Weather Underground – September 30, 2015 – Hurricane Joaquin became the 2015 Atlantic season’s third hurricane Wednesday morning, and hurricane watches and warnings have been issued for the Bahamas while we nervously eye its potential to affect the U.S. East Coast.
(MORE: Expert Analysis | Hurricane Central)
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 open on its north side.
Hurricane Joaquin continues to intensify slowly, as wind shear — harmful to the intensification of tropical cyclones — lessens, and a complicated atmospheric pattern makes its future track – including any potential landfall on the U.S. East Coast – extremely difficult to forecast.
Tropical Storm Joaquin Information
Residents along the East Coast of the U.S. should pay close attention to the forecast now through this weekend. It’s a particularly difficult forecast that hinges on the behavior of several different atmospheric features over North America and the North Atlantic Ocean.
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.
Ensemble Forecast Model Tracks
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.
(MORE: Expert Analysis | Hurricane Central)
Visible Satellite
Because Joaquin is strengthening and drifting ever closer to the Bahamas, the government of that country has issued a hurricane warning and watch for most of its islands.
Watches, Warnings
Joaquin is expected to slowly churn toward the Bahamas Wednesday and Thursday. The extent of the effects on those islands will depend heavily on how close it gets and how much time it spends nearby before making the anticipated northward turn.
Although computer model simulations run Tuesday evening had the advantage of ingesting high-resolution real-world data from the Air Force reconnaissance flight earlier in the day, it doesn’t seem to have brought them any closer to a consensus.
The American GFS model forecast showed Joaquin making an alarming northwestward turn, slamming it right into Virginia and Maryland this weekend. Meanwhile, the European ECMWF model showed Joaquin staying well away from the U.S. East Coast, and eventually curving out into the North Atlantic well off the coasts of New England and Atlantic Canada.
It is simply too soon and the uncertainty is too high to determine any impacts from Joaquin itself for the U.S. East Coast at this time.
The National Hurricane Center’s official forecast cone is below.
(MAP: Track Hurricane Joaquin with our New Interactive Storm Tracker)
Projected Path
Regardless of the ultimate outcome of Joaquin’s path, portions of the East Coast will still see multiple impacts from the evolving large-scale weather pattern, including flooding rainfall, gusty winds, high surf, beach erosion and some coastal flooding. Click the link below for more information on that story.
(MORE: Significant Impacts Likely on East Coast)
Late Week and Weekend Setup
In summary, here’s what we know about Joaquin:
- Tropical Storm Joaquin’s center was located about 245 miles east-northeast of the central Bahamas.
- Maximum sustained winds were pegged at 75 mph, a Category 1 hurricane on the Saffir-Simpson hurricane wind scale.
- As wind shear over the storm lessens, Joaquin should strengthen further the next 2-3 days.
- This system is moving slowly to the west-southwest and this is expected to continue through Thursday before turning north Friday into Saturday.
- A hurricane warning is in effect for the central Bahamas.
- A hurricane watch is in effect for the northwest Bahamas, except Andros Island. This includes Nassau and Freeport.
- Joaquin may directly or indirectly affect the East Coast late this weekend or early next week, and a landfall cannot be ruled out.
- Moisture and/or energy associated with Joaquin could enhance rainfall along the cold front in the Northeast late this week. Regardless, the East Coast will see significant impacts from the larger scale weather pattern taking shape.