Hurricane Sally has inched its way to the northern Gulf Coast, making landfall near Gulf Shores, Alabama, at 4:45 a.m. local time. The Category 2 storm is dumping what is expected to be 10-20 inches of “devastating” rainfall to southeastern Mississippi, southern Alabama, and the western Florida Panhandle — and as much as 30 inches in some areas. A “life-threatening” storm surge of as much as seven feet is expected along the coastline. Thanks to the storm’s sluggish speed, its strong winds and rainfall are likely to batter and soak the region through as late as Thursday, potentially triggering record-breaking freshwater flooding in some areas.
Below are the latest updates on the storm, its path, and its impact as it proceeds:
The current forecast
Sally came ashore with top winds 105 mph, traveling northwest at an incredibly slow 3 mph. As of 4 a.m. Wednesday, the National Hurricane Center warns that “historic and catastrophic flooding is unfolding along and just inland from the coast from west of Tallahassee, Florida to Mobile Bay, Alabama.” Hurricane conditions are expected to continue throughout the day, affecting the Mississippi and Alabama coastlines and the western Florida Panhandle. There is also a possibility that tornadoes may develop.
With regard to the expected rainfall, the National Hurricane Center warns that “Sally is forecast to produce 10 to 20 inches of rainfall with isolated amounts of 30 inches along and just inland of the central Gulf Coast from the Florida Panhandle west of the Apalachicola River to far southeastern Mississippi. Historic life-threatening flash flooding is likely. In addition, this rainfall will lead to widespread moderate to major flooding on area rivers.”
The storm surge, meanwhile, could reach as high as seven feet above normally dry land, and coastal flooding could persist through multiple tide cycles.
Later Wednesday, Sally is expected to turn inland and head across the Southeast where it is expected to drop four to eight inches of rain (and possibly as much as 12 inches in some places). By late afternoon, the storm picked up its pace slightly to 7 mph and was downgraded to a tropical storm. It is forecast to travel to the northeast through Alabama on Wednesday night before hitting Georgia and South Carolina on Thursday.
The northern Gulf Coast is already under siege
Some parts of the coast have already received over two feet of rain:
In Pensacola Bay, a barge appeared to have taken out a chunk of the Three Mile Bridge:
The biggest risk is water
As we’ve seen with multiple Atlantic storms over the last several years, intensity and the hurricane category system can be a misleading indicators of the destructive potential of a hurricane or tropical storm — the impact of rainfall and storm surge can far surpass the damage done by high winds. Here is what Eye of the Storm meteorologist Dr. Jeff Masters had to say about that on Tuesday:
Regardless of its landfall intensity, the primary damage from Sally is likely to result from the slow-moving storm’s torrential rains. Sally is expected to move at 5 mph or less through Thursday, leading to rainfall measurements in feet rather than in inches.
NOAA’s Weather Prediction Center has placed portions of the Gulf Coast in its “High Risk” category for excessive rainfall. It warned of rainfall rates of up to three inches per hour, and a large corridor of 10-20 inches of rain near the coasts of Mississippi, Alabama, and the extreme western Florida Panhandle, with isolated amounts up to 30 inches. There will be a sharp western cutoff to the heaviest rains … but the exact placement of that cutoff is still uncertain. It’s not out of the question that an all-time state precipitation record for a tropical cyclone could fall …
Sally’s storm surge is also a major threat, with 4-7 feet of surge predicted to the east of where the center moves ashore. Mobile Bay is of particular concern given the high population density along the coast. The surge in the bay is not expected to approach that of Hurricane Katrina of 2005, which brought a storm tide 10.29 above the high tide mark, but flooding may exceed that of Hurricane Nate in October 8, 2017, which brought a storm tide of 5.22 feet.
River flooding is also expected, per the Capital Weather Gang:
All [the excess water from the rainfall] will pour into area rivers, many of which are likely to reach moderate to major flood stage even after the rains begin to taper down Wednesday night. Hardest hit will probably be parts of southern Alabama and the adjacent Florida Panhandle, where at least a dozen rivers are expected to crest at moderate or major flood stage. Record crests are possible based on current forecast trends.
Another problem, with regard to the inland rainfall, is the flood-insurance factor:
Putting the storm in historical context
The upside and downside of Sally’s sluggish pace
As Matthew Cappucci at the Washington Post’s Capital Weather Gang blog explained on Tuesday, Hurricane Sally’s extra-slow speed is both good and bad:
By churning up cooler waters below the sea surface, the storm has worked to slow its intensification, its strength plateauing as an 80 mph Category 1 hurricane. But by moving at a snail’s pace, Sally’s prolonged rainfall will continue to deluge parts of southern Mississippi, Alabama and the Florida Panhandle, causing widespread significant freshwater flooding …
Predicting the track of slow-moving or stalled storms is challenging, since the system can be influenced by subtler atmospheric features that would ordinarily pale in comparison with stouter steering currents.
This post has been updated throughout to reflect the most recent forecast and developments.