MAFOR

Key takeaways

MAFOR belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect MAFOR to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of MAFOR from memory before moving on to harder problems.

Reference excerpt

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.'

Format 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

Example of a Marine Forecast MAFOR 0403/ - Superior 12646 14755 245H 12720 - Ontario 15820 12804 Referring to the codes above, this may be decoded as follows: MAFOR 0403/: Marine forecast valid from 03 Coordinated Universal Time of the fourth day of the current month Lake Superior: first 6 hours of the forecast period -wind west at 28 - 33 knots, with rain. Next 12 hours of forecast period - wind northwest 34 - 40 knots, with drizzle. During the same period - visibility 1/2 - 1 nautical mile, with rough seas, wave heights of 2.5 - 4 m. Final 6 hours of the forecast period -wind northwest at 17 - 21 knots, visibility greater than 3 nautical miles Lake Ontario: First 18 hours of forecast period -wind north 17 - 21 knots, visibility greater than 3 nautical miles, final 6 hours of forecast period - wind north at 10 knots or less, with fog reducing visibility to less than 1/2 nautical mile.

MAFOR Synopsis Each MAFOR broadcast is followed by a brief technical synopsis of the current weather map in plain language. The synopsis gives the location of the centers of significant high and low pressure areas, and their forecast motion (direction and speed). Reference is occasionally made to marked wind shift lines, giving the anticipated time at which the wind shift will occur at key points. The following is an example of the type of synopsis that is issued: Low Chicago moving ENE 35 High New York City moving e 15 Wind shift SW to NW Detroit early morning Kingston late evening

References

[https://www.canada.ca/en/environment-climate-change/services/general-marine-weather-information/understanding-forecasts/mafor-decode-table.html?_ga=2.168472801.1955427095.1529179108-1310113161.1529179108 MAFOR marine forecast decode table (Environment Canada)}

Worked examples

Example 1 — a first encounter with MAFOR

Start with the simplest possible case. Write down what MAFOR claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to MAFOR before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about MAFOR ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of MAFOR

In research: MAFOR appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses MAFOR in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: MAFOR is common in secondary-school and first-year university syllabi. It links to neighbouring topics Meteorological data and networks, so understanding it makes those chapters shorter.
In everyday life: Look for MAFOR outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study MAFOR in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what MAFOR means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain MAFOR out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is MAFOR in simple terms?

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 valid…

Why does MAFOR matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study MAFOR?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on MAFOR.