This one ?

Prunus 'Autumnalis Rosea' is a small deciduous tree of spreading habit with ovate leaves turning yellow in autumn, and pale pink, semi-double flowers opening during mild weather from late autumn to early spring.

There is also a winter Cherry tree also, Prunus subhirtella ‘Autumnalis’. It normally flowers in late Dec, early Jan - depends on weather, location etc. That one is pink. The Tibetan Cherry tree is also winter flowering and has that red peeling bark that some people like (I think it looks messy)