Eric Berger

One-sentence summary

We’re nearing the end of the Atlantic hurricane season, but we need to continue tracking Invest 94L as it is likely to track across or near the northern end of the Lesser Antilles this weekend, including the islands Antigua and Barbuda.

Happening now: Invest 94L

There is precisely one system we need concern ourselves with in the Atlantic, and that is an area of low pressure that is approaching the Caribbean Sea. It continues to lack a center of rotation, but the system is starting to get its act together. The National Hurricane Center projects that it has an 80 percent chance of becoming a tropical depression or storm over the next week. Even if it does not the tropical system will bring heavy rains to parts of the Lesser Antilles this weekend.

By the way, what do we mean when we say the Lesser Antilles? It can be a little confusing, both for readers and forecasters. So let’s spend a moment walking through it. We’ll start with the Greater Antilles, which are the larger Caribbean islands—Cuba, Hispaniola, Jamaica and Puerto Rico—that mark the northern boundary of the Caribbean Sea. As this arc of islands extends further eastward and to the south, the islands get smaller, places like Antigua and Barbuda, Barbados, and Saint Kitts and Nevis.

These islands stretch almost all the way south to South America, and form the eastern boundary of the Caribbean Sea. These are the “Lesser” Antilles since they’re smaller islands. To make things even more confusing, the islands of the Lesser Antilles are divided into three groups: the Windward Islands in the south, the Leeward Islands in the north, and the Leeward Antilles in the west. So Invest 94L is threatening the Leeward Islands, which are part of the Lesser Antilles. Still with me? Good. There will be a quiz at the end.

The good news for the Leeward Islands is that if 94L organizes into a stronger system it is likely to turn to the northwest before reaching land. If it remains weaker, then it could follow a more westerly track into the islands, bringing some winds, high seas, and rains, but nothing too crazy. We’ll fine tune the forecast in a day or two.

What else is out there?

Not much in the Atlantic Ocean.

After 94L does whatever it does, the only other watch area over the next 10 days or so will be in the southern or southeastern Caribbean Sea, where we may see a home-grown storm develop. But that is only a vague threat at this point. And as we approach the end of October, we can generally expect to see the Atlantic tropics winding down for the year.

Here’s the quiz: Anyone got any problems with that?

One-sentence summary

Tropical Storm Lidia dissipated this morning over Mexico, but will bring rainfall and mudslides to part of the country; and its remains will merge with other moisture in the Gulf to bring rains later this week in the southern United States.

Tropics now: Goodbye Lidia, and hello Sean

After rapidly intensifying on Tuesday and slamming into the Pacific Coast of Mexico, Lidia has been shredded by the mountainous terrain of Central Mexico. The big concern with Lidia, accordingly, is now rainfall. The remnants of the system could cause urban flooding and mudslides in Western Mexico today.

After today, those remnants will be drawn into the Gulf of Mexico along with the remains of another Pacific storm, Max, as well as a warm front lifting north. This mess will eventually move to the northeast, toward Florida. We have zero expectations for these lows to congeal into something threatening from a tropical storm standpoint, but it should heighten rain chances for areas from Louisiana through Florida.

Overall rainfall totals look fine, with 1 to 3 inches from Southern Louisiana along the Gulf coast all the way to the Tampa area of Florida. Some locations may see higher amounts, but this system will be pushed out of the region by Friday and Saturday as a broad front brings drier air into the southern United States. So, not a huge concern.

Hi Sean, Goodbye Sean

Tropical Storm Sean has formed in the Atlantic tropics, about halfway between Africa and the Caribbean Sea. This system is expected to piddle along for a few days before it gets swamped by wind shear this weekend most likely. It will not threaten land. That’s probably about all we need to say about Sean.

Tropics later

Beyond Sean there are some mildly interesting features that we are watching.

The first of these is a tropical wave that just moved off of Africa, and should continue to move due westward through the weekend. The atmosphere isn’t overly favorable for development, so the National Hurricane System only gives this system a 30 percent chance of becoming a tropical storm over the next week. But eventually, and we’re talking at least a week to 10 days from now, this system might be something that eventually approaches the Leeward Islands. It’s not something I am really concerned about at all right now, but we will continue to watch it for you.

