Yesterday, I made the mistake of stepping outside in New York City without an outer layer. I was totally fooled by the sunshine, and I didn’t realize that temperatures were bound to drop around 50 degrees. However, unlike yours truly, it seems as though Kaia Gerber checked the forecast before hitting the streets of Manhattan. On Thursday, May 7, the model kept warm in spring’s most quintessential layer—a tailored trench coat . Her version featured soft collars, buttoned shoulder tabs, and a chartreuse-colored lining. Gerber steps out in NYC wearing an easy-to-copy spring outfit. (Image credit: Backgrid) As for the rest of her outfit, she embraced classic transitional staples—including a button-down shirt , a pair of straight-leg jeans, and a sophisticated set of ballet flats (which she designed in collaboration with Repetto). To complete her easygoing uniform, she carried Gucci ’s Jackie 1961 shoulder bag.…