From:
http://www.charlotte.com/mld/observe...al/6262119.htm

Friday, Jul 11, 2003
Charlotte Observer
Posted on Wed, Jul. 09, 2003

City gauge creeps past official 89
SCOTT DODD
Staff Writer

The gauge isn't broken.

For weeks, despite five forecasts calling for 90-degree days -- and backyard
and bank thermometers reading well above that temperature mark -- the
official reading at Charlotte/Douglas International Airport hadn't topped
89.

It was enough to make sweltering people across the city wonder if the darn
thing was stuck.

But shortly before 4 p.m. Tuesday, the gauge finally registered 90 degrees,
and stayed that way for about an hour.

That marks the latest date that Charlotte has officially hit 90 since 1878,
when weather record-keeping started.

It also gave National Weather Service meteorologists a bit of relief. If
Charlotteans had sweated much longer without official confirmation of the
city's heat, somebody might have started asking questions.

Actually, somebody did.

The temperature gauge at the airport is just one piece of a sophisticated
weather recording station known as the Automated Surface Observing System,
or ASOS for short.

Its main purpose is to provide temperature, wind speed and precipitation
readings to pilots and the airport control tower. But it also serves as the
official weather station for the Charlotte area.

Visitors can see the station clearly from the airport overlook parking lot,
north of the runways. Its most prominent feature is a 33-foot-tall wind
tower, painted orange and white.

From a distance, the rest of the equipment looks small. But most of the
gauges are actually taller than a person.

Besides the wind tower, ASOS has eight components, including a rain gauge, a
temperature/dewpoint sensor and a ceilometer, which emits a laser beam to
measure cloud height.

All the data is constantly relayed to a weather station at the airport,
where observers working for the Federal Aviation Administration monitor the
information. It's automatically relayed to the control tower, the National
Weather Services and various news outlets.

The current system has been operating since July 1998, said Terry Benthall,
the data acquisition program manager for the National Weather Service office
that covers Charlotte. But the airport has been the official site for
weather service readings for about 30 years, he said.

The system is serviced at least four times a year, and is cleaned and
checked over more often for accuracy. It has its own diagnostic systems that
report any problems. And the airport observers take some of their own
readings, so they can see if something doesn't match up.

That's not to say that other parts of the city don't experience different
temperatures than the airport. Benthall's sure that parts of Charlotte
topped 90 degrees before Tuesday, as did most other cities in the region.

"Downtown in the metro area, you have all that concrete heating up," he
said. "It's just a big heat island. It's going to be a few degrees warmer,
typically."

So why not move the official weather station to where the most people live?
Benthall said it's a matter of priorities. Pilots need the most accurate
weather information, so the airport gets the most sophisticated sensors.
They're placed by the runway so they can record the weather planes will
experience at takeoff.

Temperature and rainfall readings also are collected from other locations.
The weather service has more than 11,000 weather observers nationwide, and
about 130 in the area covered by the Greenville-Spartanburg office, which
includes Charlotte.

Those readings, though, don't make it in the record books.


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FIND OUT MORE

See more about ASOS at www.nws.noaa.gov/asos. Track hourly observations from
the Charlotte airport weather station at
www.srh.noaa.gov/data/obhistory/KCLT.html.


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Scott Dodd: (704) 358-5168; sdodd@charlotteobserver.com.