The path to Dow Jones 21,000 is clearer than some investors may imagine, and there's currently a green flag waving to help usher it to that lofty record height, according to Wall Street Sector Selector's John Nyardi.

The benchmark index has amassed a gain of about 1,500 points in less than a month, but Nyardi says that's no reason for it to stop now as it pushes toward its next millennial hurdle of 18,000.

"Throughout its history, the Dow has been known for big V-shaped moves, and once it gets on a roll, momentum seems to pick up as global investors and traders pile into the high visibility index," he writes in a guest column published by USA Today.

Nyardi notes the Dow has gained about 2,000 points since November 2013, and if it duplicates that performance again, it will be at about 20,000 by Thanksgiving 2015. From there, he claims, it would be reasonable for the Dow to hit 21,000 by July 2016.

"A lot of this depends upon how the U.S. market adjusts to and digests the end of the Federal Reserve's quantitative easing program," he writes. If both the end of the taper and the Fed's expected hike in interest rates in mid-2015 turn out to be benign events, Nyardi says it could be off to the races for stocks.

For the short term, he is looking for year-end buying to help boost stocks, and thinks there is also positive rub-off from the positive quarterly earnings season just completed.

"With 90 percent of the reports in the books, analysts and investors are widely shocked at how successful it was. Earnings were mostly strong, and coupled with nine straight months of new monthly job formation above 200,000, a record not seen since 1995, analysts have become even more bullish about the overall health of the U.S. economy."

And after the 2014 year-end uptick he sees ahead now?

"Beyond New Year's Day lurks the great unknown, however, Dow 21,000 could come onto the radar screen sooner than we all expect. For today, we remain in 'green flag' status, expecting higher prices ahead," Nyardi predicts.

The Wall Street Journal's Paul Vigna reports the stock market may be in year-end Santa Claus rally posture, but the fact utility stocks — generally regarded as defensive plays — are one of the strongest sectors shows some caution as well.

"Bonds, with U.S. yields confounding the experts this year by not rising, are about safe havens. Stocks, with the major indexes continuing to hit record highs, are about animal spirits," Vigna notes.

"But when you mull over how well these defensive names are doing, it's worth pondering whether stocks and bonds are actually telling the same story, one about safety."

Lance Roberts, chief portfolio strategist for STA Wealth Management and host of the "StreetTalk" radio show, also urges a bit of wariness.

Roberts notes that bulls are pointing out low interest rates, higher corporate profits and concerted central bank stimulus efforts globally as supports for the market.

"While I do not disagree with any of those points, it should be remembered that each is artificially influenced by outside factors. Interest rates are low because of central bank actions; corporate profitability is high due to share buybacks and accounting gimmickry and central bank interventions have artificially inflated asset prices," Roberts writes.

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