What is it called when it's snowing with the sun out?

sun snowburst?

The meteorological definition of a snowburst is as follows:

"A short period of heavy snowfall, say on the order of 10-14 hours or so with snowfall rates around two inches per hour and greater. It is believed that snow frequently forms and falls out within "short" distances - say hundreds of feet. There is a tendency for the larger flakes to fall out closer to the shore."

NOAA defines snowburst as:

"Very intense shower of snow, often of short duration, that greatly restricts visibility and produces periods of rapid snow accumulation."

Wikipedia