Invest96L data breakdown: What changed overnight

Newly-minted Invest 96L out in the Atlantic is still a few days away from having an opportunity to get better organized, but there is some info within the models that may shed light on the potential forecast down the road. Right now, the System Formerly Known As Invest 95L is barely clinging-on to existence and Invest 96L is starting to gain some steam. The two areas of interest are highlighted, on the same map as above, below.

The National Hurricane Center continues to monitor both areas for possible development. However, Invest 96L has a much better chance of getting organized.

From the NHC:

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 AM EDT Thu Aug 1 2019

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

1. An area of disturbed weather stretching across Cuba and the Bahamas is forecast to move northwestward and then northward, producing locally heavy rainfall over portions of the Greater Antilles, the Bahamas, and Florida during the next few days. Conditions could become marginally conducive for development over the weekend while the system turns and accelerates northeastward off the southeastern U.S. coast.
* Formation chance through 48 hours…low…near 0 percent.
* Formation chance through 5 days…low…10 percent.

2. A broad low pressure system located about 900 miles west-southwest of the Cabo Verde Islands is producing a large area of disorganized showers and thunderstorms. Gradual development is possible during the next couple of days while the system moves west-northwestward at about 15 mph across the central tropical Atlantic Ocean. Conditions are forecast to become more conducive for development over the weekend, and a tropical depression is likely to form by early next week several hundred miles east of the Lesser Antilles.
* Formation chance through 48 hours…low…10 percent.
* Formation chance through 5 days…high…70 percent.

Out to Sea

In the open Atlantic, as Invest 96L tries to get better organized, it will be riding along the southern edge of a big ridge of high pressure. This ridge will help guide the system to the west across the Greater and LEsser Antilles and toward Puerto Rico.

Because the eventual strength of the ridge of high pressure (also known as the Bermuda High) is unknown, that curtails our ability to give a precise forecast byond five days. However, a general pattern can be estimated from model trends.

And, as of now, model trends are trending toward a more stout, elongated ridge in the Atlantic that may usher Invest 96L closer to the Bahamas and the Florida coast than originally shown 48 hours ago.

Oh, the anomaly of it all!

While the big Bermuda High sits out there, I like to look at the 500mb geopotential height anomaly map. Because it can highlight how the current orientation of the ridge compares to the average. And that can help give clues as to how this tropical system may behave as it travels to the west. Can it tell you exactly where Invest 96L is going? It can not.

But it can give clues as to why certain models have it doing this or that. And even give hints as to which vector along a particular direction that Invest 96L may be more likely to take.

In the above map, it shows that there is ‘higher than normal’ ridging out ahead of Invest 96L. This may – ‘may’ being the key word – help guide Invest 96L along a more southern-ish route than it otherwise might.

To the Data, Batman!

Take a look at the guidance from the TAB (Trajectory and Beta) models

The TAB models show Invest 96L moving west-northwest in the coming days, with only the TABD model (deep convection) showing it nearing the Great & Lesser Antilles and Puerto Rico.

Meanwhile, the GEFS Ensemble model shows Invest 96L staying farther south. The consensus between all of the different ensemble members is for a path near Puerto Rico.

Given the NHC’s red-shaded ‘area of interest’ in the map toward the beginning of this article, they agree with the GFS and GEFS models. That said, trying to figure out eventual specific forecast track for Invest 96L, at this point, is an exercise in futility. However, trying to figure out where it is most likely to develop is probably an exercise in better judgement.

12Z ensemble packages certainly raises the bar on the prospect of tropical developments across the Atlantic as we head into the weekend and into next week. pic.twitter.com/nlUikB7wGG

— John Kassell (@JPKassell) August 1, 2019

The ECMWF, as pointed out in these tweets, offers an estimation as to where development is most likely to occur.

The interesting thing to note is how quickly the models develop Invest 96L into a Tropical Storm and then Hurricane. The NHC is forecasting a 70-percent chance of organization and development into some kind of tropical system between Day 2 and Day 5.

Meanwhile, model guidance suggests between 48 hours and 120 hours, Invest 96L could be anywhere from a weak Tropical Storm and a Category 2 Hurricane.

That is a big spread. So, let’s look at the SHIPS Rapid Intensification numbers.

Not much help there.

That is normal, too. Given that Invest 96L hasn’t really formed yet, it means there is no centralized area of low prssure for the model to ‘grab’ and make a solid estimation for the future.

Answering a few questions

How strong will it be?

We can’t know that yet. Sadly our ability to place where something in the Tropics will be exceeds our ability to know how developed / strong it will be when it gets there.

What should I do now?

Check your Hurricane Preparedness Kit. That’s about it. Make sure you have enough supplies to last a few days without power and water.

Not because this system is anticipated to wipe out power and water to an area, but rather, you should always have enough supplies to last a few days without power and water during Hurricane season.