South America Daily Snow

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By Luke Stone, Forecaster Posted 6 months ago August 16, 2023

Atmospheric River to Unleash Massive Snow in the Andes

Summary

There's just a few times a year, if that, where the models are showing the insane snow totals they are right now. We have a warm storm impacting the region today and tomorrow, before the real action begins on Friday. A series of moisture rich storms will barrel through the Andes for the next seven to ten days, bringing the biggest snow totals of the year.

Short Term Forecast

We are looking at some exceptional snow totals possible during the next week plus. Let's focus on the pieces coming together that will allow these storms to deliver so much snow. 

First, we have an active and progressive upper level pattern setting up over the region. A series of low pressure systems, which bring stormy conditions, will move through the Andes, as seen below.

The blue areas are associated with areas of low pressure in the atmosphere, and storms typically form in these regions of low pressure. You can see one after another storm, seemingly non stop, target Chile and Argentina. 

In addition to the series of storms, there is abundant moisture available to these series of storms. You can see this in the precipitable water figure below, with a strong plume of moisture extending from the tropics to the Chilean coast. 

This gif shows the water available in the atmosphere that the storms have access to. For the first active period from Friday to Wednesday, this atmospheric river will provide plenty of moisture. 

Let's take a look at the mind-boggling precipitation potential in another way. Below is the precipitation anomaly for the next ten days. 

Compared to climatological averages, most of the resorts in the Andes are forecast to receive greater than 125% of the normal precipitation during this time. The scale stops at 125% however, with the true values falling somewhere between 125% to 600% of normal!

Further, all three major models agree on absolutely daunting precipitation totals during this period. The American, European, and Canadian models all show a large area of over 500 mm, or 50 cms, or nearly 20 inches of precipitation. Once again, the scale stops at 500 mm, with some of the true totals falling between 500 mm and 1100 mm. 

While some of this rain/snow is expected in the seven to ten day period, where model accuracy is significantly lower, most of it is falling between days two to seven. Generally, the temperatures will be cool enough for mostly snow at most resorts during this time as well.

This series of atmospheric river fueled storms has the potential to drop 1 - 2 + meters, with the northern resorts like Portillo, Valle Nevado, and Las Lenas, and higher elevation central resorts like Nevados de Chillan and Corralco favored. 

I will have a more detailed post with totals on Friday. 

Extended Forecast

The models are showing another round of storms starting around the 25th, so this could wind up one of the snowier ten day periods in recent memory. 

Thanks for reading the South America daily snow! Follow me @lstone84 on Instagram to check out some new content I will be creating for the North American summer months. 

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About Our Forecaster

Luke Stone

Forecaster

Luke Stone earned his M.S. in Atmospheric Sciences from the University of Utah, with a research focus on seasonal forecasting. Luke has scored deep days around the world, including coast-to-coast across the United States, Canada, and Europe.

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