Major Hurricane Joaquin in the Central Bahamas

Hurricane Joaquin, in an impressive bout of rapid intensification, strengthened from a tropical storm to a category three, major hurricane yesterday. As of the 12pm advisory today, Joaquin had strengthened some more and had 125mph maximum 1-minute sustained winds, with a minimum central pressure near 942mb as reported by continued aircraft reconnaissance flights into and around the storm. Joaquin is still a category three hurricane and there is potential for additional strengthening today.

Hurricane Joaquin 11am 1 Oct 2015
An estimated wind field of tropical storm and hurricane force winds, past track of Joaquin, and latest watches and warnings for Hurricane Joaquin as of 12pm ADT 1 October 2015. See: National Hurricane Center

Hurricane Warnings are in place for the Central and Northwestern Bahamas Islands and Tropical Storm Warnings are in effect for the rest of the Bahamas and for the Turks and Caicos Islands. Hurricane conditions are already occurring on some of the central Bahamas Islands where Joaquin has either already made a direct hit or will in the next 24 hours. The main threat from Joaquin in the Bahamas appears to be the violent winds, particularly in the Hurricane Warned areas. Additionally, heavy rain related flooding and storm surge flooding are also significant threats. Joaquin is expected to spend another 12-24 hours drifting southwestward then northward through the Bahamas before exiting the archipelago to the north on Friday afternoon, so a long duration event of hurricane conditions with torrential rains and storm surge is possible on some of those islands. I wouldn’t be surprised if the geography of some of the low lying islands that take a direct hit are dramatically altered by this hurricane because of its duration and severity.

Hurricane Joaquin 1445UTC 1 Oct 2015
RGB Satellite imagery of Hurricane Joaquin over the Central Bahamas at 14:45UTC this morning.

The future of Joaquin still remains unclear despite efforts to improve the model guidance initialization with increased upper air observations. Multiple aircraft missions into and around Joaquin combined with extra weather balloon launches around both the hurricane and the mid-latitude system that is expected to steer Joaquin have been made in hopes to improve the model initialization and therefore produce a more confident and consistent forecast. As of last night’s model runs, however, model guidance continued to show an unusually high level of spread in the potential track of Joaquin. This likely will be the case until around tomorrow afternoon. By the time the system over the central United States begins to approach and interact with Joaquin (~24 hours from now), the model guidance will probably get a better handle on how it will impact Joaquin’s path.

Hurricane Joaquin is expected to continue strengthening as it drifts into the Bahamas, potentially becoming a category four hurricane by tonight. This strengthening is supported by high sea surface temperatures, decreasing vertical wind shear, and a very moist environment. Potential convective structural changes that are common in major hurricanes could result in weakening or at least fluctuations in intensity as Joaquin exits the Bahamas on Friday night. Over the weekend the approaching mid-latitude system could impact Joaquin’s intensity by either resulting in weakening, or resulting in deepening and extratropical transition – again this remains unclear due to the unusual model guidance disagreement.

The most recent National Hurricane Center track follows somewhat of a consensus or mid-point of the forecast models and takes Joaquin northward into New England by Tuesday. However, it should be noted that there are still three distinct potential tracks for Joaquin once it exits the Bahamas and any threat to land thereafter from Joaquin will likely begin on Monday:

  1. A turn to the north then northeast – either out to sea, or with possible impact to Bermuda.
  2. Almost due north – either then turning and going out to sea, or impacting New England and Atlantic Canada.
  3. A turn to the north, followed by a turn to the northwest with possible impacts in North Carolina and the Mid-Atlantic states.

The eventual solution seems to depend on how far Joaquin drifts into the Bahamas, this will impact the timing of when the approaching mid-latitude system from the Central US begins to impact Joaquin, and subsequently will impact where Joaquin goes. Each of these scenarios has support from traditionally reliable model guidance and so essentially everyone in those mentioned regions should monitor the progress of Hurricane Joaquin and for updates in track confidence and alterations in the track forecast as they come. However, it appears that regardless of track, South and North Carolina through the Mid-Atlantic states could see significant flooding as the approaching mid-latitude system interacts with deep tropical moisture already im place. See: National Hurricane Center | Bermuda Weather Service for the latest official information.


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