Tropical Development Chances Increase for Wave Expected to Emerge Off Africa

Activity across the tropical Atlantic continues to bear watching as the National Hurricane Center monitors two tropical waves for possible development during the upcoming week.

The biggest change with the Sunday afternoon update is an increase in the development chances for the tropical wave expected to move off the west coast of Africa early this week.

Its seven-day formation chance has increased from 40 percent Sunday morning to 50 percent Sunday afternoon.

Neither system poses an immediate threat to North Carolina or the United States, and it remains far too early to determine whether either system will eventually affect land.

Eastern and Central Tropical Atlantic

The system attracting the most attention is a tropical wave expected to move off the west coast of Africa early this week.

Environmental conditions are forecast to become favorable for gradual development after the wave emerges over the Atlantic.

A tropical depression could form during the latter half of this week as the system moves westward to west-northwestward across the central tropical Atlantic.

The chance of tropical cyclone formation remains near 0 percent during the next 48 hours but has increased to 50 percent during the next seven days.

That is now considered a medium chance of development.

The increase from 40 percent to 50 percent since Sunday morning is something worth watching, but it does not indicate that development is guaranteed.

Central Tropical Atlantic

Farther west, a broad area of showers and thunderstorms associated with another tropical wave remains several hundred miles west-southwest of the Cabo Verde Islands.

Some gradual development remains possible during the early to middle portion of this week as the system continues moving westward across the central tropical Atlantic.

However, upper-level winds are expected to become less favorable for development later in the week as the system approaches the Lesser Antilles.

The chance of formation remains near 0 percent during the next 48 hours and 20 percent during the next seven days.

There has been no change in those probabilities since Sunday morning.

What Does a 50 Percent Development Chance Mean?

The 50 percent probability refers to the chance that the tropical wave develops into a tropical cyclone during the next seven days.

It does not represent a 50 percent chance of the system affecting North Carolina, the East Coast or any other specific location.

At this stage, the system has not even moved off the African coast, and there is no reliable way to determine where it may eventually travel if development occurs.

There are many steps between a tropical wave emerging from Africa and a system potentially becoming relevant to the United States.

Atlantic Activity Typically Increases During August

The increase in activity comes at a time when the Atlantic hurricane season typically begins becoming more active.

August marks the beginning of the climatologically busier portion of the season as atmospheric and oceanic conditions across the tropical Atlantic become increasingly favorable for tropical cyclone development.

The historical peak of Atlantic hurricane season occurs in September.

Tropical waves emerging from Africa during this portion of the season are therefore watched closely, particularly when environmental conditions appear favorable for gradual organization.

No Immediate Threat to North Carolina

There is currently no immediate tropical threat to North Carolina from either of these systems.

The wave expected to emerge from Africa has a very long journey ahead of it, assuming it develops at all. Changes in atmospheric steering patterns, wind shear, dry air and other environmental factors will ultimately determine its development and track.

For now, there is no reason to speculate about potential impacts to North Carolina or the United States.

The important development Sunday afternoon is simply that the National Hurricane Center has increased the seven-day formation probability for the eastern Atlantic wave to 50 percent.

Rowan County Weather will continue monitoring both tropical waves and provide updates as new information becomes available.