southerly vs southward

southerly and southward both are nouns.

Word	Noun	Adjective	Verb	Adverb
southerly	Yes	Yes	No	Yes
southward	Yes	Yes	No	Yes

As adverbs, southerly and southward are synonyms defined as:

Other synonyms of southerly include southwards.

southerly (noun)	southward (noun)
a wind from the south	the cardinal compass point that is at 180 degrees

southerly (adjective)	southward (adjective)
from the south; used especially of wind	moving toward the south
situated in or oriented toward the south

southerly (adverb)	southward (adverb)
from the south	toward the south
toward the south