Cumulonimbus arcus praecipitatio (pano I)
First arcus cloud I captured and I see like this. When I climb the little Turó de Can Mates, at Sant Cugat, I didn't realize that was coming. Once up there I appreciated its fast movement and after the pictures I start running to my house and warning the other people in the streets to run away. It finally did caught me and it was a really heavy, but short, storm.
My (mini-home-notveryprecise) meteorological station registered gusts from SW up to level 6 in Beaufort scale, 988hPa (maybe there was more wind but it is not a real meteorological station of any agency...)