Investors await Federal Reserve Chair Janet Yellen's closely watched speech on Tuesday at the Economic Club of New York -- and they're expecting some clues on when the central bank will hike short-term rates next.

"I would expect some type of verbiage addressing the timing of the next rate hike," said Scott Wren, senior global equity strategist at Wells Fargo Investment Institute. "In our opinion, we'll see one [hike] this year."

That's more dovish than the Fed's forecast back in December of four rate hikes in 2016. It's also more dovish than its forecast earlier in March of two rate hikes in 2016. The Fed has become more accommodative to markets in its tone and language so far this year amid the recent drop in the stock market and falling oil prices, two themes that have dominated the markets.

Still, Wren thinks the economy is slowly moving in the right direction. He expects the economy to grow 2.1% in 2016, similar to the Fed's forecast of 2.2% growth. 

"Clearly the labor market has been OK, but wages are going nowhere fast and I think that's likely to be the case for a few more months," he said. "The Fed wants to be careful -- they don't want to raise rates too many times, but I do expect that we'll see a [rate hike in June]."

Wren expects the Fed to give signals of a looming rate hike two to three months in advance of the central bank pulling the trigger.

In her speech, Yellen is likely to reiterate how data-dependent the Fed is when it comes to rate hike decisions. The next big data point comes on Friday via the March jobs report. Still, Wren doesn't think the nonfarm payrolls number is as important as it once was.

"Over the course of the last six to nine months, the nonfarm payroll number has been fairly steady," Wren said. "The number I'm watching is the year-over-year change in average hourly earnings, and I think the Fed is keeping a very close eye on that. It's expected to be 2.2% this year, which is a disappointing number." Wren added that the Fed would like to see annual wage growth between 3% and 4%.

As of February, average hourly earnings rose 2.2% year over year.