Not a tornado. Not a derecho. Not a microburst either—but close. This time, the damage from roughly 70 mph winds around Springfield, Massachusetts, was caused b
Not a tornado. Not a derecho. Not a microburst either—but close. This time, the damage from roughly 70 mph winds around Springfield, Massachusetts, was caused by a macroburst.
Think of it as the bigger brother of a microburst. Both are types of downbursts—powerful thunderstorm downdrafts that hit the ground and spread outward.
It starts inside a thunderstorm as rain and hail fall through the cloud, helping drag air downward. Drier air can also mix into the storm, causing some of that precipitation to evaporate. And evaporation requires energy—it absorbs heat from the surrounding air, cooling it.
Now you have a pocket of cooler, denser air accelerating toward the ground. Just as warm air tends to rise, that colder, denser air wants to sink. When the downdraft slams into the ground, it has nowhere else to go, so the wind races outward in all directions.
A microburst does this over an area less than about 2.5 miles across. A macroburst is the same basic process, but its damaging wind footprint extends more than about 2.5 miles.
And despite there being no tornado, those straight-line winds can still reach—or even exceed—tornado strength.
