Downbursts and hail hit South Mississippi; here is how they form

How downbursts form

BILOXI, Miss. (WLOX) -While summertime thunderstorms are a part of life in South Mississippi, they can still cause problems. One of the biggest threats with thunderstorms in the summer time are downbursts.

Downburst winds were likely to blame for tree limb and minor roof damage in parts of Harrison and Jackson counties Wednesday, June 27, 2019.

Downburst Ocean Springs 6.27.19 by Mickey Gurley

More video of the downburst in Oceans Springs today. Notice the lightning strike in the beginning a trash can gliding across parking lot. This video is from Mickey Gurley.

Posted by Meteorologist Eric Jeansonne on Thursday, June 27, 2019
Ocean Springs Downburst by Cheryl Schram 6.27.19

Downburst winds howling through Ocean Springs this evening. This video was captured by Cheryl Schram. Downbursts are caused when dry air enters a thunderstorm causing rain to rapidly evaporate and cools the air. The dense cool air rushes to the surface, sometimes violently.

Posted by Meteorologist Eric Jeansonne on Thursday, June 27, 2019

So what is a downburst?

Thunderstorms form when warm air rises, cools, condenses and forms clouds. Eventually enough moisture gathers in the cloud to fall to the surface as rain.

Sometimes, a layer of dry air can get entrained into the thunderstorm cloud.

When rain falls through this layer of dry air, it evaporates and rapidly cools. This cool air is very dense and rushes down to the surface, sometimes violently.

A viewer photo shows the view of a thunderstorm from Gulfport looking east towards Biloxi and Ocean Springs. Rain can be seen pushing out ahead from the thunderstorm due to high downburst winds. This is called a rain foot
A viewer photo shows the view of a thunderstorm from Gulfport looking east towards Biloxi and Ocean Springs. Rain can be seen pushing out ahead from the thunderstorm due to high downburst winds. This is called a rain foot

How large are they?

Downbursts fall into two categories: macorburst and microburst. A microburst is typically have a radius of strong winds of about 2.5 miles. While a microburst has a radius of strong winds greater than 2.5 miles. Downbursts typically are responsible for wind damage in very small areas. One block may see just heavy rain, while one block over trees are knocked down.

How strong can they be?

For winds to be considered severe, they must be at least 58 mph or greater. Some downbursts can produce winds up to 150 mph and produce as much damage as a tornado.

Hail often accompanies downbursts

How does hail form?

Hail forms when upward moving winds inside a thunderstorm called updrafts keep water particles suspended high in the cloud where it is freezing.

The particles freeze then start to fall. But updraft winds through the hail back up into the cloud and another layer of ice forms.

Eventually the ice grows so large, the updraft can not hold it in the cloud anymore and it falls to the ground as a chunk of ice. Sometimes violently at speeds of over 80 mph.

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