Satellite image of the tropical disturbance Monday morning. (NASA)

The fifth tropical storm of the season is going to arrive early this year. The National Hurricane Center could be just hours away from naming a well-organized cluster of thunderstorms just south of Hispaniola “Tropical Storm Earl.”

On average, the fifth named storm of the Atlantic hurricane season forms Aug. 30, so if it does get named, Earl will be a month ahead of schedule. The National Hurricane Center is giving the system an 80 percent chance of becoming at least a tropical depression by Wednesday morning.

We have been tracking this area of thunderstorms for more than a week, and it’s very close to being named. A Hurricane Hunter mission will fly into the disturbance later today to try to find a closed surface circulation, but its rapid motion could make that difficult to pin down. The system is moving quickly to the west. It is a compact system, but rain bands were already affecting Haiti and Dominican Republic on Monday.

Conditions around the disturbance will make it easy for Tropical Storm Earl to form. Vertical wind shear is expected to be low, in the ballpark of 10 to 15 mph, for the rest of the week. Sea surface temperatures are adequately warm and will only increase as the storm moves west.


Sea surface temperatures across the Caribbean are plenty warm for tropical systems to form and intensify. (UMiami/RSMAS)

Forecast models continue to agree this system will keep tracking west across the Caribbean, with a potential landfall in the Yucatan or Belize on Wednesday.

It would weaken as it crosses land, so whatever emerges in the Bay of Campeche will have some reorganizing to do before it poses a major threat to the gulf coasts of Mexico or Texas.

At this point, a south-Texas impact looks unlikely, but it’s far too early to completely rule it out.


Five-day track forecasts from the suite of global and regional dynamical models. (UAlbany)

Looking back at all of the “E” storms since 2000, seven of them became hurricanes. The storm that most closely resembles this year’s soon-to-be-named “E” storm was Ernesto in 2012. The strongest since 2000 was Emily, which developed in 2005 and became a 160-mph Category 5 hurricane near Jamaica. Ernesto and Emily traveled the full length of the Caribbean and hit the Yucatan Peninsula as hurricanes.


Tracks of the past 15 “E” storms (2001-2015). (NOAA)