The big cooling off: New thermometer site should lower the highs

By Dan Vierra Copyright 1998 Sacramento Bee September 12, 1998

Temperatures soared past the 100-degree mark a record 16 days during the month of August in Sacramento. Or did they? Some local meteorologists aren't so sure.

"Was it really that hot in Sacramento? I don't think so," said Tom Loffman, Channel 13 (KOVR) meteorologist. "The National Weather Service has its thermometer on a roof where the sun hits and makes it too hot. I've been pestering those people for years with little success."

Daily high and low temperatures and forecasts reported by local TV and radio stations often are based on data provided by the National Weather Service, which gathers, records and reports temperatures.

This fall the NWS will relocate its equipment, moving the gizmos from the hot, dead air on the roof of the post office building at 8th and I streets to an undetermined site away from high-rise buildings and much closer to ground level.

"Next year there won't be any more record highs," said Loffman.

Roger Pappas, an NWS meteorologist in Sacramento, agreed with Loffman about the rooftop site.

"It's not a good place," he said. "It's particularly bad because there's a tar roof, and where (the thermometer) sits there's like a penthouse structure near it. We really don't have a representative exposure on the roof."

The current location is 210 feet above city streets, surrounded by high-rises and in a spot where there's virtually no wind circulation. When the "official" high is reported on TV as 100 degrees in downtown Sacramento, it may actually be 94 or 95. And when the low is officially 68, it might be 64 or 63 degrees. Loffman said the World Meteorological Organization recommends temperature-reading equipment be placed 6 feet above ground and preferably over grass.

"I kind of looked at the August record of "warmest ever' like maybe it was and maybe it wasn't," said Channel 3 (KCRA) chief meteorologist Mark Finan. "It was a record at the post office, but then not that many people live on top of the post office. They probably can find a residential area near downtown, which would make it more representative of what people actually are feeling out there."

According to Pappas, the NWS has ordered all rooftop sites to move to "more representative locations."

"That's the problem with weather records; they get influenced by where they're sited," he said.

Sacramento isn't the only NWS office getting orders from national headquarters in Washington, D.C., to move its gauges and thermometers. Concerns about possible global warming have spurred an effort to get more accurate temperature readings nationwide.

Pappas said a similar move in San Francisco resulted in "quite a difference" in temperatures. He estimated Sacramento might cool down "a couple of degrees," but added the readings would depend on where the equipment is relocated. Among the sites being considered are TV stations in the downtown area (Channels 3 and 10) and a firehouse.

"Capitol Park would be great, but I'm not sure we could get permission as it may not fit into the beauty of the park," Pappas said. "We plant a pipe in the ground, and the instruments hang off it."

Wherever the instruments are relocated, Loffman estimated a five-degree drop-off in high temperatures next summer, while Finan calculated a more conservative three-degree drop.

"On a day-to-day basis, we'll look at readings from McClellan, Executive and International airports, the other reporting sites," said Finan. "When you average those three, you're looking at about three degrees higher for the downtown temperature."

Downtown temperatures have been affected by Sacramento's rising skyline. More concrete, steel and glass in downtown high-rises has increased what is called the "heat island effect," where heat is trapped and stored in the daytime and released at night, affecting low temperatures, too.

Once the new site is determined and the equipment put in place, there likely will be more record lows.

"One thing I find a little suspicious is that in the seven years I've been in Sacramento there have been maybe 30 record highs and no record lows," said Finan. "It stays so much warmer in the downtown area, you're not going to get record lows. If we do get a cold snap this winter, we might set some records."

Pappas said rainfall totals also might be affected.

"We've noticed that since all the tall buildings have gone up, certain wind patterns are different and the gauge doesn't catch rain the way it used to."

One thing is certain -- the weather is about to change in Sacramento.

DAN VIERRIA'S column appears Tuesday and Saturday in Scene. Write to him at P.O. Box 15779, Sacramento, CA 95852, call (916) 321-1119 or send e-mail to dvierria

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