howling vs phenomenal

howling is a noun but phenomenal is not a noun.

Word	Noun	Adjective	Verb	Adverb
howling	Yes	Yes	No	No
phenomenal	No	Yes	No	No

As adjectives, howling and phenomenal are synonyms defined as:

howling and phenomenal: extraordinarily good or great; used especially as intensifiers

Other synonyms of howling include fantastic, grand, marvellous, marvelous, rattling, terrific, tremendous, wonderful, wondrous.

howling (noun)	phenomenal (noun)
a long loud emotional utterance

howling (adjective)	phenomenal (adjective)
extraordinarily good or great; used especially as intensifiers	of or relating to a phenomenon
	extraordinarily good or great; used especially as intensifiers