Hilary may have outlasted Don, but could Irwin do her in?
A pair of eastern Pacific storms — Hilary and Irwin — are forecast to be locked into an ultimately fatal dance this week, with each spinning around like a meteorological fidget spinner.
Hurricane Hilary and soon-to-be Hurricane Irwin will pivot around a specific point by mid-week in a phenomenon meteorologists call the Fujiwhara effect. One storm should then eventually absorb the other.
he effect describes the rotation of two storms around each other. It's most common with tropical cyclones such as typhoons or hurricanes, but also occurs in other cases.
"Think of the teacup ride at Disney or the Tilt-a-Whirl at your local county fair, but with tropical systems instead," Weather Underground said, describing the phenomenon.
WeatherBell meteorologist Ryan Maue wryly tweeted that "Hurricane Hilary on clear path west to victory ... then comes Hurricane Irwin with 'Fidget Spinner' and wreck."
The National Hurricane Center thinks the "winner" in the Hilary-Irwin battle could be Hilary, but admits the storm's "long-range forecast is a mess with the likelihood of some binary interaction with Tropical Storm Irwin."
As is typical with many Eastern Pacific hurricanes, neither Irwin or Hilary are likely to impact any land areas.
And although Hilary's maximum winds are forecast to be around 126 mph, making it a Category 3 storm, it likely won't be the world's strongest tropical cyclone so far this year, Maue said. That title goes to the 150-mph Cyclone Ernie in April, which remained off the northwest Australia coast and "bothered nobody," he said.
Amazingly, two western Pacific storms, Typhoon Noru and Tropical Storm Kulap, are also locked into the Fujiwhara dance pattern this week, Weather Underground said.
Noru is the first typhoon of the year in the western Pacific Ocean, an unusually late date for the season's first one, according to Colorado State University meteorologist Phil Klotzbach.
Storms in the Fujiwhara effect rotate around one another as if they locked arms and were square dancing. Rather than each storm spinning about the other, they are actually moving about a central point between them, as if both were tied to the same post and each swung around it separately of the other.
A good way to picture this is to think of two ice skaters who skate quickly toward each other, nearly on a collision course, grab hands as they are about to pass and spin vigorously around in one big circle with their joined hands at the center.
The effect is named after Sakuhei Fujiwhara, the chief of the Central Meteorological Bureau in Tokyo after WWI. In 1921, he wrote a paper describing the motions of "vortices" in water. Water vortices, such as whirlpools, are little water whirls that spin around.
As for Tropical Storm Don, it went out with a whimper in the Caribbean last week.