affluence
afflux
affluxion
brash
burst of rain
cascade
cataract
chute
cloudburst
collapse
comedown
concourse
confluence
conflux
course
crash
crosscurrent
current
debacle
declension
declination
defluxion
deluge
descending
descension
descent
down
downbend
downcome
downcurve
downfall
downflow
downgrade
downrush
downtrend
downturn
downward trend
drencher
drift
driftage
drop
dropping
fall
falling
flood
flow
flowing
fluency
rain
rainfall
rain cats and dogs
barrage
blizzard
bombardment
cannonade
clamor
drizzle
drought
drumbeat
fusillade
gale
gust
onslaught
rainstorm
shower
sleet
snowstorm
squall
tempest
thunderstorm
tornado
torrent