WeatherExtreme Forecast Discussion 9/02 1345Z

Saturday, Sunday and Monday all look like possible flying days before the next front moves in on Tuesday. Monday would probably be difficult because the pre-frontal conditions bring too much of a northerly component to the wind, both at the surface and aloft. The storm Tuesday doesn’t appear to do much more at El Calafate than ruin flying conditions. Wednesday provides a brief respite before a more significant front comes ashore early Thursday morning with some rain possible in El Calafate. Depending on the low level winds, Wednesday could be a flying day, upper winds are difluent over Patagonia and may add to the lift.

WeatherExtreme Forecast Discussion 8/31 2025Z

A weak cold front exits the region Saturday morning leaving partly cloudy skies and westerly winds behind in its wake. The polar night jet should be positioned somewhat south of El Calafate with 175 kt winds at the 10 mb level, but a small shift in the position could make a big difference for flying. As of now updrafts look only modest on Saturday, at best, but that could change if the position of the westerlies shifts northward. Sunday is a mixed bag, winds aloft improve and there will presumably be better updrafts, but clouds may make flying conditons marginal, with overcast below FL100. Monday is pre-frontal and may be better, but wind direction will be crucial, and right now it’s looking too northerly.

WeatherExtreme Forecast Discussion 8/26 1450Z

Front and associated low dissipates off the west coast over the next couple of days. While the surface front weakens the associated upper low and trough moves north of El Calafate Monday, turning the upper winds to a southerly direction. As the weak trough and upper low past generally north of the area on Monday and Tuesday, models are forecasting generally westerly upper level winds, however the direction will be determined by the exact path of the trough passage, and small deviations to the path could result in large swings in upper winds at El Calafate. Upper winds become briefly westerly again mid-day Wednesday with the passage of a dirty ridge over the area. Another stronger frontal system develops and comes onshore Friday, bringing rain to El Calafate in the Friday-Saturday time frame.

WeatherExtreme Forecast Discussion 08/23/2017 0545Z

Another weak front moves in late Wednesday, bringing lowering clouds and east winds at the surface. A few rain showers Wednesday afternoon possibly turning to snow flurries during the night night. Clearing and winds turning westerly Thursday afternoon, with a possible flying opportunity. Still another storm brings rain or snow late Friday into Saturday.

WeatherExtreme Forecast Discussion 8/22/2017 0445Z

A deep 946 mb low passes south of South America on Tuesday. A cold front trailing behind it weakens as it interacts with the Andes and remains almost stationary. Wednesday brings another, weaker cold front to the west coast, bringing northerly winds ahead of it. Another cold front moves in overnight Wednesday and early Thursday, bringing light snow to El Calafate. Clearing and winds turning westerly Thursday afternoon. Still another storm brings rain or snow late Friday.