Residents of Kauai County, including Kauai and Niihau, are under a Tropical Storm Watch, while a Hurricane Watch is in effect for parts of the Papahanaumokuakea Marine National Monument. Heavy rainfall could lead to flash flooding and mudslides, particularly on Kauai and the Big Island. Large swells generated by Lowell are expected to create life-threatening surf and rip currents, with potential coastal flooding and inundation of low-lying areas late Monday into Monday night. These conditions pose significant risks to both residents and marine activities in the affected areas.