Weather Services for Shipping

• Weather Services for Shipping per STCW Table A-II/1

Sources of Weather Information

• Marine VHF/MF Radio: Used for local broadcasts.
• NAVTEX and INMARSAT: Provides text-based weather and navigational warnings.
• HF/Single Sideband Radio: Useful for longer-range forecasts and charts.
• Public service radio: Broadcasts weather information.
• Internet: Access to a wide range of weather data via WiFi, cell, or satellite phone, even HF amateur radio.
• Telephone: Can be used to access weather information.
• Media: Traditional sources like TV and radio.

Internet Weather Information

• The internet provides access to weather information in internet cafes, via WiFi, cell phones, satellite phones, and marine HF/amateur radio.
• Using internet based weather services is valuable when in harbor, at anchor, or at sea.

Transmitting Weather Charts

• Facsimile machines transmitted weather charts internationally via HF radio.
• Radio transmission of weather charts is flexible for marine and aviation users, providing weather information and forecasts for voyage planning.

Weather Services Provided by Metoffice

• Metoffice provides information on oceanic and coastal climatology.
• Metoffice provides ground-truth for satellite observations.
• Metoffice services include ice analysis, forecasts, and iceberg reports.
• Metoffice provides tide predictions and observations
• Metoffice provides storm surge forecasts.

Recording and Reporting Weather Observations

• Meteorological codes are composed of values defined in tables, referenced to positions within strings of information.
• Defined values make up a code form, and binary codes are made up of groups of letters.
• Code groups represent meteorological or other geophysical elements.
• Different code forms represent different observation types or products.

Weather as Observed: Code Groups

• N: Total amount of cloud in oktas (eighths).
• TT: Dry-bulb air temperature in degrees Celsius.
• ww: Present weather.
• dd: Wind direction in degrees.
• ff: Wind speed in knots.
• W: Visibility in meters or kilometers.
• TaTa: Dew-point temperature in degrees Celsius.
• C or C: Type of low cloud.
• W.W.: Past weather.
• pppa or pppa: Pressure tendency and trend (black: rising, red: falling) in millibars.
• PPP: Atmospheric pressure in millibars.
• C or C: Type of medium cloud.

Beaufort Letters - A System for Weather Reporting

• Beaufort Letters are a system using letters and numbers to indicate various weather types.
• Beaufort Letters are used to record phenomena at a particular time.
• Standard reporting order includes:
• State of Sky
• Thunderstorm (if present)
• Precipitation (if present)
• Atmospheric obscurity (if present)
• Any other phenomena

State of the Sky Codes

• b: Total cloud amount 0 to 2 oktas (eighths covered).
• bc: Total cloud amount 3 to 5 oktas.
• c: Total cloud amount 6 to 8 oktas.
• o: Uniform thick layer of cloud covers the sky (8 oktas) with no gaps, mainly used with St, Ns and thick As.

Thunderstorm/Allied Phenomena Codes

• l: Distant lightning; storm too far for sound.
• t: Thunder heard; no lightning seen.
• t!: Thunderstorm.

Precipitation Codes

• d: Drizzle, freezing drizzle (uniform precipitation with small drops < 0.5 mm diameter).
• dr: Drizzle and rain mixed.
• h: Hail, small hall, snow pellets, diamond dust, ice pellets.
• hr: Hail and rain mixed.
• hs: Hail and snow mixed.
• r: Rain, freezing rain (liquid water particles > 0.5 mm diameter or smaller widely scattered drops).
• rs: Rain and snow mixed, or partially melted snow (sleet).
• s: Snowflakes.
• sh: Snow grains ('granular snow').

Other Phenomena Codes

• e: Wet air, without rain, snow etc. falling.
• g: Gale (mean speed 34–47 knots over a 10 minute period).
• G: Storm (mean speed 48 knots or more over a 10 minute period).
• i: Intermittent (used with precipitation and fog).
• j: Phenomenon within site but not at the location of the observer.
• kq: Line Squall.
• p: Shower – see notes against precipitation for usage.
• u: Ugly, threatening sky (in addition to bc/c/o etc.).
• w: Dew deposit (make sure that "dew" is really being deposited, and not just 'guttation' water extruded from plant leaf surfaces on some cold nights.).
• x: Hoar frost deposit.
• y: Dry air – less than 60% relative humidity.

Atmospheric Obscurity Codes

• f: Fog, ice fog (visibility < 1000 m).
• fe: Wet fog (visibility < 1000 m).
• fg/fs: Shallow land/sea fog (visibility above the fog >=1 km).
• F: Fog, Ice fog ^(visibility < 200 m).
• ks: Drifting or blowing snows.
• kz: Dust or sandstorm (visibility < 1000 m).
• m: Mist (visibility >=1 km) (Relative Humidity >~95% ).
• z: Haze.

Weather Station Plot

• Wind: Plotted with the outer end of the symbol pointing to direction wind is blowing from, speed determined from flags and lines
• Sea-level pressure: Plotted in tenths of millibars, with leading 10 or 9 omitted.
• Pressure trend: Has two components: a number and a symbol indicating pressure change in the last three hours.