I think (stress, think) that the Sky Harbor weather station is automated, and can detect that there is precipitation falling, but sometime not the type. So when it could be rain or snow, the observation is "unknown precip."

That said, at 43 degrees I can't imagine it would be anything other than rain.

I drove into Duluth twice today - both times, it was snowing steadily at my house a few miles north of town, changed to rain mid-trip, changed back to snow briefly, and then back to rain as I neared the hill. Awesome.