Hurricane Michael made landfall at Mexico Beach, Florida as a category-4 storm reportedly with 155 miles per hour winds, but after the storm moved through, the highest wind speeds recorded were only around 130 miles per hour. So, where did the 155 mile per hour winds come from?
The top wind speeds are an estimate from an instrument on the Hurricane Hunter aircraft. It generates a real-time measurement of the surface wind speed. This is then sent to the National Hurricane Center as the official winds for the storm.
So why weren’t the 155 miles per hour winds reported on the ground at landfall? That could be due to a few reasons. One could be that the anemometers were destroyed after recording 130 mph winds. Or, the power went out at the weather station and nothing was recorded. A time lapse video of weather reporting stations during Michael’s landfall showed the reporting stations losing power and disappearing from the map as the storm moved inland.
The Automated Surface Observing System Anemometers are only rated to record up to 145 mile per hour winds.
Another reason is that the estimated surface winds are measured over the water, which is a smooth surface. Then, when the storm moves over the land, the friction of the land can actually slow them down. Also, the strongest winds were on the right side of the eye, and, since the anemometers can be spaced far apart from each other, they would not be in position to measure those winds at that time and that happened in this case as well.
Just like with a tornado, wind damage assessments will be conducted over the next few months. That will show how fast the winds were to cause the specific damage. Based on the findings of that research the Hurricane Center may reassess the speeds either up or down.