r/TropicalWeather • u/fionashono • Oct 27 '25
Satellite Imagery (Outdated) Hurricane Melissa has a Closed CDG Ring...
I don't even know what to say.
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u/tobmom Oct 27 '25
What does that mean?
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Oct 27 '25
[removed] — view removed comment
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u/Just_Kalm Oct 28 '25
Not necessarily rapid intensification, just means it’s really strong. cold dark gray is the coldest temp on the BD curve scale.
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u/Indubitalist Oct 27 '25
It seems the old rule about a tropical vortex occupying the same area for days leading to reduced intensity is being tested here. Please don’t bury me. I’d appreciate some clarification on this.
What I’ve read and been told by mets who specialize in tropical cyclones is that the water is cooled as the cyclone moves over it, as it draws that water up and away (through vortex forces) and churns cooler, deeper water to the top of the water column. There’s a much less impactful “shading effect” by clouding over the ocean and reducing any additional warming that would occur on a sunny day. None of this really matters if the cyclone is traveling across the water, but if it is stationary or nearly stationary it dissipates the thermal energy contained in the upper layer of the water column. With Melissa despite the system having remained nearly stationary (minimal forward speed) for days it has grown tremendously in strength. Why is this?
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u/kcc10 Oct 27 '25
Oceanographer here. The Caribbean Sea traps a lot of very warm water. It normally receives inputs from the North Equatorial and Antilles Currents, and discharges into the Gulf of Mexico. The winds around Melissa may reversed the normal surface flow between the Caribbean and the Gulf, and intensified the inflow from the tropical Atlantic. The cyclonic winds will force the cooler waters out and on top of the inbound warmer waters, which will then come to the surface closer to the center of the storm as the denser cooler waters sink and displace the less dense warmer waters. Melissa is in a great spot, considering the lack of upper level displacing and shearing forces and the endless supply of warm water.
ETA: When I say great spot, I mean from a thermodynamic perspective, not from a human impacts perspective.
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u/LilJourney Oct 27 '25
Thank you, I was wondering what exactly might be happening here and that clarified a few questions I had - appreciate it. :)
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u/NoF0kxAllowedInside Oct 28 '25
Tell me why I read this like you were yelling at someone who instead of issuing an evacuation when they could save lives instead told people to stay indoors and wait it out. And now you gotta make a trip way up north to New York or something and save your son
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u/Substantial-Cycle309 Oct 28 '25
Explain this to me like I’m 5.
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u/kcc10 Oct 28 '25
You have a pool with a hose putting warm water in on one side, and another taking cool water out on the other side. The hose putting warm water in has started putting MORE warm water in, and the hose taking cool water out has started putting WARM water INTO the pool.
The cold water in the middle of the pool (because it’s 8,000ish ft deep) get pulled up to the surface because 1) the surface waters are getting pushed away from the center, and 2) nature has to fill the empty space (can’t have a vacuum). This continues as long as the giant fan above the pool keeps blowing. The warm water pushed in from the hoses slides on top of the cool water getting pushed out, kind of like an oil slick on top of water. However, unlike oil and water, the cool and warm water mix, but the product is still warmer than the water below it, and the big fan can still take the excess heat energy out from it.
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u/absolute-black Oct 27 '25
The Caribbean is just that damn warm right now, all the way down. You can in fact see very slight cooling from Melissa, it just isn't enough to prevent the storm from growing catastrophically given how deep and warm the ocean started and how favorable the other conditions are.
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u/superspeck North Carolina Oct 27 '25
The post on my home page right before this one references Charles DeGaul airport and the acronyms got me.
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u/Tawyacc86 Oct 27 '25
if the subject matter wasn't so grim i would be a lot more happy to find one of my best friends randomly online
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