Hurricane warnings have been expanded to include more of the Bahamas as Hurricane Joaquin churns toward the nation of islands east of Florida. Despite considerable uncertainty, the odds of a landfall on the U.S. East Coast appear to be increasing, and the official forecast track suggests that Joaquin could become the first land-falling hurricane on the U.S. mainland in 15 months.
An Air Force Reserve Hurricane Hunter reconnaissance aircraft measured sufficiently strong flight-level winds and low surface pressure to prompt the National Hurricane Center to upgrade Joaquin Wednesday morning. The Hurricane Hunters found a 55-mile-wide eye, but it was open on its north side – meaning that robust thunderstorms had not fully encircled the Joaquin’s center of circulation.
Computer forecast models – and the meteorologists who rely on them for guidance – are grappling with a complex interaction between Joaquin, a cold front near the East Coast, the remnants of Tropical Storm Ida, a strong bubble of high pressure aloft over the North Atlantic Ocean, and a potentially strong area of low pressure aloft digging into the southeastern U.S. later this week.
Joaquin’s future depends critically on the position and relative strength of those players – not to mention its own strength. Strong wind shear had kept most of Joaquin’s thunderstorm activity (convection) south or east of its center of circulation, but that changed Tuesday afternoon and evening as thunderstorms developed closer to its circulation center.