Snow can fall when air temperatures near ground level are higher than freezing because air has a very low specific heat. It takes very little heat energy to raise the temperature of air, and very little heat energy has to be given off to cool the air. Another way to see (or feel) that is when you take a cake out of a hot oven. If the oven is set to 400°F, the cake, the pan, and the air inside the oven will all be heated to 400°F. If you touched the cake or the pan with your finger you would get a burn, but the 400°F air touches your skin without burning you. It feels hot, but as long as you do not leave your hand in the oven too long, you are not injured.

The same thing happens in with the snow. Up in the clouds, it is cold enough to form the snow. As each snowflake falls through the warm air, it is similar to your hand reaching into an oven. The snowflake is warmed slightly, but it does not get enough heat energy from the air to melt the ice. In this case, the ground was already very cold, so the snow accumulated (about 4") even at an air temperature well above freezing.