25 May 2018

Subtropical Storm Alberto forms, kicking off hurricane season 1 week early

On Friday morning, the tropical disturbance we have been watching for what seems like forever was upgraded to Subtropical Storm Alberto, the first named storm of the 2018 Atlantic hurricane season.  It also makes 2018 the 4th consecutive year with a pre-season named storm, an unprecedented string.

Alberto is expected to transition to a fully tropical storm later, but as of now it does meet the criteria.  The difference between the two is really just academic, as it pertains to the structure of the system... not the impacts. If and when it becomes Tropical Storm Alberto, nothing will be magically different about it, other than the distribution of the wind field and perhaps the symmetry of the thunderstorms around it.  Cyclones come in many shapes and sizes across a spectrum!

Just as before it was named, the biggest impact will be extremely heavy rain over a large region.  The forecast 5-day rainfall totals are shown below:

Secondly, storm surge flooding will become a concern along Florida's west coast and along the northern-to-northeastern Gulf coast.

Models remain in pretty good agreement on the track and timing, but with any tropical cyclone, it's big, so impacts will extend far beyond the center line.  A series of 3-day track forecasts from dynamical models is shown below.  Wind shear should keep the system lopsided, so the messier, rainier side will be to the east of center, including the Florida peninsula.

Stay tuned to the National Hurricane Center website for the latest forecasts, watches, and warnings.

It is interesting to note that since 1851, only 3 other tropical cyclones formed within 200 miles of where Alberto is now during May (plus one in February 1952). All three May ones formed on May 31st!

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