Although the weather has evolved drastically over the past few decades, some forecasting tips are rooted in tradition.

One of the oldest tales revolves around the behaviors of the plants around us. The legend says that trees’ behavior can predict the arrival of storms, especially when the leaves on trees flip. Does this claim have any accurate basis in the modern day? Or is this just another myth that should be lost to folklore?

 

 

To get behind the claim, let’s first understand how storms behave. Thunderstorms typically form during periods of warm weather and high moisture, often in the late afternoon. This flow of warm air must continue uninterrupted to sustain a thunderstorm. When storms are particularly strong, they release a downdraft, which is a strong flow of air out from underneath the thunderstorm. The air gets cooled mainly by rain that falls and the interactions that air has aloft. When this downdraft comes down and reaches the ground, it is called an outflow boundary. Outflow boundaries on a map can look like if you were to throw a rock in a pond; it starts as a small, compact circle, which expands out while losing energy. When a storm is mature, these outflow boundaries can extend miles ahead of the storm, acting as a switch between warm, summerlike air and cool, storm-induced air.

While outflow boundaries change the temperature of the air, they can also change the direction of the air, as well. These are two principal reasons why gust fronts exist- they are the boundary between a warm air mass moving in one direction, and a cooler air mass moving in another, specifically within thunderstorms.

 

 

When storms are strong, gust fronts are particularly notable. This is because the change between air masses can be so stark, where a calm summer breeze can quickly turn into strong, gusty winds from the opposite direction before a storm. It isn’t just noticeable with us, as nature can respond to it as well. This change in wind direction is the primary reason why trees’ leaves suddenly flip, and the timing also aligns with the leaves flipping before the storm’s arrival.

 

 

A shift in wind is just one way that leaves on trees tend to flip before storms arrive. While storms form in warm environments, they also need a humid atmosphere to get as much moisture out of it. With high humidity, this also acts to soften the stems of leaves, making the structure of the leaf easier to move and flip.

It is important to note that flipped leaves are the result of changing weather, rather than a clever way to predict it. This is why the legend roots itself in working only when strong storms arrive, as simple rain showers do not have the power to generate strong winds ahead of themselves.

 

 

While weather lore and legends can be things of the past, we rate this claim as being generally true, and backed by science. Let’s give a nod to our ancestors for picking up on this one!