El Niño winter almost guaranteed.

[Trix]

Optimistic article for CO snow. An El Nino winter is absolutely guaranteed because we have El Nino conditions. However, above average snow fall is not guaranteed. We only have about 7 months to find out.

Colorado’s Rocky Mountains are almost guaranteed to see an El Niño winter. Here’s what that could mean for ski season.

It may be August, but early indicators are already brewing for what the 2023-24 winter season could look like in Colorado. At Breckenridge Ski Resort, a dusting of white on Peak 6 was photographed on Aug....

www.skyhinews.com

 

[Colorado Expat]

Although persistence on an El Niño pattern through this coming winter is a near certainty, there is basically no good statistical correlation between ENSO cycles and snowfall in the Central Rockies. For instance, we just had three back to back La Niña winters. The first two had well below average mountain snowfall, while the third and most recent one had well above average snowfall. So no evident pattern emerges. The same holds true for the El Niño side of the ENSO cycle. The one thing that has been striking since the El Niño pattern set up is the east-to-west inversion of the summer monsoon, with the Western Slope of Colorado having had a very weak monsoon season with relatively light rainfall (no thunderstorms and flash floods closing I-70 through Glenwood Canyon this year), whereas the Eastern Slope has been locked into an anomalously wet pattern, with Denver receiving over a year's worth of annual rainfall in May and June alone, and then remaining wet after that. Essentially, the summer moisture for the most part went to the east of the Continental Divide, and even the couple of anomalous extratropical hurricane remnants that pushed north in recent weeks did not really bring that much moisture to the Upper Basin as a whole.

The drought response index map for Colorado pretty much tells the story of how the summer has gone so far:



As does the vegetative drought response map, which show quite a bit of stress:



If fall is moist, and winter comes early, then we should still be fine. By contrast, if we have a dry, warm fall and a later onset of winter, then there will be carryover moisture deficits on the Western Slope going into next year. It is too early to know how all that turns out, although at the moment we seem to have a heat dome still well emplaced and oscillating back and forth across the southern tier of states, which will keep things pretty warm and dry into September, so probably no early big snows or freezes. If you want to know how El Niño will effect all this, just flip a coin, since the odds are basically 50-50 either way.

 

[dallas massie]

Colorado River yesterday and Glenwood Canyon closed one lane for small mudslide. We have been getting monsoon rains and some pretty big ones on the Western Slope lately . Silt ,Colorado.

 

[Trix]

I don’t trust anybody who uses anomalous and extratropical in the same sentence.
Thanks for your expert explanations!

 

[JFRCalifornia]

This is a repost of something I responded to on a similar thread from a while back, but worth adding here, since it's relevant to the topic...

******

Well I've been following this but until now didn't have time to chime in on what I think is going on relative to El Nino, La Nina, and inflow (as if I know!)...

But I'll start with breaking down the data we have, at least in an overly simplistic way. Let's start with this website, which is a pretty good summary of all the El Nino and La Nina events back to 1950:

El Niño and La Niña Years and Intensities

That website does a nice job not just summarizing the different events each year, but whether a particular El Nino (or La Nina) was weak or strong.

First, a few housecleaning things to set up the analysis...

Let's start with the "ground zero" of a lot of people's thinking, which is that we all know that 1983 was the biggest inflow year in the past half century, and it was a very strong El Nino year too. That's when most people were introduced to the concept of "El Nino". I remember that year very well too--I was a sophomore at UC Davis, and northern California was just getting hammered all winter...never a day I didn't ride my bike to school without getting drenched, and the Sierras got pounded, with what looked like a Death Star trench of snow where I-80 crossed Donner Summit. So the popular assumption has always been "El Nino = huge snowfall"…

…And then on the flip side, some of the worst inflow years in recent memory (like 2018, 2021 and 2022) were La Nina years, reinforcing the idea that "La Nina = drought".

But let's look at this idea more critically.

It's an almost even distribution of El Ninos and La Ninas when you go back to 1950:

El Nino - 26
La Nina - 24
neither - 22

And then you'd think that maybe we've had more La Ninas in recent years, which is a reasonable hypothesis to explain why we have had a prolonged drought. But that's not really the case. Here's the distribution since 2000:

El Nino - 7
La Nina - 10
neither - 5

Maybe a slight skew toward La Ninas, but not enough data points to call that a trend. As my brother the meteorologist would say, there's more to the story... but what exactly is the story?

