On the Frosty Mornings when you are outside your house scraping your cars windshield to prepare for your drive to work. Take a look at the Roof of your Home. -Lack of Frost or Snow on your Roof is a sure indication that it was melted by the Heat as it rises from the Interior of your House into the Attic Area-
In a nutshell: as the hot air escapes and rises in a home it eventually makes its way to the attic where it melts the snow off the roof. This could be why with identical looking houses one will have snow on its roof and one will not