Invest 98-L May Become a Tropical Depression or Storm in the Eastern Atlantic

Jon Erdman
Published: August 15,2016
A tropical disturbance in the eastern Atlantic Ocean has some potential to develop into the Atlantic hurricane season's next tropical depression or storm this week.
(MORE: Hurricane Central)
Invest 98-L is a tropical wave, an area of low pressure without a closed, counterclockwise surface circulation south of the Cabo Verde Islands off the west coast of Africa.
(MORE: What is an Invest?)

Invest 98-L Infrared Satellite Image

This tropical wave emerged off the west African coast this past weekend, and is now flaring some convection, according to infrared satellite imagery.
(MORE: Why Tropical Waves Are Important During the Hurricane Season)
Despite its appearance, the National Hurricane Center (NHC) noted the convection was well ahead of the surface location of the tropical wave. For a tropical cyclone to form, you need persistent convection near a surface low-pressure circulation.
The NHC says this system has a high chance of development into a tropical depression or tropical storm over the next five days.
Invest 98-L will continue tracking west-northwest the next few days in the open eastern Atlantic Ocean.
(MORE: Three Things to Know About Spaghetti Model Forecasts)

Forecast Model Tracks: Invest 98-L

For now, this system is no immediate threat to the Lesser Antilles, as it is over 2,000 miles away.
Furthermore, even if Invest 98-L does develop into a tropical depression or storm - the next named storm would be called "Fiona" - it faces a familiar pair of nemeses later in the week.
First, the system is expected to face increased wind shear, namely, differing winds aloft compared to near the surface, roughly near or just the halfway point between Africa and the Lesser Antilles.

Current Satellite, Wind Shear

Wind shear tends to displace a tropical system's convection from its center of circulation and can also tilt that circulation. While some intense hurricanes can fend off some light to moderate wind shear, weaker systems can be ripped apart if the shear is too strong.
(MORE: Hurricane Season Outlook Update)
The increased southwest winds aloft responsible for the anticipated wind shear, along with a fairly weak Bermuda-Azores high may also help to draw the system more northwest this week, eventually gaining too much latitude to ever be a threat to the Lesser Antilles.
Dry air in the central Atlantic later in the week could also disrupt the system by encouraging stronger thunderstorm downdrafts, dispersing the convection from the system's center.

Satellite Image: Where the Dry and Moist Air Is

For now, this system is not a threat to the Windward and Leeward Islands.
Assuming it develops at all, it wouldn't make it to the longitude of these islands until early-mid next week, and may be pulled well north of that as discussed above.
However, this is another sign that we're headed into the climatologically most active time of the Atlantic hurricane season.
(MORE: When Atlantic Season Peak Arrives)
This time of year, you can see tropical waves, also known as African easterly waves, lined up over Africa south of the Sahara Desert, ready to emerge into the eastern Atlantic Ocean.
A fraction of these tropical waves serve as the seed for an Atlantic basin tropical storm or hurricane each season.

Africa Infrared Satellite

So, while Invest 98-L may have a rough road ahead, subsequent tropical waves may have a more favorable atmosphere in place to develop next week.
Check back with us at weather.com for the latest on this system and any other systems during the hurricane season.
Jonathan Erdman is a senior meteorologist at weather.com and has been an incurable weather geek since a tornado narrowly missed his childhood home in Wisconsin at age 7.