Hurricane Irma Brings Fresh Threat to U.S. Sep 8-10

“Harvey” degenerated into just a rainstorm over Tennessee on August 31, the same day that a new threat emerged, Category 3 Hurricane “Irma” in the eastern Atlantic. This storm is a long way out to sea and not moving particularly fast; this means we’ll have until after Labor Day to watch it before it affects any land areas.

The likely “first strike” points will be the eastern Caribbean islands, places such as Barbados, Guadeloupe, St. Kits, St. Maarten and the like. From there, the future of “Irma” becomes murky as there will be an atmospheric tug-of-war between high pressure to the east and a low pressure trough diving southward from Canada.

Sea surface temperatures over the eastern Caribbean and southwestern Atlantic are in the mid-80s, so there will be no shortage of energy for the hurricane to feed upon; the question will be one of shear, which looks low (favorable for strength) and steering currents.

Will Irma recurve out to sea and spare the U.S., or will it remain far enough south to avoid the trough and get into the Gulf? Or perhaps an “in-between” path where it hits the Bahamas or Bermuda? As the model comparison shows (see image), 10-day forecasts must be taken with a grain of salt as the same storm is predicted to be in two places some 1,500 miles apart by the 10th day!

Having said that, I’m quite confident we’ll see a major hurricane approaching the Caribbean, or perhaps the Bahamas, by Sep 5 or 6. A direct threat to the U.S., if it takes place, would be more likely in the Sep 8 to 10th time frame.

Take Care,
Steve LaNore
Chief Meteorologist
News 12 / KXII-TV