A drastic change from cyclonic to anticyclonic and in meridionality and cyclonicity from the 20th of January in the 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. indices.