Summary
In this case study the life cycle of hurricane Ophelia is analysed.
Ophelia was the 10th, and last, hurricane of the 2017 hurricane season. It was the farthest east major hurricane (category 3 or higher) on record in the Atlantic Basin. It was formed after a passage of a cold front (31.1 °N, 39.9 °W - in the middle of the Atlantic) on the part of the ocean where the surface temperature usually is not warm enough for hurricane development. It lingered there for a couple of days before continuing northeast; eventually reaching its maximum strength of category 3. After that it became embedded within the fast flow of another large, mid-latitude trough moving eastwards over the Atlantic. It reached landfall as an extratropical storm.
The minimum pressure and maximum intensity were on 14th October at 12:00 UTC, when pressure was 959 hPa and wind speed was 100 kt.
The lifecycle of Ophelia is divided into three phases - the formation and development of tropical cyclone, hurricane phase and extratropical phase. The hurricane phase was characterised by the presence of the cooler than average mid and upper level air and low wind shear, which allowed the system to intensify through baroclinic instability. The highest peak intensity, when Ophelia was located about 500 nautical mi (about 920 km) southwest of the Azores, it lasted for 6 hours. The last phase began when Ophelia was grabbed by the fast flow of another large mid-latitude trough. Interaction with the strong upper-level trough and jet stream flow caused the hurricane to begin losing its tropical characteristics and become an extratropical cyclone.
As an extratropical cyclone, Ophelia reached landfall in Ireland on 16th October, and experienced a large drop in strength. Its major impact was through gale force wind causing significant infrastructural damage and indirect loss of life (3 people). The whole process was well monitored and forecasted; therefore, all the warnings were issued on time through government officials and media delivered to the public.