The morning after a Billerica storm is usually the bluest sky of the whole winter, hard sun, single-digit air, everything white and holding still. Blue Bird Snow Removal Services is out long before that, plowing driveways and lots and clearing the walks while it is still blowing sideways across the Shawsheen. Snow here comes wet one week and light the next, and each kind wants a different pass, a different place to stack the banks so there is room left for February. Salt goes down where the shade keeps a lot slick past noon, because the plow is only half of it. By the time that blue sky opens up, the pavement is dark and dry and the day gets to start on schedule.