Two days before Thanksgiving the snow, sleet and wind again danced through Pittsburgh, putting the total for this season at 6-inches plus.

Time to brush up on millibars and Skew T graphs, double-check the whereabouts of the National Weather Service's two-a-day data balloons and, if all science fails, stick a well-informed finger into the wind.

The vagaries of winter make for a busy time for all meteorologists, but perhaps none more so than at a mom-and-pop operation called Air Science Consultants Inc.

Based in a former Lutheran church turned artist studio off Route 50 in Bridgeville, Air Science is a blip on the private weather service industry radar compared with cross-state giant AccuWeather Inc. in State College.

There, a 100-deep staff of meteorologists got to explain to livid Philadelphia Phillies fans everywhere why AccuWeather didn't demand Major League Baseball call off rain-slimed Game Five of the World Series last month.

Short answer: The customer is always right.

Not that the seven-deep staff at Skywatch, Air Science's weather service, doesn't curry to its own list of clients, which includes both Pittsburgh International and Allegheny County airports, the University of Pittsburgh, PennDOT, Dick Corp., shopping malls and what might be the core of its business, two dozen or so school districts across the region.

With annual revenue in the $250,000 to $500,000 range, Air Science President Stanley Penkala said the firm also handles pollution monitoring. Clients such as U.S. Steel, which represent perhaps 25 percent of the business, use Skywatch to gauge things such as the sulfur dioxide dispersion at the Clairton Works.

Why do school districts insist on paying for something that the National Weather Service essentially provides for free?

It's all about detail and minute-by-minute communication, said Bonnie Berzonski, spokeswoman for Fox Chapel Area School District.

For $425 a year, Skywatch provides site-specific forecasts for the Fox Chapel district that cover bus routes crossing six municipalities.

"On the updates, they give you things like probability of occurrence, the storm timing, when it starts and ends," said Ms. Berzonski.

"Last year we were expecting some bad weather. Rather than delay we were on time. Some other districts delayed into the storm and ultimately canceled," she said.

Private forecasters don't compete with the National Weather Service, Mr. Penkala said, because they can customize their services to an extent that the government agency cannot.

Firms like Air Science, in fact, rely on commercial vendors who buy National Weather Service information, such as satellite images and balloon soundings.

"We all look at the same raw data," said Mr. Penkala. "As far as what we do with it, it's a combination of software tools that we built and experience over 30 years doing forecasts. In the Pittsburgh area, experience counts."

If soothing the nerves of school officials and bus drivers seems profitable and worthwhile but maybe mundane, Skywatch has had a few unusual clients during its 28 years.

Take the liability lawyer in Ohio who sought expert testimony to defend his client, a motorist who had rear-ended a horseback rider at "civil twilight" -- a term used to refer to the point minutes after dusk where vision just begins to adapt to darkness.

Skywatch built a scale model of the horses, the cars and the intersection. Mr. Penkala said penlights doubled as headlights in an attempt to re-create the blind spots caused not by driver negligence but by the glare from oncoming and cross-traffic headlights.

"He probably could have seen the horses without the influence of the light from the car stopped at the side road," Mr. Penkala recalled.

A more recent client was Rose Plastic USA, a California, Pa., subsidiary of a Lindau, Germany, packaging manufacturer that wanted to build a wind turbine.

Rose hired Air Science last year to determine whether there was enough wind at the factory to make the project worthwhile; the data showed the wind speed to be nowhere near the sweet spot of 10 meters per second or 20 mph.

Still, Mr. Penkala said, by spending a few thousand dollars for a feasibility study, Rose saved millions on a capital investment doomed to fail.

Companies often tell Mr. Penkala that getting perhaps a 10 percent edge on anything can make a difference. For a construction crew, he said, that might mean squeezing out a few more minutes of work.

"If we can get you a half-hour extra before or after the rain, you can get that extra 10 percent."