So let's start with what the inflows have been since 1963, and before Lake Powell, what the flows past Lees Ferry were. And you get a pretty clear pattern emerging:

1951-60 - 12.3 maf
1961-70 - 10.5 maf
1971-80 - 11.1 maf
1981-90 - 13.2 maf
1991-00 - 11.3 maf
2001-10 - 8.2 maf
2011-22 - 9.1 maf

1951-2022 - 10.6 maf

What you see there is some variation from decade to decade, with the 1980s being a high point, but then an obvious drop since 2000. Whatever is going on, it wouldn't seem to be explainable with just an uptick in La Nina events. But let's follow up on that a bit.

Here are the ten highest inflows since 1950, and what sort of season they happened in:

1983 - 21.8 maf - very strong El Nino
1984 - 21.6 maf - weak La Nina
1952 - 20.0 maf - moderate El Nino
1957 - 19.5 maf - neither
1986 - 18.4 maf - neither
1985 - 18.2 maf - weak La Nina
1962 - 17.0 maf - neither
2011 - 16.3 maf - strong La Nina
1997 - 16.2 maf - neither
1958 - 16.0 maf - strong El Nino

Well that looks inconclusive. But what you CAN see is that with the exception of 2011, all of these big years happened before 2000. An even finer eye would notice a 22-year period covering most of the 1960s and 70s (1963-1982) that had none of the top 10 inflows, a period that more or less coincides with the filling of Lake Powell. Remember it took 17 years to fill, when the original estimate was closer to 7. But that's a digression for the moment, just a simple reminder that there were recent times before just the last 20 years that were not as robust for snowpack and inflow as the 1950s or 80s, or even the 1990s were...

Okay, what about the flip side? What were the ten worst inflow years like? Here they are:

2021 - 4.0 maf - moderate La Nina
2002 - 4.1 maf - neither
1990 - 5.2 maf - neither
2013 - 5.3 maf - neither
2018 - 5.4 maf - weak La Nina
1977 - 5.6 maf - weak El Nino
2004 - 5.6 maf - neither
2022 - 5.6 maf - moderate La Nina
2012 - 6.1 maf - moderate La Nina
2003 - 6.3 maf - moderate El Nino

There perhaps it looks something a little more skewed toward "La Nina = less inflow", but again, not enough data points to really draw that conclusion. But what you can say with absolute certainty is that 8 of the 10 lowest flow years since 1950 have happened since 2000. Now that begins to looks something like a trend. And it looks like it takes more than the ENSO cycle to explain it.

By the way, if you're still thinking El Nino is going to save us, we've actually had 7 El Ninos since 2000. How good were those years? Well, a mixed bag at best, and nothing spectacular:

2016 - very strong El Nino - 9.9 maf
2003 - moderate El Nino - 6.3 maf
2010 - moderate El Nino - 8.8 maf
2005 - weak El Nino - 11.3 maf
2007 - weak El Nino - 8.1 maf
2015 - weak El Nino - 9.4 maf
2019 - weak El Nino - 11.7 maf

And remember, the best inflow year since 2000--which was 2011--was a strong La Nina!! So that seems to buck the conventional wisdom about El Nino vs. La Nina...

I could sit here searching for trends in the data, but without some high-powered model and a couple of PhD grad students, nobody's going to pick those out of the soup. To me, maybe the most interesting thing is this:

When you go back to 1950, here's the average inflow for El Nino, La Nina, and neutral years:

El Nino years - 11.2 maf
La Nina years - 10.4 maf
Neutral years - 10.1 maf

Again, nothing jumps out, except maybe this: maybe if you squint, it seems that perhaps extreme ENSO cycle conditions produce the most extreme results, either for better or worse. Sometimes we get great runoff with El Nino (as in 1983), and sometimes with La Nina (as in 2011). And El Nino years do seem to generally correlate with higher runoff, although the variation in that is huge. Honestly, there's not enough there to really draw any conclusive result... there has to be more to it the just El Nino.

But the one trend that remains clear--there has been less runoff since 2000. Could that be related to higher temperatures we've seen since then? And resulting drier soils and higher evaporation? Or shifts in precipitation patterns? These are certainly reasonable explanations, but above my grade to analyze in depth here... but whatever the cause, it’s clearly not really just about El Nino...

 

[thekid26]

This is a repost of something I responded to on a similar thread from a while back, but worth adding here, since it's relevant to the topic...

