PORTLAND —  One of the first things I had to learn about being a TV meteorologist was how to let people see what you’re talking about when you can’t.

Charlie Lopresti – chief meteorologist at Portland CBS affiliate WGME-TV (Channel 13) – said I should begin my night on the job by practicing how to use the “green screen.” It’s basically a blank screen that TV folks stand in front of so that various images can be displayed behind them on air.

So I stood in front of the green screen, looked at it and saw nothing. Then I turned around and saw myself, and a weather map, on a monitor about 10 feet in front of me.

“You’re blocking out the state of Maine, which is not good when giving a forecast for Maine,” said Lopresti. “But remember, it’s sort of like looking in a mirror. If you want to shift your position on screen to one side, you actually have to move to the other side.”

Huh?

I tried moving all the way to one side, but I still covered eastern portions of Maine, from Bar Harbor to Canada. Then I moved so far to the other side that only part of my head was still on screen. Lopresti told me not to worry, I’d get the hang of it.

As I practiced, I could see not only the maps and graphics in front of me, but also a monitor on each side of me. A trick Lopresti taught me was that if you turn toward one of those side monitors and point at it, to viewers it sort of looks like you’re pointing at a spot on the map. When I tried to point to Waterville for the first time, I realized I was instead pointing somewhere closer to Farmington.

“After a while this all becomes second nature. When I first started, it took some getting used to. The presentation stuff was hard to learn,” said Lopresti, 32, who has a degree in meteorology from Plymouth (N.H.) State University.

“I had originally thought I was going to work on the research side of weather, but that was mostly crunching numbers. I like forecasting.”

When I went to see Lopresti, he was preparing his late-night forecasts in his weather office, using computer forecasting models on various computer screens.

Some were from the U.S. government, some were from other countries, some were from weather companies. Most of the satellite images and maps Lopresti showed me looked to my untrained eye like a mass of color and scribbled lines.

But as Lopresti went over the data, he’d see findings he didn’t agree with and mutter,  “This model is out to lunch.” He did this at one point when he got a report from an automated station at the Portland International Jetport showing clear skies at 9 p.m.

All the other information he had indicated that Greater Portland was shrouded in heavy clouds, and he had already planned to include this fact in his 10 p.m. and 11 p.m. forecasts.

“Sometimes the human eye is better than this stuff,” said Lopresti, as he led me out of the studio and into the station’s darkened parking lot on Washington Avenue. We walked 100 yards from the building and confirmed it was indeed cloudy.

I learned that Lopresti tries hard to use everyday language in his forecasts and stay away from weather-speak like “barometric pressure.” People just want to know if it’s going to rain, and how that affects their day, he told me.

As he said this, it occurred to him that he should personalize his upcoming forecast – a chance of rain late in the day the next day.

“So I should probably say something like, ‘If you’re working outdoors tomorrow, you’ll probably get the day in,’ ” said Lopresti.

During the hourlong 10 p.m. newscast (shown on Portland’s Fox affiliate, Channel 23, but done by the WGME staff), I watched Lopresti give his forecast several times, talking for as long as 3 minutes during any single forecast.

I’d have my turn during the 11 p.m. newscast, but since the 10 p.m. news was going on live, just feet away from where Lopresti and I were sitting in his weather office, I couldn’t rehearse or practice anymore.

A minute before 11 p.m., Lopresti talked into his microphone to ask a producer when my weather segment would come on.

“Oh, it’s the lead,”  he said, surprised.

Just then, Lopresti realized I wasn’t hooked up for sound.

Someone handed me a tiny clip-on microphone, and anchor Kim Block, who had just finished the 10 p.m. news, came over and helped me put it on and tuck the cord out of sight. I stood on a duct-taped spot in front of the green screen and heard anchors Gregg Lagerquist and Kiley Bennett start the newscast.

Then Lopresti introduced me, and in a second, I saw my own face in the monitor. I whipped into my pitch about “we had a lovely day, lots of sun, high of 59, but you can see the clouds and a storm coming our way from New York. It may bring, uh, a little rain to our south later tomorrow, but Charlie will have more on that in his forecast.”

Then I clicked to the current temperature map and pointed. On screen, my hand landed on Caribou, which was not part of my forecast, so I slowly adjusted it until I was pointing vaguely to southern and central Maine and began reading temperatures.

Then I said,  “Those clouds are making things cooler tonight, but not as cool as last night, when we had a low of 29.”

Then, in my favorite moment of the evening, I said something like “Now back to Charlie.”

Later, during a commercial break, Block high-fived me. Lopresti and the other on-air people said they couldn’t believe how well I did.

Neither could I. I didn’t even use a teleprompter.

But then I realized I had been listening to Lopresti give weather details for something like three hours, so enough of that information stuck in my brain that I was able to recite 30 seconds worth of it without much trouble.

“When you’re thinking about the weather all day long, it’s not that hard to tell people what it’s going to be,” said Lopresti.

I agree. It’s the thinking that’s the hard part.

Staff Writer Ray Routhier can be contacted at 791-6454 or at: rrouthier@pressherald.com