[frenchyatwork]

In English, Wuhan is typically pronounced with a "w" (/wuːhæn/ or /wuːhɑːn/), see https://en.wikipedia.org/wiki/Wuhan.

[HKH2]

In Mandarin, it's pronounced like the latter. You can definitely hear a 'w' sound.

[thaumasiotes]

> You can definitely hear a 'w' sound.

Compare "han wudi de muzang" here: https://www.youtube.com/watch?v=t9TeG6MdbmY#t=117

Or "wuhan de yi tian" here: https://www.youtube.com/watch?v=cWw6emkxmos#t=82

Or "yi zuo shi da wuhan" here: https://www.youtube.com/watch?v=cWw6emkxmos#t=66 (same video as above, earlier timestamp)

[HKH2]

You can argue it's not as strong as a 'w' in English, but it's definitely there, enough to justify saying 'a' instead of 'an'.

[frenchyatwork]

This is kind of complicated because [u] is a rounded vowel, so it's slightly "labialized" even if it's not preceded by [w].

Additionally, English spelling rules are complete insanity, and if an English speaker sees "uhan" they'd probably pronounce the 'u' as [ju:].