A fast-moving spring storm system is expected to bring potentially severe thunderstorms to northern Illinois, with the main threat likely to be near and south of Interstate 80. The National Weather Service predicts that temperatures will rise into the 70s and low 80s before the front of the system, falling quickly into the 40s and 50s later in the day, with even colder readings near Lake Michigan. The main threat is large hail and damaging winds, which could cause tree limb damage and potentially lead to downing tree limbs. While there is no tornado potential, the atmosphere is unstable enough to support intense storms.