Jim McKenney wrote -- Spanish vowels are technically divided into strong vowels (a,e, o) and weak vowles (i, u). How Textbook! No one ever considers the Y. In Spanish, the Y is a vowel. But when it precedes another vowel in the same syllable it is pronounced as a palatal glide. This is not unlike English, where the Y is considered a semi-vowel. In English the Y is treated as a palatal glide only when it is [part of] the opening sound of a syllable; elsewhere it is treated as a vowel.