Introduction Air masses -Understanding air masses -Air directly from polar regions -Air indirectly from polar regions -Air from the subtropics -Tropical air -Air mass with a land track -Fog -Sea fog areas -Other causes of sea fog -Showers and thunderstorms -Lightning -Lightning protection -Avoiding the risk -Other dangers of thunderstorms Fronts and depressions -Frontal lows and their formation -What you may see at sea level -Occluded fronts -Non-frontal lows -Relationship of wind to isobars -Use of synoptic charts -Forecasting winds Sea and land effects -How breezes are formed -The sea breeze front -What affects the sea breeze? -Land breezes -Sea/land breeze cycles -How strong? How far out to sea? How far inland? -Cliffs, straits and headlands -Summary Waves and swell -Understanding sea state -Wind waves -Swell -Water depth and tidal stream -Reflection and refraction -Sea state - general advice -Lagoon, bay and seiche effects -Tsunamis Weather forecasting - the background -Why weather prediction is so difficult -Before computers -Numerical weather prediction (NWP) -Limitations to NWP -Ensembles and probability forecasts -Grid spacing -Small-scale NWP -Computers -Summary Using forecasts - and your experience -Planning -Weather and whether to go? -Day sailing and coastal passages -Passage making -Examples -Learning by experience -Ocean crossings -Summary Sources of weather information -Types of marine forecast available -The Global Maritime Distress and Safety System (GMDSS) -Forecast areas and schedules -Forecast texts -GRIB files and products -Accessing GRIB data -Processed, pre-selected GRIB data -Model comparisons -Sea state -Location specific forecasts -Fine-scale GRIB data -On prepayment -Consultants -Actual weather reports Getting forecasts -Communications -Radio -NAVTEX -The internet -Internet access - coastal and ashore -Internet access - long range Observing - learning by experience -Weather lore and rules of thumb -Nowcasting -Examples of unusual cloud patterns -Mountain waves -Bora cloud -Mammatus cloud -Climate change Appendix -The Coriolis effect and Buys Ballot's law -Factors affecting the pressure-wind relationship -Acronyms and abbreviations -Meteorological terms -Terms used in marine weather forecasts -Beaufort wind scale -Douglas sea state -Gale and strong wind warnings -Wind direction -Visibility -Terms used in UK Met Office forecasts -Gale warning timings -Movement of pressure systems -Pressure tendency in station reports -Sources of marine weather information -Sources of (mainly free) GRIB data and products Index.