While we have a few areas of the Atlantic Basin highlighted on the National Hurricane Center's outlook graphic today, the tropics are strangely quiet. It's September 20, prime time for tropical cyclone formation, but there is only one tropical wave to track across the entire tropical Atlantic.
Here's a view of the Atlantic from space to show y'all what the cloud patterns with these features look like this morning:
This loop of visible satellite images covering the Atlantic Basin shows the three areas of interest for tropical cyclone development today.
Image Source: University of Wisconsin RealEarth
The two yellow blobs over the subtropical Atlantic on NHC's outlook (the area from the Tropic of Cancer near 23½° north to 35° north is generally considered the northern subtropical region) are only worth a brief mention. The one to the east is the remnant of Tropical Storm Gordon, still valiantly holding on in its fight to remain dead. Dry air and shear have plagued Gordon since day one, and they show no sign of relenting. It's unlikely to redevelop, but if it did, it is too far away to affect us in South Carolina. The feature to the west is a broad area of low pressure that formed along a decaying front. This feature is also unlikely to develop further before getting pulled northward over cool waters by an upper-level trough over the East Coast.
The area near Central America is more concerning for the long term. A tropical wave is in that area today, but this wave will drift west over Central America and then over the Pacific Ocean in the coming days. It may become involved in the process that leads to a tropical cyclone forming next week. We expect to see a broad area of low-pressure form over Central America next week called a Central American Gyre (it's been a while since that term popped up; Wikipedia can get you in enough trouble if you want to know more about CAGs). Swirls on the outskirts of these low-pressure areas sometimes spawn an Atlantic tropical cyclone; sometimes, the entire ball of wax becomes a tropical cyclone in the Atlantic or Pacific. Computer models are bullish on a CAG forming and leading to a tropical cyclone forming over either the Gulf of Mexico or the western Caribbean Sea by the end of next week, and this is why NHC has put an orange blob in this region with a 40% chance for development over the next week.
While the models are giving us a strong signal for development, they strongly disagree on just about everything else, like exactly where it will form, where it will go after forming (aside from going into the Gulf of Mexico), and how strong it will get while tracking northward through the Gulf of Mexico. While it's a reasonable possibility that this feature will impact South Carolina later next week or next weekend, it's also possible that it moves toward Texas or Louisiana instead and sidesteps us. Even if it does come this way, it may be too weak to be anything but a rainmaker (which would be a net positive because it's been so dry since Debby despite the risk of flooding that would arise).
Things are relatively tranquil over the tropics now, but that could change within a week. So, it's important to maintain your readiness. If you need help with storm preparations, SCEMD has your back at hurricane.sc.
The tropics are quiet for the short term, and so is our weather. High pressure centered to our northeast will control our weather this weekend to keep it mostly tranquil. However, enough moisture is in place that we'll see a couple of stray pop-up afternoon showers or storms each day. So, most South Carolinians will see rain-free weather this weekend, but not everyone. Look for a warming trend with highs in the summery 90s covering the Central Savannah River Area and Midlands by Sunday, with middle to high 80s elsewhere in the state.
Next week starts summery with highs mostly in the 85-90° range Monday and Tuesday, though increasing moisture levels will result in more widespread summery afternoon thunderstorms. By midweek, another upper-level trough and attendant cold front will move into this part of the country. That will make our weather unsettled and less warm for the rest of next week. This setup plays a role in how our potential tropical feature next week may behave; if this system develops faster, it would be more likely to get caught up in the upper trough and front and head our way. A slower-developing feature would be more likely to be left behind, stewing around in the Gulf of Mexico for a while and more likely to end up in Texas, Mexico, or Louisiana.
