Hurricane Ophelia is forecast to move North toward the United Kingdom and interact with the jet stream and westerly flow in the next 24 hours.
Although Ophelia will be undergoing a tropical transitioning between hurricane and an extra tropical feature she will likely exhibit some strong tropical characteristics as she makes an approach to Southern/Western Ireland on Monday morning.
Hurricanes tend to form over warm tropical waters with sea surface temperatures of 26oC> at a minimum depth of 60m. These warm oceanic surface currents provide the energy required for hurricane maintenance and to sustain convective bands that typically spiral in toward the centre of storm circulation. Ophelia will still maintain a warm central core within her circulation but the interaction with the jet-stream will gradually result in weakening of these convective elements and the development of frontal features more typically found in a mid latitude cyclone.
The track of Ophelia is beginning to be firmed up with the most likely path expected to take Ophelia just to the West of the West Coast of Ireland, although it is still possible that Ophelia will make a direct landfall somewhere close to County Kerry in the South West of Ireland on Monday morning or early afternoon.
Some minor adjustments in tracking forecast are to be expected in the next 24-48 hours but it is now with growing confidence that Ophelia will bring the worst weather conditions to much of the Republic of Ireland. Ireland should expect widespread inland gales to develop, especially in the South and West of the country with inland gusts of 55-65mph, locally 70mph in a few isolated spots. Coastal areas of Southern and Western Ireland should be on alert for storm force 10 to violent storm force 11 winds equivalent to post tropical strength. Gusts in exposed locations across mountains and immediately long the coast are expected to range 70-90mph, with isolated gusts to 100mph across mountains. These wind speeds will cause structural damage, damage to trees and the risk of power outages to worst affected areas, therefore their is a risk of localised severe disruption.
Ophelia’s influence will also be felt across England, Scotland and Wales, mainly across Western areas during Monday and Northern England and Scotland during the early hours of Tuesday into the late morning period. Whilst Ophelia is expected to weaken significantly as she tracks across Scotland or just to the North she will bring strong to very strong winds inland for many Western and Northern parts with gales or severe gales developing along exposed coastal regions and to higher ground across hills and mountains. The post tropical winds will be gusty with 40-50mph, locally 60mph to lower ground and higher gusts across hills and mountains 60-70mph, locally up-to 90-100mph possible in well known valleys such as Capel Curig in North Wales. Some localised mainly minor damage to buildings is possible, with a elevated risk of tree damage due to the relatively full bloom this early in the Autumn. As a result some disruption to transport and isolated power cuts are possible.
Ophelia will have strong tropical characteristics as she makes landfall across Ireland on Monday morning with large amounts of moist tropical air wrapped around her central circulation and as a result will produce very heavy rain bands. The main risk of flooding related to rainfall will be immediately around her central circulation currently expected to be across or close to County Kerry and W Ireland Monday evening before moving toward Scotland later on Monday into Tuesday. Rainfall totals ranging 30-50mm or considerably more are possible, with orographic ehancement of rainfall expected across the South West/Western up-slopes of Western and North Western Scotland. In light of recent heavy rains in these areas some river and pluvial flooding is expected.
Ophelia will make landfall with a low central pressure of sub 976hpa/mb accompanied by violent winds wrapped around her core circulation and as a result storm surge inundation along coastal Southern Ireland is a concern. There is the potential of coastal flooding along the South Coast of Ireland progressively increasing in probability through Monday afternoon and peaking in the evening hours. Latest model data predicts offshore waves in excess of 10m, with 7-8m likely in onshore regions. England will be less at risk of storm surge related flooding although some localised coastal flooding is likely with 3-4m waves along the West coast of South West England and highest around the Penbrokeshire coast of South Wales 6-7m peaking later Monday night. Generally the advice would be to avoid at all costs Southern Ireland exposed coastal regions during Monday afternoon/Evening and exposed Western coastal areas of England, Scotland and Wales during late Monday and Tuesday.
In addition to the extreme weather conditions post tropical Ophelia will be delivering to our shore she will also be responsible for drawing up an insurgence of very warm moist tropical air up from the tropics. You should already notice the change in the feel of the air further South and for many further North too and during the weekend many parts of England and Wales will feel temperatures considerably warmer than the seasonal average making it feel almost summer like. In fact, temperatures bare expected to surge toward the low twenties celcius in the North of England and potentially up-to 25-26oC in the South East.
Post tropical storm Ophelia’s track will still wobble in the coming days and we will bring you any significant changes in the forecast in future updates. Stay safe and our advice is to avoid travelling altogether during the height of the storm, especially where Ophelia makes direct landfall across Ireland.