carto - How do you change the data type of a column for a synced table?

A synced table I setup against the 311 dataset at data.cityofnewyork.us works great!

However, the date columns come over as string, preventing me from doing date functions in queries, and from using the date columns in a Torque visualization.

I successfully issued an ALTER TABLE command to change the data type to date, but when the table is synced against source, the date columns revert back to string.