Today on the short geocaching trip I've barely escaped hail storm. It wasn't very long, but I was without any special equipment. Light umbrella would survive a few minutes, and my jacket would provide a limited protection from water for a short period of time.
What are the strategies to deal with such situations? Look for the protection of big tree (yes, I know, thunders, but staying on open ground is not a good idea either)? Search a thick bush? Improvise some umbrella from sticks and leaves?