Named storms and the Gale Index

This has to have been been the windiest autumn/winters of the last four across the IONA. There have been fived named storms up until going to press, three of them in February alone when it was particularly stormy, especially so at weekends for some reason. The bar chart represents the gale index [GI], as generated as a by product of the objective Lamb Weather Type data which you can download from the CRU at the University of East Anglia. The index roughly approximates to the wind speed at a location situated at 55° north and 5° west. Gale force 8 or 34 knots is equivalent to GI 30, whilst storm force 10 or 48 knots, is equivalent to GI 50. Because the objective LWT data is only derived from the 12 UTC chart each day, it is possible that some storms can slip through this net. The line series outlined in yellow is the LTA of the GI to give you an idea of how the actual GI compared with average. At a glance there seems to have been a series of four peaks in the 10 day moving averages, one at the start of November, the other in the first week of December, the next in the second week of January, and finally the largest surge in mid February.

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