The official 2023 Winter forecasts for Chile and Argentina were released last week, and that will be the main focus of today's post. As is the case in North America, ENSO (El Niño/La Niña) conditions impact the temperature and precipitation during the Winter months in South America. Currently, the sea surface temperatures in the equatorial Pacific are warmer than normal, and with the typical atmospheric response, El Niño conditions have been reached. Models suggest that not only will the El Niño conditions continue, but likely intensify, with sea surface temperatures rising during the South American Winter.

Below is a figure showing sea surface temperatures and the atmospheric response to the ocean, one many of you have seen before. Due to the warmer surface and sub surface temperatures in the equatorial Pacific, the general atmospheric circulation changes. This eventually impacts the jet stream, which determines the storm track, and what region ultimately receives more rain/snow.

Generally, El Niño results in warmer and wetter conditions in both Chile and Argentina. The same disclaimers that apply to North America are pertinent here too. Warmer and wetter conditions during El Niño represent an average across all Winters with these conditions. Some of these El Niño Winters saw below normal precipitation and/or below normal temperatures, and either of those conditions could happen this year too. Ultimately though, it is more likely that Chile and Argentina will have a warmer and wetter than normal season.

Now let's review the predictions from the national weather service agencies of Chile and Argentina. These predictions follow the general expectations for El Niño winters, with some minor adjustments. Let's take a look at Chile, first, with the seasonal forecast for temperature.

This figure shows the forecast for minimum and maximum temperatures for June, July, and August. For most of Chile, the national weather service is predicting above normal temperatures. However, they expect normal or below normal temperatures for the central zone, opposite to the rest of the country.

Chapa Verde, Alto del Padre, Nevados de Chillan, Antuco, Corralco and Araucalrius have the best chances of having a colder than normal Winter. Meanwhile Pucon, Antillanca, Volcan Orso, La Parva, Valle Nevado, El Colorado, Farellones, Lagunillas, and Portillo have a lesser chance of below normal temperatures.

For precipitation, the national weather service predicts most of the region to be normal or above normal this Winter. However, there are a few narrow areas where normal or below normal precipitation is expected, as seen in the figure below. 

(Note that 'about' should say 'above' in the figure)

Since the Andes are such a narrow mountain range, and Argentina spans a similar territory longitudinally, similar conditions are expected this Winter, as seen in the figure below.

Regarding temperatures, the national weather service of Argentina predicts normal temperatures this Winter, except for the northern region, at resorts like Las Lenas, Los Puquios, and Los Penitentes, where above normal temperatures are expected.

The national weather service of Argentina is forecasting normal or above normal precipitation for the northern mountains, with greater chances for wetter conditions in the central and southern zones, especially near Cerro Bayo, Cerro Catedral, Chapelco, La Hoya, and Perito Moreno. 

Well there you have it, folks. Most areas are forecast to be warmer and wetter than average, which typically is good news, as most storms will feature a cold front that will produce a lot of good quality snow. There may be some storms that are warmer than we'd like, but overall this forecast is good news. 

I will be back on Friday with an update on the weather.

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