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But it doesn't look like the tropical storms I've been seeing and learning about all season. It doesn't look very tropical. On the water vapor the temperature of the center isn't all that warm, the convection doesn't look the same like I'm used to seeing, and there's some kind of lack of, I'm not sure how to put it, but the band doesn't seem like a feeder band, with a force driving the convection into the center. It's more like a group of clouds that are all moving around the center, but only because of the rotation, like they're all just sitting in place, like a record on a turntable; staying the same, static. It seems like there is some dynamic that is missing.

Unbelieveably, the Circulation that Wouldn't Die is still spinning and now pulling along some convection as it heads into Central America at the border of Panama and Costa Rica.

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You're right, in a lot of ways Margie, these relatively 'cold' tropical systems are an odd entity. they exist in relatively cool waters, forming in isolation from an extra tropical low. even when/if this storm develops an eye, you won't see cloud tops in the -60 - -70 degree range, instead you'll see a ring in the -40's maybe -50's that just look unimpressive compared to the storms that typically form, but there is still winds of 70 - 80mph in the center.

I Know I keep coming back to Olga in 2001, but it really was the Archetype 'cold' warm core system. The system was over relatively cold water (22 - 23 degress centigrade) when it was finally classified first, ST, then tropical storm and then deemed a hurricane.

http://www.nhc.noaa.gov/archive/2001/OLGA_text.html

From:
HURRICANE OLGA DISCUSSION NUMBER 9

AFTERNOON SATELLITE IMAGERY INDICATES AN INTERMITTENT EYE AT THE
CENTER OF OGLA...WHICH AS OF THIS WRITING IS BECOMING BETTER
DEFINED. SATELLITE INTENSITY ESTIMATES ARE 65 KT FROM SAB AND
AFWA...AND 77 KT FROM TAFB. ON THIS BASIS...OLGA IS UPGRADED TO
A 65 KT HURRICANE.

Then later in the discussion:

OLGA IS CURRENTLY OVER 22C-23C SEA SURFACE TEMPERATURES...AND THIS
IS NOT LIKELY TO CHANGE MUCH ON THE CURRENT FORECAST TRACK.

an extra point made in a later disussion:

THE OCEAN IS COOL...BUT ACCORDING THE THE SHIPS
MODEL...THE 200 MB TEMPERATURES ARE COOL ENOUGH TO PRODUCE A
POSITIVE CONTRIBUTION TOWARD INTENSIFICATION

The south atlantic Hurricane was also an example of a 'cold' tropical system. They do pop up from time to time, it just takes several things to happen to create one. Hopefully this will help us all understand hybrid systems and the cool tropical systems when they develop. (The more we can study the better we can understand them)

-Mark

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M. S. Earth and Atmospheric Sciences, Georgia Tech - May 2020
Brookhaven National Laboratory
U. Arizona PhD Student

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