Storm Isha brings 80mph gusts with spectacular 'explosive cyclogenesis', says Wick weather watcher
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Wick weather watcher Keith Banks sent in a report on the gale force winds experienced across the far north this morning with Storm Isha.
Across the county there were power outages and damage to properties reported today after the rare Met Office Red Warning was issued late last night.
"Wick experienced its strongest wind velocity for more than a decade during the early hours of this morning when a severe gale force 9 westerly wind gusted up to 80mph/69.6knots, hurricane force 12 on the Beaufort scale," reported Keith.
"From 2.50am until 4.20am the mean or average wind velocity in Wick was between severe gale force 9 and storm force 10. There were frequent gusts during this period in the violent storm 11 and also the hurricane force 12 categories. Violent storm 11 is 64mph-72mph, and hurricane force 12 are velocities of 73mph/63.5knots or greater.
"Subsequently the westerly winds moderated to gale force 8, however there were still frequent gusts in the storm force 10 category (55mph-63mph), as late as 8am, when the mean wind velocity had decreased to force 7 in the town. The westerly winds will continue to moderate and gradually veer north-westerly later on Monday as Storm Isha moves north-eastwards towards the Norwegian Sea.
"Provisionally, the westerly gales witnessed early Monday morning were the most severe to affect Wick since 9th January 2015 when a severe gale force 9 to violent storm 11 westerly gale gusted up to 93mph/80.9knots.
He noted that the mildest temperature of the month so far in Wick occurred overnight with the temperature reaching a balmy 9.4C.
"Storm Isha developed off the eastern seaboard of the USA on Friday and subsequently became entrained in a very powerful polar front jet stream, with velocities in excess of 200mph above the NE Atlantic. This reinvigorated jet stream has been energised by the existence of a steep temperature gradient over the southern USA between a mass of very cold Arctic air over the east and central states and a feed of warm air originating from the Gulf of Mexico.
"In terms of atmospheric dynamics, Storm Isha entered what meteorologists call the 'left exit' of the jet stream. Crucially this development facilitated a spectacular deepening phenomenon called 'explosive cyclogenesis' as Storm Isha barreled north-eastwards towards the British Isles during the weekend."
