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Hurricane Ian hits South Carolina » Yale Climate Connections

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Hurricane Ian made landfall near Georgetown, South Carolina, about 55 miles northeast of Charleston, at 2:05 p.m. EDT Friday, September 30. On landfall, Ian was a Category 1 storm with winds of 85 mph and a central pressure of 977 mb. Ian’s largest impacts from this second US landfall will likely be flooding from storm surges of up to 5-7 feet and inland flooding from 4-8 inch rainfall. However, the damage caused by this second American landing will most likely be more than a factor of 20 less than that caused by its landing in southwest Florida. Hundreds of people were rescued Thursday in the hardest-hit areas of southwest Florida, and severe flooding from record rains affected parts of central and northeast Florida.

Figure 1. Weather-related disasters that cost at least $20 billion (USD 2022), according to NOAA/NCEI. Hurricane Ian will definitely join this list, probably in the top 10.

Tiered Insured Losses

Even with Ian’s course of destruction still incomplete, it is virtually certain that the storm will rank among the most damaging in US history. CoreLogic estimate that assured the damage caused by Ian in Florida alone would be between $28 billion and $47 billion; Fitch Ratings estimated insured losses at $25 billion to $40 billion. Many more billions will be incurred by residents who do not have adequate insurance. Florida has a strict building code for hurricane damage, but most of Ian’s damage comes from storm surges and inland flooding, and home insurance typically doesn’t cover these hurricane-related threats. ‘water. Only one small fraction of southwest Florida residents outside the 100-year floodplain have federal flood insurance. Total damages usually end up being twice the insured damages, so the total price of Ian’s rampage could be between $50 billion and $100 billion, making it one of the ten worst weather disasters. costliest in U.S. history (Figure 1).

Figure 2. Hurricane Ian’s rainfall forecast for the two-day period ending at 8 a.m. EDT Sunday, October 2. (Image credit: NHC)

In the early afternoon of Friday, torrential rains exceeding an inch per hour were falling along the South Carolina coast, which was taking the brunt of a primitive eyewall Ian had built just before landing. . No rivers in South Carolina or North Carolina were in the flood stage Friday afternoon, but five rivers in those two states are predicted to reach at least minor flood stage this weekend. In Florida, however, 14 river gauges were in the stage of major flooding Friday afternoon from Ian’s rains, including a number at their highest levels on record.

Wind gusts of 40 to 70 mph were common along the South Carolina coast late Friday morning through early Friday afternoon. A Charleston Harbor WeatherFlow Station recorded a wind gust of 92 mph at 12:44 p.m. EDT Friday, and a WeatherFlow station at the Morris Island lighthouse reported sustained winds of 75 mph with a gust to 82 mph shortly before 2 p.m. EDT.

Destructive storm surge forecast for parts of South Carolina and North Carolina

Parts of the Carolina coast to the right of where the center of Ian makes landfall are expected to receive damaging storm surge, with up to 5 to 7 feet of surges forecast along the northeast coast of South Carolina. The timing of the surge relative to the tide will be important: the tidal range is greater than five feet along much of the coast, and some of the highest tides of the month – the king tides – occur this week. High tide in Myrtle Beach, South Carolina was at 11:30 a.m. EDT Friday, and the highest water levels (storm surge) associated with Ian’s landfall in South Carolina occurred around an hour and a half after that.

Significant flooding occurred early Friday afternoon in myrtle beach, South Carolina, where a storm surge of 6.2 feet and a storm tide of 5.17 feet above mean high water (MHHW) were observed at 1:36 p.m. on Friday, September 30. It was the third highest water level ever recorded at this location. below the 8.77 feet recorded during Hurricane Hugo in 1989, but still enough to produce significant flooding. (See tweets below from Garden City and Lichfield Beach, both within 10 miles of Myrtle Beach). Second place in Myrtle Beach is held by Hurricane Matthew of 2016 (6.13 feet). Archives date back to 1957 on the site.

