The Atlantic tropics remain quiet with no organized tropical cyclones. The deep tropics likely remain tranquil for the rest of July, with a slight chance for a storm to form close to us later next week.
Four tropical waves are crossing the deep tropics:
- Along 88° west, mostly over Central America
- Along 77° west, south of Jamaica
- Along 58° west, approaching the Lesser Antilles
- Along 36° west near the middle of the tropical Atlantic
None of the four shows any signs of further organization, and none of them are generating any significant thunderstorm activity. You can also see, in the color visible satellite imagery below, a large cloud of dust from the Sahara drifting over the far eastern Atlantic. That's a sign of arid air that tropical cyclones hate.
This loop of GeoColor visible imagery shows a lack of activity over the tropical Atlantic and a cloud of Saharan dust over the eastern Atlantic.
Image source: University of Wisconsin RealEarth
The reason for the quiet is that our sometimes friend and sometimes enemy, the Madden Julian Oscillation (MJO), has come to life again and is now causing sinking air over this part of the world. Sinking air suppresses thunderstorms and makes it much harder for tropical cyclones to form. Meanwhile, on the other side of the world, the opposite is true; rising air associated with the MJO is contributing to the development of a tropical storm near the Philippines and an ongoing out-of-season tropical storm in the southern Indian Ocean.
We're likely to see the MJO continue to suppress thunderstorm activity and tropical cyclone formation in the Atlantic Basin for another week or so. However, the MJO slides eastward, so those more favorable conditions should eventually reach the Atlantic. We'll be on the lookout for this in early to mid-August.
In the meantime, it's unlikely we'll see any tropical cyclones form over the tropical Atlantic. However, we sometimes see storms form over the Gulf or off our coast this time of year, and we have a slight chance to see this later next week or next weekend. We'll see a cold front farther south than usual again, and if it becomes stationary over the water, there would be a risk for a home-grown development. Right now, the odds look very long for something to develop, though. The front may become stationary over land, or an area of low pressure may form, but it remains weak, as seen with the feature that formed near Florida and moved toward Louisiana earlier this week.
It's good to be free of worry about tropical cyclones for the short term, but we're not even to halftime yet in the hurricane season. Tranquil times are the best time to prepare, so make sure you're ready for storms that may affect us later in the season. If you need prep advice, hurricane.sc is the place to go.
We'll Simmer This Weekend
I'm sure y'all noticed that the thermostat has been turned up over the last couple of days, and it's going to be raised a bit more over the next few days. We won't be setting any records, but we'll simmer over the weekend. Once again, an upper-level ridge has formed over the southeastern states. Those features promote above-average temperatures with lower rain chances. For the weekend and Monday, expect bright sunshine each day with highs in the 95-100° range over most of the state (beaches and higher ground northwest of I-85 are exceptions). The heat index will peak around 105°F each day. While any spot can see a cooling afternoon shower or thunderstorm, few places will. The best (but still not great) chance for a thunderstorm will be inland along the Coastal Plain, where the sea breeze can act as a trigger, and along and north of I-85, where thunderstorms originating over the mountains may wander in.
On Monday, it looks hot again, but a front to our north may get close enough to us that thunderstorms get more widespread for the afternoon and evening. If so, the hot and steamy air mass in place could fuel a locally severe storm for a few places.
If you're traveling north this weekend, a grindingly slow-moving cold front over North Carolina, Tennessee, and Virginia will bring repeated rounds of heavy rainfall. Their soils have become saturated due to Chantal and a recent stationary front, so there is a risk of flooding in that area.
Once we reach Tuesday, that front will shift far enough south that we will feel its effects. We will see more widespread afternoon and evening thunderstorms, which will result in less-hot temperatures with highs near average for this time of year, or a little below average.
There are questions for Wednesday and beyond. Some computer models indicate that the front will shift to our south and east by midweek, resulting in a less humid air mass settling over South Carolina for a few days. That would be delightful, but also seems like a fantasy in late July and probably has a snowball's chance in Columbia of being correct (this past winter reminds us that those odds are low but not zero). It appears more likely, and most computer models indicate, that it will remain warm and muggy with a front nearby, contributing to a routine diurnal cycle of afternoon and evening thunderstorms. Those in the Upstate and upper Pee Dee have the best chance to enjoy a drop in humidity levels at midweek. But, like you, I'll be pulling for that less-humid air to get as far south as it can!