The pronunciation 'Yahweh' is not based on the Hebrew language, or the meaning of His name. The 'weh' part of Yahweh is based on a Samaritan substitution word for His name and the writings of the 'Latin Fathers (2 groups that did not keep the way of YHWH.)' In the 19th century a linguist/historian named Wilhelm Gesenius (1786–1842) suggested 'Yahweh' as the most probable pronunciation. Most scholars and religious leaders base their pronunciation of YHWH on his work.
1) For the pronunciation for the first part of the name he recognized that there are many names that have 'YaH' and 'YaHW/YaHoo' as a shortened name for YHWH.
2) For the pronunciation of the last part of the name we can look at the first part of the name. The 'H' or Hebrew letter 'Hey' makes the sound 'ah' so we have YH = Yah the last 'H' is the same 'ah'. The 'W' or Hebrew letter 'Waw' makes the 'oo' sound. Yah-oo-ah. We can also go to the word 'Judah' or 'Yahudah' in Hebrew. It has the same letters except for a letter D. i.e. YHWH -YHWDH. Yahudah is pronounced - YaH - OO - Dah. Take out the letter D and we have 'Yah - oo -ah.'