Are you on your journey of becoming the next Maverick? The next Chuck Yeager perhaps? Even these master flyers could not take off without referencing the weather. Weather is one of those things that will make or break your flying day. It is important to be able to look at all different types of weather products and be able to decipher them to make sure you will be A-Ok to take off.
Why put yourself in danger or in a sticky situation if you do not have to. This is where a nice little handy dandy weather report comes in. The METAR. In this METAR guide, we will get into some of the more common METAR questions so you do not have to go looking in any other location.
What Is A METAR?
A METAR or a meteorological aerodrome report is a reported weather observation predominately used in aviation for pilots. It is standardized throughout the world so a pilot despite their geographical location will be able to understand and decipher the METAR.
In Layman’s terms, it is a report of the weather that has been observed recently at a specific location that provides necessary weather information that is helpful to pilots.
A METAR is a line of different weather information put in a specific order. We will get more into this specific order and how to decipher it later on.
Why Do METARs Matter?
METARs are one of the most current weather reports at any one time. Most airports or other sites that produce a METAR provide them hourly. Some locations post a new METAR 3 times an hour, which is one every 20 minutes!
This allows pilots and air traffic control to stay updated with the current conditions of the airfields. This information is helpful because it provides insight on whether or not it is safe to operate in the area due to weather and what to expect while taking off or landing at an airfield. It also can hint towards what runway may be in use and if you’re take-off and landing data is valid.
What Information Does A METAR Contain?
A METAR will normally contain information regarding the temperature, dew point, wind direction and speed, precipitation, visibility, cloud cover, the associated cloud heights, and barometric pressure.
Outside of the normal conditions, METARs can also add in precipitation amounts such as snow, lightning, and other pertinent information that can be useful.
What Does A METAR Look Like?
KCBM 211855Z AUTO 31015G20 3/4SM+ TSRA BR BKN007 OVC011CB 19/17 A2970 RMK PRESFR
A typical METAR has a lot of very useful data that is packed into a short line. Once you learn how to decipher one, you can decipher them all.
How Do You Read A METAR?
When looking at a METAR you read it like a book, left to right. The best way to learn the order of information is to break it down. As you can see below, it seems like it is jumbled together, but it is actually put together in a specific sequence that is standardized worldwide.
We will break it down starting with “KCBM” and work our way across and explain each and every piece of information.
KCBM 211855Z AUTO 31015G20 3/4SM +TSRA BR BKN007 OVC011CB 19/17 A3005 RMK
- Station identifier (KCBM) —a four-letter code as established by the International Civil Aviation Organization (ICAO). In the 48 contiguous states, a unique three-letter identifier is preceded by the letter “K.” For example, Columbus Air Force Base in Columbus, MS, is identified by “KCBM” K being the country designation and CBM being the airport identifier. In other regions of the world, the first two letters of the four-letter ICAO identifier indicate the region, country, or state.
- Date and time of report (211855Z) — The first two digits are the date, the 21st of the month, and the last four digits are the time of the METAR, which is always given in coordinated universal time (UTC), otherwise known as Zulu time. A “Z” is appended to the end of the time to denote that the time is given in Zulu time (UTC) as opposed to local time. Zulu time is the primary time standard by which the world regulates clocks and time. It is in 24-hour time form. This is to make sure everyone is at the same time regardless of location and its associated local time.
- Modifier (AUTO)—denotes that the METAR came from an automated source or that the report was corrected. If the notation “AUTO” is listed in the METAR, the report came from an automated source. When the modifier “COR” is used, it identifies a corrected report sent out to replace an earlier report that contained an error.
- Wind (31015G20)—reported with five numbers (31015). The first three numbers indicate the direction from which the wind is blowing to the nearest ten degrees in relation to true North. If the wind is variable, meaning it is shifting frequently, then “VRB” will go after the numbers. The last two digits indicate the speed of the wind in knots. If the winds are gusting, the letter “G” follows the wind speed numbers, and then the numbers right after G indicate the highest expected wind gusts (G20). The number prior to the “G” indicates steady-state wind.
- Visibility (3/4 SM) —the prevailing visibility (3/4 SM) is reported in statute miles as denoted by the letters “SM.” It is reported in both miles and fractions of miles. In this case, ¾ of a mile. This gives you an idea of how far down the runway you’ll be able to see. Disasters have taken place because of the visibility, so it is very important.
- Weather (+TSRA BR)— Do not rack your brain trying to learn each and every abbreviation, we will provide a link to find those later. The intensity may be light (-), moderate ( ), or heavy (+). If there’s any kind of weather phenomena that’s in the immediate vicinity of the airport, that’ll be shown. In this example, TS stands for thunderstorms, and RA stands for rain. Lastly, the descriptors, which are used to describe certain types of precipitation and obscurations. So here we’re seeing BR, which stands for mist. The way we like to think of it is “Baby Rain.” You might also see things like RA. If you are ever curious about what something is, you can look here.
- Sky condition (BKN007 OVC011CB)—This denotes cloud coverage and the heights of the clouds and sometimes types of clouds. The letters (BKN) indicate cloud coverage, which is saying, if you looked up towards the sky, how much of it would be covered by clouds? It goes from a clear sky, or SKC to OVC, or overcast which is a fully covered sky. The number part represents the cloud base height. This number is reported in hundreds of feet above-ground-level or AGL. In this example, “007” stands for 700 feet. When there are multiple layers of clouds, such as in this example, the METAR will reflect that. In this example, there is an overcast at 1,100 feet. Like mentioned earlier, we may even see a cloud type, “CB” is the abbreviation for cumulonimbus, which tells the pilot that there may be a storm which is what this type of cloud is known for.
- Temperature and dew point (19/17)—the air temperature and dew point are always given in whole degrees Celsius (°C) and separated by a forward slash (/). Temperatures below 0°C are preceded by the letter “M” to indicate minus. If the two are close together, there is a good chance that there may be fog that restricts visibility, which is typical for morning flights.
- Altimeter setting (A3005) —A3005 tells a pilot to set his or her altimeter pressure to 30.05 Hg, or inches of mercury.
- Remarks (RMK)—the remarks section always begins with the letters “RMK.” Comments may or may not appear in this section of the METAR. The information contained in this section may include anything extra that could be useful information for pilots that were not covered in the rest of the METAR.
How Long Are METARs Valid For?
METARs are only valid up to one hour, or when they are replaced by the next METAR, whichever comes first. This is what makes them a good piece of information for pilots who will be using the airfield soon because of a snapshot of current conditions.
Where Can I See METARs?
The best places to view METARs would be NOAAs Aviation weather website, or through an app. Anyone who has access to a cell phone and a connection has access to the weather. There are powerful complete apps that will give you more than just the METAR.