Fig. 1: Surface land and ship station SYNOP observations of Storm Ciarán at 06 UTC 2 November 2023 extracted from the MetDB database52,53, which holds data including surface and upper air observations and some satellite data.

The observations are shown as simplified station circles using conventional notation54. Circle shading indicates cloud cover in octas, wind barbs and feathers indicate wind speed in knots with the wind direction towards the circle, and numbers are the last three digits, including a decimal place, of the MSLP (in hPa) e.g., 543 equates to 954.3 hPa. Some thinning of observations has been performed for clarity and note that two ships both reported at 51.1oN, 1.7oE with different wind speeds and directions.