The second storm in this series remains on track this Wednesday morning, with modest totals expected in the Andes over the next few days. Las Lenas still has the potential to see bigger snow totals, given the period of easterly winds, with snow lingering through Saturday morning. 

The expected snow totals for most of the region haven't changed since Monday, with 8 - 16 cm in the southern half of the central zone. Totals will drop off in the northern part of the central zone and for most of the northern zone as well, with < 10 cm is expected.

The upper-level low lingering off the northern Chilean coast will bring a period of easterly winds to the Argentinean side of the northern zone. I expect winds out of the southeast at lower elevations backing to the northeast up high. This will produce greater orographic snowfall on the eastern side of the Andes in Argentina, especially at Las Lenas. 

As I mentioned in the last post, this wind pattern is not that common in this region, and is the result of a closed-off upper-level low above a strong area of high pressure, as you can see below.

The general wind directions around high-pressure (counter-clockwise) and low-pressure (clockwise) systems are indicated. Remember, these are the opposite of the winds in the northern hemisphere. 

Below is an animation of the winds on Friday. The areas of high and low pressure in the mid-levels are displaced somewhat from the upper-levels, but you can see a similar flow around them. As the winds circulate counter-clockwise around the eastern side of the high pressure, they interact with the continent and Andes range which ultimately leads to easterly winds near Las Lenas in the northern zone. The forcing on the Chilean side is very weak.

The end result of these easterly winds will produce enhanced orographic snowfall in the Argentinean Andes in the northern zone, which you can see in the latest snow forecast from the European model below.

The heaviest snow will fall Thursday morning through Friday afternoon, and 20 - 40 cm is possible. Temperatures will be falling during this period and winds won't be too strong. Friday is looking like a really good powder day at Las Lenas. The Chilean resorts in the north won't see much action during this time given the weak mainly northerly winds. 

Things will clear out in the central zone by Thursday night and by Friday night in the northern zone, though snow showers may return Saturday night through Sunday there.

The upper-level low will stick around for several more days before moving off to the east, keeping the chances for snow showers going in the northern zone through the weekend. A few inches are possible at Portillo and Valle Nevado during this time. 

The region will see another high pressure develop in the south on Friday and last through the middle of next week. The models diverge on the storm track around that time, with some keeping the storms to the south while others would bring storms through the central and southern zones. Next update on Friday.

Thanks for reading the South America Daily Snow!

Luke Stone
Forecaster, OpenSnow

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