Forecasting supercells using "ingredients"

 

When baking a cake, you need to make sure you use the right ingredients. Without strawberries, one can’t bake a strawberry cake! Much like baking, there are ingredients for a given weather event.  For example thunderstorms require three ingredients.  The first one is known as conditional instability.  As air is rising, once a cloud forms, this air will be warmer than the surrounding air if instability is present, much like a hot air balloon.  The result is that the air is accelerated upward and a strong updraft forms.  The second ingredient is humidity in the air.  Without humidity there would be no cloud.  Also, the condensation during cloud formation warms the air and thus helps the hot-air balloon effect.  The final required ingredient for thunderstorms is a lifting mechanism that causes the cloud formation needed to release the instability.  Much like with a cake, different amounts of ingredients will result in a different flavor of thunderstorm.  For example, if there is plenty of lift, a line of thunderstorms may form, while weak lift may favor more isolated thunderstorms. 

 

On some occasions, you add additional ingredients to your cake to make it special.  The additional, special ingredient for thunderstorms is vertical wind shear, meaning that winds increase and change direction with height.  Vertical wind shear leads to rotating updrafts and it intensifies the storm.  Such intense and long-lived storms are known as supercells and they almost always produce large hail and strong wind gusts.  If there is strong wind shear in the lowest layers of the atmosphere, strong near-ground rotation may develop, which can lead to tornadoes. 

 

So, cakes and severe weather have a lot in common.    The correct amount of ingredients is needed, and the more ingredients you add, the more flavor you add to the cake.  Thunderstorms likewise require a certain mix of ingredients, and the more you add, the more special the storm becomes.  Forecasters are constantly tracking the different ingredients needed for severe storms.  When the ingredients overlap they know that severe weather is possible.  Inspired by the joy of baking, the scientific term of this approach to weather prediction is called "ingredients-based forecasting," and it helps meteorologists predict when the weather turns wild over West Texas.