Then on December 21 a sudden thaw accompanied by heavy rains caused landslides and flooding.
(a sudden thaw; accompanied; by heavy rains) (a sudden thaw accompanied by heavy rains; caused; landslides and flooding; T:Then; T:on December 21)
a sudden thaw a sudden thaw accompanied by heavy rains
accompanied caused
by heavy rains
landslides and flooding T:Then T:on December 21