Helene (2006)

Helene formed from a tropical wave that moved off the coast of Africa on 11 September 2006 and became a tropical depression on 12 September about 200 nautical miles south-southeast of the Cape Verde Islands. It moved generally west-northwestward across the central Atlantic, turned northwest around 17–18 September, then westward and finally northward ahead of a trough. Helene remained over open water throughout its tropical life, became extratropical on 24 September about 275 n mi northwest of the Azores, and the remnant low passed near the west coast of Ireland on 27 September before merging with a larger system on 28 September.

Helene did not make any tropical cyclone landfalls while it was a tropical system. After becoming extratropical it passed very near western Ireland on 27 September and then northwest Scotland on 27–28 September as a gale‑force extratropical low.

The hurricane’s maximum estimated intensity was 105 knots (about 121 mph) with a minimum central pressure of 955 mb, reached at 0600 UTC 18 September. Best-track data show Helene attained Category 3 status (major hurricane) at 0000 UTC 18 September and was at peak intensity shortly thereafter. Later aircraft and satellite data indicate brief fluctuations, with a highest well-sampled flight-level wind adjusted to about 89 kt surface and other measurements supporting the 95–105 kt range during peak.

Storm surge and heavy rainfall impacts were minimal in affected land areas because Helene stayed well offshore as a tropical cyclone. Observations of note include buoy reports of strong winds and falling pressures: drifting buoy 44613 reported 971.8 mb at 0900 UTC 24 September and buoy 44774 reported 967.0 mb at 2300 UTC 24 September as the system became extratropical. After extratropical transition, Ireland reported gale gusts up to 49 kt at Valentia Observatory and western Scotland reported a gust to 64 kt on South Uist; the report did not list specific storm surge heights or large rainfall totals tied to Helene.

There were no reports of damage or casualties associated with Helene during its tropical or extratropical phases. The regions most affected by winds as an extratropical low were western Ireland and northwestern Scotland, where only gale‑force gusts were documented.

Noteworthy items: Helene was a long‑lived Cape Verde hurricane that reached major hurricane strength while remaining over the open Atlantic. Forecast track errors were smaller than recent averages — NHC track forecasts were notably accurate for much of Helene’s journey — though some models had trouble with Helene’s slowdown and northwest turn around 17–18 September.