The Eyewall

One-sentence summary

While the Gulf or northwest Caribbean may see action next week, Tropical Storm Franklin is on its way away from the Caribbean islands and will meander north over the next few days.

Tropical Storm Franklin maneuvering north

Franklin has exited Hispaniola and is on its way north today. It is slowly trying to get its act together.

Maximum sustained winds are 50 mph, and you can see from satellite that there’s a pretty healthy burst of convection (or thunderstorms) indicated by the deep red cloud tops showing up north of Hispaniola. That said, Franklin is not yet really organized, as almost all of these thunderstorms are to the east of the center of circulation.

Franklin’s track is interesting but makes meteorological sense. It will continue north and turn northeast, but as high pressure builds west a little over the Central Atlantic, Franklin will slow down and turn back northwest or north, before continuing north and northeast and eventually out of the picture. The challenge regarding Franklin is that exactly where this maneuvering occurs will determine what sort of impacts are experienced on Bermuda — and for that matter, Atlantic Canada. Model consensus overnight shifted Franklin’s track a little farther west; good news for Bermuda. Folks in the Maritimes will want to monitor Franklin’s progress as it comes north next week. Anyone on the East Coast should probably expect a bit of rough surf and rip currents to become an issue later this weekend or next week as well.

We’ve seen most storms struggle this year, and Franklin has been no exception to date, but as we go into the next few days, Franklin should find a more hospitable environment in which to organize, which should lead to it becoming the season’s second hurricane.

Gulf & western Caribbean mischief

Yesterday evening, the National Hurricane Center dropped a lemon (20% development odds) on the map for the potential of development in or near the Gulf of Mexico next week. Today, that’s an orange, with a 50 percent chance of development over the next week.

As noted in the caption, it’s important to remember that when the NHC posts these hatched development regions, they are showing what region they believe a system may form, not where it will track.

Models have been oscillating back and forth on this area for days now. The overnight GFS operational run delivered a sheared, disorganized batch of moisture to Cuba and Florida. No organization. The overnight operational European model brought a tropical storm-type system north of Tampa.

A look at the ensembles this morning shows some decent consensus that is not that different from the operational guidance: The GFS ensemble is unenthused overall, while the European ensemble is excited, though generally low-end on intensity. Remember, ensembles run each model 30 to 50 different times with some tweaks to produce a more realistic “spread” of outcomes. We need them because single deterministic (operational) models give us no real forecast uncertainty gauge. You need that, especially with tropical storms. The map below shows the two ensemble groupings and their spreads so you can get a sense of what we’re looking at.

Based on those maps, what we see in operational guidance, and what we know about the Gulf and northwest Caribbean, what can we say today?

Well, for one, we are fairly confident that whatever happens will track north and/or northeast. The weather pattern next week favors west to east or south to north moving winds over most of the central and eastern Gulf of Mexico. This should steer whatever develops (if anything) to the north and/or the northeast. So for folks in Texas and Mexico outside the Yucatan, keep tabs, but this is probably not going to be a big concern. For folks from eastern Louisiana eastward and especially in Florida, it is a good idea to continue watching. Perhaps it’s just an uptick of rain chances instead of an organized tropical system that you see next week, but it’s far too early to say which outcome is more likely right now. We will keep you posted.

Elsewhere

The good news is that there are no other items of concern for land anywhere on the board right now. Emily’s remnants continue to look likely to regenerate into a tropical storm over the open Atlantic, west of the Azores. Invest 92L still has an outside shot at developing over the next 5 to 7 days.

Between August 19 and 21 we saw the formation of a flurry of tropical storms—Gert, Emily, Franklin, and Harold. The first two storms remained at sea and did not affect any landmasses, although Emily may be resurrected later this week. Harold moved inland into South Texas, bringing largely beneficial rains to the Rio Grande Valley, and is now rapidly dissipating over Northern Mexico.

That leaves Tropical Storm Franklin, which is presently near Hispaniola and is a threat to bring heavy rainfall there and in other Caribbean locations. We’ll start with Franklin, and then look at what else might be lurking out in the Atlantic tropics.

Tropical Storm Franklin

The system has improved its circulation overnight, and as of 8 am ET packed sustained winds of 50 mph. This is probably the top end of its strength for now. For the rest of today it will slowly move north, across Hispaniola, brining heavy rainfall and potentially mudslides to the Dominican Republic and Haiti. By tonight, it could also bring tropical storm conditions to Turks and Caicos.

Franklin is likely to weaken somewhat today as it interacts with the landmass of Hispaniola, and also struggles with wind shear. The intensity forecast is complicated later this week, as the system moves north of the Caribbean Sea. Sea surface temperatures are plenty hot, but wind shear could put a damper on the system. The National Hurricane Center predicts that Franklin will become a Category 1 hurricane this weekend, but my confidence in such a forecast is low.

By early next week we’re going to have to watch the track of Franklin closely, as the system may come near Bermuda as it starts to meander north. Like with the intensity forecast, I would not place high confidence a in track forecast for the storm after this weekend.

Emily, zombie-fied

Do you remember Tropical Storm Emily? It’s OK if you don’t. The storm produced some gale force winds for several hours on Sunday, in the middle of the Atlantic Ocean, and then succumbed to dry air. However, the remains of Emily have started to show signs of organizing as the storm finds more favorable conditions over the central Atlantic. It has a pretty decent chance of regenerating in the days ahead.

