Hi all. For years, family members have been debating why my dad pronounces certain words in a way we haven't heard before, and I was hoping to call on you experts to finally put this to rest. The main "unique" pronunciations we hear from him are as follows (apologies for not knowing IPA, I hope my explanations will still be clear).
-Wash pronounced as why-sh
-Days pronounced like Mon-dee, Tues-dee, etc.
-Partner pronounced like pard-ner (this one I've actually heard before...from TV cowboys)
In particular, I've never heard a single person say wash the way he does. He's lived in the same town for most of his life, other than 6 or so years in a neighboring state for college. I've never heard anyone else in these regions pronounce these words like this. We jokingly call it his cowboy accent. I'd love to hear any insight you have into these pronunciations! I didn't mention where he's lived to avoid biasing responses, but I can share if people think it's necessary. For extra context, he's a native speaker of American English and doesn't have a brain injury or anything like that that would affect his speech.
ETA he spent the majority of his life in Boise, Idaho with a couple years in Oregon in his 20s.