Key Points:

Helene is now a hurricane with 80 mph maximum sustained winds, centered just east of Cancun, Mexico.

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A loop of visible satellite images from this morning featuring sunrise over the region revealing Helene, now the Atlantic Basin's newest hurricane.

The latest NHC experimental forecast cone, watch, and warning graphic shows the extent of Tropical Storm Watches and Warnings in our state.

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Helene will cause all four of the usual tropical cyclone impacts to some or all of South Carolina. First, we must address the threat of extreme rainfall and flooding. Below are the Excessive Rainfall Outlook graphics from the Weather Prediction Center (WPC) to break down the risk for heavy to extreme rainfall and flooding through Friday.

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A front that will become stationary over much of the Upstate will cause a predecessor heavy rainfall event through tonight, with the potential for significant flash flooding over the western Upstate and isolated flash flooding in other parts of the state. Extreme rain from Helene will affect much of the state Thursday into Thursday night, resulting in widespread flash flooding for the Upstate, especially areas that get heavy rain through tonight. In that area, some areas that see flooding only in the most extreme rain events will flood, and the high-risk area indicates the risk for severe flash flooding and should be taken very seriously. Flash flooding may be widespread and significant in the 'Moderate Risk' areas. In the green and yellow areas, there can be isolated flash flooding from heavy rain, with yellow areas at a somewhat higher risk.

River flooding is going to be a problem in the Upstate as well; be prepared for moderate to major river flooding in this area. This will flow downstream, of course, and the rest of the state will get soaking as well, so we will see river flooding become a problem over most of the state's rivers as we go into the weekend.

Now, to address the damaging wind risk. Helene will have an unusually large field of strong winds on its east side so South Carolina will get a taste of the strong wind.

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The slightly westward shift of the forecast track has reduced my concern for strong winds a bit. However, peak gusts in the 50-55 mph range over areas near the Savannah River will still be enough to cause some downed trees and power lines. It wouldn't shock me if someone in the western Upstate or coastal Lowcountry had a 60 mph gust. Areas farther to the east will see less wind, but the wind combined with heavy rain might cause isolated tree and power line damage. Should Helene track farther east than expected, the concern for damaging wind will increase.

The tornado risk is looking potentially serious over parts of the state. Here's the Storm Prediction Center's Severe Weather Outlook graphic for Thursday and Thursday night to illustrate the concern:

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The level 3 of 5 'enhanced risk' area over the Lowcountry is concerning. I've said before that concern for a more serious severe storm outbreak hits harder when you see SPC has us in level 3 and up areas. I've read that they are evaluating whether to expand that further north and northeast, They might well have to as that area is going to have an unusually favorable setup for tropical tornadoes Thursday and Thursday night. At least a few tornadoes further north and west are likely but will be more isolated. While there might be isolated severe storms with a couple of tornadoes on Thursday, the main time of concern will be Thursday night as Helene barrels northward through the Southeast, especially late at night and the wee hours of Friday.

A tornado outbreak at night is never a good thing. Usually, people are trying to sleep and many miss warnings. So, it's important to have tornado preparations in place ahead of Helene. Decide on your best shelter area in advance, as you might not get much lead time. Tropical tornadoes often hit fast without much lead time on warnings. Also, be sure you have at least a few ways to receive tornado warnings, and make sure one of them will make enough noise to wake you if you're sleeping. More tornado preparation advice is available from the National Weather Service.

Oh, it's worth mentioning that any storm along the stationary front in the Upstate and vicinity this afternoon and tonight can be locally severe with damaging wind; an isolated tornado can't be ruled out.

Finally, storm surge:

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The current forecast from NHC allows for a 1-3 foot storm surge along and south of South Santee River. It wouldn't surprise me if they extended this further north in time, but the Lowcountry has the greater storm surge risk. However, timing, which is a little uncertain still, will be key. A 2-3 foot storm surge that hits at high tide would be enough for moderate to major coastal flooding, but if it hits at low tide or between the tides, there may be little or no impacts from the surge. Of course, especially for the Charleston area, should heavy rainfall occur right at high tide with a coinciding storm surge, the coastal flooding gets even worse.

Helene is coming. The worst will pass to our west, but we will see major impacts in South Carolina. So, please prepare. If you need advice, SCEMD has you covered at hurricane.sc.