By Zach Koons Early indications out of the Bay Area point to a rain-soaked field for Saturday’s playoff tilt. When the 49ers and the Seahawks take to the field at Levi’s Stadium for Saturday’s first wild-card game, they’ll have to deal with an uncontrollable variable that may have a significant impact on the outcome of the contest: the weather. Forecasts show that Santa Clara, Calif., the site of the matchup between the two NFC West rivals, is expecting thunderstorms around 4 p.m. local time, which would coincide with the second half of the game. Additionally, rain has already started to pour …