Altostratus typically signals widespread precipitation on the way.
Tips
memory
Cloud taxonomy in Chinese is built systematically: 高 (high) + 层 (layer) + 云 (cloud) = altostratus. Compare 高积云 gāojīyún (altocumulus), 卷云 juǎnyún (cirrus), 积雨云 jīyǔyún (cumulonimbus). Once you know the morphemes the names self-decode.
