After a wet Thursday night, things will dry out as we go through the weekend, but it will also come at the cost of some very cold temperatures. A dry and frigid airmass will push the atmospheric river to our south, leaving behind clearing skies (although a few snow showers are possible Friday.) Low temperatures will drop into the teens and even single digits over the weekend, and high temperatures will struggle to get back to the freezing mark. Things do warm back up to near seasonable levels (in the 40s) by Tuesday.
A couple of days ago I introduced the term adiabatic cooling. Adiabatic cooling refers to the temperature drop that air will experience as you reduce its pressure. Of course, as you rise in elevation, the air pressure drops, and therefore in a mixed atmosphere the temperature drops as you go higher in elevation. The amount of temperature drop per unit of elevation is called the lapse rate, and is very useful for calculating temperatures at different ground elevations as well as predicting the stability of airmasses.
So how fast should the air cool as you rise in elevation? I’ll tell you tomorrow.