No idea about the calories, but I feel for you! I grew up in the tropics (87 degrees year round) and was always under the impression that snow was nothing but light and fluffy powder.. And then I moved to Buffalo in winter for college...eek! Rude rude awakening.
sometimes we get that light and fluffy snow so it doesnt take much time and i dont really feel the burn if you will...however sometimes here on the eastern shore of md we get these lovely snow storms like last night that drop nothing but heavy snow...was outside about 30 mins or so shoveling with snow blowing everywhere and it was very cold and i just kept telling myself its a work out you can do it...
I looked it up. According to the activity calculator I found, a person of your size burns 700 calories an hour shoveling snow. It is most definitely a workout.
Incidentally I have to shovel snow at work, I'm on the snow team and it is part of my job. If I include the shoveling I did at home I was at it for close to four hours yesterday. When I got home from work I could barely move.