Mainly minor to moderate flooding from storm surge Ian in the southeastern United States

Along the coasts of Florida and Georgia, Ian’s second American landing caused mostly minor to moderate coastal flooding, with no areas of major flooding observed. In northeast Florida near Jacksonville, the St. John’s River in Mayport reported a water level of 2.48 feet above mean high water (MHHW) on Thursday afternoon, causing moderate flooding. It was the third highest water level on record there, with records dating back to 1897. Only Hurricane Matthew in 2016 (3.22 feet) and Irma in 2016 (2.80 feet) resulted in higher water levels.

Fernandina Beach, Florida, reported that a water level of 3.36 feet on Thursday afternoon also caused moderate flooding, the sixth-highest water level on record. Archives date back to 1897 on the site.

Fort Pulaski, minor storm surge flooding in Georgia did not rank in the top 10 on record.

In South Carolina, Charleston Harbor had a crest of 1.16 feet, below the minor flood mark, with high tide Friday at noon. That’s below the 1.83ft peak on Thursday morning, and not among the 10 highest ridges recorded there.

The 3.54 foot ridge at Wrightsville Beach, North Carolinaat 1 p.m. EDT Friday fell just below the moderate flood threshold, as the fourth highest water level on record there, behind Hurricane Hazel (1954), Fran (1996) and Florence (2018). Archives date back to 1954 on this site.

Ian is expected to transition to an extratropical storm Friday night and dissipate Saturday night.

Figure 3. Visible nighttime (moonlight) satellite imagery from Monday, September 26 (left) and Friday, September 30 (right) showing where Hurricane Ian caused power outages, near Havana, in Cuba, and Sanibel Island, Florida. (Image credit: NASA worldview)

Power cut for 1.8 million people in Florida, 270,000 in the Carolinas and much of western Cuba

As of 3 p.m. EDT Friday, Sept. 30, Ian had shut off power to about 1.8 million customers in Florida (about 16% of customers in the state), down from a peak of 2.7 million on Thursday, according to poweroutage. us. In South Carolina, Ian’s winds had knocked out power to 210,000 customers and 60,000 were without power in North Carolina.

In Cuba, where Ian had caused an island-wide blackout on Tuesday, power was still out Friday in much of the capital Havana, satellite imagery visible at night shows (Figure 3) . Reuters reported isolated street protests over the long blackout in Havana Thursday night. Ian hit western Cuba on Tuesday as a Category 3 hurricane with winds of 125 mph, killing two people.

Meanwhile, in Puerto Rico, which suffered an island-wide blackout on September 19 due to Hurricane Fiona, power was still out. 230,000 customers Friday, about 16% of customers on the island.

Figure 4. A large area of ​​disturbed weather off the west coast of Africa, shown here at 1545Z (11:45 a.m. EDT) Friday, September 30, 2022, could become the next Atlantic tropical cyclone. (Image credit: RAMMB/ACEI/CSU)

New system likely to develop in the Eastern Atlantic

A disturbance that moved off the coast of Africa on Thursday, which has yet to be given an “investment” number, could develop over the next few days as it drifts generally westward. The broad disturbance occurred Friday at low latitudes in the eastern tropical Atlantic, about 200 miles west of the African coast. Convection (showers and thunderstorms) was weak and scattered, and it will likely take several days for any development to occur.

In its tropical weather forecast released at 2 p.m. EDT Friday, the National Hurricane Center gave the system a 10% chance of development by Sunday and a 60% chance by Wednesday.

The new disturbance will move through a moist mid-level environment without intense wind shear or a dry Saharan air layer and atop warm sea surface temperatures (SST) of about 28 degrees Celsius (82 degrees Fahrenheit) .

Many Friday morning ensemble runs from the GFS and European models show a tropical depression forming early next week. A break in the subtropical high pressure ridge should allow the nascent system to first track north towards the center of the North Atlantic. Anything that develops could end up being a long-lived pest, as longer-range models suggest the ridge could strengthen and push the system into the subtropics of the northwest Atlantic, where SSTs remain exceptionally warm. The next name on the Atlantic list is Julia.

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