Eyes on the Sky at the RTS Weather Station

Jordan Vinson, for the U.S. Army Garrison-Kwajalein Atoll’s Kwajalein Hourglass

Mike McMurphy, a technician at Kwajalein’s RTS Weather Station, pulls gingerly on the long, white string tied to the bottom of a helium-filled weather balloon he is about to send 20 miles into the Earth’s atmosphere.

“OK, here we go,” he says, letting go of the string.

He cranks his head back, watching the balloon shoot away into the air, climbing at a pace of 300 meters per minute. Within half a minute, it’s but a small white dot amongst a sea of blue sky. Trailing quickly behind at the other end of that long string, a small white package called a radiosonde begins its journey up into the atmosphere.

Weighing only about 250 grams, it contains a small suite of sensors that measure humidity and air temperature, as well as its Global Positioning Satellite location data. An antenna on the ground feeds incoming data delivered by the radiosonde via radio waves to operators at the station who follow the unit’s position on their computer monitors. In only 1.5 hours the 3.5-foot-wide orb will have ascended to an altitude of 110,000 feet, reaching 20 miles into air and well into the lower stratosphere. Significantly lower air pressure there will allow the balloon to swell up to 20 feet in diameter—more than five times its size at ground level—before its thin mylar skin stretches beyond its limit and bursts.

Today, weather agencies throughout the world have been outfitted with increasingly sophisticated satellite and radar technology. But the trusty weather balloon is still a mainstay in their arsenal of tools used to probe, measure and monitor local and regional meteorological conditions; the RTS Weather Station is no exception. For the folks working there, sending a radiosonde via weather balloon into the stratosphere is daily ritual that still yields a heap of helpful data.

“It measures its position via GPS and radios back down its three-dimensional position, and the positional change tells you what the winds are,” says Mark Bradford, the chief meteorologist at the station. “From that we can derive everything we need to know about the atmosphere. … And it’s still critical. Even though we have satellites everywhere, those observations twice a day form the basis for our forecasting of the weather everywhere.”

Back inside, the data fed into McMurphy’s computer by the ground antenna tracking the radiosonde gives the technician a bird’s eye view of its location, speed and direction of movement and more. A little white dot on his computer monitor represents the device’s location and shows it’s moving in a lazy arc to the northwest. After the swollen weather balloon breaks up in the lower stratosphere, the radiosonde will probably fall into the ocean within about 20 miles of Kwajalein, Bradford says. But some drop way outside that range.

“Maybe the farthest that they get out is like 100 miles or something like that,” he says. “So if we have strong Trade Winds and we have Upper Level Flow going strongly [to the west], then they might make it out 100 miles, maybe 150 at the farthest.”

Tucked into the middle of Holmberg Fairways on the southern rim of Kwajalein, the RTS Weather Station staff launch these balloons and electronic devices every day as part of their effort to keep their eyes on the weather for the RTS and U.S. Army Garrison-Kwajalein Atoll. They perform several daily forecasts of numerous weather conditions, which they distribute via TV, email, on their website and in the Hourglass. During test range missions, the station provides frequent, specialized forecasts of weather conditions using everything from radiosondes and rain gauges spread throughout the atoll, to its prized Kwajalein Polar Metric Radar—one of the most sophisticated radars in the world used for meteorology.

The station also searches for and alerts local communities of any and all dangerous weather conditions that might impact the atoll. It covers aviation hazards for aircraft, high possibilities of lightning strikes, rough winds and ocean conditions affecting small vessels, as well as incoming typhoons and tsunamis.

Fortunately, Kwajalein Atoll doesn’t have to contend with serious storms too often.

“We are in the un-sexy end of weather,” Bradford says. “For tropical meteorology, the sexy end is hurricanes, typhoons, tropical cyclone development and the last-stage impacts of them when the storms are really intense. We almost never get that here.”

One area of caution, however, is the low elevation of the islands making up Kwajalein Atoll and the greater Marshall Islands.

“When we’re 10 feet above the ocean with no protecting topography, a little bit of water can be quite disastrous,” Bradford says. When asked about the greatest meteorological threat to the area, he’s frank. “It’s [a] typhoon,” he says. “So we average a typhoon about every … five-to-seven years. But now it’s been nine years since we’ve had one. So you’d say that we’re overdue.”

Typhoons in the past have been catastrophic in the Marshall Islands. Typhoon Paka in Dec. 1997, for instance, inundated Ailinglaplap Atoll with water up to a depth of 12 feet in some places, damaging 70 percent of houses there and destroying most of the coconut trees and vegetation on the islands. The Japanese, meanwhile, recorded water to a depth of three feet on some islands of Kwajalein Atoll during storms in the 1930s, says Bradford. Since the beginning of the United States’ presence on the atoll, nothing as serious as what the Japanese experienced has passed through the area. But Bradford says that’s unlikely to be the case forever.

“When I do the monthly island orientation, I always point out that all the vegetation—all the trees on this island—have been completely destroyed twice,” Bradford says. “Once in 1944 by the 7th Infantry Division artillery and once in 1875 by a typhoon. So the question is just when is it going to happen again?”

Of course, the most pressing meteorological issue to impact Kwajalein Atoll lately hasn’t been anything to seriously worry about— unless you absolutely hate rain. During last month alone, the station registered a staggering 13.82 inches of rainfall. And the current amount of rain the area has received is more than 14 inches above average for the year.

“It’s more than we’ve ever measured,” Bradford says. “It’s the most rain we’ve ever had in February.” Believe it or not, Bradford explains, all that rain was actually a byproduct of the Polar Vortex that ravaged parts of North America with some of the worst winter conditions seen there in some time. While 7,000 miles separate Kwajalein from the eastern United States, the Marshall Islands’ climate is part of an interconnected global system that can be impacted from halfway around the world, Bradford says.

“Even though the systems and everything are very different, it’s totally interrelated,” the meteorologist says with a smile.