Re. closed passes: I frequently drive around the Dolomites and Austrian Alps in winter ski season and almost all passes and through routes are kept open/cleared promptly, even after substantial snowfalls. Driving basic rental cars, on dozens of trips, I have only ever needed snow chains once (Arlberg Pass 23 years ago).
A minority passes are not kept open in winter. Those which are classed as in operation will be opened within a few hours unless there is a huge fall.
In December a few years ago I was returning from Italy to Innsbruck Airport, over the Brenner Pass, in heavy snow. Traffic flowed freely at 80kph, following teams of snowploughs 3-abreast at 5 minute intervals in both directions. The road surface never got the chance accumulate more than a few mm of snow.
In May it's possible that some passes may still be closed but with those that are intended to be open I think the chance of disruptions are pretty small.
A minority passes are not kept open in winter. Those which are classed as in operation will be opened within a few hours unless there is a huge fall.
In December a few years ago I was returning from Italy to Innsbruck Airport, over the Brenner Pass, in heavy snow. Traffic flowed freely at 80kph, following teams of snowploughs 3-abreast at 5 minute intervals in both directions. The road surface never got the chance accumulate more than a few mm of snow.
In May it's possible that some passes may still be closed but with those that are intended to be open I think the chance of disruptions are pretty small.