the East. This is especially true when the NAO is negative. It appears this could be the large-scale setup that favors a more intense snow gradient.

This year may actually end up being more in the "not so clear cut camp" with a lingering +QBO in the lower levels and a strengthening -QBO at 30mb. Throw in the extreme warm pool in the North Pacific and suddenly we have a case for a strong Aleutian High. If the 50mb QBO heads negative, we'll probably look more like the -QBO composites, seasonally-speaking.

The compression of the "SE ridge" has been a contention of mine for a while. It obfuscates cyclone potential because at first glance, a +PNAP look to the pattern may appear promising for S/Ws ready to break in the means. But these S/Ws will shear (damp out actually) when there is too much gradient, which is what takes place when there are height around or above 582dm near MIA while anomalous low heights pass near Dayton Ohio (this can be off-set by a strongly negative AO). The southern aspect of the S and S/W medium of the S/W will tend to damp because the native wind streak is not sufficiently differentiating relative to the flow. In other words, the wind maxes in the S/Ws are not subtracting (differentiating) against the ambient balanced wind.

What you are describing is a -PNA set atop a -NAO, and I agree. I was just discussing a gradient pattern with some of the other New England folk at our gathering this evening. The thing is, 2010 was a gradient year (regardless of the ENSO) - it just so happened to be that the big snow was S. I suspect we have a gradient introduction this year, featuring coastal storms with snow inland as a favored solution. It doesn't have to be a death sentence for the coastal plain.

[Amped]

SE ridge, no problem DC will get hit with 4 PD1storms..

[40/70 Benchmark]

Nude prancing atop the treadmill.

[dryslot]

I like the analog years that are being tossed out to comparisons of what we may see this winter season....

[HM]

Just a note about this winter: this post wasn't necessarily trying to suggest the upcoming winter will be any one way. This thread is more about the QBO-La Nina connection Will and others have made about the snow gradient. I am interested to hear his thoughts on that or anyone's for that matter because I know I switched the years up on him a bit.

The upcoming winter has a strong possibility of seeing a major mid-winter warming in the stratosphere; and if it times just right, could really screw over a monthly temp map.

[okie333]

Just a note about this winter: this post wasn't necessarily trying to suggest the upcoming winter will be any one way. This thread is more about the QBO-La Nina connection Will and others have made about the snow gradient. I am interested to hear his thoughts on that or anyone's for that matter because I know I switched the years up on him a bit.

The upcoming winter has a strong possibility of seeing a major mid-winter warming in the stratosphere; and if it times just right, could really screw over a monthly temp map.

In a good way, that is

[HM]

In a good way, that is

Indeed. I hope it times nicely with the calendar. By the way, how are you? I saw your post in the main forum and will comment soon. I thought it was great insight.

[OKpowdah]

Just a note about this winter: this post wasn't necessarily trying to suggest the upcoming winter will be any one way. This thread is more about the QBO-La Nina connection Will and others have made about the snow gradient. I am interested to hear his thoughts on that or anyone's for that matter because I know I switched the years up on him a bit.

The upcoming winter has a strong possibility of seeing a major mid-winter warming in the stratosphere; and if it times just right, could really screw over a monthly temp map.

[okie333]

Indeed. I hope it times nicely with the calendar. By the way, how are you? I saw your post in the main forum and will comment soon. I thought it was great insight.

Coming from Henry Margusity's brother, thanks!

[ORH_wxman]

Hey HM, very interesting thread and thanks for starting it RE: snowfall gradient in the other thread. I haven't really had any time to post on here the last few days as I had a friend from Chicago visiting, but I plan on looking over this more thoroughly tonight and perhaps responding in some detail if I can think of anything useful to add.

[ORH_wxman]

Hey HM, very interesting thread and thanks for starting it RE: snowfall gradient in the other thread. I haven't really had any time to post on here the last few days as I had a friend from Chicago visiting, but I plan on looking over this more thoroughly tonight and perhaps responding in some detail if I can think of anything useful to add.

Ok, I just read the post more in depth and thought about it for a while. Great read BTW.

Some thoughts on the Aleutian high and NAO configuration...Scott had speculated and I agreed that perhaps years where the Aleutian high was more amplified poleward that it may actually help feed back into a -NAO or make a -NAO a bit more stable...this thought is currently independent of what the QBO was, but taking a look at the -QBO years by your definition seems to support the tendency for the more suppressed Aleutian high. The overall composite still shows a -NAO, but breaking it down a little further reveals this:

The two groups are split by snowfall gradient. I took the years with the most intense snowfall gradients and then the ones with lesser or non-existent gradients from your list and made separate composites. The first composite are the years with the very intense gradients. They also have much less blocking in the Atlantic and perhaps not coincidentally, a much more suppressed Aleutian high.

