It Is All About The Journey (From Canada)

Coming our way is an air mass and that air mass will change during its trip to the tristate.


First an air mass (sometimes written airmass) is a big blob of air that is  fairly homogeneous. It developed over a geographic region and the characteristics of that region were inherited by the air of the air mass.


It is a simple concept. For example: air that sits over the cold Canadian plains in winter is cold and fairly dry because the air developed over the cold continent. Air that sits over the Caribbean Sea is warm and humid.


The air masses that affect the continental U.S. and their source regions are shown below.

More info available at http://www.shorstmeyer.com/msj/geo165/airmass.html

 "m" means maritime or an air mass that formed over water and is fairly moist. "c" means continental and a continental air mass is dry because it formed over land. "T" means tropical, "P" means polar and "A" means arctic and you already know which are warmer and which are colder than the ground they move over on their way to the tristate.


Here is where the journey comes in. As soon as the air mass begins to move it encounters ground that is either warmer or colder than the air. The farther it moves the more it is modified and by the time it gets here air that brought central Canada low temperatures in the teens will bring Cincinnati low temperatures in the 30s.


This weekend the center of a continental polar (cP) air mass will arrive. It is from the western and central Canadian Plains and it is colder that the air we now have here in the Cincinnati Tristate. So get ready for morning lows in the 30s in spots Saturday morning and in  many locations Sunday morning.  Of course valleys will be colder and there we may see the faint glimmer of frost on exposed metal and glass surfaces.