Here are three stocks with buy rank and strong momentum characteristics for investors to consider today, Dec. 19:MongoDB, Inc. (MDB) : This provider of a database platform has a Zacks Rank #1 and witnessed the Zacks Consensus Estimate for its current year earnings increasing 27% over the last 60 days.MongoDB’s shares gained 31.2% over the last three months compared with the S&P 500’s advance of 1.1%. The company possesses a Momentum Score  of A.Hallador Energy Company (HNRG) : This steam coal company has a ...