Subtropical Storm Alberto Forms in Caribbean, Will Drench Miami All Weekend

Six days before hurricane season even begins, we already have our first named storm of the year. And it will absolutely drench South Florida just in time for a three-day weekend.

Subtropical Storm Alberto officially formed around 10 a.m. just off the Yucatán Peninsula in the northwestern Caribbean Sea, which means the system has picked up a noticeable rotation and kicked up winds topping 39 mph.

The National Hurricane Center will begin issuing regular advisories on Alberto beginning at 11 a.m., and the storm's track is still difficult to nail down with any certainty. But what is certain is that Miami will spend Memorial Day weekend pretty much under water.

"Locally heavy rainfall is forecast across western Cuba and over much of Florida and the northern Gulf Coast into early next week," the National Hurricane Center (NHC) warns. "This system could also bring tropical-storm-force winds and storm surge to portions of the northern Gulf Coast by late this weekend or early next week."

For Miami, that could translate to half a foot of rain by the end of the weekend:

440 am 5/25/18: Another surge of tropical moisture will bring periods of heavy rain to much of South Florida later today into Monday. Totals of 2-6 inches will be common, with locally heavier amounts. The rain may bring an increased risk of flooding this weekend. #FLwx pic.twitter.com/frHjiu7D24

— NWS Miami (@NWSMiami) May 25, 2018

It's still unknown how big Alberto could get — some forecasting models show it hovering around as a tropical depression with heavy rains, while others show its wind speeds growing all the way to hurricane force.

"The latest... Thursday runs of our top intensity models... predicted [the storm] could get considerably stronger than previously thought, with peak winds ranging from 40 mph... to 80 mph," writes Jeff Masters of the Weather Underground. "Heavy rain from [the storm] is still likely to be its number one threat, though we may also need to be concerned with storm surge damage and wind damage if the storm does manage to over-achieve. "

Update 11 a.m.: The first forecast models are in from the NHC, and they show Alberto avoiding South Florida. But forecasters say the wide-ranging storm should still dump heavy rain on Miami:

5/25: 11AM Subtropical Storm Alberto forms in the NW Caribbean Sea. Impacts for South Florida remain unchanged as heavy rainfall is expected across South Florida through the weekend #FLwx pic.twitter.com/QOA44fsFJj

— NWS Miami (@NWSMiami) May 25, 2018