Hurricane Francine nears landfall in Louisiana » Yale Climate Connections

Hurricane Francine is closing in on landfall in central Louisiana, expected to occur Wednesday afternoon or evening as a Category 1 storm with 90 mph (145 kph) winds. Francine closed off an eyewall overnight, enabling it to take advantage of record-warm ocean temperatures and intensify into a top-end Category 1 storm with 90 mph winds at 2 a.m. EDT Wednesday. However, high wind shear is now affecting the hurricane, and Francine is not expected to intensify any further before landfall.

Francine would be the third U.S. landfalling hurricane so far in 2024, joining Beryl, which hit Texas as a Cat 1, and Debby, which hit the Florida Big Bend as a Cat 1. The record for most U.S. hurricane landfalls in one year is six, set most recently in 2020.

Francine levels out in intensity

At 11 a.m. EDT Wednesday, Francine was located 150 miles (240 km) southwest of Morgan City, Louisiana, moving northeast at 13 mph (20 kph), with top sustained winds of 90 mph (150 kph) and a central pressure of 976 mb. The winds have not changed since 2 a.m. EDT Wednesday, and the pressure has fallen only 1 mb, so Francine has been level in intensity.

Satellite imagery and radar showed that Francine was suffering the impacts of high wind shear of 20-30 knots. No eye was visible, the cloud pattern was elongated along the west-southwest to north-northeast axis of the strong upper-level winds affecting Francine, and the eyewall was incomplete on the south side, where the high wind shear was driving dry air into the storm’s core.

On Wednesday morning, Francine brought sustained hurricane-force winds of 75-79 mph (121-127 kph) to two offshore oil platforms in the eyewall. These winds were at an elevation of about 150 feet (46 m) and were stronger than the standard winds one would measure at the surface (the standard height for surface wind measurement is 33 feet, or 10 meters).

Heavy rains from the storm were affecting the coasts of Louisiana and Mississippi on Wednesday morning, with rainfall amounts of 0.5-1 inches (12.7-25 mm) commonly measured.

Forecast for Francine

There is not much mystery left on Francine’s future. The hurricane will make landfall on the central Louisiana coast between 6-8 p.m. EDT today, with the center passing just west of New Orleans tonight. At landfall, Francine is likely to be a Category 1 hurricane with top sustained winds of 75-90 mph (121-145 kph) and will weaken quickly once inland.

Winds

Damaging winds will be a significant hazard this evening, primarily for areas in east-central Louisiana, west of New Orleans and east of Lafayette. Morgan City (pop. 11,000) has the greatest risk of wind damage and associated power failures. In their 11 a.m. EDT Wednesday Wind Probability Forecast, the National Hurricane Center gave Morgan City a 36% chance of seeing sustained hurricane-force winds of 74 mph (119 kph) or higher. These were the highest odds for any city in their list.

Storm surge

A storm surge of one to two feet (0.6-1.2 m) was already being observed along most of the central and eastern Louisiana coast and coast of Mississippi on Wednesday morning, causing some minor coastal flooding during the morning high tide, according to NOAA’s Tides & Currents website. A much larger storm surge of five to 10 feet (1.5-3 m) is expected late this afternoon and this evening along the Louisiana coast near and to the right of where the center makes landfall, causing major flooding.

Fortunately, Francine is expected to hit near low tide: the 11 a.m. EDT Wednesday National Hurricane Center forecast called for a landfall near 7 p.m. EDT. Low tide at Amerada Pass in central Louisiana is Wednesday afternoon at 5:30 p.m. EDT (21:30Z), and high tide is early Thursday morning at 3:30 a.m. EDT (7:30Z). The difference in water level between high and low tide is about 1.5 feet (0.5 m), so Francine’s peak water levels at the coast will be a foot or more lower than would have occurred had the hurricane hit at high tide.

The coast of Louisiana is one of the most vulnerable locations in the world for high storm surges because of the large expanse of shallow water offshore. Francine’s angle of approach to the coast – from the south-southwest – makes it less of a storm surge threat for New Orleans than for a storm approaching from the south or the southeast.

Rainfall

Inland flooding from Francine’s heavy rains of four to six inches will be a significant hazard from the storm. The National Weather Service has placed much of eastern Louisiana and southern Mississippi in their “moderate” risk zone for flash flooding, meaning that flash flooding is at 40% likely in this region.

An analog storm that Francine will fall short of: Hurricane Zeta of 2020

Hurricane Zeta made landfall in Southeastern Louisiana on October 28, 2020, as a Category 3 storm with 115 mph winds. Zeta’s fast forward speed of 40 mph (64 kph) allowed it to maintain hurricane-force winds farther inland than most hurricanes, and when it passed over New Orleans, it brought wind gusts up to 94 mph (151 kph). Zeta brought a peak storm surge of six to 10 feet (1.8-3 m) to the coast and dumped widespread rainfall amounts of four to eight inches (10-20 cm). The hurricane killed five and did $5.3 billion in damage but was deemed not impactful enough to get its name retired.

Francine will not be as strong as Zeta and will be traveling over a less populated area, so the impacts are likely to be considerably less than Zeta’s.