Watching a pair of systems for tropical development

There are two main weather features we are monitoring this morning across the Atlantic Basin. Both are strong tropical waves that we have been tracking over the past couple of days and one or both could develop into a tropical system over the next 24-48 hours.

One wave, designated as 97L, is located near 15 north, 52 west and is quickly moving west at 25-30 mph toward the Lesser Antilles. This feature is much better organized compared to this time yesterday, with a fairly symmetrical area of showers and thunderstorms per latest satellite imagery. There are some things working for it to develop over the next day or two. 1) It is moving into an area where dry, dusty air is nearly non-existent. 2) Sea-surface temperatures are sufficiently high enough to support development. 3) Wind shear, while not low, is not high enough to be a debilitating factor between its current location and around the Lesser Antilles. What is going against development is its quick forward speed. It is moving at 25-30 mph and any tropical wave moving that quickly tend to have a hard time organizing into a tropical entity. Invest 97L will continue to move quickly toward the west today and reach the Lesser Antilles late tonight or early on Sunday morning. Another factor against development, is this system will move into the eastern Caribbean later in the day on Sunday, where stronger southwesterly wind shear and somewhat drier air will affect the system. With all of this said, the window for development into a tropical depression is 24-36 hours, which is not much time. At this point, we are still going with a low chance for development, but we will continue to closely monitor for bursts of thunderstorms that can help lower the surface pressure.

Models show this wave will continue to move across central and northern portions of the Caribbean early next week and approach the Yucatan Peninsula at midweek. Wind shear is expected to be weaker across the western Caribbean and this system could enter a more favorable area for development on Tuesday or Wednesday.

The other wave, designated as 96L, is the other system we are closely watching. It is located near 11 north, 27 west, southwest of the Cape Verde Islands and is moving toward the west at around 13 mph. The thunderstorms with 96L are not quite as symmetric compared to Friday, but it’s still a formidable wave.

It is located in an area of fairly low wind shear and sufficiently high sea-surface temperatures. These factors do favor development but its window for development is short due to the presence of dry, dusty air and higher wind shear to its west. The drier air and higher wind shear will begin to negatively impact this disturbance sometime on Sunday.

A wave passing through the Caribbean is associated with an upper-level low and is not expected to develop into an organized tropical system.

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