The 2nd group quite clearly has some blocking present in the Atlantic, and on the PAC side, the Aleutian high is very amplified. Not surprisingly, the western US is also a lot different. If you get rid of 1989-1990 (which was the least cold in the enso region of any year), its even more intense in each ocean.

Both the high gradient set and low gradient set show the penchant for SE ridging in the -QBO, but the higher gradient set seems to be centered much west, just off the SE coast while the lower gradient set is pushed much further east into the Atlantic.

The small sample sizes become a problem, but its interesting to see the higher Aleutian high amplitude years of that -QBO/-ENSO set more likely to have a -NAO than the lower amplitude years.

I'm sure I'll be able to present some of these thoughts a little bit better later on when I have more time to think about the maps and such, but these were just some of the first crude ideas that popped into my head. So even with still crude ideas, I thought I'd might ask:

1. What do you think of the connection between higher amplitude Aleutian high and Atlantic blocking?

2. The predictability of the amplitude of the Aleutian high?

I may check out some of the high gradient +QBO years (there aren't as many, but they still exist)...and see if the Aleutian high/SE ridge configuration is similar nor not.

[HM]

1. What do you think of the connection between higher amplitude Aleutian high and Atlantic blocking?

2. The predictability of the amplitude of the Aleutian high?

Before I get to your questions, I just had a comment on your breakdown. The high-gradient years seemed to be, overall, associated more with defined La Nina events/periods; while, the low-gradient years were not. Now 2000-01 was part of a decent La Nina stretch, but just look at its h5 pattern for DJFM. That is not anything like your typical la nina with an Aleutian Low, an extended Pacific Jet leading into a big ridge anomaly from Hawaii to the western coast of Canada. A lot of that had to do with December because if you take it out of the composite, you end up with a very displaced "Aleutian" High (JFM avg) --more like 30-40N not 50-60N. Now that is more like your -QBO years!

This is why we have to keep this very broad/general because the samples become too insignificant, as you've already stated. Having said that, I do agree that a more westward ridge toward the Southeast would make sense for a stronger gradient.

Now onto your questions:

1. I think that connection is sound, especially when the overall PDO/Atlantic/solar states favor blocking. The Aleutian High didn't help much in 96-97.

2. The Aleutian high is a very tough thing to forecast but a general guideline is to see where the forcing will setup; what are the stratospheric indicators suggesting; how will the MJO behave; what does the PDO configuration look like...

This year's stratospheric setup is more complicated than the pure -QBO years. This year will end up being one of my "throw-away" years; because in all likelihood, the 50mb QBO will average positive or trend neutral while 30mb goes solidly negative.

[ORH_wxman]

Before I get to your questions, I just had a comment on your breakdown. The high-gradient years seemed to be, overall, associated more with defined La Nina events/periods; while, the low-gradient years were not. Now 2000-01 was part of a decent La Nina stretch, but just look at its h5 pattern for DJFM. That is not anything like your typical la nina with an Aleutian Low, an extended Pacific Jet leading into a big ridge anomaly from Hawaii to the western coast of Canada. A lot of that had to do with December because if you take it out of the composite, you end up with a very displaced "Aleutian" High (JFM avg) --more like 30-40N not 50-60N. Now that is more like your -QBO years!

This is why we have to keep this very broad/general because the samples become to insignificant, as you've already stated. Having said that, I do agree that a more westward ridge toward the Southeast would make sense for a stronger gradient.

Now onto your questions:

1. I think that connection is sound, especially when the overall PDO/Atlantic/solar states favor blocking. The Aleutian High didn't help much in 96-97.

2. The Aleutian high is a very tough thing to forecast but a general guideline is to see where the forcing will setup; what are the stratospheric indicators suggesting; how will the MJO behave; what does the PDO configuration look like...

This year's stratospheric setup is more complicated than the pure -QBO years. This year will end up being one of my "throw-away" years; because in all likelihood, the 50mb QBO will average positive or trend neutral while 30mb goes solidly negative.

Good point about 2000-2001, December really skews it, though I'm sure there's some other winters where 1 month can really change the look. That's probably part of what makes this tough to analyze. It definitely seems we are making some kind of a connection between the Aleutian high placement in Ninas and the bigger gradients.

