The Hunt for Hurricanes
October is prime hurricane season. So these pilots are on call. They're ready at a moment's notice... to fly into a hurricane?
Hurricane Bob is on the loose. 160 km (100 mi) per hour winds are screaming through New England, flipping over boats and tearing off roofs. Waves 5 meters (16 ft) high crash on the coast as 20 cm (8 in.) of rain pours from the sky.
But the hurricane isn't the only Bob out and about.
"I flew into Hurricane Bob on two different missions," weather expert Bob Brines told us. Flew? Why was he up in an airplane flying right smack into a hurricane? Because he's a hurricane-hunting Storm Tracker.
"Storm Trackers" is the nickname of a special unit of the U.S. Air Force Reserves. These pilots and their crews fly into hurricanes and collect weather information for the National Hurricane Center.
What's it like to fly into a massive ocean storm full of rain, lightning, and high winds? Some say you feel like a can of paint — in a fast-shaking paint mixer! It can get rough up there. "Hurricane Bob was up in the 100 knot range," remembers Bob Brines. (That's about 185 km per hour — or l15 mph — to you landlubbers.)
How Bad Was Bob?Hurricane Bob killed 18 people and caused 1 1/2 billion dollars in damage. But it wasn't as deadly as some — for instance in 1900 a hurricane killed 6,000 people. Overall, 1991 was a pretty mild season for Atlantic Ocean hurricanes. Bob was the only hurricane that caused deaths or damage. Plus it was the only hurricane to hit the U.S. — usually at least two come aground. The other three Atlantic hurricanes of the season all stayed out at sea.
Most years there are about six Atlantic hurricanes — two or three very strong ones. Why so few lately? Because some years — like the last few — there's less of what's needed to make a hurricane.
Hurricane SoupHurricane scientist Hal Gerrish says that hurricanes need four key ingredients:
Heat: "A hurricane is an engine that runs on heat," explains Hal. And where does that heat come from? Deep, warm tropical ocean water.
- Humid (moist) air: The moisture in the air will later fall out — as rain.
- Certain wind patterns: They need to be just right to get the hurricane going.
- A cloud cluster, or seedling: "Seedlings typically come off the coast of West Africa," says Hal.
"Africa has been dry for the past few years," explains Hal. No rain means no seedling cloud clusters leaving the West African coast. "So we haven't had as many hurricanes as we used to."
Believe it or not, hurricanes are even more complicated than they sound. Weather forecasters (predictors) trying to follow a hurricane have hundreds of things to think about. So they need all the weather information they can get.
Forecasting the FuryA forecaster starts with a view from space — satellite pictures taken from 36,000 km (22,300 miles) above the Earth. When spiral-shaped storms show up on satellite pictures, weather experts start to track (follow) them.
"Satellite pictures are very important," says weather scientist Joanne Simpson.
"Hurricanes are very often in parts of the ocean where no ships go," she explains. "And you might not know that the storms are there until they blast onto land."
But knowing exactly where a hurricane is — or if it's getting worse — just from satellite pictures can get tricky. Satellite pictures can be off by many kilometers. Joanne says Hurricane Camille — the second most intense U.S. hurricane ever — is a good example.
Joanne's husband worked at the National Hurricane Center in 1969 when Camille hit. "The people looking at the satellite pictures said that the hurricane was weakening," says Joanne. "But he didn't believe that. So he sent an Air Force airplane out into the storm." And? It was worsening, the winds were at record high speeds!
"Because of that, they evacuated 75,000 people," explains Joanne. "Some of them would have been killed if the center hadn't had the correct forecast."
That's what Storm Trackers can do best — bring in very exact information.
"We will start flying when it is suspected that a tropical depression (a storm that could turn into a hurricane) has formed," says Bob Brines.
Once in the storm, instruments on the plane collect weather information like temperature, moisture in the air, and wind speed.
The weather information goes to the National Hurricane Center along with the storm's position.
"We wind up telling them the hurricane's latitude and longitude (position) very precisely — down to less than a mile," says Bob.
All the flight information goes into the Center's computer — along with other information about the hurricane from satellites and radar.
"They'll use their computer models to figure out where the hurricane is going and make a forecast," explains Bob.
Future ForecastsSo Storm Trackers are here to stay, right? Well actually, probably not. Newer and better satellites may be on the way. And scientists are working on an automatic aircraft that goes in and collects weather information without a pilot or crew!
And what about the forecast for future hurricanes? Are the days of hurricanes like Camille over?
"It's expected to become wetter in Africa in the next decade," warns Hal. That could mean more hurricanes. So until they retire from the stormy skies, these hurricane hunters may be mighty busy!