A tropical wave in the Atlantic, identified as Invest 98L, is showing increased signs of organization and has a high probability of developing into a tropical depression or storm later this week. The National Hurricane Center (NHC) is closely monitoring the system as it moves westward toward the Caribbean Sea.
According to the latest tropical outlook, atmospheric conditions appear favorable for continued development. Forecasters have increased the formation chance to 70% over the next seven days, prompting interests in the Caribbean to monitor its progress closely.
Key Takeaways
- A tropical wave, Invest 98L, is showing signs of organization in the Atlantic.
- The National Hurricane Center gives it a 30% chance of formation in 48 hours and a 70% chance within seven days.
- The system is expected to move into the central Caribbean Sea, where a tropical depression could form this week.
- If it becomes a named storm, it will be called Melissa.
System Shows Potential for Development
The National Hurricane Center reported on Sunday that Invest 98L, a tropical wave located over the central tropical Atlantic, is becoming better organized. Satellite imagery indicates that the system is producing a broad area of showers and thunderstorms that are gradually consolidating.
Forecasters note that environmental conditions, including warm ocean waters and relatively low wind shear, are conducive for further strengthening. These factors are critical for the transition from a tropical wave into a more structured cyclonic system.
What is an 'Invest'?
The term "Invest" is short for "investigation." It is a designation used by the National Hurricane Center and other forecasting agencies for a weather system they are monitoring for potential tropical cyclone development. Assigning an "Invest" number allows for the collection of specialized data sets and the running of advanced computer models to better predict its future track and intensity.
As of the 2 p.m. advisory, the NHC has assigned a medium chance of development in the short term and a high chance over the next week. This steady increase in probability suggests that forecasters are growing more confident in the system's potential to become a named storm.
Projected Path and Forecast Uncertainty
Current forecast models are in general agreement that Invest 98L will continue on a westward track over the next several days. This path is expected to bring the system into the central Caribbean Sea by the middle of the week.
Once it enters the Caribbean, a tropical depression is likely to form. A tropical depression is a cyclonic system with maximum sustained winds of up to 38 mph (62 km/h). If the system continues to strengthen and winds reach 39 mph (63 km/h), it will be classified as a tropical storm and given the name Melissa.
Storm Naming Convention
The World Meteorological Organization maintains a rotating list of names for Atlantic tropical storms. The next available name on the 2025 list is Melissa. Using pre-determined names helps with clear communication and reduces confusion when multiple storms are active at once.
While models agree on the general direction into the Caribbean, there is low confidence regarding its specific track and intensity beyond that point. Long-range forecasting for developing systems is inherently challenging, as small changes in atmospheric steering currents can lead to significant shifts in the storm's ultimate path.
"Atmospheric conditions appear favorable for further organization as the system moves across the Caribbean Sea, and a tropical depression could form sometime this week," the National Hurricane Center stated in its latest outlook.
Residents and authorities in the Lesser Antilles and across the wider Caribbean basin are advised to stay informed and review their hurricane preparedness plans.
Understanding Tropical Development Stages
Tropical cyclones form over warm ocean waters and go through several distinct stages of development. Understanding these stages is key to preparing for potential impacts.
The process typically begins with a pre-existing weather disturbance, like the tropical wave that is now Invest 98L. For this disturbance to intensify, several conditions must be met:
- Warm Ocean Water: Sea surface temperatures of at least 80°F (26.5°C) are needed to a depth of about 150 feet (50 meters). This warm water provides the energy for the storm.
- Low Vertical Wind Shear: Wind shear is the change in wind speed or direction with height in the atmosphere. Low shear allows the storm's structure to remain vertically aligned and strengthen.
- Moisture: A moist middle atmosphere is necessary to support the development of widespread thunderstorms.
- Coriolis Effect: The system must be at least a few degrees north of the equator to allow the Earth's rotation to help the storm begin to spin.
Progression of a Storm
If these conditions are met, the system can progress through the following stages:
- Tropical Depression: An organized system of clouds and thunderstorms with a defined surface circulation and maximum sustained winds of 38 mph (62 km/h) or less.
- Tropical Storm: An organized system with a clear surface circulation and maximum sustained winds of 39 to 73 mph (63 to 118 km/h). This is the stage at which the storm is given a name.
- Hurricane: An intense tropical weather system with a well-defined eye and maximum sustained winds of 74 mph (119 km/h) or higher. Hurricanes are categorized from 1 to 5 on the Saffir-Simpson Hurricane Wind Scale based on their wind speed.
Currently, Invest 98L is in the pre-depression phase, but its structure and the surrounding environment suggest it is on a path toward further intensification. The coming days will be critical in determining its future strength and potential impact on land areas.