The core of now category two Hurricane Nicole is expected to pass near or over Bermuda early on Thursday. As of the 3pm advisory from the NHC, this could mean dangerous coastal flooding from a 6-8 foot storm surge, flooding away from the coast due to heavy rain of 4-8″, and isolated damage from possible tornadoes. Tropical storm conditions are expected to begin after midnight tonight and last through much of Thursday with a period of hurricane force winds beginning Thursday morning lasting through mid-afternoon. Sustained winds are expected to peak near 90 kts (105 mph), and will be higher in elevated and exposed locations (possibly near category three strength) with higher gusts.
Last night, Nicole quickly strengthened from a tropical storm to a category two hurricane, increasing winds by 30 kts and decreasing pressure by 21 mb in the 24 hours between 12pm yesterday and today. Nicole had stalled or drifted slowly to the west during this time as it interacted with the front left behind as the extratropical remnants of Matthew exited the Canadian Maritimes and left Nicole in a weak steering environment.
Nicole is poised for some additional modest strengthening as the hurricane sits in a region of warm sea surface temperatures (~28 °C), low vertical wind shear, and generally high moisture content. However, some drier and more stable air to the west, might be intermittently wrapping into the circulation and slowing the pace of intensification. Nicole is expected to be a strong hurricane and it is still possible for Nicole to become a major hurricane before reaching the island.
The track forecast philosophy has proved true for the last five days and hasn’t changed; Nicole has made the turn to the north and is still expected to pass close to or over Bermuda Thursday morning as it turns more northeastward. Wobbles either side of the track could make a huge difference in terms of conditions felt. These wobbles are due to inner-core dynamics are hard to predict with skill.
- Track more to the left: easterly winds veer to the south, increasing to hurricane force as Nicole passes (east eyewall)
- Track more to the right: easterly winds increase to hurricane force as Nicole approaches, suddenly become light and shift to the west, suddenly increase to hurricane force as Nicole passes (eye)
- Track even more to the right: easterly winds increase to hurricane force and back to the north as Nicole passes (west eyewall)
Wind direction strongly controls who/where sees the most significant coastal flooding due to storm surge. For instance, should winds reach their peak out of the south, then south shore would take the brunt of any storm surge. Similarly, this changes wind exposure as windward hilltops see dramatically higher winds than the sheltered lee-side valleys. It is therefore imperative to both know your exposure and prepare for the scenario that exploits your exposure.
Expect scattered to widespread tree damage and power outages, isolated structural damage (mainly to roofing on elevated and exposed locations or along the track of any tornadoes, and along the coast if an inundating storm surge develops), and isolated flooding from rainfall in low-lying and poor drainage areas. Significant coastal erosion will likely begin to take shape tonight as seas inside the reef become rough, and isolated power outages are likely before dawn tomorrow as winds begin to reach 50 kts in exposed locations.