"Get snow on top of all houses, businesses, municipals, and trees. Light up all houses and decoration trees in your city! Come spring time, March 20th 2011, the snow will melt."
The Snow Top is a theme that costs 
500 Coins and added snow to the top of the buildings in your City.
It was released during the Winter Event (2010) and was unlocked for purchase after completing the 
Winter Wonderland Goal.
To remove this theme from your city, you needed to buy Remove Snow Top. Otherwise, the snow melted on April 7th, 2011.