What happens to the pressure as a front approaches?

As a front approaches, atmospheric pressure typically falls just before the frontal passage. This decrease in pressure occurs because the incoming air mass associated with the front is usually less dense than the existing air mass it is replacing. As a front nears, the warm air rises over the cold air, leading to a reduction in surface pressure.

Understanding this phenomenon is essential for pilots, as changes in pressure can indicate shifting weather conditions, which can affect flight operations.

After the front passes, pressure often begins to rise as the colder, denser air takes over. This characteristic behavior is key in recognizing and predicting weather patterns associated with frontal systems.