GRAY – Roger and Margaret Turcotte of Lewiston stood in the rain Saturday, waiting their turn to take a tour of the NOAA’s National Weather Service station.

He looked up and identified a heavy cloud. “Here it comes,” Roger said.

Within seconds the rain grew heavier. Turcotte’s forecast was accurate.

They used to have a camper on the ocean, he said. “You can see the storms coming across. You get to recognize what’s coming.”

The couple came to the National Weather Service open house because it would be interesting, he said.

John Mollica of Cumberland Center came with his son, Jonas, 11, today.

Jonas is a bonafide weather spotter. When there’s interesting weather in his town – hail, strong wind, heavy snow – Jonas reports that to the National Weather Service. “I only reported once,” he said. “We don’t get a lot of intense weather.”

The father and son came to the open house two years ago. “We wanted to check it out again,” the elder Mollica said.

Inside, crowds were taken in to different rooms to see the forecasting tools: radar equipment, satellite pictures, a weather balloon with an instrument tied to it. Weather balloons are released twice a day, said meteorologist John Jensenius. As the balloon rises it expands, reaching 100,000 feet before it bursts.

As the balloon goes up, “we get a snapshot of temperatures, dew point, humidity and wind speed and wind direction,” said meteorologist John Cannon.

From the operations room, Cannon offered a crash course on making forecasts and weather warnings.

The operations room is staffed 365 days a year, all day and all night, by two meteorologists, Cannon said. In one corner was Steve, a long-term forecaster. Steve waved. In the other corner was Eric, the short-term forecaster. Eric waved.

Meteorologists need to get good snapshots of the atmosphere and build computer models. “We take those models and then tweak them a little bit. That’s how we make the forecast,” Cannon said.

As he spoke, an oversized picture of New England appeared on the wall. It was a satellite photograph, a camera looking down at the cloud tops, Cannon said.

The picture showed rain falling especially on the coast. Before noon the Brunswick Naval Air Show was getting heavy rain, Cannon said. He pointed to the low cloud cover over Maine and New Hampshire. Then, almost like he couldn’t help it, predicted “a big cold front coming from New York and a general improvement. You might see a peek of sun later today.”

The sun did come out later.

Another wall-sized picture showed color-coded radar. Brighter colors mean heavier rain. Wind also shows on radar. “Blue is wind moving toward us, red away from us. As long as the wind is carrying bugs, dust or whatever, the radar can pick up wind and report it to us.”

In addition to high-tech equipment, meteorologists get data from private and public organizations and citizen volunteers like Jonas. Cannon pointed to several amateur radio operators in the room. During storms they use their radios to collect and report extreme weather.

Data from all the above sources are collected and used in forecasts and warnings, Cannon said.

He then took questions.

How do they give extended forecasts?

Five-day forecasts just offer general trends of moisture and temperature. “We don’t get overly specific,” Cannon said.

Do meteorologists go outside and look at the weather?

Yes, that’s critical. “There’s nothing like a reality check of going outside and feeling the maritime moisture in the air.”

During the ice storm of 1998, were they down at all?

Very briefly, Cannon said. They have “big diesel tanks that run generators.”

More than 500 people turned out for Saturday’s 9-3 open house. Since one was held two years ago, meteorologists weren’t sure how many people would show. “People are enjoying this,” Cannon said. “People love weather.”

The next open house will likely be offered in September 2009.