WeatherExtreme Forecast Discussion 8/19/2017 0455Z

Short window open Saturday between storms. Clouds possible near FL150 early Saturday afternoon, lowering and thickening to a possible FL85 to FL115 layer. Surface winds westerly during the afternoon. Wave looks best between 16Z and 18Z, with mountain wave possibly extending up to secondary wave. The core of the 200+ kt polar jet is just north of El Calafate. Wednesday still looks like the next flying day, with storminess returning Thursday

WeatherExtreme Forecast Discussion 8/17/2017 2015Z

Saturday offers the best hope of flying until Wednesday. A 984 millibar low moves onshore west of El Calafate on Friday morning, spreading light snow across the area, with one or two centimeters in the early morning, with a few flurries possible throughout the day Friday. Clearing overnight with west winds at the surface backing to 50 kts from the west-southwest at FL200 and increasing to more than 100 kts higher in the column. The polar jet core will be positioned just north of El Calafate on Saturday with highest level winds exceeding 150 kts, supporting a vigorous secondary wave.

Another storm spreads inland overnight and during the day Sunday, with an extremely intense 960 mb passing by the southern tip of South America on Monday. Precipitation looks like it will start as snow on Sunday, changing to rain on Monday. The complex series of storms finally exits the region Tuesday, leaving Wednesday as the next flying day. Thursday is a possibility, too, before the next system arrives.

WeatherExtreme Forecast Discussion 8/15/2017 0545Z

Moist westerly flow combined with a weak frontal passage should bring showers or light rain at various times throughout the day Wednesday, with only weak wave action expected. As a low system passes north of El Calafate surface winds turn east on Thursday and El Calafate is likely to be in a upper level col region Friday through early Saturday, with light, confused winds aloft. Friday through Sunday looks wet, except for Saturday, possibly. Upper level winds on Saturday northerly at low levels, westerly aloft.

WeatherExtreme Forecast Discussion 8/15/2017 0500Z

As the shortwave energy exits to the Atlantic, Tuesday should bring decent flying weather early, but with strengthening surface winds and lowering clouds in the late afternoon. Some occasional showers overnight Tuesday into Wednesday Friday and Saturday find El Calafate situated in a col between a low to the southeast and a trough to the northwest,with most energy going north and south, leaving it in a region of light winds both at the surface and aloft. Mostly cloudy with light rain or snow.

WeatherExtreme Forecast Discussion 8/14/2017 1445Z

Scattered lower clouds early, with higher wave clouds forming later. Winds mostly westerly to south-southwesterly at all levels, 10-20 kts below FL80 and 30-60 kts above that level. Tuesday should bring decent flying weather early, but with strengthening surface winds and lowering clouds in the late afternoon.