Synonyms for Impend:

n.

hover, threaten, menace. overhang, hang over, brew, lower.

v.

approach (verb)
come, near, close, threaten, advance, loom, approach, gain, access, converge.
brew (verb)
develop.
ensue (verb)
develop, eventuate, follow, ensue, destine, result.
hang (verb)
hover.
impend (verb)
advance, loom, brew, lower, approach, hang over, menace, overhang.

Other synonyms:

brew. overhang. lower. threaten. endanger
threaten.
Other relevant words:
hover, menace, brew, overhang, lower, hang over, threaten.