/a/ vs /)/

[Rudolph C Troike]

Terry,

        My thought is that if you are trying to define an "underlying"
vowel, it makes most sense to take a historical point of departure. The
orthography is often a good clue on this, though it may reflect a state of
affairs anterior to the point from which you wish to depart (presumably,
the point of settlement on the east coast from which interior settlements
derive, unless otherwise historically derived). The spelling would
indicate that all of the "short o" words had a low back rounded
pronunciation at one time, and probably the historical evidence and
regional distribution in England would support this. The /a/ in <wash>,
<water> is certainly historically earlier, with rounding due to the /w/.

        Rudy