By Frank Strait
Severe Weather Liaison
S.C. State Climate Office
S.C. Department of Natural Resources
Now that we have Milton out of the way, we’re heading into a quiet spell for the Atlantic tropics for a week or so. We can thank the Madden-Julian Oscillation for that (more on the MJO if you’re new here). The part of the MJO that helps to trigger tropical cyclones has been over us for weeks but is moving on to the east. Conditions that suppress tropical thunderstorms and tropical cyclone formation will be over the Atlantic tropics for 7-10 days.
Milton is no longer tropical, but it’s a powerful extratropical storm that will pass nearby to the south of Bermuda today. While it’s moving away, it’s generating swells heading toward the East Coast, so surf and seas along our coast will be hazardous this weekend.
There are two features to track over the eastern Atlantic today: Tropical Storm Leslie and a robust tropical wave over the Cabo Verde Islands.
Leslie is no worry for us. It’s moving north toward cool waters, and winds aloft are causing strong vertical shear over that part of the Atlantic. It will last another day or two before becoming non-tropical and heading toward Europe.
The tropical wave over the eastern Atlantic that the National Hurricane Center is calling Invest Area AL94 might be a problem for us down the road. Computer models tell us it will remain over the tropical Atlantic while drifting westward for the next week. It will move through a region of sinking air during this time. By the end of next week, the models tell us that the feature will be over or near the Lesser Antilles. It may encounter a more favorable environment for development once it gets there. It’s still too early to tell whether it could eventually affect South Carolina.
Another thing to watch starting in a week or so will be the western Caribbean Sea. It looks like we’ll see another Central American Gyre (Wikipedia does well enough with an explanation of CAGs) form next week, which may spawn (or become) a tropical cyclone toward the end of the month. Waters remain exceptionally warm in this area, and the waters are warm to considerable depth, so there is a ton of hurricane fuel in those waters should a tropical cyclone form there.
We’re entering a quiet stretch in the tropics for now, but there are concerns for later in the month, and we have another month and a half of the hurricane season left. So, stay ready. SCEMD has hurricane.sc to help you stay prepared.
A pleasantly cool air mass has settled into the Southeast behind Milton. If you were out trying to view the aurora last night (and it was spectacular at times over our state), you noticed it was cool. It’s the coolest we have seen since spring. For example, it was the first night in the 40s in Columbia since June 1 and the coolest night since April 23.
High pressure will remain overhead through Saturday morning, and the high will give us beautiful weather this weekend. We’ll have another chilly night tonight, about the same as last night, then highs in the low to middle 70s across the state on Saturday. Saturday night won’t be as cool, then Sunday looks warmer, with highs of 78-82° for most of the state.
Another cold front moves our way on Monday; a surge of warm air will arrive ahead of it. Most of the state will see highs well into the 80s on Monday, though the front may reach the Upstate and Catawba region in time to keep temperatures in the 70s there. I don’t want to rule out an isolated brief shower as the front moves through, but most places will remain dry. One thing to watch out for is that the wind will pick up as the front moves through. We may see gusts over 30 mph again for several hours Monday afternoon and evening as cooler air blasts in.
The air mass arriving behind this front will be even cooler than the one over us now. Most places will see highs only in the 60s Tuesday through Thursday. It may only be in the low 60s in the Upstate on Wednesday! Lows will mainly be in the 40s during this time, and colder spots of the Upstate will likely see some 30s. Look for a modest warmup after that, and it likely remains dry through next weekend.
If you’re worried about rainfall, I am, too. The feast-for-famine rainfall pattern we’ve been in since the spring is back in famine mode, and parts of the state are getting too dry again, especially the Coastal Plain. I hope we can find a way to get rain soon without it being a tropical deluge.
