Knell Lee, 24, is a math and actuarial science graduate of the University of Minnesota who was hired as a policy auditor at SFM Mutual Insurance early this year.

He joined the ranks of thousands of Minnesotans who have started or returned to work this year as the state’s unemployment rate dropped to 4.6 percent and the state recovered all the jobs lost during the Great Recession.

“I applied for about 30 jobs,” said Lee, who passed on an opportunity at huge UnitedHealth Group to take a position with the small specialty insurer. “I really like it here. They really focus on work-and-life balance and seem to care about employees. When I started college, the [Great Recession] was underway, but the economy has come back. It was good timing for me.”

But at least one informed observer already sees a looming skilled-worker shortage. And we’re not just talking welders and machinists.

Bob LaBombard, CEO of Minneapolis-based GradStaff, expects to place a record 1,000-plus college graduates — many of them liberal arts majors — in entry-level jobs that average about $35,000 salary plus benefits. They will join mostly small to midsize growth companies, which have led the jobs recovery.

Employers tell LaBombard that their biggest fear is losing talented baby boomers, millions of whom are now in their 60s, to retirement. Some of them are leaving for other jobs or part-time consulting gigs. Their retirement accounts were replenished in recent years and they feel confident enough to quit working or to try something different.

LaBombard, an environmental chemist who changed careers to become an entrepreneur more than a decade ago, says the economy will lose 3.5 million boomers from the workforce every year for the next 15 years.

“A lot of baby boomers are hurting financially and will work for an extended period of time, but it won’t have as big an impact on the job market as we think because of the number leaving the workforce,” LaBombard said last week from his Minneapolis Warehouse District office.

The demographics are undeniable.

The 78 million baby boomers born in the United States between 1946 and 1964 dwarf Generation X, born 1965-1981, and Generation Y, the 18- to 30- year-old crowd.

According to a 2011 study by LaBombard and Sarah Sladek, CEO of XYZ University, a consulting organization that helps employers connect with the younger generations, the recession caused most employers to suspend training-and-development programs, on top of hiring freezes.

So now they are faced with hiring a lot of corporate greenhorns in their 20s and 30s just out of colleges and coffee shops. They grew up in a tech-savvy environment but with little knowledge of organizations and business process. They are “vastly unprepared” to take on the professional and managerial jobs about to be vacated by boomers, LaBombard said.

Employers are going to have to work hard to retain at least some boomers, LaBombard said, as they bring on younger workers to work with them and learn from them.

And that sounds easier than it is: The generations are very different.

The good news is that LaBombard says the young people that his 35-employee staff are placing are bright, communicative and can think on their feet. Many of them can text but can’t type. They question process and old way of doing things. That can be the root of change and innovation.

But at the end of the day, we will have a skilled-worker shortage exacerbated partly by generational and cultural segre­gation. The young people are more used to immediate gratification, thanks to technology, and they are less deferential toward the traditional corporate pecking order.

“We love people who’ve worked as bartenders,” LaBombard quipped. “They know how to deal with difficult situations.”

LaBombard says GradStaff has an 80 percent two-year retention rate, higher than average, because his model incorporates GradStaff hiring the applicants first, then placing them with employers at a billable rate of $21 to $33 per hour for several months. After about a four-month trial period, trainee and employer reach a mutual decision that can lead to permanent employment.

GradStaff, which has up to 300 trainees on the job at any one time, makes its money on the difference between its billing rate and a lower trainee rate that it pays until the trainee is hired at a beginning wage that averages around $16 an hour.

Although this is a challenge, we boomers can teach some of these young folks to type with 10 fingers and refrain from self-idolization on Facebook. And they’ve already taught us old boomers a few tricks. Generational and cultural mixing in the workplace refreshes our economy.

This is a challenge. But I’ll take a job-growing economy over the millions of idled workers we experienced during the Great Recession of job-poor 2008-09.