Eastern Atlantic Disturbance May Become a Tropical Depression But Won't Last Long

Jonathan Erdman
Published: July 13, 2019

A disturbance in the eastern Atlantic Ocean may develop into a tropical depression over the next day or so, but it's not a significant threat to the Windward Islands or Caribbean.

This area of low pressure, known as a tropical wave, was located roughly halfway between the Windward Islands and the west African coast, moving westward at 15 to 20 mph.

The National Hurricane Center (NHC) has dubbed this system Invest 93L, a naming convention it uses to identify features it's watching for potential development.

(MORE: What Is an Invest?

Potential Development Area

The NHC has assigned a low chance that this area of disturbed weather could eventually strengthen into a tropical depression over the next day or so.

Hostile Environment Ahead

There are barriers ahead for this disturbance that should keep it from significant development and limit the threat to the Windward Islands.

First, satellite imagery indicates an expansive area of dry air lies ahead of the disturbance, well east of the Windward Islands.

Atmospheric Moisture Satellite Image

Dry air is hostile for tropical development because it strengthens thunderstorm downdrafts, not allowing thunderstorms to persist near an area of low pressure. Dry air can also be quite warm several thousand feet above the surface, which may act as a lid or cap for thunderstorms to form. Without thunderstorms, you can't get tropical development.

As Invest 93L nears the Windward Islands, it may also encounter increasing west-to-east winds aloft.

These winds thousands of feet above the ocean, when combined with winds blowing the opposite direction near the surface, introduce wind shear, which can tear apart a tropical system wannabe and disrupt or weaken those that already formed.

Satellite and Wind-Shear Analysis

So even if a tropical depression does form in the next few days, current forecast guidance suggests it won't last long and may eventually move across either the northern coast of South America or the Windward Islands as one of many tropical waves that do so each hurricane season, producing just an uptick in shower activity and some occasionally gusty winds.

The majority of July named storms form closer to the U.S., either in the Gulf of Mexico or off the East Coast.

(MORE: What July Is Usually Like During Hurricane Season

Origin points of tropical storms and hurricanes in July.

However, a number of storms have formed in the strip of the Atlantic Ocean between the Windward Islands and Africa in July.

Last July, Hurricane Beryl rapidly intensified roughly halfway between the Windwards and Africa, one of only two such hurricanes to form that early in July east of the Lesser Antilles.

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