Re: 600 AM EDT Mon Sep 02 2019 - 165 mph, 916 mb, W at 1 mph
Posted by
Chris in Tampa on 9/2/2019, 7:53 pm
The NHC said this at 5pm EDT:
"Some
additional decrease in wind speed is likely in the short term due
due to a possible eyewall replacement and upwelling of cooler
waters caused by the very slow motion of the hurricane."
From: https://www.nhc.noaa.gov/text/refresh/MIATCDAT5+shtml/
I'm not sure about friction. The storm gets its energy from the water. The islands seem to be very flat, and with the surge I assume inundating a large area, it might be more like Katrina was over the Everglades. It's not simply land it's over. Of course the island is small enough that it might not be weakening too much from being over some land anyway. The NHC mentions upwelling. I don't know the water depth around Dorian, but if it's not really deep in places, I would think you wouldn't upwell as much cooler water in those areas because the shallow water would be warmer. Because Dorian is over the water shading it with clouds, the water would cool down from that too, but maybe not as cold as upwelling colder water in deep water. I'm not sure. I don't know how deep storms churn the water below the surface, accessing much cooler water down deep when it is over open ocean. This might be more related to any possible eyewall replacement cycle.
Wind travels easier over the water than land. In general, that's why right along the coast at the surface you get the highest winds than a mile inland. The wind had no friction if it comes in at you and you are standing on the shore. A little bit inland the wind has gone over the land some at the surface so friction in that case would in that area slow the wind at the surface some. Although, I don't know how winds mix vertically, such as stronger winds mixing with the winds at the surface slowed some by friction. But as for changing the entire storm, not just at the surface, due to friction, I would think that being more and more cutoff from water as a storm moves inland over a large land mass would be much more the culprit. For Dorian, I don't think friction would have much of any impact on the storm itself even if that is something that normally might have more, because the islands are rather small. |
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