******

Well I've been following this but until now didn't have time to chime in on what I think is going on relative to El Nino, La Nina, and inflow (as if I know!)...

But I'll start with breaking down the data we have, at least in an overly simplistic way. Let's start with this website, which is a pretty good summary of all the El Nino and La Nina events back to 1950:

El Niño and La Niña Years and Intensities

That website does a nice job not just summarizing the different events each year, but whether a particular El Nino (or La Nina) was weak or strong.

First, a few housecleaning things to set up the analysis...

Let's start with the "ground zero" of a lot of people's thinking, which is that we all know that 1983 was the biggest inflow year in the past half century, and it was a very strong El Nino year too. That's when most people were introduced to the concept of "El Nino". I remember that year very well too--I was a sophomore at UC Davis, and northern California was just getting hammered all winter...never a day I didn't ride my bike to school without getting drenched, and the Sierras got pounded, with what looked like a Death Star trench of snow where I-80 crossed Donner Summit. So the popular assumption has always been "El Nino = huge snowfall"…

…And then on the flip side, some of the worst inflow years in recent memory (like 2018, 2021 and 2022) were La Nina years, reinforcing the idea that "La Nina = drought".

But let's look at this idea more critically.

It's an almost even distribution of El Ninos and La Ninas when you go back to 1950:

El Nino - 26
La Nina - 24
neither - 22

And then you'd think that maybe we've had more La Ninas in recent years, which is a reasonable hypothesis to explain why we have had a prolonged drought. But that's not really the case. Here's the distribution since 2000:

El Nino - 7
La Nina - 10
neither - 5

Maybe a slight skew toward La Ninas, but not enough data points to call that a trend. As my brother the meteorologist would say, there's more to the story... but what exactly is the story?

So let's start with what the inflows have been since 1963, and before Lake Powell, what the flows past Lees Ferry were. And you get a pretty clear pattern emerging:

1951-60 - 12.3 maf
1961-70 - 10.5 maf
1971-80 - 11.1 maf
1981-90 - 13.2 maf
1991-00 - 11.3 maf
2001-10 - 8.2 maf
2011-22 - 9.1 maf

1951-2022 - 10.6 maf

What you see there is some variation from decade to decade, with the 1980s being a high point, but then an obvious drop since 2000. Whatever is going on, it wouldn't seem to be explainable with just an uptick in La Nina events. But let's follow up on that a bit.

Here are the ten highest inflows since 1950, and what sort of season they happened in:

1983 - 21.8 maf - very strong El Nino
1984 - 21.6 maf - weak La Nina
1952 - 20.0 maf - moderate El Nino
1957 - 19.5 maf - neither
1986 - 18.4 maf - neither
1985 - 18.2 maf - weak La Nina
1962 - 17.0 maf - neither
2011 - 16.3 maf - strong La Nina
1997 - 16.2 maf - neither
1958 - 16.0 maf - strong El Nino

Well that looks inconclusive. But what you CAN see is that with the exception of 2011, all of these big years happened before 2000. An even finer eye would notice a 22-year period covering most of the 1960s and 70s (1963-1982) that had none of the top 10 inflows, a period that more or less coincides with the filling of Lake Powell. Remember it took 17 years to fill, when the original estimate was closer to 7. But that's a digression for the moment, just a simple reminder that there were recent times before just the last 20 years that were not as robust for snowpack and inflow as the 1950s or 80s, or even the 1990s were...

Okay, what about the flip side? What were the ten worst inflow years like? Here they are:

2021 - 4.0 maf - moderate La Nina
2002 - 4.1 maf - neither
1990 - 5.2 maf - neither
2013 - 5.3 maf - neither
2018 - 5.4 maf - weak La Nina
1977 - 5.6 maf - weak El Nino
2004 - 5.6 maf - neither
2022 - 5.6 maf - moderate La Nina
2012 - 6.1 maf - moderate La Nina
2003 - 6.3 maf - moderate El Nino

There perhaps it looks something a little more skewed toward "La Nina = less inflow", but again, not enough data points to really draw that conclusion. But what you can say with absolute certainty is that 8 of the 10 lowest flow years since 1950 have happened since 2000. Now that begins to looks something like a trend. And it looks like it takes more than the ENSO cycle to explain it.

