The Chicago area is hosting one of its biggest weekends of the year as Lollapalooza takes center stage, but could rain spoil the party in Grant Park? Low-lying and poor drainage area are at especially high risk of flash flooding, as are urban areas around the region according to the National Weather Service. As for timing, rain could start entering the Chicago area on Friday afternoon, and it will gradually build in coverage as the day wears on, according to forecast models. Next week those pleasant conditions are expected to continue, though highs will eventually rise back into the 80s. Stay tuned to the NBC 5 Storm Team for all the latest weather news and information, and be sure to download the NBC Chicago app for real-time weather alerts sent to your phone.