The Arizona monsoon brings summer storms, dust storms, and occasional micro-gusts. Every summer, these weather patterns cause dangerous situations and damage.
What is a microburst?
A downdraft is defined as a strong downdraft with damaging wind current on or near the ground. If the strip is less than 2.5 miles, it is called a microburst.
A micro gust is a small and very intense downdraft that descends to the ground resulting in a strong divergence of the wind. The size of the event is usually less than 4 kilometers in diameter. Micro gusts are capable of producing winds of over 100 mph causing significant damage. The pot life of a microburst is about 5-15 minutes. There are wet microbursts and dry microbursts.
When rain falls below the cloud base or mixes with dry air, it begins to evaporate and this evaporation process cools the air. The cold air descends and accelerates as it gets closer to the ground. When the cold air approaches the ground, it spreads in all directions and this divergence of the wind is the signature of the micro explosion. In humid climates, microbursts can also be generated from heavy precipitation.
Microbursts are fast and extremely dangerous events for aviation. Microbursts are subclassified as dry or wet microbursts, depending on the amount of rain that accompanies the microburst when it reaches the ground. If the strip is more than 2.5 miles, it is called a macroburst. Macrobursts last longer than microbursts.
Is a microburst a tornado?
No, but there are some similarities. There is often a lot of wind that develops very quickly. However, unlike a micro explosion, the wind flows into a tornado and not outward, as it does in a storm. Tornadoes also produce that swirling wind seen in most movies and videos, which is not necessarily present during a micro explosion. Microbursts are much more common than tornadoes, and it is very rare to have a tornado in the Phoenix area, even during the summer monsoon.
Do microbursts cause damage?
Yes, they certainly can. Tornado damage often has a chaotic appearance, with larger uprooted trees often crossing each other, while microburst damage often leaves them in the same direction or flattened.
