Not kousa. The bracts on kousa are pointed, not rounded. I'd guess one of the many hybrids now on the market, based on the flowering after the leaves have emerged and the extra bracts. Perhaps 'Eddies White Wonder', a cross of C. florida and nuttallii and can produce 4-6 bracts per flower.

Thanks, gg.

Going by images on the web, it isn't 'Eddies White Wonder'. The bracts are too small, but it does have similarities to C. nuttallii.

The bract size on Eddies is variable......not always as large as standard literature reports :-) Also C. nuttallii is not widely grown outside of its native range. In fact, it is rarely even seen here (where it is native) in a cultivated or garden setting, as it dislikes those conditions.