COURSES        WEATHER    

Marine Weather will teach you to understand and demonstrate the proper use of weather information in planning and adapting navigation during local and voyages. Demonstrate the ability to use both the latest technological tools as well as traditional maritime skills to forecast weather conditions.

Prerequisites: None

Specific topics to be learned include:

Basic Concepts
• The role of marine weather in your boating plans, particularly wind forecasting
• The relationship of temperature, precipitation, visibility, wind, and waves and their impact on forecasting
• Wind terminology and units used in speeds, distances, temperatures and pressures
• Utilizing data from the Ocean Prediction Center, National Data Buoy Center, and Marine Weather Services Charts

Pressure and Wind
• Pressure and wind, including the flow of wind around highs, lows, ridges and troughs
• Conversion of apparent wind to true wind
• Calibration and setting of barometers, both aneroid and digital
• Pressure distributions and related labeling practices on weather maps
• Predicting wind speed and direction from isobars on a weather map

Global Winds and Currents
• The basic properties of the atmosphere and their influence on wind and weather
• Air mass classifications and vertical stability basics
• The role of equatorial heating in establishing the doldrums, horse latitudes, trade winds and prevailing westerlies
• The role the polar front plays in generating low fronts, and how these subsequently cross the mid-latitudes of the globe
• The origins and behavior of the winds aloft and how they contribute to the development and transport of surface systems around the globe
• The distribution of ocean currents around the globe and how to predict their values in voyage planning

Strong Wind Systems
• Forecasting conventions and warnings available for strong wind systems
• The distinctions between lows and fronts, and between tropical and extra-tropical storms
• Predicting squall behavior
• Finding and using Quick Scat satellite wind measurements
• Typical behaviors of tropical depressions, storms, and hurricanes

Clouds, Fog, and Sea State
• The ten basic cloud types and what they can indicate
• Cloud sequences at frontal passage
• Fog formation and forecasting
• Practical distinctions between sea fog and radiation fog and between swells, wind waves and ripple
• Predicting wave height and speed based on wind speed, duration, and fetch
• The Beaufort Wind Force scale that relates wind speed to sea state

Wind and Terrain
• Presence and topography of land and how it affects the wind flow over adjacent waters
• Prominent local winds such as: sea breezes, land breezes, channeling and gap winds, blocking and lifting and downslope winds
• The interaction between thermal winds and pressure system winds

Weather Maps Review
• The types of weather maps available and how to access them at home and underway
• The process of weather routing, including sequencing of analyses and forecasts to confirm the forecasts
• Accessing and utilizing GRIB forecasts, taking into account their pros and cons compared to analyzed products prepared by meteorologists
• Using the 500-mb maps and weather discussions to help evaluate surface forecasts
• Utilizing shipboard observations of wind and pressure to evaluate analyses and the subsequent forecasts

Sources of Weather Data
• The use of both traditional and modern sources of climatic data for planning the time and route of voyages-for inland and coastal voyaging, as well as ocean crossings
• The latest sources for weather data underway and the wireless options for obtaining it
• The distinctions and pros and cons of commercial weather services compared to free public services from the National Weather Service
• The role of professional weather routing services and how they might fit into your voyaging plans

On-board Forecasting and Tactics
• Proper use of barometer, wind speed, wind direction, clouds, and sea state for shipboard forecasting
• Gauging the direction of the winds aloft from cirrus cloud patterns
• Know which weather-related old maritime sayings have some value in forecasting
• The role of weather routing in improving sailing tactics

Southern Hemisphere Weather
• Which aspects of weather are unique, and which are and are not reversed in the Southern Hemisphere
• The sources for weather information specific to the Southern Hemisphere