Dancing Hurricanes? Two Tropical Systems Off Southeast U.S. Coast Could Get Weird

Tropical storm Humberto, the blotch on the right
and what might become Tropical Storm Imelda, the
blotch of clouds near the center of the satellite
photo, are too close to each other. They might
end up dancing around each other in a circle,
which experts call the Fujiwhara effect. 

This weekend and early next week, we might see two hurricanes, or at least a couple tropical storms, do an odd do-si-do off the southeast U.S Coast.  

In essence, the two systems might participate in a meteorological dance craze known as the Fujiwhara.

 Sounds fun, but it's a horrible headache for meteorologists that need to forecast tropical storms and hurricanes. 

It's also a complicated set up. Kind of like if the dance was designed for advanced performers like Derek Hough and not amateurs like the rest opus. 

HOW IT'S WORKING

The trouble comes from what is now Tropical Storm Humberto, which at 11 a.m. this morning was in the middle of the tropical Atlantic, well northeast of the Leeward Islands. 

Humberto's top winds were only 50 mph as of 11 a.m., but the storm is expected to grow into a hurricane -possibly a rather powerful one - by Sunday or Monday. 

By then, Humberto is expected to be heading toward the northwest, well northeast of the Bahamas. 

That's an iffy forecast, thanks to another tropical disturbance starting to get going near the Dominican Republic. That thing is expected to move toward the northwest as well and develop into Tropical Storm Imelda. 

Wannabe Imelda would then move toward and into the Bahamas over the next few days, turning into a tropical storm or even hurricane. 

In the grand scheme of things, Humberto and wannabe Imelda will get pretty close to each other, at least in the opinion of our tropical storms. 

 That's where the Fujiwhara effect, or dance starts

The two storms find a spot halfway between the pair, and they rotate around that spot. CNN explains it better:

"Think about it like the final round of musical chairs: Two kids circle the same chair until the music stops. The Fujiwhara effect describes that dance, playing out on a much bigger scale."

Tropical storms and hurricanes are loners. They don't like each other, and don't want to be close together. Things get weird, much like a lot of bad dates do. 

If one storm is much weaker than the other, the more lame one might get absorbed into the stronger one. Every once in a great while, two hurricanes of similar strengths might become one bigger one, but that rarely happens.

More often, the storms will - I don't know - get dizzy and go off in opposite or strange or unexpected directions. 

That's why the fine folks at the National Hurricane Center might be dreading the next few days. There's probably going to be surprises. We don't even know yet whether the two storms will dance the Fujiwhara. (Thought as an aside, I think a choreographer should design a Fujiwhara for humans).

The best guess, at least for now, is that Humberto, which should turn into a hurricane, might or might not briefly dance with wannabe Imelda, then head off to the northeast, missing the United States much like Hurricanes Erin and Gabrielle did. 

The future of Wannabe Imelda is more iffy. We don't know whether it will become a full -fledged hurricane, but it might. Some projections bring it to a landfall in the Carolinas early next week.

Who knows? Expect lots of changes to the forecast.

By the way, the Fujiwhara effect is named after Japanese meteorologist Sakuhei Fujiwhara, who published a 1921 paper theorizing two storms would dance around each other. Once satellite views became common, we learned that the Fujiwhara dance exists among tropical storms and hurricanes.  

Off the dance floor, meanwhile,  Hurricane Gabrielle wants to avoid the whole drama and is getting out of Dodge - fast. 

The other day, it peaked as a huge hurricane with top winds of 140 mph while it was east of Bermuda. 

Now, Gabrielle is much weaker as it races eastward in pretty much the opposite direction of Humberto. Gabrielle's forward speed was 32 mph as of late this morning.  That's traffic ticket territory for a tropical system.  

Until now, Gabrielle hasn't hit any land, so it hasn't been that big a deal, despite its strength. However, Gabrielle is forecast to lash the Azores with hurricane force winds later today or tonight.

Gabrielle will finally run out of steam early next week over or near Portugal.