a storm resulting from strong rising air currents; heavy rain or hail along with thunder and lightning
"The sudden drop in temperature triggered an intense thunderstorm that dumped hail on the highway within minutes."
A storm consisting of thunder and lightning produced by a cumulonimbus, usually accompanied with heavy rain, wind, and sometimes hail; and in rarer cases sleet, freezing rain, or snow.
"The sudden onset of a violent thunderstorm forced us to rush inside just as hail began pelting the roof."