- The primary threat from Debby is still excessive rainfall and flooding.
- The heaviest rain has ended in the Lowcountry, but additional downpours will worsen ongoing flooding in this region.
- Extreme rainfall returns to the Pee Dee region this evening as Debby finally starts moving northward, and there is a risk for widespread flash flooding. The heavy rain will spread into much of the Midlands and Catawba River Area tonight and continue into Thursday, and localized flash flooding is likely in these areas.
- While rainfall will be less in the Upstate, there will be a risk of isolated flash flooding along and east of I-26.
- Rivers will continue rising and moderate to major river flooding is ongoing or will commence in the coming days across the Coastal Plain.
- Storm surge risks are lower than feared, but a 1-3 foot storm surge will lead to minor coastal flooding tonight and worsen the risk of flooding from heavy rain.
- Strong winds from Debby will spread over the Grand Strand and vicinity this evening as it tracks northward. The primary area of concern for damaging wind is at the coast, but isolated wind damage can occur across the eastern part of the state, especially in the Pee Dee region.
- Isolated tornadoes can occur along the Grand Strand and vicinity through this evening.
Debby continues to swirl off our coast and send locally heavy rainfall into South Carolina. It has wandered southeastward and is mostly over water again, so it is beginning to gain strength again. However, it will not have much time over water, so we don't expect it to get much stronger, though the coverage of showers and thunderstorms will likely increase considerably from current levels before it does move ashore.
This loop of visible satellite images shows Debby spinning off the South Carolina coast.
Source: University of Wisconsin RealEarth
Debby has a ragged appearance today after recently ingesting a slug of dry air to its west. The cloud pattern should fill in this afternoon and evening before Debby's center moves ashore around 10 p.m. near the Charleston-Georgetown county line.
Our primary threats from Debby going forward are still excessive rainfall and flooding. The flash flooding risk doesn't look as extreme as we thought earlier, but it will still be serious tonight through tomorrow over the Pee Dee region, the Catawba River Area, and the upper Lowcountry. Our Coastal Plain has seen tremendous rainfall with 10-16 inches in many areas over the last 72 hours. Additional rainfall of 1-2 inches in the south to 6-8 inches in the north will cause renewed flash flooding on the soggy soils of the region. Another round of heavy rainfall will affect the I-77 Corridor through Thursday and spread into the eastern part of the Upstate. Localized flash flooding can affect these areas.
Isolated flash flooding cannot be ruled out in the Central Savannah River Area from Debby's downpours, while the limited rain that will fall over the western part of the Upstate will be welcomed as it remains mighty dry in that part of the state.
Debby will move through tonight and Thursday and finally pull away on Friday. All the rain that has fallen here and in the vinegar sauce zone will end up in our rivers in the coming days, so moderate to major river flooding is forecast through this weekend and beyond. Pay attention to the recommendations of local officials if you live along our flood-prone rivers like the Lumber, Little Pee Dee, and Waccamaw, and get ready to bug out if your situation calls for it.
There is still time to study flood prep info from ready.gov if you're in a flood danger zone.
Storm surge hasn't been too bad with Debby, and the surge risk will remain more of a nuisance than a major hazard. Nonetheless, be on the lookout for a 1-3 foot storm surge from northern Charleston County northward into coastal vinegar sauce territory through this evening as Debby comes ashore. This will result in minor coastal flooding and exacerbate the flooding from heavy rain.
While Debby is regaining strength, wind remains a minor to moderate threat for us through tonight. Debby's strengthening will mainly come from the gusty winds becoming more widespread rather than getting stronger.
In the area highlighted in yellow above, isolated wind and power line damage and other minor damage should be all we see; that's potentially serious but manageable. In the orange area, the damaging winds can be more widespread, with peak gusts of around 60 mph. Some minor structural damage to shingles or siding is possible with winds this strong.
A part of the state will be subject to seeing isolated tornadoes through tonight as Debby finally gets moving and pushes through. We've already seen a few tornadoes and perhaps as many as seven (the NWS is working to survey damage and confirm or refute that a tornado occurred).
The Storm Prediction Center's Severe Weather Outlook graphic for today and tonight indicates a low-end risk for tornadoes along and near the Grand Strand. The risk farther inland and southward toward northern Charleston County is not zero, so stay on your toes through this evening if you're in this area, too. Stay alert for tornado warnings and ready to follow your action plan should a tornado warning be issued for your location. The National Weather Service has tornado safety information to help you prepare for tornado threats.
We have two more days of dealing with Debby but the storm should finally be out of our hair by Friday night. It looks like a brief quiet spell is coming to the Atlantic behind Debby, as it's the only game in town in the Atlantic Basin right now.
This loop of visible satellite images shows Debby off our coast and tropical waves crossing the tropical Atlantic this afternoon (now along 80°, 55° and 33° west longitude).
Source: University of Wisconsin RealEarth
The only tropical wave showing signs of life is about to move into Central America, so it probably won't develop until it reaches the East Pacific (where there has been a spurt of activity lately). Conditions are unfavorable for the two tropical waves over the tropical Atlantic right now but that is likely to change over the next week as more favorable conditions in terms of shear and rising motion spread eastward from the Pacific basin. Development is unlikely in the short term but the wave near Cabo Verde will have a chance to develop when it reaches the area around 65° west in a week. Early indications are that it will be more of a concern for Bermuda than the East Coast after that, but it's far too early to promise that.
Debby may only be the first storm we must deal with this year. So, remain vigilant and ready, and check hurricane.sc for storm prep advice.