WeatherExtreme Forecast Discussion 9/11/2017 06Z

Monday has mostly westerly winds aloft, but a trough stretching to the northwest of El Calafate could shift the winds to the southwest depending on its exact positioning. The primary wave decreases substantially by 17Z, so it’s best to get above FL460 before that time. Wednesday brings excellent updrafts (and precipitation) in the pre-dawn hours, but in the morning hours the winds shift from westerly to southwesterly and then to southerly as a deep trough digs northward across South America. As the winds swing around the updrafts all but disappear. Thursday afternoon brings more clouds and precipitation to El Calafate

WeatherExtreme Forecast Discussion 9/10/2017 0520Z

Not much to update from last discussion. Conditions for flying will be generally favorable on Sunday, but lower and mid-level lift will be light to moderate at best. On Tuesday an intense low pressure system moves south of El Calafate, bringing some light rain to the area, then more light rain moves into the area Turesday through Wednesday as a longwave trough settles over southern South America and keeps a moist westerly flow going the rest of the week.

WeatherExtreme Forecast Discussion 9/8/2017 2230Z

Saturday has a weakening trough to the west with light northwesterly winds at the surface shifting to westerly aloft, generally 50 knots above FL200 and less than that below. Extensive wave clouds present in the afternoon with moderate to strong updrafts at most levels, but with weakness near FL400. A weak frontal system comes onshore Sunday, but should only produce a few low level clouds at El Calafate, with easterly surface winds in the morning, shifting to westerly in the afternoon. A more significant storm moves in overnight Monday into Tuesday, with weather generally unsettled with rain or snow through Saturday.

WeatherExtreme Forecast Discussion 9/6/2017 2240Z

Light and variable winds and some widely-scattered drizzle or light rain Thursday morning. Winds aloft northwesterly above FL100 with broken low- to mid-level clouds. Weak updrafts early, changing to moderate updrafts at all levels in late afternoon. Some light rain or snow overnight Thursday into Friday. Pre-frontal conditions Saturday with light northerly surface winds shifting to stronger westerly winds aloft.

WeatherExtreme Forecast Discussion 9/5 0515Z

A front moves ashore on Tuesday and brings some light rain or snow flurries to El Calafate. Wednesday is a pre-frontal situation with good lift at high levels but unfavorable wind direction and weak lift at lower levels. Thursday brings rain changing to snow on Friday morning. Clearing Friday afternoon but once again pre-frontal, with favorable upper winds but unfavorable low level winds.