[Not by Michael Snow; this is a link for an article by Glenn T. Stanton]
From the Gospel Coalition
FactChecker: Does ‘Abba’ Mean ‘Daddy’?
In the Aramaic language of the time of Jesus, there was absolutely no other word [than Abba] available if Jesus wished to speak of or address God as father. … it [Abba] is… the only possible form!
See full article
Be sure to read the “Comments” there for a clearer understanding.