[HM]

Good point about 2000-2001, December really skews it, though I'm sure there's some other winters where 1 month can really change the look. That's probably part of what makes this tough to analyze. It definitely seems we are making some kind of a connection between the Aleutian high placement in Ninas and the bigger gradients.

Also, 2000-01 had an awesome MJO display (even in the summer). It produced a monster El Nino-like atmosphere in January. It is probably one of the rarer La Nina January temp profiles you are ever going to see--warmer than normal across the northern-tier and cooler than normal across the southern-tier. It's no wonder the gradient in 00-01 was weaker than normal.

[CoastalWx]

Also, 2000-01 had an awesome MJO display (even in the summer). It produced a monster El Nino-like atmosphere in January. It is probably one of the rarer La Nina January temp profiles you are ever going to see--warmer than normal across the northern-tier and cooler than normal across the southern-tier. It's no wonder the gradient in 00-01 was weaker than normal.

Sort of like what we saw this past January, only perhaps on a smaller scale, this time. Would these wintertime MJO waves be more likely in a +QBO regime thanks to the higher tropopause in the subtropics? Not sure if this is a far fetched question or not, but it seems there is some sense to this from a dynamic standpoint if the troposphere in general is higher in +QBO in the subtropics.

[CoastalWx]

Sort of like what we saw this past January, only perhaps on a smaller scale, this time. Would these wintertime MJO waves be more likely in a +QBO regime thanks to the higher tropopause in the subtropics? Not sure if this is a far fetched question or not, but it seems there is some sense to this from a dynamic standpoint if the troposphere in general is higher in +QBO in the subtropics.

I know the QBO was in transition from + phase in '00-'01 so perhaps that helped the process along, instead of it trying to occur in a raging negative phase. It still could occur, but perhaps it was facilitated by an overall higher tropopause.

[HM]

Sort of like what we saw this past January, only perhaps on a smaller scale. Would these MJO waves be more likely in a +QBO regime thanks to the higher tropopause in the subtropics? Not sure if this is a far fetched question or not, but it seems there is some sense to this from a dynamic standpoint if the troposphere in general is higher in +QBO in the subtropics.

The 2001 case is just plain insanity and most likely a "fluke" in our attempt at figuring out what affects the weather. First of all, 2000-01 was mainly a -QBO year; although, there were neutral winds in the lowest levels. By January, 2001 the 50-70mb temperatures were below normal across the equatorial regions, while last year was solidly above normal in January. The PDO did come up during the winter with a solid cold pool across the Northwest Pacific, which helped enhance the El Nino-like atmosphere. Finally, there was a CW in November (stratospheric warming over Canada) that downwelled into the troposphere by January. All of these things combined to make that unusual monthly temp/height map.

Many different things can make the Tropics suitable for MJO waves to develop.

[ORH_wxman]

Also, 2000-01 had an awesome MJO display (even in the summer). It produced a monster El Nino-like atmosphere in January. It is probably one of the rarer La Nina January temp profiles you are ever going to see--warmer than normal across the northern-tier and cooler than normal across the southern-tier. It's no wonder the gradient in 00-01 was weaker than normal.

Yeah the gradient was more over the central Mid-Atlantic that winter and I think most of it had to do with the December 29-30, 2000 storm. There was a decided secondary gradient over southern New England though...mostly because of Feb/Mar 2001. But sometimes these occur just because a couple storms took a tight track. You're right in that it was definitely a really fluky type year.

I'm going to try and look at some +QBO gradient years later...there are fewer of them, but they are still there like 1975-1976 as one example. I'm wondering if some of the same features in the PAC appear during those winters even if they aren't necessarily favorable for +QBO climo.

[CoastalWx]

The 2001 case is just plain insanity and most likely a "fluke" in our attempt at figuring out what affects the weather. First of all, 2000-01 was mainly a -QBO year; although, there were neutral winds in the lowest levels. By January, 2001 the 50-70mb temperatures were below normal across the equatorial regions, while last year was solidly above normal in January. The PDO did come up during the winter with a solid cold pool across the Northwest Pacific, which helped enhance the El Nino-like atmosphere. Finally, there was a CW in November (stratospheric warming over Canada) that downwelled into the troposphere by January. All of these things combined to make that unusual monthly temp/height map.

Many different things can make the Tropics suitable for MJO waves to develop.

Cool, thanks. I know you've banged the QBO drum with tropical forcing, so just trying to see what was up with '00-'01. I know the QBO is one of many factors to MJO waves and it's tough to figure out how relevant it is when it comes to this stuff. Thanks, man.