The chart shows the mean MSLPMSLP Mean sea level pressure is the pressure at sea level, or, when measured at a given elevation on land, the station pressure reduced to sea level assuming an isothermal layer at the station temperature. over the last 16 weeks across IONAIONA Islands Of North Atlantic. Yes I know there's an island called Iona, but this is so I don't have to use the term 'British Isles' when referring to the whole of Ireland and the UK. and the corresponding objective LWTLWT Lamb Weather Types are often used in UK-based analyses, with individual weather patterns based on the eight primary cardinal directions (N, NE, E, SE, S, SW, W, NW) plus cyclonic (C), anticyclonic (A) and unclassified (U) types. for each of those weeks. It’s evident that the last anticyclonic spell occurred in the third week of September and since then the circulation has been mobile and usually from the W or SW.
