cloudburst

Etymology

cloud + burst

noun

1. A sudden heavy rainstorm.
   [B]ut the sound . . . expressed an utter abandonment to grief; not the cloud-burst of some passing emotion, but the slow down-pour of a whole heaven of sorrow. 1899, Edith Wharton, “A Cup of Cold Water”, in The Greater Inclination
   A cloudburst in the China Creek district followed by continued heavy rains was responsible for the increased water. 1908, Stewart Edward White, chapter 38, in The Riverman
   In Uniontown, Pa., John Walchesky & family rushed from their house when lightning set it afire, rushed in again when a cloudburst put out the blaze. Aug 17 1936, “Miscellany”, in Time, retrieved 2014-05-20
   [H]e walked across the lawn, wet from a fleeting late-afternoon cloudburst, the first rain in a month. 2007 Feb. 25, Norman Howard, "Devotion, chapter 1" (book excerpt), New York Times (retrieved 20 May 2014)