What causes a hurricane to move?
The path of Hurricane Katrina was determined by its surrounding environment.
Photo gallery: Eyewitness photos from inside a hurricane.
JB: This is Earth & Sky with a question from a listener.
DB: Charles Davis wrote, “We’re always told hurricane so-and-so is moving at a certain speed in a certain direction. But what makes it move in that direction at that speed?”
JB: Charles, we took your question to Dennis Feltgen, a meteorologist with the National Oceanic and Atmospheric Administration. He said a hurricane’s path is determined by the weather environment surrounding the storm, from the ocean surface to the upper atmosphere. And he said jet stream winds in the upper atmosphere contribute to a hurricane’s forward speed. For example, the subtropical jet stream will accelerate storms to the northeast.
DB: Feltgen said that satellite technology has been driving huge advances in scientists’ ability to predict what hurricanes are going to do. But unanswered questions remain.
Dennis Feltgen: Our worst nightmare is that a hurricane is approaching a coastal section, and everybody goes to bed thinking they’re going to get a Category 1 hurricane. Then you wake up the next morning and the hurricane has intensified rapidly overnight and now you have a Category 3 coming at you. We do very good with tracks, but we still have a long way to go on intensity, especially rapid changes in intensity with hurricanes.
DB: One thing to remember is that until the 1960s, when satellites began orbiting Earth, meteorologists only knew a hurricane was brewing due to sporadic reports from ships at sea. Our thanks today to NOAA, the National Oceanic and Atmospheric Administration. We’re Block and Byrd for Earth & Sky.
Speaking of a hurricane’s direction of motion, Dennis Feltgen said, “What will typically happen when these storms accelerate is that high pressure along the east coast begins weakening as a big area of low pressure begins advancing across the eastern half of the country.
“Ahead of that low pressure area, the winds are typically accelerating from the southwest to the northeast. A hurricane approaching from the east will get caught up in that flow, turning the storm to the north, and quickly to the northeast, and accelerating the storm out towards the northeast.”
Feltgen said that because a hurricane is an area of low pressure, an area of high pressure can block it. For example, hurricanes in the Atlantic Ocean are usually steered around a large area of high pressure called the Bermuda High.
Feltgen also added, “Satellite technology has been an absolute blessing. Until they came along in the early sixties, the only way we knew a hurricane was out there was based on sporadic ship reports. We did have some hurricane reconnaissance aircraft going into hurricanes in the 1950s which helped, but really before that, we didn’t know a hurricane was coming until it was on top of us and it was too late to get out of its way.”
Our thanks to:
Dennis Feltgen
Meteorologist
Public Affairs Specialist
NOAA-NWS
Additional Teacher Resources
NOAA: Hurricane Models
To forecast the track and intensity of tropical cyclones, the NHC uses several different mathematical computer models that represent the tropical cyclone and its environment in a greatly simplified manner. Each of the models has particular strengths and weaknesses, and researchers are constantly working to improve them.
NOAA: Hurricane Basics
There is nothing like them in the atmosphere. Born in warm tropical waters, these spiraling masses require a complex combination of atmospheric processes to grow, mature, and then die. They are not the largest storm systems in our atmosphere or the most violent, but they combine these qualities as no other phenomenon does.
