The stretch of inactivity in the Atlantic tropics continues. We have no storms to track right now and no imminent threats. It's hard even to find a thunderstorm over the tropical Atlantic right now.
This loop of visible satellite imagery shows a general lack of thunderstorm activity
over the Atlantic Basin this morning.
Image Source: University of Wisconsin RealEarth
We have three tropical waves bunched up over the Caribbean Sea and its vicinity:
- Along 82° west, approaching Central America
- Along 69° west, over and south of the Dominican Republic
- Along 60° west, moving into the Lesser Antilles
East of there, we have a break in the wave train for now, but some robust-looking tropical waves are over West Africa and will soon move over the eastern Atlantic. Dry and stable air ahead of them will prevent any development way out there in the short term.
Of the three tropical waves we're watching, only one shows any promise for development. It's the one near the Lesser Antilles, as there is a broad turning motion associated with the wave. It won't develop in the short term because it's in a dry and stable environment.
However, it's moving into a region where conditions will become less hostile. As I mentioned last Friday, the thunderstorm-enhancing phase of the Madden-Julian Oscillation (MJO) is tiptoeing eastward steadily over the central and eastern Pacific basins (where there are two hurricanes and another will likely form soon) and it will slide over the Atlantic in the coming days. It looks like this wave will track through the Greater Antilles over the weekend and early next week and then over South Florida and into the Gulf. Around the middle of next week, it could be a feature to watch for development.
Speaking of the Gulf, that area and the area off the Southeast Coast will have to be monitored for development starting this weekend. The cold front that will finally end our heat wave will turn stationary over that area for a while, starting this weekend, and that is a setup that sometimes brings us a nearby tropical cyclone development. Our computer models show this to be a possibility, but also show steering currents over the next 3-4 days taking any storm that might form away to the east-northeast. Starting around midweek, the steering flow becomes weaker, so if a storm forms around that time, it would have a better chance to affect us.
Make sure you're fully prepared for storms that could affect us. We're heading into the busy part of the hurricane season, and seeing the MJO turning more favorable for us as we go through the next week or so tells me that a spurt of tropical cyclone activity is possible. If you need advice on how to prepare, hurricane.sc is the place to go.
Cooling Off This Weekend
I'm pleased to report that today will be the last day of our heat wave, and that a cold front moving in tonight will bring a major drop in temperatures starting Saturday.
As our cold front moves into the hot, sweaty, and sultry air we have in place today, it results in some hazards. There is a risk for locally damaging wind with the stronger storms we see this afternoon and tonight, and there will be a risk for localized flooding with the storms. The Storm Prediction Center (SPC) has the entire state in a level 1 of 5 risk area for locally damaging wind through tonight, and the Weather Prediction Center (WPC) has nearly all of South Carolina in a level 2 of 4 risk area for enough rainfall to cause flash flooding.
Cooler and drier air will push in from the north on Saturday, reducing the risk for heavy rain and flooding. However, there can still be soaking downpours over much of the state, especially in the Lowcountry. WPC has that area in a level 2 risk area again, with most other areas at level 1.
Sunday may also be an active day across the Lowcountry. Models differ on where the front will be that day, so there's a chance that we'll see rain further north.
The wonderful thing will be the considerable drop in temperatures. We'll get well into the 90s across the state one more time today, with the heat index peaking over 105 across the Midlands, Central Savannah River Area, and Lowcountry (a Heat Advisory is in effect for those areas). However, Saturday's highs will range from the upper 70s in the Upstate to the middle 80s in the Lowcountry. Most of the state will see our trademark thick humidity go on hiatus for a while starting on Saturday as well. In other words, we're about to get an early taste of fall! Temperatures remain well below normal for Sunday as well, again in the 70s and 80s.
There is uncertainty for early next week. Will the front remain offshore, bringing a nice break from the heat and humidity to most of the state, and only coastal areas have a chance for rain? Or, will the front retreat northward, making it unsettled statewide for most of the week? The more reliable computer models call for clouds and rain to be more widespread over the state. That's not the end of the world, as parts of the Upstate have been dry lately and are back in drought. However, rain or no rain, temperatures are going to remain below average through all of next week, and there is no sign of a return to extreme heat. That sounds like a pretty good deal for us in August!