Tropical Troubles BrewingWe have a pair of tropical waves with potential for development over the next few days. The National Hurricane Center (NHC) has a ‘code red’ area for both of these features. Both of them have the potential to affect South Carolina. 
At least Gabrielle behaved as expected over the last few days and passed east of Bermuda; its next stop will be the Azores, followed by a trip to Europe. Our two features of interest in the tropics have been designated as invest areas by NHC, with the one to the east called AL93 and the one to the west called AL94. Satellite imagery shows that AL93 is getting better organized with a spin evident and thunderstorms starting to wrap around it, so it’s likely to become a tropical cyclone soon. 
Visible satellite imagery of the Atlantic Basin shows Gabrielle moving toward the Azores and the two tropical waves of interest over the western Atlantic and Caribbean Sea. Image Source: University of Wisconsin RealEarth NHC assigns a 90 percent chance of development to AL93 within the next two days. That looks reasonable; it will probably be named Humberto soon. For AL94, the development odds are 30 percent over the next two days and 80 percent over the next seven days. The next name on this year’s list after Humberto is Imelda. We’ll have to monitor both closely, but the one most likely to affect us directly is AL94. However, there is a ton of uncertainty right now due to the complex weather pattern developing near the East Coast. In addition to the two tropical waves that could soon be two named storms, we have an upper-level low spinning east of the Bahamas and a storm over the nation’s midsection that will push into the Southeast and stall over the next few days. Computer models struggle with this level of complexity, and so we are presented with a wide range of reasonable possibilities by the models. AL93, Humberto-to-be, is likely going to remain well offshore, taking an Erin-like track between the Carolina coast and Bermuda. Impacts to us likely will be limited to rough seas and surf along our coast. However, its behavior, including how strong it gets, will be a significant factor in what happens with AL94, perhaps Imelda eventually. If AL93 ramps up quickly and becomes a hurricane, it could prevent AL94 from developing or maybe eat it for lunch on Saturday or Sunday. A weaker storm would make it more likely that AL94 develops, but it might also help steer it away from the Southeast Coast. A weak and further east track of AL93 would allow AL94 to become more of a force to be reckoned with. Then we must consider what might happen with AL94. Possibilities include a track toward us, but a last-minute turn to the east due to interactions with the storm to the east, or being pulled into the Carolinas early next week by the storm moving in from the nation’s midsection, or possibly even stalling near our coast for a while. There’s also a chance that it will remain disorganized and never get its act together. As much as I hate to say this, the possibilities range from no significant impacts in South Carolina to a hurricane early next week. The weather pattern is too complicated to say definitively what will happen with AL94. However, I thought it was best to let y’all know that something’s up since we’re 5-6 days from potential effects here in South Carolina. I hope this turns out to be a false alarm, but we have some real risk, so it’s better to be aware and be prepared. Ensure your general disaster preparation is in place, especially if you live along our coast. As always, you can find storm prep advice at hurricane.sc. Frank Strait
Severe Weather Liaison
S.C. State Climate Office | 
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