MAJOR HURRICANE IDA: STRONG CAT 4 STORM, NEAR PEAK STRENGTH AT LANDFALL
Major Hurricane Ida made landfall just to the west of Port Forchion, Louisiana just before noon on the 29th of August as a strong CAT 4 storm, on the 16th anniversary and just 45 miles to the west of Katrina.
Discussion
A depression formed in the southern Gulf of Mexico on the 26th of August and became Tropical Storm Ida later that day.
Tropical Storm Ida moved northward towards western Cuba becoming a hurricane just before landfall.
After crossing western Cuba, Ida briefly became a tropical storm again but was forecast to strengthen (rapidly) as it moved northward across the WARM central and northern Gulf of Mexico.
The NHC and weather models forecast rapid strengthening on the 28th with landfall late on the 29th. The track was initially a little further to the west and then a slight shift to the east into southern Louisiana…the track was well forecast two or more days out.
In the hours before landfall, Hurricane Ida rapidly intensified and surface winds increased about 35 to 40 knots.
Water temperatures in the Gulf are currently running 1°C to 4°C warmer than normal. As we’ve seen in recent years, rapid intensification is more common just before landfall.
Ida became a strong CAT 4 at landfall and was at or very near peak intensity.
After landfall, the rapid weakening forecast by the NHC, GFS (and ECMWF) model did not occur with hurricane Ida slowing and maintaining strong winds (especially strong gusts for several hours after landfall).
Ida had a slightly more northerly course than forecast by NHC (and GFS) which brought the storm (and the eyewall) closer to New Orleans and increased the wind gusts and the persistence of strong winds.
Ida made an unfortunate and impactful wobble to the right yesterday just as it was approaching the New Orleans metropolitan area. That shift put the eye closer to the city, and therefore the winds were higher as the strong bands rotated through.
Even though the winds were only Category 2 strength, they wreaked havoc on the electrical grid in Louisiana.
Ida was the 5th strongest storm to hit the US. The straight-line path of the storm increased tidal flooding along and to the east of the track in an areas of Louisiana that is already highly vulnerable to tidal flooding.
The GFS model track was excellent (and quite consistent). The GFS failed to adequately forecast the rapid intensification in the hours leading to landfall and then the GFS and NHC weakened Ida too quickly.
The Brown Ocean Effect occurred at landfall as Ida moved over the warm/wet bayous, behaving as if it was still over water and maintaining Cat 4 strength inland.
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