A lot of people across the region are reporting some light snow on their lawns this morning. A very cold and damp air mass is changing drizzle into ‘snizzle’.
Typically in a setup like this, we get an inversion – meaning that the air aloft (above the ground) is warmer. This allows the cold air to sink to the lowest elevations. Cold air actually weighs more than warm air. We call this stable air.
An airmass is considered unstable, when lifted air continues to rise on its own because it’s warmer than the air above. Think about the old adage: warm air rises.
Since the air today above the surface is cooler, the surface air is rising, cooling and condensing out this moisture in the form of snizzle and sometimes light snow.
Science aside, as we make our way through the later half of today and especially all week-long, the air above will warm-up. This means that we return to a ‘typical’ set-up where the coldest air will remain along the valley floors with a lot of fog.
Air in the mountains and along the coast will be warmer and much sunnier.