Weather Alert  –  September 12, 2025

Tropics Still Quiet, But May Perk Up Next Week

Tranquil times continue across the Atlantic Basin, which is the exact opposite of what we usually see in mid-September.

We have no tropical cyclones to track and only a couple of areas of interest. There are four tropical waves traversing the tropical Atlantic today:

• Along 80° west over the western Caribbean Sea
• Along 57° west, just east of the Lesser Antilles
• Along 34° west, west of Cabo Verde
• Along 22° west, having just emerged from West Africa

Visible satellite imagery of the Atlantic Basin today shows four tropical waves over the Caribbean Sea and tropical Atlantic, a band of clouds off the east Coast associated with a stationary front, and clouds with an extratropical storm southeast of Bermuda.

Image Source: University of Wisconsin RealEarth

The only one of these that is of any concern for development is the one that has just moved over the Atlantic from Africa. The other three are disorganized and in an unfavorable environment due to strong winds aloft, causing shear and sinking air, suppressing thunderstorm development. The easternmost wave has a broad turning motion associated with it, but not a lot of thunderstorm activity. 

Computer models are in good agreement that the wave between Cabo Verde and Africa is likely to become a tropical cyclone over the middle of the tropical Atlantic next week, so it’s one to watch closely. The National Hurricane Center says it has a 40% chance of developing in this area next week.

So, this is a feature to watch closely. The unfavorable conditions we currently see over the Atlantic will shift eastward over the next few days, and a wave of more favorable conditions (rising air and less shear) will move in from the west. Usually, we blame the Madden-Julian Oscillation, but it’s weak right now, so we have other factors at work this time. So, I don’t think we’ll see a repeat of last week, when a wave over the middle of the tropical Atlantic seemed to have all systems go for development, but it fizzled instead. What’s left of that feature is the wave over the western Caribbean Sea today.

It’s far too early to say with certainty whether it will eventually have impacts on South Carolina, but most models take the feature toward Bermuda instead of the East Coast. If that’s right, we’d only see beach and boating impacts.

Elsewhere in the Atlantic, a non-tropical storm system southeast of Bermuda is causing thunderstorms, but it’s unlikely to evolve into a tropical entity. We also still have an old stationary front over the far western Atlantic, and features like that sometimes pull tropical shenanigans. We have seen that many times, including this year with Chantal. We’ll pay close attention to this area early next week because some models show an area of low pressure forming off the Southeast Coast, then moving into one or both Carolinas around Tuesday. The feature will likely be weak and probably non-tropical, though—more on that situation below.

As always, maintain your readiness for hurricanes and other disasters. SCEMD’s hurricane.sc and earthquake.sc websites are great resources for disaster prep information.

It has turned dry over most of South Carolina over the last few weeks. My backyard near Gaston has only seen measurable rain once since August 23, and that was only 0.06″. Most of South Carolina has been dry for the last month; the one notable exception is the coastal Lowcountry, which saw soaking rains at the end of August and earlier this week.

This plot of percent-of-normal rainfall across South Carolina over the last 30 days ending at 8 a.m. today from HRAP shows how dry it’s been lately over most of our state.

Image Source: WeatherBELL

Strong high pressure centered over eastern Canada and New England has been in control of our weather most of the time since late August and is responsible for the dry spell. This setup will continue through this weekend, so the dry and tranquil weather will continue through Sunday. It will remain warm (highs will be in the lower to middle 80s) with low humidity, so expect a lovely weekend overall.

Early next week, we’ll watch for a low-pressure area to form along a stationary front offshore. Models are in good agreement that a weak storm system will form, but they don’t all agree that it will move northward into the Carolinas. The more reliable models (including everyone’s favorite, “The Euro”) call for the feature to develop later Monday or Monday night and move northward slowly, causing some rain along our coast Monday night and perhaps most of the state on Tuesday into Wednesday. Hopefully, this is how it comes to pass because we really could use the rain. If this is what we see, then temperatures will be held down with highs mainly in the 70s to low 80s those days due to clouds and rain.

If the minority view of the models (including sometimes non-trustworthy GFS) carries the day early next week, then we remain dry and warm with highs in the 80s as a very weak storm system tracks offshore.

The end of next week is likely to be warm and rain-free, though another cold front could arrive with low-end rain chances as early as late Friday.

Frank Strait
Severe Weather Liaison
S.C. State Climate Office
X: @SCwxFrankStrait