Nicole (2016)

A tropical storm formed from a tropical wave about 460 nautical miles northeast of San Juan, Puerto Rico on October 4, 2016. Nicole moved generally northwest then stalled and looped several times in the west-central Atlantic. It experienced two separate rapid intensification episodes: first to hurricane strength on October 6–7, then a major strengthening beginning October 11–13 as it moved northward. After passing near Bermuda it interacted with mid-latitude troughs, expanded into a much larger, partly hybrid cyclone over the North Atlantic, and became extratropical on October 18 before being absorbed by a larger storm southeast of Greenland.

Nicole made a direct strike on Bermuda on the morning of October 13, 2016. The island was within the hurricane’s strike circle and experienced hurricane-force winds as Nicole’s northwestern eyewall passed over between about 1400 and 1500 UTC that day. No other U.S. or Caribbean landfalls were recorded; the system stayed well offshore of other land areas as it moved northeast and later east across the North Atlantic.

Peak sustained winds for Nicole were 120 kt (about 138 mph) with a minimum central pressure of 950 mb at 0600 UTC on October 13, which corresponds to a Category 4 hurricane on the Saffir–Simpson scale. Aircraft and surface measurements support the 120 kt peak estimate. The hurricane weakened below major strength soon after passing Bermuda, and became a tropical storm by 0000 UTC October 18 before completing extratropical transition.

Storm surge and rainfall on Bermuda were notable but not extreme. The highest tide reading was 3.72 ft (1.13 m) at St. George’s tide gauge on October 13 (this occurred near low tide); the maximum water level above mean higher high water was about 1.28 ft (0.39 m), implying roughly one foot of inundation in places. Rainfall totals on Bermuda were widespread and heavy, commonly 6–9 inches, with some stations reporting totals near 9 inches (for example, Cedarvale South reported about 8.96 in; L.F. Wade Airport recorded 6.77 in; Southhampton station about 7.82 in; Hamilton about 7.40 in).

There were no reported fatalities from Hurricane Nicole. Damage on Bermuda included snapped trees, downed power lines, roof damage, flooded homes and businesses, and boats broken from moorings; insured losses were estimated at about $15 million. The overall impact was less than from Bermuda’s 2014 hurricanes, in part because the strongest winds were of relatively short duration and the island’s building standards are robust.

Noteworthy aspects include Nicole’s unusual life cycle: two separate rapid intensification periods, a tight loop and strong ocean upwelling that cooled nearby sea surface temperatures, and a later transition to a much larger cyclone with hybrid subtropical characteristics driven by interaction with mid-latitude troughs. Forecasts underestimated the timing of genesis and failed to predict both rapid intensifications in advance; track forecasts were relatively good through 72 hours but had larger-than-average errors at longer ranges.