From the National Weather Center:
• Tropical Depression 18 (TD 18) over the south-central Caribbean Sea now has a well-defined circulation. TD 18 will strengthen into a tropical storm later today and approach western Cuba as a hurricane on Wednesday.
• There are no tropical storm watches or warnings in effect for any portion of the Florida Keys at this time.
• There is moderate confidence in a forecast track across western Cuba into the south-central Gulf of Mexico. Due to uncertainty in the exact structure of the storm, there remains some uncertainty in the level of potential impacts on the Florida Keys. However, these impacts may include:
o Coastal flooding, with potential saltwater flooding for oceanside portions of the Florida Keys Wednesday. Water levels could reach up to 2 feet above mean higher high water, or about a foot higher than recent high tides.
o The potential for tropical storm force winds remains steady, with the highest chances just above 1-in-3 at Key West, or about 40%. If realized, tropical storm-force winds could arrive as early as late Tuesday evening, but will most likely arrive Wednesday morning.
o There is a Marginal Risk (level 1 of 5) of severe thunderstorms, including a few tornadoes Wednesday and Wednesday night. Outside of severe thunderstorms, thundery squalls are likely with localized wind gusts of 50 to 55 mph.
o Locally heavy rainfall is possible from passing squalls, resulting in flooding of streets and poor drainage areas, especially Tuesday night through Wednesday night.
• Residents and visitors in the Florida Keys should closely monitor the future progress of TD 18 in the event protective actions become necessary.
The next Weather Brief concerning TD 18 for the Florida Keys of Monroe County will be issued by 5:00 PM EST Monday evening.
Briefings are also posted to https://www.weather.gov/media/key/DSS/dssbrief_land.pdf