South America Average Snowfall and Drought


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When do years of below-normal Andes winter snowfall start to lower long-term average snowfall?

I have casually looked at Portillo, Vallee Nevado, Las Lenas and Bariloche over the years - and notice there have been few banner years since 2000 and many abysmal. This year the Vallee Nevado YTD snowfall is 20 inches?!!

Is this a new norm? It looks similar to the long-term droughts of New Mexico and Arizona.

This site is a copper mine at 9,000 feet between Portillo and Valle Nevado. It confirms my belief that the last above average season was 2009. The data is through 2018 but we know that 2019 and 2021 are horrible. Could 2021 rally like 1991 in California? Don't bet on it. By the end of July Santiago has normally received 68% of its season precipitation vs. 51% by the end of January in Los Angeles. It is extremely rare to see a big dump in the Central Andes after the "Santa Rosa" period of late August/early September.

2020 had a lot of snow in June but the rest of the season was lean and it was clear from Portillo stats by late August that 2020 was going to end up below average too.

As bad as the last decade has been, note that 1958-1969 wasn't so good either. The volatility of Central Andes snowfall makes California look like a model of consistency. Mammoth''s standard deviation as percent of average is 36%. Taos' is 29% and Arizona Snowbowl's is 39%. Portillo's from 1970-2007 was 56%. Portillo is the only ski area down there with reliable measuring. Its website posts season-to-date when the ski area is open, which it is not in 2021.

Here's Taos 1973-2021 for comparison:

And Southern California:

Unlike Taos and the Central Andes, SoCal ski areas can get rain and the 2011, 2017 and 2019 seasons were much worse than that graph implies due to excessive rain.

On an absolute basis the Central Andes are far worse than Taos and SoCal in recent years. But the trend lines are similar due to those bad years in the early years of the Lagunitas graph. And Taos' data happens to start in its record high year while 2018 was its record low year.

Those late 50's/early 60's years were not good in at least some of western North America either.

The Alta Collins site within the ski area only goes back to 1980-81 so you need to use the Utah Dept. of Transportation stats from the base for a longer dataset. Note that Alta had only one above average season from 1953-1963 just as it's had only one in the past decade.

Returning to the suspicious latitudes of 33-35, here's Los Angeles rainfall:

Notice how dry 1945-1964 was.
ChrisC":1y0af852 said:
When do years of below-normal Andes winter snowfall start to lower long-term average snowfall?
For the direct answer to that question, it depends on how long the dataset is as a long dataset will lower its average more gradually.

So for the above examples:
Lagunitas, Chile since 1958: 353; Up to 2009: 373; 2010-2018: 236 (-33%). That 236 number won't improve by adding the past 3 years. 1958-1969: 285 (-19%)

AltaGuard, Utah since 1946: 486; Up to 2011: 502; 2012-2021: 380 (-22%) 1953-1963: 411 (-15%)

Taos, NM since 1973: 254; Up to 2010: 265; 2011-2021: 215 (-15%)

SoCal Ski Area Estimate since 1969: 126; Up to 2010: 135; 2006-2021: 106 (-14%)

LA Rainfall since 1878: 14.65; Up to 2005: 15.10; 2006-2021: 11.07 (-24%) 1945-1964: 11.46 (-22%)

Here's another disturbing situation:
Alyeska mid-mountain since 1979: 475; 1979-2013: 521; 2014-2021: 300 (-37%)
Alyeska top lift service since 1979: 636; 1979-2013: 655; 2014-2021: 553 (-13%)
This looks like an issue of rising rain/snow line.

What any of this means is still speculative. The Chilean data for the last 12 years is horrible, but we know that precipitation volatility down there is much higher than in North America.

The Alyeska divergence between top and mid was only 6 years 2014-2019 but it was dramatic. The ratio of mid to top in each of those years was lower than any single year before 2014 and averaged 48% vs. long term average of 75%. But that ratio was 74% and 73% the past two years.
Here's a new grim chart from CaseyE on TGR:

Upper chart is Santiago precipitation deviation since 1950, thin lines being entire year and colored bars being winter only.

La Parva closed on Aug. 8 and Chillan on Aug. 13. Chillan's base today is 4-27 inches with 11 inches new and another 4 feet predicted the rest of this week. But the rain/snow line is at or just above resort level so odds of a reopening aren't all that great.
Great stats as always.

Las Lenas is on my bucket list for some year, but I am never going to book anything until there is a reasonable base.
The resorts dependent upon international tourists, Portillo, Valle Nevado and Las Lenas, have not opened at any time the past 2 seasons due to COVID. Considering that 2019 was almost as sparse for snow as this year I have to wonder about the finances at these places.

It's hard for me to believe that the proposed Cerro Punta Negra ski area in this same climate zone (upper Uco valley, across the Andes from Santiago/Valle Nevado) will ever move forward.
These pictures say it all for South America weather volatility:

Yes that looks like actual skiers on the lower slopes of Las Lenas after last week's dump of 2-3 meters. Will any upper lifts open? I’m actually surprised to see anything open. Who can get there on short notice? No one from outside Argentina AFAIK. No surprise Las Lenas’ own website as well as consolidator websites like OnTheSnow and snow-forecast still show Las Lenas as closed.