Falling snow possibly sublimating before reaching the ground from cumulus congestus cloud due to very cold airmass contrasting with the much warmer sea surface temperature. Another photo illustrates this showing what seems like a non-complete line of falling precipitation. Such clouds may have been part of a cloud street which were initiated by the so called sea-effect precipitation which is very similar to what happens in the Great Lakes of the USA. The weather situation is explained here `Graupel shower video`. Of course a surface low pressure had formed due to this contrast between the cold air and warm sea. Max Temp was only 8C while MIN fell to 4C.