It is 7 p.m. at the National Weather Service office on North Main Street in Caribou — time to launch the weather balloon.

Two volunteers step out of a group of a dozen women gathered outside the building’s back entrance to assist National Weather Service staff with the twice-daily ritual.

It is the monthly meeting of the Caribou branch of the American Association of University Women and release of the balloon is the centerpiece of the Aug. 6 program.

A light breeze helps lift the helium-filled balloon from the hands of Brenda Felch and Sharon Ouellette, carrying it about 100,000 feet, or almost 20 miles, into the upper air. Within minutes, the radiosonde transmitter, dangling on a cable attached to the balloon, begins sending data to the weather service computer.

A continuous feed of data, such as temperature, pressure, moisture, wind direction and speed, flows across the computer screen in the operations area of the station during the 90 minutes it takes the balloon to reach its peak altitude.

Association members and guests gather around one screen then others as meteorologist Corey Bogel introduces them to the vast and diverse information generated by the National Weather Service, the largest division of the National Oceanic and Atmospheric Administration, a unit of the U.S. Department of Commerce. Of the 122 offices across in the nation, there are two in Maine, including the Caribou office that covers northern and eastern Maine as far south as Hancock County.

“A lot of people, like us, don’t realize what’s housed in that building,” Shirley Ayer said after the visit, echoing comments of others in the group who, even though they live nearby, had never been inside. “It’s quite amazing. I had no idea of the technology involved. It was an enlightening experience,” she said, mentioning the benefits of information for farmers and sailors.

“It’s right in our backyard,” said Carol Pierson, who lives a few doors from the office on Main Street.

The visitors were impressed with the amount of information available at weather.gov, which displayed a map of the United States defining all National Weather Service regions. A click on Maine brought up the Caribou Forecast Office website, with 18 icons leading to current and past details on weather in the region.

“I was thrilled to learn from Corey that the ‘Rivers and Lakes’ icon of the NOAA web page has local river depths and percent of average depths at a glance,” said Catherine Brewer, who will use the information on river water levels for paddling.

Colleen Murphy, who also lives nearby on Main Street, said that, “aside from the wealth of data” available online, she was interested to learn “protection of life and property” is central to the weather service’s mission.

“I guess I hadn’t really thought of safety as their role, but that really is the essence of what they do,” Murphy said.

“We’re here 24-seven, 365 days a year,” Bogel said, adding there are always at least two people in the office, with staff members rotating in day, evening and night shifts. When severe weather threatens, the weather service issues watches, warnings and advisories for public protection.

Extreme weather also may prompt staff to launch a weather balloon outside of the regular 7 a.m. and 7 p.m. schedule.

In addition to general daily forecasts issued every three hours, the Caribou office provides aviation forecasts for six Maine airports, marine, fire, weather and river forecasts. The latter are relayed from the Northeast River Forecast Center in Taunton, Massachusetts.

Bogel also stressed to the group the difference between weather — day-to-day temperature and precipitation — and climate — long-term statistics of weather trends over time.

As an example, he noted that weather in the Northeast has been “trending wetter” since 2005, with moisture off the north Atlantic bringing more “extreme heavy rain events” to the region.

“Of the 10 wettest years on record, four are within the last 10 years: 2005, 2008, 2011 and 2013,” he said, adding two of the wettest growing seasons occurred in the last four years.

Globally, increased carbon dioxide in the atmosphere has resulted in a warming trend.

“Climate models show the expected warming to be more rapid,” he said, noting the average global surface temperature has increased one degree Fahrenheit in the last 100 years.

Bogel also told the group to expect the effects of El Nino — the warming of tropical waters in the Pacific Ocean — in the coming year, typically between January and March. He directed those interested to the Climate Prediction Center website for details on El Nino, including animated maps showing the current warming of the Pacific Ocean between May and August 2015. Typically, according to the weather service, El Nino episodes feature “a strong jet stream and storm track across the southern part of the U.S.” and “less storminess and milder-than-average conditions across the North.”

While the National Weather Service staff welcomes groups like American Association of University Women to the Caribou office throughout the year, Bogel said their biggest audience is on Facebook, which even nonmembers can access by clicking on “Social Media” under “Local Programs” at weather.gov/car. The click also brings up the Twitter and YouTube feeds.

Activity on the Caribou National Weather Service website ranges from an average of about 1,500 visits a day to as many as 10,000 during a storm, Bogel said.

“It depends on the weather.”

Kathryn Olmstead is a former University of Maine associate dean and associate professor of journalism living in Aroostook County, where she publishes the quarterly magazine Echoes. Her column appears in this space every other Friday. She can be reached at kathryn.olmstead@umit.maine.edu or P.O. Box 626, Caribou, ME 04736.