3 Things We Know About Invest 99-L and 3 Things We Don't Know Yet

Jonathan Belles
Published: August 26,2016
We're watching an area of storminess that has moved into the Caribbean and southwest Atlantic, and this one could bring impacts closer to home.
But Invest 99-L is still in development, and there are a few questions we still have, in addition to the things we already know about this system.
(FORECAST: The Latest on 99-L) 

What We Know So Far

1. Invest 99-L Will Be A Rainmaker in the Caribbean, Bahamas and Florida
The broad area of low pressure associated with a tropical wave will bring scattered areas of rain to the Bahamas, Turks and Caicos and Cuba through Friday.
By this weekend, the moisture with this system will spread into South Florida. This will likely be the case no matter whether Invest 99-L has developed into a named storm or not. This could result in some flooding concerns materializing, and the situation will have to be monitored.

Forecast Rainfall

2. This Disturbance Will Trek Toward the Northwest or West-Northwest
Current computer model guidance solutions are tightly packed initially, which improves our confidence that this system will move through the southern and western Bahamas the next day or so and then towards the Florida Straits or Keys, or even scrape by Cuba by this weekend.
(MORE: What is an Invest?)
The forecast gets less clear after that, but parts of the Gulf Coast will likely be in line for impacts early next week. Anything beyond that is more suitable for the "things we don't yet know" section below.

Forecast Track Models

3. Invest 99-L Continues to Fight Wind Shear, Dry Air and May Use Atlantic Heat Content To Its Advantage
The last few days, Invest 99-L has been battling dry air over the eastern Caribbean and southwestern Atlantic.
Wind shear is anticipated to continue dropping throughout the day on Friday to more favorable levels, but short term development could still be stunted.
Wind shear and dry air can slow or prevent the development of tropical systems.
This wind shear and dry air, however, will continue to lessen this weekend when the system reaches the northern Bahamas and Florida Straights allowing it to develop.
Deeper, warmer ocean temperatures are ahead of this tropical wave. A few patches of cooler waters do exist, but the general trend will be for waters to warm throughout the next several days. Sea surface temperatures in the Bahamas range from the mid-80s to near 90. This effect alone could enhance thunderstorm activity.

Conflicting conditions that 99-L will have to face. Dry air (flashing orange) may hinder 99L's use of the very warm ocean temperatures in dark red and pink.

(MORE: The Most Intense Landfalls Have Happened in this 17-Day Period)

What We Are Trying to Figure Out

1. How Strong 99-L Will Get?
There remains a large array of possible outcomes in terms of intensity. At one end of the spectrum, this disturbance could remain weak throughout its lifespan. On the other end, many favorable conditions could come together in the Bahamas, but the odds of significant development are moving downward.
Part of this variation is due to the lack of organization with this system so far.
Scheduled Hurricane Hunter missions over the next couple of days should prove helpful.
(MORE: What is a Tropical Wave?)
2. When Will Florida's Hurricane Drought End?
Florida has seen numerous tropical storms in the last decade, but the state's lucky hurricane streak is up to 11 years. It is looking less likely that this will be the system to bust the streak, but it is always a good time to get prepared. It only takes one.
(MORE: 11 Years and Counting: Florida's Lucky Streak)
3. Ridge of High Pressure May Steer This System Into the Gulf
 The main steering feature will become a ridge of high pressure in a day or two that is forecast to be parked over the Carolinas.

The clockwise flow around the ridge of high pressure could send it into the Gulf of Mexico through the Florida Straits or over southern Florida. This would, of course, put parts of the U.S. Gulf Coast in play for possible impacts...especially heavy rainfall. That would not likely occur until early next week, however, and the future track is uncertain.
We are also unsure of how strong this ridge of high pressure will be in a few days. Some models keep this ridge stronger, which would lead to a more western route. Some models allow the ridge to break up, which would lead to a more eastern or northern route.
For more details, see our full forecast article at this link.
(MORE: 3 Things You Should Know About Spaghetti Models)
MORE: Hurricanes, By The Numbers