Forensic meteorology has come a long way from the day when insurance claim professionals and experts simply relied on weather data from public NOAA sites. Steve Harned, President of Atlantic States Weather, Inc. and a distinguished Certified Consulting Meteorologist, recently educated me about one aspect of the behavior of wind in a hurricane.
I’ve known for a long time the general rule that wind speed increases with height. That means that if a Doppler radar measured a certain wind speed at 2,000 to 5,000 meters above ground level, the wind speed would likely be significantly lower at ground level. For example, wind speed of 80 mph at 5,000 meters could translate to a 40 mph at ground level.
However, Steve says, strong areas of convection in the hurricane spiral bands are known to create downdrafts which bring intense rainfall and strong winds to ground level. In these areas of strong downdrafts, the wind speed at ground level can be the same as that measured at higher levels. The Texas Tech University Wind Science and Engineering Research Center showed this with experiments conducted in 2004 during Hurricane Jeanne at the Titusville Airport near Cape Canaveral, Florida. The Doppler radar was pointed to the east into the oncoming winds from the hurricane, and scanned up and down to measure the wind from ground level to 5000 meters above the ground. The resulting imagery showed the downdrafts bringing the strong, high-level winds to ground level at times.
According to Steve, a properly trained and experienced meteorologist can determine the likelihood of such downdrafts occurring by reviewing the frame-by-frame radar images and other data which is not generally available to the public on NOAA’s websites. You can find more information about Steve at his website, asweather.com.