Weather forecasts up in air

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David Minton/DRC
National Weather Service meteorologist Jamie Gudmestad prepares to release a weather balloon at the organization’s office Tuesday in Fort Worth.
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FORT WORTH — Before dawn Monday morning, data and satellite images on Mark Fox’s computer station at the National Weather Service showed a low-pressure system developing over the Pacific Ocean, southwest of the California coast.

Would that spiraling mass of clouds and moisture be pulled into the upper-level winds over the western U.S. and bring more needed rain to North Texas by Friday?

Fox and the other meteorologists couldn’t be sure. For one thing, that was five days out. The colored lines of the computer models, representing the many possible tracks the system could take, often stay closely aligned for the first 24 to 48 hours, making predictions more confident. But that alignment begins to drift at about three days. By five days out, the models look more like multi-colored spaghetti strewn across the computer screen.

The satellite data presents another problem, Fox said, because, similar to our limited, earthbound view of the bottom of the clouds, all those orbiting satellites see only the tops.

For all the technological advances made in predicting the weather — supercomputers, satellites, telemetry and the many flavors of radar and their algorithms — meteorologists still start with basic data gathered in the same way it’s been gathered for decades.

Launching a weather balloon.

Not long after 18th-century scientists sent kites into the air to learn more about the weather, early meteorologists began experimenting with ways to capture and record “vertical” data with kites and with manned balloons. By the 1920s, they added radio transmission to the flights. By 1937, the Weather Bureau established a network of balloon-launching stations that continues today.

Weather can cause major disruptions to business and government. And weather kills. In 2011, severe weather killed 1,096 people and injured 8,830 more in the U.S. It also caused $23.9 billion in property damage.

At the National Weather Service unit in Fort Worth, a technician prepares and launches a weather balloon at least twice a day. The unit is home to one of six balloon launch sites in the state, and it is the only site in North Texas.

On Monday, it took Victor Corbelli about 30 minutes to prepare the balloon’s payload for the flight and fill the balloon with 1,300 grams of hydrogen. Helium, though more stable, has become too expensive and rare.

From a stash on the shelf, he grabs a small cardboard box, not much bigger than a paperback dictionary, and sets up the battery, radio and gauges that will collect information during the balloon’s flight. Once he’s satisfied that the communication lines between the payload and his computer are good, he treks back to the balloon building, attaches the payload to the balloon, opens the launch door, walks out the length of line he needs to launch the balloon into the winds, and lets go.

After about a minute, the balloon — which sometimes catches the eye of an alert, early morning commuter as it floats over Interstate 820 — has risen more than 1,000 feet and disappears from sight.

Meteorologists all around the world launch balloons at the same time, so the data that is gathered is related and meaningful. For Fort Worth, that means the crew has a 10- to 15-minute window to launch a balloon at 6 a.m. and 6 p.m. every day. Across the United States and in several U.S. territories, the National Weather Service launches from about 80 stations in order to get the data it needs to feed its computer models.

But no one is launching balloons over the open oceans to measure there. That means less data and predictions such as five-day forecasts are a lot less reliable, Fox said.

Meteorologists will also send a balloon up during the middle of the day, should local conditions warrant. On April 17, when meteorologists weren’t sure the path severe weather would take, they sent up another balloon at midday.

The balloon and its payload sent back good news, Fox said, that a temperature cap was holding over North Texas. Any storms that would form here weren’t expected to be severe.

And they weren’t. But storm chasers in Lawton, Okla., about 150 miles to the north, caught a tornado’s formation on camera.

By the time Corbelli returns to his computer Monday, the balloon and its payload have already sent back a small mountain of information. Corbelli monitors the data as it comes in over the next 90 minutes or so to make sure it’s robust. Retired from the U.S. Navy, Corbelli says he remembers when it took several people to record the readings and perform the calculations that became the weather forecast.

“We’ve come a long way when one person can do it,” Corbelli said of the balloon launch.

Then, he uploads the information to the weather service’s supercomputers in Silver Spring, Md., which will make the thousands of calculations needed to run the models. The computer models are superimposed on satellite data and images to help meteorologists make their final forecasts.

By the time Monday’s balloon burst, it had reached about 110,000 feet above the Earth and had drifted east-southeast about 90 miles. Somewhere over Athens, the balloon and its payload — marked “harmless weather instrument” — began the long fall, nearly 21 miles, back to the ground.

The weather service is able to recover about 20 percent of the payloads, which cost about $300 apiece, and reuse them, Corbelli said.

The National Oceanic and Atmospheric Administration, the parent agency of the National Weather Service, is also dealing with the recent sequester cuts. The agency had a hiring freeze, but that was not enough to cover the budget gap, according to the agency’s spokeswoman, Ciaran Clayton.

She said NOAA will be talking with union representatives about how to implement a furlough of four days per employee and keep the agency’s critical functions — weather forecasts and warnings, satellite operations, fishery observations and law enforcement, and real-time navigation services and information.

Even though powerful computers are running the calculations, it takes a few hours for the computers to finish the work. Once the lead meteorologist decides what the forecast will be and briefs the team, everyone goes about the business of monitoring and communicating that information to the millions of people who need to know whether to reroute a flight, go ahead with the day’s plantings or postpone a golf match.

Monday’s briefing focused on Tuesday’s cold front, where the morning low was expected to be the daytime high. It brought a small possibility of rain.

By Thursday, that system off the California coast was pulled into the upper-level winds and was heading to Texas, Fox said.

Meterologists expect rain to fall in North Texas starting about midnight today, with stormier weather along the Red River and into Oklahoma. The rain was expected to end by Saturday morning.

“It’s still a system, but it’s become part of the bigger picture,” Fox said.

PEGGY HEINKEL-WOLFE can be reached at 940-566-6881 and via Twitter at @phwolfeDRC.


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