Idalia's Almost Here

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Key Points:

  • A Hurricane Warning is in effect for our coast from Edisto Beach south into Georgia. A Tropical Storm Warning is in effect north of Edisto Beach through North Carolina. A Hurricane Watch is in effect from Edisto Beach to South Santee River.
  • Tropical Storm Warnings extend inland to cover parts of the Central Savannah River Area, Midlands and most of the Pee Dee region.
  • A Storm Surge Warning is in effect from South Santee River southward.
  • A more intense Idalia means stronger winds and a worse storm surge in the Lowcountry late today and tonight.
  • Impacts will stretch far inland. Damaging winds and flooding rainfall are in the forecast for much of South Carolina.
  • Some rivers along the Coastal Plain will go above flood stage due to Idalia's rainfall but major flooding is not in the forecast.
  • The wind and rain will diminish from southwest to northeast late tonight and early Thursday. A stretch of several days of dry and tranquil weather will begin Friday.

Idalia made landfall this morning in Florida near Keaton Beach, Florida, as a Category 3 hurricane. It reached Category 4 intensity for a time before making landfall.

Here are the current tropical storm and hurricane watches and warnings in effect across the state.

With Idalia becoming so intense before landfall, we'll see increased impacts in South Carolina. Here's what to expect:

Wind:

Winds are picking up in Savannah as of 11 a.m. and the Lowcountry will see gusty winds increase this afternoon.

While hurricane-force winds will primarily affect coastal areas of Jasper, Beaufort, and Colleton Counties, damaging winds will occur all along our coast. The damaging wind risk extends to the I-20 Corridor and I-95 northeast of where it meets I-20. Gusts of 75-90 mph are possible in the Hurricane Warning area and 60-75 mph over the rest of the Lowcountry. 50-60 mph gusts are likely along the Grand Strand and the rest of the Coastal Plain. Peak gusts of near 50 mph look likely along the I-20 Corridor. Winds trail off as you look farther to the northwest but gusts may reach 40 mph in the southern part of the Upstate and into the Catawba River Area (by that I mean York, Chester, and Lancaster Counties).

Tree and power line damage can be widespread over the southernmost part of the state, and power outages may last more than a few hours here. There's a chance for minor structural damage as well. Elsewhere, the concern is for scattered tree and power line damage.

Rain and Associated Flooding:

Much of the state is at risk for extreme rainfall from Idalia. Rain from the storm already covers most of the state as of midday, and the rain will spread northward as the day wears on. The heaviest rain will occur late today and tonight; the Weather Prediction Center (WPC) says we have a risk of widespread flash flooding.

Those in the level 3 of 4, 'moderate risk' zone should be ready for widespread flash flooding. More isolated flash flooding is a risk in the level 1 and 2 areas. Be ready to move to higher ground if your location is flood-prone. You can find more detailed flooding preparation and safety information at ready.gov.

Storm Surge and Coastal Flooding:

A stronger Idalia in South Carolina means that storm surge flooding looks a little worse than we thought yesterday for the coastal Lowcountry.

With this, the forecast for peak water levels in the Charleston area have been raised since yesterday. 

Thanks to our high astronomical tides due to a full moon, minor to moderate tidal flooding is in the forecast for the end of the week and this weekend. The coastal flooding forecast has been increased for the Grand Strand, too. The Grand Strand will also see minor flooding at high tide later this week.

These tide gauge forecasts include the astronomical tide and storm surge but do not include the exacerbating effects of tropical downpours that may be ongoing during high tide. Coastal residents should rush any remaining storm preparations to completion and be ready to move to higher ground.

Tornado Threat:

The Storm Predication Center (SPC) has increased their risk level for tornadoes associated with Idalia.

We already have a tornado watch out for our coastal areas, and we may see more watches issued later today and tonight.

Much of the Coastal Plain now has a level 3 of 5 'enhanced' tornado risk, and level 3 is where this gets truly serious. Please stay alert for tornado warnings as Idalia moves through tonight, as we may see several tornadoes in our coastal areas and isolated tornadoes farther north and west to near I-20. Be sure to have at least two ways to receive warnings (like a weather radio and properly configured emergency alert app on your phone), and decide in advance on the best shelter location in your home. The risk continues into the late night hours, so ensure your alert systems can wake you up if you doze off. We have a special case tonight in that there is also a flood risk, and your primary shelter might be flooded, so have an alternate, second-best shelter in mind.

Idalia's wind and rain will wind down late tonight and early Thursday. Once we're rid of Idalia, several tranquil days are ahead. This weekend should feature good weather for storm cleanup and recovery.

No other systems in the Atlantic appear to be a threat to South Carolina right now. I'll talk more about longer-range risks from the tropics in the next report coming up on Friday.