How cold fronts function and why they bring thunderstorms
A cold front passed through the area yesterday evening, and the effects of that front are being fully realized today. Much of the area yesterday afternoon still felt like it was near or in the triple digits, with areas like Jefferson City and Linn experiencing heat index values around 103-106 degrees during peak heating hours.
Now, temperatures this afternoon have only maxed out in the low to mid 70s, meaning there is around a 12 to 15 degree difference area-wide compared to the air temperatures measured yesterday. This difference is caused by a couple features, most namely, the shift in winds from southerly to northerly and the increase in cloud cover that's been seen throughout the day. Some areas also received thunderstorms and heavy rainfall, which also assisted in temperatures cooling off yesterday. These features all came along with the cold front, which is the main culprit in this noticeable cooldown.
The basic setup of a cold front arrives with a larger low pressure system moving into the area. The air behind this cold front is much colder and more dense than the air it is moving into. Since it is more dense, it pushes the warmer, less dense air into the upper levels of the atmosphere.
The warmer air ahead of the front is typically associated with southerly winds at the surface, while the colder air behind the front is typically associated with northerly winds at the surface. This wind shift is what typically results in more breezy conditions as the front passes through the area.
The colder air is typically the more noticeable impact, but thunderstorms that often come with these cold fronts can have many impacts as well. These thunderstorms are caused by the warmer, less dense air rising into the upper levels of the atmosphere. The air ahead of the front is often unstable and energetic, meaning all it needs is for something to give it a "push" in order for it to develop into thunderstorms. In our case yesterday, a couple storms ended up developing due to the passage of this cold front, bringing heavy downpours and strong winds to some areas in central Missouri.
The more long lasting impact, the colder air, will be felt throughout all of this weekend. Temperatures for Saturday and Sunday are expected to be in the upper 70s and low 80s, with a mix of clouds and sun both days. Winds will be out of the west at 8-12 mph, all leading to a great setup to get outside and enjoy events around the area this weekend.
