On September 16, 1961, Hurricane Debbie made landfall in County Mayo, Ireland, becoming (possibly) the first tropical cyclone on record to reach the British Isles.
Debbie formed in the usual location, near the Cabo Verde Islands, on Sept. 6th. It was very nearly a full hurricane at the time it was detected. It took a more northwesterly course than climatology taking it toward the central Atlantic, which made it difficult for NHC to track. On Sept. 11th, it was photographed by the TIROS III satellite. It had a distinct eye and banding features and was upgraded by forecasters to hurricane-status. Also on that day, it had turned due north at about 46° West and was now within range of Navy Hurricane Hunters based in Puerto Rico. They estimated maximum sustained winds at 100 mph (160 km/hr).
The Air Force Hurricane Hunters, based in Bermuda, continued the surveillance over the next four days as Debbie moved northward and then abruptly swerved to the northeast. By Sept. 15th, it hit the Azores with 80 mph (130 km/hr) winds. At this time, U.S. Weather Bureau forecasters in Washington DC declared that Debbie had become extratropical and ceased issuing hurricane warnings on it.
Debbie continued to move rapidly northeastward toward the British Isles. A ship reported a 970 mb pressure as the storm center passed near and by the morning of Sept. 16th, the center passed over Belmullet, Co. Mayo with sustained 66 mph (106 km/hr) winds and a 961 mb (28.39 inHg) pressure. The storm continued to race northeastward, affecting Scotland, Norway, and Russia.
There is some dispute as to when Debbie transitioned from tropical to extratropical. At the time, the forecasters felt it had done so shortly after passing over the Azores. But observational tools (especially satellites) available were primitive and subsequent analysis estimated the transition occurred after passing Ireland. Either way, Debbie was among the most severe storms to hit the Emerald Isle and responsible for 78 deaths and an estimated US$50 million in damages.