Hurricane warnings and storm surge warnings are in effect along much of Louisiana's coast as Tropical Storm Francine approaches landfall. Francine is expected to intensify into a hurricane Tuesday night before leveling off or weakening in intensity before making landfall in Louisiana as a Category 1 storm Wednesday afternoon or evening.
Francine becomes more organized
At 11 a.m. ET Tuesday, Francine was located 425 miles (690 kilometers) southwest of Morgantown, Louisiana, moving north-northeast at 8 mph (13 km/h) with maximum sustained winds of 65 mph (100 km/h), central air pressure is 988 MB (29.18 inches). Satellite imagery and radar in Brownsville, Texas, indicate an area of moderately severe thunderstorms in Francine that are becoming more organized. Heavy rains from the storm affected the coasts of northeastern Mexico and southern Texas.
Conditions favoring development include record ocean temperatures near 30.5 degrees Celsius (87°F), light wind shear of 5 to 10 knots, and a moist atmosphere. However, there was some dry air over Texas and Mexico to the west of the storm, interfering with overnight development.
Gulf of Mexico sea temperatures hit record high
Francine will benefit from record warm ocean temperatures near 30-30.5 degrees Celsius (86-87°F) Tuesday into Wednesday morning. That's about 1 degree Celsius (1.8°F) above the 1981-2010 average and the hottest temperature on record for this time of year. According to the Climate Central Ocean Shift Index (Figure 1), human-caused climate change increases the likelihood of ocean warming in parts of Francine's orbit by more than 200 times. Warm water extends to great depths along Francine's path, feeding the storm with large amounts of ocean heat energy that intensifies the storm's intensity.
Francine's trajectory forecast
There is a degree of uncertainty in track forecasts, both across the track (which part of the coast the storm will hit) and along the track (when the storm will hit). Forecast models have shifted more eastwards in recent runs, increasing the threat to New Orleans. More than four inches of rain is expected along a swath of the Gulf Coast from western Louisiana to coastal Alabama.
Francine intensity forecast
Favorable conditions for the Francine intensification will continue until early Wednesday morning. However, the likelihood of rapid intensification (defined as a 35 mph increase in wind speeds in 24 hours) appears to be less likely than yesterday: Tuesday's 12Z run of the SHIPS model showed the likelihood of Francine's rapid intensification of 35 mph in 24 hours Only 12% of the 24 hours ending at 8 a.m. ET Wednesday will see winds reaching Category 2 with 100 mph winds. The model gives a 10 percent chance that Francine will become a Category 3 hurricane with winds of 115 mph by Wednesday night.
As Francine approaches the Louisiana coast late Tuesday night into Wednesday, wind shear is expected to rise into the high 20-30 knot range, and dry air from the west side of the storm may attack the storm's core, causing weakening. There will also be less available ocean heat. These factors should cause Francine to cease intensifying six hours or more before landfall, with peak intensity models predicting Francine will make landfall (Category 1) with sustained winds of 75-100 mph (120-160 km/h) or Category 2 hurricane). Ensemble models indicate that if Francine moves more eastward (resulting in an increased threat to New Orleans), it could be a stronger storm (Figure 2).
Louisiana hit by devastating storm surge
Storm surges of 1-2 feet (0.6-1.2 m) were observed along much of the Texas coast Tuesday morning, causing some minor coastal flooding, according to NOAA's Tides and Currents website. A larger storm surge of 5 to 10 feet (1.5-3 m) was expected near the center landfall and along the Louisiana coast to the right, causing severe flooding. With large areas of shallow water offshore, the Louisiana coast is one of the most vulnerable areas in the world to high storm surges. Francine's angle as it approached the coast from the south-southwest made it less of a storm surge threat to New Orleans than storms approaching from the south or southeast.
High tide at the Ameralda Pass in central Louisiana is 3:30 a.m. EDT (7:30Z) on Thursday; low tide is at 5:30 pm EDT (21:30Z) on Wednesday. The difference in water levels between high and low tide is about 1.5 feet (0.5 m), so the timing of Francine's landfall will be an important factor in determining the extent of coastal flooding. At 11 a.m. ET Tuesday, the National Hurricane Center forecast the hurricane would make landfall at 6 p.m. Wednesday (near low tide time). However, we expect landfall times may differ by up to four hours from this. Our six top hurricane models have a nine-hour range for Tuesday's landfall of 06Z, from 2 to 11 p.m. ET.
Louisiana Hurricane History
Louisiana has been hit by so many devastating hurricanes in recent years, and the damage from Francine's landfall will be less than expected because there will be so little left to destroy. Since 2000, 12 hurricanes have made landfall in the state. Katrina's $190 billion in damage ($2,024) is still ranked as the most devastating weather disaster in world history; Rita's $28 billion in damage was the fourth costliest hurricane in the United States at the time.
Louisiana has been hit by five hurricanes in the past five years, including Laura in 2020 and Ida in 2021, two Category 4 storms with 150 mph winds. The hurricane was the strongest storm ever recorded in the state west of the Mississippi River. Mississippi was a Category 5 hurricane. Hurricanes Zeta (2020, $5.3 billion) and Hurricane Delta (2020, $3.5 billion) also caused significant damage.
Bob Henson contributed to this article.
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