Meteorology & Passage Planning Flashcards

The Beaufort Scale Force 6 is described as a:

Answer: Strong breeze — 22–27 knots, large waves beginning to form

Force 6 = Strong breeze, 22–27 knots. Sea state shows large waves with extensive white foam crests. Day skippers should be cautious in Force 6, especially offshore.

In the UK, a shipping forecast uses the term 'imminent' for a gale warning. This means the gale is expected:

Answer: Within 6 hours

BBC Shipping Forecast timing: 'imminent' = within 6 hours; 'soon' = 6–12 hours; 'later' = more than 12 hours from the time of issue.

A rapidly deepening low pressure system (bomb cyclogenesis) is characterised by:

Answer: Central pressure falling by 24 mb or more in 24 hours — very dangerous rapidly worsening conditions

A 'weather bomb' or explosive cyclogenesis is defined as central pressure falling 24 mb or more in 24 hours. It produces very rapid onset of severe conditions with little warning.

On a weather map, what does a cold front symbol (triangular teeth) indicate about the wind direction as it passes?

Answer: Wind backs (shifts anti-clockwise) ahead of the front, then veers (shifts clockwise) sharply after passage

As a cold front passes in the northern hemisphere, wind veers sharply (clockwise shift), pressure rises rapidly, temperature drops, and conditions may improve after a brief squall.

A skipper is planning a Channel crossing. The forecast shows a 'ridge of high pressure' between two lows. This provides:

Answer: A brief but often favourable weather window of light winds and possible fog

A ridge provides a temporary improvement — often lighter winds and good visibility — but may be accompanied by sea fog as warm air cools. The window is typically short-lived.

When planning a coastal passage, SOLAS V requires all mariners to:

Answer: Use all available weather information and plan the voyage before departure

SOLAS Chapter V (Safety of Navigation), applicable to all vessels, requires passage planning including consideration of weather, hazards, and escape routes before departure.