1903 J. Fox iv. 59 Send us, not a gentle sizzle-sozzle, but a sod-soaker, a gully-washer. Give us a tide, O Lord!
1961 36 153 An old farmer looked at the threatening sky..and said, ‘It's goin' to be a gully washer and a chunk floater.’
1969 22 Aug. 4/6 Other two-word names for a heavy rain [are]..gully-washer, [etc.].