Forbes gives three reasons to be skeptical of Tesla's success

The future's cloudy, but you should still buy the stock. That's the message Forbes is sending about Tesla Motors.

Tesla's stock price may rise another 50 percent or so, but the electric-vehicle maker's steep ramp up, potential competition and dependence on a single model for its success (for now) pose risks to the automaker's future, Forbes writes.

The company, which has more than 12,000 reservations for its Model S sedan so far, is planning on ramping up to build as many as 20,000 units next year. Earlier this year, it was making around 10 units a week (this past Thursday, Tesla confirmed that it made its 100th production Model S), and to ramp up that quickly creates the potential for quality control and supplier performance issues, said Forbes. Nonetheless, Forbes has a $41 price target on the stock; Tesla was trading at about $29 a share on Friday.

Tesla started deliveries of the Model S in June and said last month that its second-quarter loss widened by 84 percent to $106.5 million because expenses jumped and revenue fell as the company prepared for the car's debut.

Additionally, with companies like BMW and Audi jumping into the advanced-powertrain fray, Tesla can expect to see increased competition just as it looks to expand production of the Model S.