August may have been unusually quiet in the tropics, but it’s now September. This is the month when tropical activity typically reaches its peak in the Atlantic Basin. And right on cue, WRUF Weather is tracking several potential developments over the coming days, one of which could impact the islands in the Caribbean this week.
Invest 97L, a tropical wave identified by the National Hurricane Center for possible development, was crossing the Leeward Islands Sunday night. Thunderstorm activity appeared to become more organized near the wave on Sunday and satellite data suggested it was starting to show signs of healthy rotation. The NHC is tasking hurricane hunter aircraft to investigate 97L on Tuesday. Until then, they give the system a 40 percent chance for development into a tropical cyclone. Thereafter, the official NHC forecast is for a 50 percent chance of development by the end of the week.
Early forecast model data on the track of Invest 97L is in modest agreement on taking the system to the west-northwest into the northern Caribbean through Tuesday, then possibly making a turn to the northwest and crossing the islands of Hispaniola or Cuba by week’s end. It is too early to determine if there would be a potential impact from this system on the mainland United States. Residents on all of the islands in the northern Caribbean, however, will need to watch the system closely and should prepare for – at the very least - heavy rain and mudslides when it passes nearby.
As typical with premature cyclones, the forecast intensity of 97L is very much uncertain. Water temperatures are very warm and wind shear is currently rather low, both factors that would favor development. However, dry air – the same inhibiting factor of most storms this season – is still present near the wave. Forecast data does suggest that more moisture will be available for Invest 97L by mid-week as the storm moves south of Haiti. However, at this time, faster trade winds may also create more wind shear for it to battle. Most of the reliable forecast models suggest 97L will become a weak tropical cyclone by Wednesday or Thursday, but do very little with it in terms of intensification thereafter.
Other waves of interest in the Atlantic Basin are catching our eye, but do not pose an immediate threat to the United States. The NHC has identified a tropical wave currently in the central Caribbean as having a low chance for development as it nears the Yucatan Peninsula by Thursday. WRUF Weather will also be watching a mid-level area of rotation closely showing up on some long-range forecast models by the end of the week nearing The Bahamas. Another tropical wave in the eastern Atlantic near the Cape Verde Islands has nearly dissipated entirely, and will likely move north into cooler waters. In addition to the aforementioned areas of interest, above normal precipitation can also be expected in much of the Caribbean and southern Gulf of Mexico due to a wave of greater instability and moisture moving across the globe from the eastern Pacific.
WRUF Weather will continue to monitor the tropics and will have updates on WRUF-TV at 20 and 50 minutes past every hour. Urgent tropical weather alerts are best-received on our Twitter account @WRUFWeather, or on our real-time updates page.