(National Hurricane Center)

Hurricane Ophelia is charging toward Ireland. A direct hit or close encounter by the storm, or actually its altered self, is likely on Monday.

A frequent question we’re hearing is: Has this ever happened before? The answer is, yes. This is not abnormal or even that unusual.

Hurricanes and tropical storms that form in the tropical Atlantic are fairly regularly swept northeast by the jet stream into Ireland and Britain.

By the time they reach the region, they are no longer considered hurricanes, having transitioned into what are known as post-tropical storms. They can still be powerful and quite damaging.

We looked back at historical records dating back to 1851 and, conservatively, identified 45 onetime tropical systems that passed over or very close to the region as post-tropical storms. This amounts to one every 3.5 years or so. (Due to limitations in the hurricane database, which hasn’t always included the track of storms after they lose tropical characteristics, we may be missing some.)


(Brian McNoldy)

Ophelia is not even the first tropical system to morph into a post-tropical storm and affect the region this year. Gert brought wet and windy weather to the western and northern parts of Britain in August.

Coincidentally, previous storms named Ophelia in 2011 and 2005 also impacted the region as post-tropical storms.

Sometimes when hurricane tracking maps show these systems slamming into Ireland, people become under the incorrect impression about the kind of storm bearing down. In the case of Ophelia, the Ireland Meteorological Service issued a clarifying statement Thursday, making clear “it won’t be a hurricane” when it approaches. “It means the traditional attributes of a hurricane — such as an eye or an eyewall containing a core of hurricane force winds — are very unlikely to be present,” it wrote.

While these storm lose their tropical characteristics when they sprint toward higher latitudes, they can still pack a punch.

Ophelia has the potential to produce some pretty nasty weather over Ireland and northern Scotland Monday into Tuesday, depending on its exact track. Heavy rain is a reasonably good bet and, if the center comes close enough to the coast, hurricane-force wind gusts are possible.

Presently, Ophelia is an impressive storm, containing sustained winds of 100 mph. It is “the strongest an Atlantic hurricane has been this far east (35.5 degrees W) this late in calendar year on record,” according to a tweet from Phil Klotzbach, tropical weather expert at Colorado State University.

Light wind shear and abnormally warm water have helped Ophelia reach and hold this intensity.

But it has no chance to remain a hurricane or tropical storm, in the conventional sense, when it approaches the region. The waters around the islands are much too cold to sustain a tropical weather system.

Presently, Ophelia is over sea surface temperatures around 77 degrees (25 Celsius) — just barely warm enough for a tropical weather system to maintain its characteristics. But by Monday morning, it will be over water temperatures near 60 degrees  (15 Celsius) — way too cold for a tropical system.


Sea surface temperatures in the zone where Ophelia will track. (NOAA, adapted by CWG)

Gradual weakening is forecast as the storm races northeastward but peak sustained winds are forecast to be a still formidable 60 to 80 mph when it is closest to Ireland and Britain.