YAHWEH, JEHOVAH, LORD.
Hebrew was written with consonants only, most of the vowels being left out of the words. As long as there were many well-trained people to read a language without vowels, there was no problem.
Out of reverence for the divine Name the Jews stopped pronouncing it altogether some 2400 years ago. This custom of never saying the divine Name whenever it occurred led, over the centuries, to the loss of any memory of what the original vowels were.
To this day, no one knows for certain what the real vowels are that should go with the consonants JHVH.
What complicates the problem even further is the fact that when the Jews stopped pronouncing the divine Name, they developed the custom of saying Donay (LORD) every time they saw JHVH written down. When Jews scholars in Alexandria, around 250 BC, translated the Hebrew Bible into Greek, they also translated what was read Donay (LORD) and not what was written JHVH. So whenever they came across the divine Name in the Hebrew text, they translated it as KYRIOS (LORD).
Sometime in the Middle Ages, Jewis scholars felt the need to put vowel signs in the consonant text of the sacred books. But they put the vowels of DONAY which was to be read around the consonants JHVH which were written. The jewish scholars and readers knew that the vowels of DONAY had been combined with the consonants of the divine Name, but some Christians did not know this. So they began the tradition of reading the divine Name JHVH with the vowel signs of DONAY, with the resulting hybrid name JEHOVAH. Jehovah, therefore is not the correct pronunciation of the divine Name revealed to Moses in Exod 3:14-16.What about Yahweh, is it the correct pronunciation? At present it is an educated guess, and nothing more.
Fr. Cipriano Bontacchio