Maybe a microburst [0] of air from a developing thunderstorm? Basically, an extremely powerful downward burst of cold air. Seems to have killed birds in the past [1]. This is absolutely terrifying during takeoff/landing inside an airplane [2].
[0]: https://www.weather.gov/ama/microbursts
[1]: https://lancasteronline.com/news/local/mystery-solved-unusua...