Every so often, you'll hear us talk about upper level lows and how they're impacting our weather. You probably wonder what on Earth an upper level low actually is and why anybody should ever care. Here's why we should care...
Simply put, the upper level low is a pocket of cold air aloft. Anytime the atmosphere is stacked in a way where you have really cold air over relatively warmer air, that is called unstable. The colder the air aloft and the warmer the air at the ground, the more unstable the atmosphere becomes. The larger the temperature difference, the more instability. Now let's use Tuesday's weather as an example.
The upper low was sending cold air aloft in our direction. Think back to the sunshine that we had in the morning that pushed our temperatures up into the 60s. This gave us a pretty big difference between our ground temperature and temperature aloft, fueling instability. Want proof that this was happening? We know what happened next...The clouds rolled in and some of us even saw some thunderstorms. Put another way, the sunshine was basically our undoing. It's common on days when we're influenced by an upper low to see beautiful mornings, showery or stormy afternoons, and clear nights...Making it seem like the weather is constantly changing. Now you know some of the science behind this and you can be prepared for Wednesday's forecast when we do it all again!