Nevertheless, this system is not something to get worked up about. It may noodle about the Northern Atlantic as a fish storm, but I don’t think it’s going to pass near land. Certainly, we won’t see this Emily in Paris.

What else is out there?

We’re watching a few other problematic areas, but there’s nothing that gives me too much concern. Frankly, this is a pretty good place to be in as we approach the end of August and early September.

For several days we have mentioned the possibility of a system spinning up in the Western Caribbean Sea and then moving north into the Gulf of Mexico, but there’s still not a whole lot of model support for that. In fact, my concerns are lessening there. The second watch area lies in the eastern Atlantic Ocean, where we will see new tropical waves moving off the coast of Africa. Those may eventually become a threat, but as of now there’s no concrete concerns to point to.

One-sentence summary

Tropical Storm Harold will make landfall soon near South Padre Island, TX bringing rain and storms to Texas and Mexico, while Tropical Storm Franklin is struggling in the Caribbean but still aiming to bring heavy rain to Hispaniola.

Tropical Storm Harold

Tropical Depression 9 was upgraded to Tropical Storm Harold overnight. In a twist of minor irony, Harold will make landfall about 100 miles south of the storm whose name it replaced (Harvey) on the Texas coast in about 4 to 6 hours.

Harold is struggling a bit this morning in terms of organization. It has 45 mph maximum sustained winds, but it is clearly dealing with a hostile environment for quick organization. There have been wind gusts as high as 46 mph in Corpus Christi and south of there, mostly in heavier showers.

Showers and storms are pushing across South Texas this morning and into Mexico. Steadier rain is waiting offshore and looks as if it will push into Corpus Christi and points south for the later morning. The Valley may see more intermittent rain and thunderstorms.

Within these thunderstorms, as occasionally occurs with tropical storms, isolated tornadoes are possible. Even some of the more intermittent and isolated showers well north of the center (toward El Campo or Victoria or just south of San Antonio) could produce an isolated, brief spin up. Something to be aware of in South Texas today.

Total rainfall will be on the order of 1 to 4 inches in South Texas, with the highest amounts just west of the Lower RGV back toward Laredo and into Mexico, where totals in isolated spots will approach 6 to 10 inches. Some of the rain may be heavy enough to produce isolated landslides in the mountains of Mexico, and flash flooding is possible in northern Coahuila and northern Nuevo Leon.

Harold will quickly move inland today and tomorrow, and it should be into the Desert Southwest, aiding in some rainfall by tomorrow evening.

Tropical Storm Franklin

We’re all having a bit of a difficult time finding the exact location of Franklin’s center this morning, as it is presumed to be drifting northwest in the Caribbean.

If you look at the satellite image above, you can just see South America’s coast at the bottom and Puerto Rico at the top right. Hispaniola is in the middle near the top. The bright colors indicate deep, intense thunderstorm activity. If you look closely, you’ll notice that the main area of storms is actually being pushed south. There are also a bunch of lighter looking clouds moving left to right toward those storms. That indicates a whole lot of wind shear in the atmosphere. Tropical storms do not like wind shear, as it inhibits their development. Overall, Franklin is a moisture-laden but extremely disorganized tropical storm. It’s not clear that Franklin will get much better organized over the next couple days as it moves north toward Hispaniola.

Overall, Franklin’s main concern for people will be heavy rainfall, capable of producing flooding over Hispaniola, particularly in the Dominican Republic. The models differ on exactly where the heaviest rain will be, but they all put it in the southern Dominican Republic. The greatest uncertainty may be in southeast Haiti, where models have waffled a bit between manageable rainfall and some higher totals closer to 10 inches.

Flash flooding and mudslides are possible across the Dominican Republic as Franklin passes by. Beyond Hispaniola, Franklin’s future remains up in the air. Modeling suggests it will likely become a hurricane over the open Atlantic. Exactly how close this gets to Bermuda on its way north is to be determined. There are even a couple model solutions now suggesting that Franklin comes even a bit farther west toward the Southeast coast a bit. I don’t want to speculate too much on this, particularly given that it’s currently tough to even figure out where Franklin’s center is. Bermuda should monitor Franklin’s progress closely, and folks on the U.S. East Coast should at least keep tabs on what’s happening in a couple days.

Other Atlantic systems

Tropical Depression Gert, east of the islands should dissipate today. Tropical Storm Emily dissipated yesterday. That is still on the big board, however, with a 20 percent chance of redeveloping in the open Atlantic as it curves out to sea.

The next system, Invest 92L, continues to plod along west of the Cabo Verde Islands. Development odds are down to 50 percent this morning, as a very slow organizational process may occur with this system. I think if it’s like most Atlantic systems this year, there’s something likely to act against it and who knows if it can truly get off the ground. We’ll see.

That covers all the noise out there right now.

Fantasyland (beyond day 10): Mired Gyre

The only other area really showing up at all on modeling as a development risk is off the Yucatan at some point on a few models (not the majority). We’ve discussed this whole gyre thing for several posts now, and maybe it comes to fruition, maybe it doesn’t. There’s enough signal in the model noise to say there’s a meaningful chance it could happen. But exactly what that looks like, I’m not sure. The overall background state of the Atlantic may actually become more hostile to tropical development in the early days of September, perhaps allowing us to catch our breath before the season finale and/or curtain call. The 2023 season to date has thus far been an example of quantity over quality which hopefully continues to be the case.