[Phys-L] interacting hurricanes

[John Denker <jsd@av8n.com>]

Hi Folks --

I suppose you've seen the forecast that calls for two hurricanes
(Laura and Marco) in the Gulf of Mexico at the same time.

Based on what I know about vortexes,
   https://www.feynmanlectures.caltech.edu/II_40.html

I'm starting to suspect all the forecasts are off. I expect
each hurricane to get caught up in the velocity-field of the other,
to a much greater extent than what I've seen in any forecast tracks
so far.  They should tend to orbit around each other.  Meteorologists
even have a name for this:
  https://www.usatoday.com/story/news/nation/2020/08/22/tropical-storms-laura-marco-collide-fujiwhara-effect-explained/3410073001/

I find it hard to imagine that anybody could build a forecast model
that didn't take this into account, automatically, as a natural
consequence of modeling the physics ... so probably there's something
fundamental that I'm not understanding.

Order-of-magnitude check:  For a category-1 hurricane, tropical-storm
winds (39 mph or greater) typically extend 125 miles from the center.
The speed scales like 1/r, so I would expect 20 mph or (!) greater
250 miles from the center.  That's nontrivial compared to the current
forecast of forward motion (13 mph toward the northwest).

They might not get close to each other, but if they do, it's gonna be
innnnteresting.