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I'm curious ( I'm not in FL )
So it rapidly decreased in intensity a hour or so before landfall? I know someone near Tampa that they lost their car and home, but overall damage is significantly less than what happened in the Carolina mountains from Helene, is that correct?
Any ideas why it deintensified so? Is it worse than I understand? Pretty much everywhere reads like this ended up being far less destructive than anticipated, but that the anticipated storm and destruction would have been record setting.
The storm was mainly weakened by wind shear.
Here are some key points:
Wind shear is defined as the change in wind speed, wind direction, or both, over some distance.
Hurricanes thrive in environments where their vertical structure is as symmetrical as possible. The more symmetrical the hurricane is, the faster the storm can rotate, like a skater pulling in her arms to spin.
Too much vertical wind shear, however, can offset the top of the storm. This weakens the wind circulation, as well as the transport of heat and moisture needed to fuel the storm. The result can tear a hurricane apart.
Source: What is Wind Shear, and How Does it Shape Hurricanes
As to the destruction being less than the worst-case scenario predicted, that's because the storm ended up making landfall south of Tampa Bay:
Tampa Bay remained in the hurricane’s northern eyewall, which meant that winds blew from the east—offshore—during the worst of the storm. Not only did these offshore winds spare the region the worst of the surge, but Tampa actually experienced an “anti-surge” as the storm made landfall. Strong winds pushed more than a metre of water out of Tampa Bay and into the Gulf of Mexico.
Source: How Hurricane Milton's Destructive Surge Mostly Spared Tampa Bay
The houses in Florida are built considering hurricanes, so they are more sturdy. Also, Florida is super flat and it has been raining everyday for months, so the ground was permeable but a little full already. Because it's also near the ocean, the water can spread out into sea quickly.
The houses in NC are much less sturdy, so they would be more susceptible to wind damage. Also, because of the mountains, the valleys become pools of flood water. The ground there is much harder than in Florida, so it doesn't absorb the rain as much. Since the pools are in the mountains, there's only two ways for the water to leave. For the lucky valleys that aren't entirely surrounded, the water can escape through the gaps making temporary rivers. The other route is through evaporation, which takes a long time. This delays the ability of recovery efforts because people literally can't even get to the disaster zone.