By the way, if you're still thinking El Nino is going to save us, we've actually had 7 El Ninos since 2000. How good were those years? Well, a mixed bag at best, and nothing spectacular:

2016 - very strong El Nino - 9.9 maf
2003 - moderate El Nino - 6.3 maf
2010 - moderate El Nino - 8.8 maf
2005 - weak El Nino - 11.3 maf
2007 - weak El Nino - 8.1 maf
2015 - weak El Nino - 9.4 maf
2019 - weak El Nino - 11.7 maf

And remember, the best inflow year since 2000--which was 2011--was a strong La Nina!! So that seems to buck the conventional wisdom about El Nino vs. La Nina...

I could sit here searching for trends in the data, but without some high-powered model and a couple of PhD grad students, nobody's going to pick those out of the soup. To me, maybe the most interesting thing is this:

When you go back to 1950, here's the average inflow for El Nino, La Nina, and neutral years:

El Nino years - 11.2 maf
La Nina years - 10.4 maf
Neutral years - 10.1 maf

Again, nothing jumps out, except maybe this: maybe if you squint, it seems that perhaps extreme ENSO cycle conditions produce the most extreme results, either for better or worse. Sometimes we get great runoff with El Nino (as in 1983), and sometimes with La Nina (as in 2011). And El Nino years do seem to generally correlate with higher runoff, although the variation in that is huge. Honestly, there's not enough there to really draw any conclusive result... there has to be more to it the just El Nino.

But the one trend that remains clear--there has been less runoff since 2000. Could that be related to higher temperatures we've seen since then? And resulting drier soils and higher evaporation? Or shifts in precipitation patterns? These are certainly reasonable explanations, but above my grade to analyze in depth here... but whatever the cause, it’s clearly not really just about El Nino...

amazing, simply amazing data and knowledge you share, thank you.

 

[Powelldreamer]

This is a repost of something I responded to on a similar thread from a while back, but worth adding here, since it's relevant to the topic...

******

Well I've been following this but until now didn't have time to chime in on what I think is going on relative to El Nino, La Nina, and inflow (as if I know!)...

But I'll start with breaking down the data we have, at least in an overly simplistic way. Let's start with this website, which is a pretty good summary of all the El Nino and La Nina events back to 1950:

El Niño and La Niña Years and Intensities

That website does a nice job not just summarizing the different events each year, but whether a particular El Nino (or La Nina) was weak or strong.

First, a few housecleaning things to set up the analysis...

Let's start with the "ground zero" of a lot of people's thinking, which is that we all know that 1983 was the biggest inflow year in the past half century, and it was a very strong El Nino year too. That's when most people were introduced to the concept of "El Nino". I remember that year very well too--I was a sophomore at UC Davis, and northern California was just getting hammered all winter...never a day I didn't ride my bike to school without getting drenched, and the Sierras got pounded, with what looked like a Death Star trench of snow where I-80 crossed Donner Summit. So the popular assumption has always been "El Nino = huge snowfall"…

…And then on the flip side, some of the worst inflow years in recent memory (like 2018, 2021 and 2022) were La Nina years, reinforcing the idea that "La Nina = drought".

But let's look at this idea more critically.

It's an almost even distribution of El Ninos and La Ninas when you go back to 1950:

El Nino - 26
La Nina - 24
neither - 22

And then you'd think that maybe we've had more La Ninas in recent years, which is a reasonable hypothesis to explain why we have had a prolonged drought. But that's not really the case. Here's the distribution since 2000:

El Nino - 7
La Nina - 10
neither - 5

Maybe a slight skew toward La Ninas, but not enough data points to call that a trend. As my brother the meteorologist would say, there's more to the story... but what exactly is the story?

So let's start with what the inflows have been since 1963, and before Lake Powell, what the flows past Lees Ferry were. And you get a pretty clear pattern emerging:

1951-60 - 12.3 maf
1961-70 - 10.5 maf
1971-80 - 11.1 maf
1981-90 - 13.2 maf
1991-00 - 11.3 maf
2001-10 - 8.2 maf
2011-22 - 9.1 maf

1951-2022 - 10.6 maf

What you see there is some variation from decade to decade, with the 1980s being a high point, but then an obvious drop since 2000. Whatever is going on, it wouldn't seem to be explainable with just an uptick in La Nina events. But let's follow up on that a bit.

