MAFOR
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MAFOR, an abbreviation of MArine FORecast, is a North American code used in the transmission of marine weather forecasts to compress a volume of meteorological and marine information into shorter code for convenience during radio broadcasting. The MAFOR forecast usually supplies the period of validity for the forecast, future wind speed and direction, weather, visibility and 'state of sea.'
A MAFOR code begins with a date and time group, followed by the name of the area to which the forecast applies, followed by one or more groups of five figures, which may be followed by another optional group.
Date Group
YYG1G1/ where
- YY is the day of the month in accordance with Coordinated Universal Time (UTC)
- G1G1 is the time of the beginning of the valid period of the forecasts in Coordinated Universal Time (UTC).
- "/" is the last digit of this group is not used.
Weather Group
1GDFmW1 1: is an identifying number required by international practice. Each code group following the name of the lake will begin with 1. G: is the code figure for the period of time covered by the forecast given in the group.
Time Period of Forecast Coverage
- 0 - Existing weather conditions at the beginning of the forecast period
- 1 - Forecast valid for 3 hours
- 2 - Forecast valid for 6 hours
- 3 - Forecast valid for 9 hours
- 4 - Forecast valid for 12 hours
- 5 - Forecast valid for 18 hours
- 6 - Forecast valid for 24 hours
- 7 - Forecast valid for 48 hours
- 8 - Forecast valid for 72 hours
- 9 - Occasionally
D: is the code figure for the forecast direction of the wind.
Direction of Wind
- 0 - Calm
- 1 - Northeast
- 2 - East
- 3 - Southeast
- 4 - South
- 5 - Southwest
- 6 - West
- 7 - Northwest
- 8 - North
- 9 - Variable
Fm: is the code figure for the forecast speed of the wind
Speed of Wind
- 0 - Beaufort Number 0-3 (0 - 10 knots)
- 1 - Beaufort Number 4 (11 - 16 knots)
- 2 - Beaufort Number 5 (17 - 21 knots)
- 3 - Beaufort Number 6 (22 - 27 knots)
- 4 - Beaufort Number 7 (28 - 33 knots)
- 5 - Beaufort Number 8 (34 - 40 knots)
- 6 - Beaufort Number 9 (41 - 47 knots)
- 7 - Beaufort Number 10 (48 - 55 knots)
- 8 - Beaufort Number 11 (56 - 63 knots)
- 9 - Beaufort Number 12 (64 - 71 knots)
W1: is the code figure for forecast weather.
Weather
- 0 - Moderate or good visibility (greater than 3 nautical miles)
- 1 - Risk of ice accumulation on superstructure (air temperature between 0 °C and -5 °C
- 2 - Strong risk of accumulation of ice on superstructure (air temperature below -5 °C
- 3 - Mist (visibility 1/2 to 3 nautical miles)
- 4 - Fog (visibility less than 1/2 nautical mile)
- 5 - Drizzle
- 6 - Rain
- 7 - Snow or rain and snow
- 8 - Squally weather with or without showers
- 9 - Thunder storms
2: identifies the group as a supplementary group. The 2 group is valid for the same period as the group that immediately precedes it. V: is the code figure for the forecast visibility.
Visibility
- 0 - Less than 50 meters
- 1 - 50 – 200 meters
- 2 - 200 – 500 meters
- 3 – 500 meters to 1/2 nautical mile
- 4 - 1/2 to 1 nautical mile
- 5 - 1 to 2 nautical miles
- 6 - 2 to 5 nautical miles
- 7 - 5 to 12 nautical miles
- 8 - 12 to 20 nautical miles
S: is the code figure for the forecast sea state.
State of Sea
Height in Meters
- 0 - Calm (glassy)
- 1 - Calm (rippled) - 0.0 - 0.1
- 2 - Smooth (wavelets) - 0.1 - 0.5
- 3 - Slight - 0.5 - 1.25
- 4 - Moderate - 1.25 - 2.5
- 5 - Rough - 2.5 - 4
- 6 - Very Rough - 4.0 - 6
- 7 - High - 6.0 - 9
- 8 - Very High - 9.0 - 14
- 9 - Phenomenal - over 14