Two National Weather Service experts checked Richmond’s temperature sensor on Thursday and found three possible reasons for some strange readings from the high-tech thermometer.
Bugs, grass and dirt.
A small screen through which air is drawn to keep the sensor from running hot, so to speak, was clogged with the debris.
Technicians check instruments at least every 90 days, but problems can occur quickly, said Ron Boyle, electronic systems analyst for the weather service’s Wakefield office.
“It can happen in a weekend,” Boyle said. “A swarm of bugs or something happens.”
Boyle, 45, spoke as co-worker Louie Drebing, a 56-year-old electronics technician, applied a low-tech solution to the problem, sweeping the bugs and stuff away with a small brush and cleaning the area with water.
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The men worked amid an array of weather instruments — a weather station — in a sprawling, flat, grassy area of Richmond International Airport in eastern Henrico County.
The temperature sensor, the size of a small match, was situated inside a white, metal structure that resembled a big mushroom. A fan in the head of the mushroom pulled air up from the bottom. The debris may have been blocking that air.
The sensor provides the official temperatures for Richmond. On recent hot, sunny days, weather service officials noticed that some readings seemed unusually high.
On Tuesday, in particular, the sensor registered a high of 96 — three to four degrees warmer than other sensors in the region.
Weather service experts have felt for years that the airport sensor’s readings were often a little high, particularly when winds blew out of the west or southwest. That could be because the sensor lies east of the airport’s terminal and a runway — hard surfaces that absorb heat. So those winds could be blowing extra heat to the sensor.
The location of the sensor might occasionally add a degree or two to the high temperature, Boyle said. But when the temperature looked four degrees high, “it was quite obvious that something needed to be done.”
After cleaning the sensor, Drebing checked it against a battery-powered thermometer and found the sensor’s 76.1-degree reading to be accurate.
The men worked during a cool, cloudy stretch of midday — weather that wouldn’t cause an unnatural heating of the sensor.
Removing the bugs and debris might have fixed the problem, Boyle said, “but we won’t know until a hot, sunny day.”
Jeff Orrock, meteorologist in charge of the weather service’s Wakefield office, said by phone that it’s not absolutely clear the debris was the problem.
The sensor’s temperature readings were fluctuating minute-by-minute during part of Wednesday, indicating air was flowing well around the instrument, Orrock said.
Orrock said he would confer with his staff to see if that Tuesday temperature record should be adjusted. “We’re looking into it.”
Weather observations began at the airport, then called Byrd Field, in the late 1920s. Before then, observations were taken at three spots in the city of Richmond, starting in 1897, the weather service said.
In addition to temperature, the airport station measures conditions such as visibility and winds, which are important for aviation as well as the general public.
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