Momentum investing is all about the idea of following a stock's recent trend, which can be in either direction. In the 'long' context, investors will essentially be "buying high, but hoping to sell even higher." And for investors following this methodology, taking advantage of trends in a stock's price is key; once a stock establishes a course, it is more than likely to continue moving in that direction. The goal is that once a stock heads down a fixed path, it will lead to timely and profitable trades.While many investors like to look for momentum in stocks, this can be very tough to define. There is a lot of debate surrounding which metrics are the best to focus on and which are poor quality indicators of future performance. The Zacks Momentum Style Score, part of the Zacks Style Scores, helps address this issue for us.Below, we take a look at National Storage (NSA), which currently has a Momentum Style Score of A. We also discuss some of the main drivers of the Momentum Style Score, like price change and earnings estimate revisions.It's also important to note that Style Scores work as a complement to the Zacks Rank, our stock rating system that has an impressive track record of outperformance. National Storage currently has a Zacks Rank of #2 (Buy). Our research shows that stocks rated Zacks Rank #1 (Strong Buy) and #2 (Buy) and Style Scores of A or B outperform the market over the following one-month period.You can see the current list of Zacks #1 Rank Stocks here >>>Set to Beat the Market?In order to see if NSA is a promising momentum pick, let's examine some Momentum Style elements to see if this real estate investment trust holds up.Looking at a stock's short-term price activity is a great way to gauge if it has momentum, since this can reflect both the current interest in a stock and if buyers or sellers have the upper hand at the moment. It is also useful to compare a security to its industry, as this can help investors pinpoint the top companies in a particular area.For NSA, shares are up 1.93% over the past week while the Zacks REIT and Equity Trust - Other industry is up 1.35% over the same time period. Shares are looking quite well from a longer time frame too, as the monthly price change of 4.95% compares favorably with the industry's 2.13% performance as well.Considering longer term price metrics, like performance over the last three months or year, can be advantageous as well. Shares of National Storage have increased 17.65% over the past quarter, and have gained 67.64% in the last year. On the other hand, the S&P 500 has only moved 7.89% and 30.96%, respectively.Investors should also pay attention to NSA's average 20-day trading volume. Volume is a useful item in many ways, and the 20-day average establishes a good price-to-volume baseline; a rising stock with above average volume is generally a bullish sign, whereas a declining stock on above average volume is typically bearish. NSA is currently averaging 552,758 shares for the last 20 days.Earnings OutlookThe Zacks Momentum Style Score encompasses many things, including estimate revisions and a stock's price movement. Investors should note that earnings estimates are also significant to the Zacks Rank, and a nice path here can be promising. We have recently been noticing this with NSA.Over the past two months, 5 earnings estimates moved higher compared to none lower for the full year. These revisions helped boost NSA's consensus estimate, increasing from $1.99 to $2.12 in the past 60 days. Looking at the next fiscal year, 5 estimates have moved upwards while there have been no downward revisions in the same time period.Bottom LineTaking into account all of these elements, it should come as no surprise that NSA is a #2 (Buy) stock with a Momentum Score of A. If you've been searching for a fresh pick that's set to rise in the near-term, make sure to keep National Storage on your short list. Infrastructure Stock Boom to Sweep America A massive push to rebuild the crumbling U.S. infrastructure will soon be underway. It’s bipartisan, urgent, and inevitable. Trillions will be spent. Fortunes will be made. The only question is “Will you get into the right stocks early when their growth potential is greatest?” Zacks has released a Special Report to help you do just that, and today it’s free. Discover 7 special companies that look to gain the most from construction and repair to roads, bridges, and buildings, plus cargo hauling and energy transformation on an almost unimaginable scale.Download FREE: How to Profit from Trillions on Spending for Infrastructure >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report National Storage Affiliates Trust (NSA): Free Stock Analysis Report To read this article on Zacks.com click here.