Here are the ten highest inflows since 1950, and what sort of season they happened in:

1983 - 21.8 maf - very strong El Nino
1984 - 21.6 maf - weak La Nina
1952 - 20.0 maf - moderate El Nino
1957 - 19.5 maf - neither
1986 - 18.4 maf - neither
1985 - 18.2 maf - weak La Nina
1962 - 17.0 maf - neither
2011 - 16.3 maf - strong La Nina
1997 - 16.2 maf - neither
1958 - 16.0 maf - strong El Nino

Well that looks inconclusive. But what you CAN see is that with the exception of 2011, all of these big years happened before 2000. An even finer eye would notice a 22-year period covering most of the 1960s and 70s (1963-1982) that had none of the top 10 inflows, a period that more or less coincides with the filling of Lake Powell. Remember it took 17 years to fill, when the original estimate was closer to 7. But that's a digression for the moment, just a simple reminder that there were recent times before just the last 20 years that were not as robust for snowpack and inflow as the 1950s or 80s, or even the 1990s were...

Okay, what about the flip side? What were the ten worst inflow years like? Here they are:

2021 - 4.0 maf - moderate La Nina
2002 - 4.1 maf - neither
1990 - 5.2 maf - neither
2013 - 5.3 maf - neither
2018 - 5.4 maf - weak La Nina
1977 - 5.6 maf - weak El Nino
2004 - 5.6 maf - neither
2022 - 5.6 maf - moderate La Nina
2012 - 6.1 maf - moderate La Nina
2003 - 6.3 maf - moderate El Nino

There perhaps it looks something a little more skewed toward "La Nina = less inflow", but again, not enough data points to really draw that conclusion. But what you can say with absolute certainty is that 8 of the 10 lowest flow years since 1950 have happened since 2000. Now that begins to looks something like a trend. And it looks like it takes more than the ENSO cycle to explain it.

By the way, if you're still thinking El Nino is going to save us, we've actually had 7 El Ninos since 2000. How good were those years? Well, a mixed bag at best, and nothing spectacular:

2016 - very strong El Nino - 9.9 maf
2003 - moderate El Nino - 6.3 maf
2010 - moderate El Nino - 8.8 maf
2005 - weak El Nino - 11.3 maf
2007 - weak El Nino - 8.1 maf
2015 - weak El Nino - 9.4 maf
2019 - weak El Nino - 11.7 maf

And remember, the best inflow year since 2000--which was 2011--was a strong La Nina!! So that seems to buck the conventional wisdom about El Nino vs. La Nina...

I could sit here searching for trends in the data, but without some high-powered model and a couple of PhD grad students, nobody's going to pick those out of the soup. To me, maybe the most interesting thing is this:

When you go back to 1950, here's the average inflow for El Nino, La Nina, and neutral years:

El Nino years - 11.2 maf
La Nina years - 10.4 maf
Neutral years - 10.1 maf

Again, nothing jumps out, except maybe this: maybe if you squint, it seems that perhaps extreme ENSO cycle conditions produce the most extreme results, either for better or worse. Sometimes we get great runoff with El Nino (as in 1983), and sometimes with La Nina (as in 2011). And El Nino years do seem to generally correlate with higher runoff, although the variation in that is huge. Honestly, there's not enough there to really draw any conclusive result... there has to be more to it the just El Nino.

But the one trend that remains clear--there has been less runoff since 2000. Could that be related to higher temperatures we've seen since then? And resulting drier soils and higher evaporation? Or shifts in precipitation patterns? These are certainly reasonable explanations, but above my grade to analyze in depth here... but whatever the cause, it’s clearly not really just about El Nino...

Once again the professor teaches us with simple facts. Thank you JFR for your insights and doing so in a simple way that even I, a caveman, can understand.

 

[ndscott50]

But the one trend that remains clear--there has been less runoff since 2000. Could that be related to higher temperatures we've seen since then? And resulting drier soils and higher evaporation? Or shifts in precipitation patterns? These are certainly reasonable explanations, but above my grade to analyze in depth here... but whatever the cause, it’s clearly not really just about El Nino...

Thanks for the info. It seems like El Nino is just one factor, that likely slightly increase the chances of a good year, but can easily be overcome by all the other factors, warming temperatures, dry fall, etc. I remember looking at this last fall to try and see if transition years, have any trends. I noticed years where we went from La Nina to El Nino appeared to have good snow. I think last year technically was La Nina but I think we were actually neutral by the middle of the season and in a slight El Nino by the end of the season. Over the last 60 or so years the transition winters are fairly rare so its not clear this is actually a factor. It would be interesting to see some research on this as its often more complicated then El Nino, Neutral, La Nina. Strength of each and how it evolves over the season likely have some impact.