You observe: falling barometer, backing wind (SW to S), increasing cirrus cloud, and long swell from the SW. What is developing and how much time do you likely have?

A. A depression is approaching from the SW — these are classic warm front precursors. Timing: cirrus 12-24h ahead; altostratus 6-12h; rain 3-6h; cold front passage sometime after. You likely have 12-18h before significant deterioration — use it wisely to reach shelter or revise the passage plan

B. The wind backing indicates a cold front — expect rapid clearance within 2 hours

C. Long swell from the SW is unrelated to approaching weather systems

D. These signs indicate improving conditions — high pressure is building

A. Barometric tendency only matters above Force 6 — below that, pressure changes have no predictive value

B. A rapid fall (>6 hPa in 3h is defined as "very rapid" in MET Office guidance) indicates an approaching vigorous depression — imminent deterioration. Seek shelter, shorten sail, check position and proximity to lee shores, and reassess the passage plan immediately

C. A fall of 6 hPa in 3h is insignificant — barometric changes only matter over 24h

D. This indicates a high pressure system building — expect improving conditions

A. Occluded fronts always bring fog and light winds

B. An occlusion only forms in tropical waters — not relevant to UK sailing

C. Formed when a cold front catches a warm front — the warm sector is lifted off the surface. An occlusion brings a prolonged period of disturbed weather with cloud, rain, and variable winds; the warm sector advantages (relatively settled weather) are lost

D. An occluded front is a front that has weakened and no longer has significant weather