Latest Threat In Atlantic Degenerates To Open Wave Near Windward Islands

As what was Hurricane Ernesto made its second landfall in Mexico, and subsequently dissipated over the terrain of the southern portion of that country, a new threat had emerged in the Central Atlantic.  A tropical wave in the Central Atlantic had acquired enough characteristics to be classified as Tropical Depression #7 on Thursday afternoon.

For the next day and a half, the depression moved westward toward the Windward Islands as it appeared to follow a track similiar to Ernesto’s.  However, the tropical cyclone didn’t do much strengthening.  Maximum sustained winds remained at 35 miles per hour for the next 36 hours.  Wind gusts also stayed status quo at 45 miles per hour with pressure only dropping to 1008 millibars, or 29.77 inches of Hg.

On Saturday morning, Hurricane Hunter aircraft took its first look at the depression as it moved closer to the Windward Islands.  What the researchers found was not impressive.  The sustained winds were still at 35 miles per hour.  Most importantly though, while there were shifts in wind direction near the surface, there was no closed circulation.  As a result, TD #7 was reclassified as a tropical wave and the warnings that were in effect for Guadeloupe, Martinique, Dominica, St. Lucia, Barbados, and St. Vincent and the Grenadines were discontinued.

A significant factor that hindered the progress of Tropical Depression #7 was its forward speed.  When it was first classified as a tropical depression on Thursday, it was moving at 20 miles per hour.  The storm didn’t slow down either.  Instead, it gradually ramped up to speeds of 25 miles per hour by Saturday morning.   Whenever a fledgling system like this moves at such a fast pace, the circulation often outruns the convection and nothing is able to coalesce around the center.

Ernesto had a similar problem when it moved through the Eastern Caribbean this time last week.  Once the storm was able to slow down some, it was able to gradually get better organized and strengthen into the season’s second hurricane.  We’ll have to see if the same holds true for the remnants of TD #7.  There is also another feature in the Atlantic, but it doesn’t have a lot of shower and thunderstorm activity associated with it right now, and only has a 20 percent chance of becoming a tropical cyclone in the next 48 hours.