Beyond this, we probably need to be wary of some late-season development in the Caribbean Sea. Waters remain very warm in those sun-bathed seas, and there are some hints of potential storminess during the last 10 days of October. There’s not much of a threat to point to, just the potential for something to eventually spin up.

One-sentence summary

Philippe is finally lifting north after lashing the Leeward Islands earlier this week, and it may move toward Bermuda as a tropical storm by Friday or so.

Philippe is disheveled, but not dead

Tropical Storm Philippe has a rather ragged appearance this morning, and it continues to struggle with wind shear. After proving to be a rainmaker for islands such as Barbuda and Dominica, as well as the Virgin Islands, the storm should finally find a passage north as a high pressure system gets out of its way. It has open water for a couple of days before it reaches the vicinity of Bermuda. So what will happen to the storm’s organization over the next two days?

There is a ton of uncertainty, as Philippe could use this brief window of opportunity to strengthen into a Category 1 hurricane, or it could essentially be wiped out. Given its initial disheveled state, it’s difficult to parse whether the storm will, in fact, get its act together. The official forecast from the National Hurricane Center splits the difference, calling for a strong tropical storm with 60 mph tropical storm winds as Philippe nears Bermuda. This seems like a reasonable best guess.

After interacting with Bermuda, Philippe should begin transitioning into an extratropical cyclone as it heads toward the Canadian Maritimes and northern New England. The primary threat there will be some additional heavy rainfall this weekend before the system dies out completely over Canada. Areas including Maine and Nova Scotia should continue to track the storm’s progress for a few more days until we can say au revoir to Philippe.

Beyond Philippe: Some Pacific mischief?

After Philippe’s exit, the Atlantic looks quiet for a little while. The one feature we probably need to watch is a disturbance in the Pacific Ocean south of Guatemala that is likely to become a tropical storm over the next five days or so. Much of our model guidance indicates this will move across Mexico and into the Gulf of Mexico next week.

This could bring some heavy rainfall to coastal areas of Mexico, as well as the Gulf coasts of Texas and Louisiana later next week. But we’re at the point where there is just the threat of this happening, rather than any certainty. We’ll continue to watch it for you.

One-sentence summary

Overall things don’t look too concerning for late September, as Tropical Storm Philippe continues to be a fading force, and Invest 91L appears most likely to track north of the Caribbean Sea and its islands.

Happening Now: Some pesky storms

Let’s begin with Tropical Storm Philippe. Frankly, it does not look like much of a tropical system this morning, as the storm is battling against both the influx of some drier air as well as wind shear. This is kryptonite for a tropical storm, and the most likely outcome is that Philippe will dissipate over the next day or two. By this weekend a remnant low should approach Puerto Rico, bringing some elevated rain chances. But I am not seeing anything in this forecast that particularly concerns me.

Just behind Philippe in the Atlantic lies Invest 91L, which should become the better organized system over the next couple of days. It probably will become Tropical Storm Rina fairly soon as it tracks across the Atlantic Ocean toward the Caribbean Sea. Fortunately, the preponderance of our modeling suggests that this tropical system will mostly likely turn north before reaching the northern Leeward Islands. The continued evolution of 91L will be worth watching, but again it is not something which provides us too much concern at this time.

The medium range (days 6 to 10): Bahamas high jinks

We’re getting to the point of the forecast that is more speculative. However, after the remnants of Philippe move into Puerto Rico and Hispaniola, there may be an opportunity for some sort of low pressure system to congeal in or near the Bahamas about one week from today.

There is a definite signal in some of the global models ensembles for this scenario, and the ocean waters are plenty warm in this area. But the signal is not particularly strong, so I would not put too much stock in it. As we get to the end of September, this is the kind of thing we sometimes see in the tropics, with systems spinning up closer to land. If such a system were to develop it probably would get drawn north, perhaps toward Florida or the Eastern United States. But that is super speculative at this point.

Fantasyland (beyond day 10): Some noise, but not a whole lot

When we look even further into the future, well into the first week of October, there’s just not a whole lot out there. We’ll continue to watch the area near the Bahamas mentioned above, as well as the southeastern Gulf of Mexico for potential development. But again this is all pretty vague, and we can’t point to any specific threat. In my book, that’s a good thing.