Some of our worst September gales over the years have had their origin in the process taking place at the moment, writes Brendan McWilliams.
Meteorologists are sceptics on the issue of "equinoctial gales", as such, but they do acknowledge that statistically there tends to be an abrupt increase in the average frequency of high winds during the second half of September, leading to "guilt by association" for the equinox.
But the weather problems for the Ryder Cup have been seriously exacerbated by another factor which has enhanced the reputation of the autumn equinox as a very windy period. Long after a Caribbean hurricane has ceased to be a real hurricane, a quantity of unusually warm and very moist air frequently survives, concentrated into a relatively small region of the upper atmosphere to be carried eastwards across the Atlantic.
When the cold air from Arctic regions is entrained into the circulation in mid-Atlantic, the sharp temperature contrast between the two air masses provides new energy to fuel a dramatic reintensification of the quondam hurricane. It is this process that we see in train in the threat posed at present by the former Hurricane Gordon.
Gordon followed a very unusual track. Having formed nearly two weeks ago in the lower latitudes of the North Atlantic, it did not long drift westwards as most hurricanes do, but quickly turned to head east towards Spain.
As it approached Europe, by then no longer, strictly speaking, deserving of the label "hurricane", the storm turned north and is expected to approach Ireland as a very deep depression from the south.
At the time of writing it is predicted to pass to the west of Ireland, remaining out in the Atlantic, but it will be close enough to bring heavy rain, local flooding, and very stormy winds. Again at the time of writing, the worst of these are expected during tonight and Friday morning, but the routine weather forecasts will obviously fine-tune our expectations as the storm comes nearer.
Some of our worst September gales over the years have had their origins in the kind of process taking place at present. Although the storms containing the warm, humid residues of hurricanes Isodore and Gustav in September, 1990, tracked well north of Ireland, they did their bit to perpetuate the equinoctial myth.
And the event we recall as Hurricane Debbie, which arrived on our shores 45 years ago on September 16th, 1961, is by far the best remembered; it caused great damage in the western half of the country, bringing winds with gusts in excess of 100mph and establishing records for high winds that have been unchallenged for nearly half a century.
Other months too have had their pseudo-hurricanes. In 1987, Hurricane Floyd spawned a monster that is remembered vividly in the south of England as the "October Storm", occurring on 16th of that month.
And here in Ireland, on August 25th, 1986, the former Hurricane Charley brought winds which were not exceptional, but the storm poured down rain in unprecedented quantities on southern and eastern parts of Ireland, breaking long-established records and leaving widespread flooding in its wake.