Marine Weather Interpretation Flashcards
6 cards from real SVOP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Marine Weather Interpretation flashcards as text
What weather hazard is associated with a rapidly falling barometer (pressure drop of 4–6 hPa or more in 3 hours)?
Answer: An approaching storm or strong wind system — operators should seek shelter or prepare for deteriorating conditions
A rapid pressure drop indicates a quickly deepening low-pressure system approaching with associated strong winds, rain, and rough seas. A drop of 4–6 hPa in 3 hours (a 'vigorous deepening') warrants immediate action.
What is a 'thermal wind' or 'sea breeze' and when does it typically occur?
Answer: A local daytime wind blowing from sea toward land as land heats faster than water, typically peaking in the afternoon
The sea breeze develops when land heats faster than the adjacent sea during the day, warming the air above the land which rises, drawing cooler marine air inland. It typically begins mid-morning and peaks in the afternoon, creating localised onshore winds of 10–20 knots.
What is the Beaufort Scale used for, and what does Beaufort Force 6 describe?
Answer: It describes wind speed by observable sea and wave conditions — Force 6 is 'strong breeze' with 22–27 knots and waves of 2–3 metres with white foam streaks
The Beaufort Scale relates wind speed to observable sea conditions. Force 6 ('Strong Breeze') corresponds to 22–27 knots (25–31 mph) with wave heights of 2–3 metres, white foam crests becoming more extensive, and possibly some spray.
What is 'orographic enhancement' of rainfall and why is it important for Pacific coast vessel operators?
Answer: When moisture-laden air is forced upward by coastal mountains, producing intense localised rainfall and poor visibility on the windward slopes
Orographic (mountain-forced) enhancement causes significant rainfall and low cloud on the windward side of coastal mountains. On BC's coast, this creates highly variable conditions — clear on the leeward side but heavy rain, low cloud, and reduced visibility on windward slopes and channels.
What weather information should a vessel operator check before departing on a coastal voyage?
Answer: Environment Canada's marine weather forecast for the specific zone, wind and sea state forecast, fog advisories, and Windspeed warnings broadcast on VHF WX channels
Operators must check the Environment Canada marine zone forecast (specific to the coastal or inland waters being used), wind/wave/visibility/swell forecasts, any special marine warnings, and extended outlooks for the voyage duration before departure.
What does a 'Special Marine Warning' issued by Environment Canada indicate?
Answer: Imminent occurrence of hazardous marine weather including sudden squalls, winds over 34 knots, waterspouts, or freezing spray within 24 hours
A Special Marine Warning (SMW) is issued for rapidly developing or unexpected hazardous conditions including sudden strong squalls, winds exceeding 34 knots, waterspouts, freezing spray, or other dangerous phenomena within the next 24 hours.