What Is An Occluded Front And Which Weather Conditions Occur During This Event?

What Is A Weather Front?

What is a weather front? A weather front is a boundary between two air masses, if you think of it as a border, two parties stand at the edge of this border, on one side is the warm air, and on the other is the cold air.

There can be gigantic disparities in the temperatures across the front. As warm air and cold air collide. The difference in the temperatures could indicate the strength or power of each front.

If exceptionally cold air came into contact with warm air from the tropics, the front may then be considered strong or intense.

However, if there is minimal difference between the temperatures of each front then it may be considered a weak front. 

What Is An Occluded Front?

Referring to meteorology, an occluded front is a type of weather front formed during a process named cyclogenesis. This process happens when a cold front moves at a greater speed than a warm front, this results in the formation of an occluded frontal system.

This process usually develops around the centre of a low-pressure system, or depression, during the formation of a cyclone, as the depression forms there is usually a cold front moving substantially faster than a warm front which leads to the process of occlusion. When this process occurs the warm is air separated or occluded from the cyclone centre at the earth’s surface.

Cold air is also heavier than warm air, so when the advancing cold front catches up to the warm front, it displaces it, forcing it aloft, which makes these types of occlusions more noticeable, as there is a noticeable temperature difference from the aggression and weight of the advancing cold front. When the opposite occurs the warm air is lighter and so simply rides over the cold air and presents itself at the surface of the occlusion.

There is very often precipitation along an occluded front from cumulonimbus or nimbostratus clouds, as the wind changes direction while the front passes, the temperature will change too. Once this front has passed, the sky is often much clearer and the air is drier.

You may notice on weather maps, that an occluded front will look like a purple flag with half triangles and half semi-circles along with it that will point in the direction that the front will move, It will usually end at a low-pressure area, indicated on a map with an ‘L’, while it will start showing the warm and cold air fronts as they combine.

The conditions of occluded fronts can arise whenever; cold, cool and warm air amalgamate. There are two types of occluded fronts; a cold occluded front and a warm occluded front. The cold occluded front occurs when a cold front overtakes a warm front and vice versa.

Cold Occluded Front

A cold occluded front occurs when the air behind the front is colder than the air ahead of it. With this type of occluded front, there is mimicking of a cold front.

These types of fronts are responsible for a lot of the strongest, most severe storms, often types of weather that can produce high-speed or damaging winds, hail and other phenomena such as tornadoes.

These types of occluded fronts usually show a dip in temperature prior to their aggressive behaviour, before a cold front occlusion made storm there will likely be a tip in temperature and in the wind direction, as well as a change in the wind speed.

Warm Occluded Front

On the opposite hand, we have warm occluded fronts. These are probably the preference as they are much less aggressive than cold occluded fronts.

A warm occluded front develops when the air behind the front is warmer, and the air ahead of the front is cooler. This type of occluded front acts more like a warm front. These types of occluded fronts are much less common.

A warm front is probably better known for producing light rains that over a wide area, this type of rain is usually steady. Unlike its counterpart, the cold front, a warm front does not initiate any wind changes or air temperature alterations.

What Types of Weather does an Occluded Front Cause?

Depending on the front, a warm occluded front or a cold occluded front will cause different weather conditions. Cold occlusions are by far more aggressive.

Put simply, a warm occluded front will produce light, widespread rains, that are much less of a concern to the general public or weather watchers. On the other hand, a cold occluded front will develop fearsome weather conditions.

Thunderstorms are not an uncommon occurrence from cold occlusions, neither is hail and nor is it a surprise as the temperature drops as the cold occluded front forms.

In fact, when a cold front ‘cuts off’ a warm front and presents this type of weather, the temperature drop can be so heavy, it is hard not to notice. It can also cause tornadoes.

It is safe to say that cold occluded fronts are definitely the more dramatic of the two, but nonetheless, we can also say that regardless of the type of front, it is very reasonable that if an occluded front is heading your way, there is going to be precipitation.

The Take-Away

The weather is fascinating, and there is always more to learn about it.

We are still looking to find what causes certain weather patterns and how the weather works. As for occluded fronts, we can safely say that they are no less interesting and if not a little bit terrifying, especially cold occluded fronts.

Now we all know what to expect when the weather reports say that an occluded front is heading our way, and how to prepare depending on the type of occlusion. And, we can feel a little bit safer knowing how they are formed and what they do.

Continue to learn and love the weather. And don’t forget to take a coat with you, in case of an occluded front. 

About the Author Marvin J. Snyder

I'm the research analyzer and data interpretation here at Weather Station Lab. I test various weather stations and share my conclusion here. Since my childhood, I had a passion towards weather and I'm always fascinated by that. Eventually, I pursued Ph.D. in Atmospheric Science from the University of Arizona. I hope my contribution will help you to know more about weather stations. Read more about us, here