When it comes to aviation, knowledge is power. The aviation community relies heavily upon weather reports to ensure that flights are safe and make important decisions about their flights. Two of the most commonly used weather reports are METARs and TAFs.
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In this article, we will share the following information: what is METAR and TAF; we will also comment on the difference between the two. In addition, we will look briefly at how to read or interpret a METAR and TAF report.
METAR vs. TAF
Both reports do have areas in common. Both fulfill legal requirements and deal with the essential information you need as an aviation professional about weather and runway conditions. In addition, the internationally standardized coding system used by METAR and TAF is very similar and highly abbreviated in both cases.
DTN does not produce either report, they are produced by local authorities.
However, there are some critical differences between the two. To put it simply, a METAR outlines observations. It lets the aviation community know the weather conditions at a specific location at the time that the report is prepared. A TAF forecasts the weather conditions for a certain period.
What is METAR?
According to the NOAA (National Oceanic and Atmospheric Administration), “METAR is the international standard code format for hourly surface weather observations.” METAR stands for Meteorological Aerodrome Report. The METAR reports are issued frequently, and since they deal with current weather conditions, they are weather observations, not forecasts.
In some cases, a report simply called a “trend” would be appended to a METAR. This report is a forecast that is valid for two hours.
METAR reports use the standardized format directed by the International Civil Aviation Organization (ICAO). This format is accepted worldwide. The information contained in a METAR report gives you the current weather conditions recorded at the facility issuing the report. The METAR report is given out at regular, scheduled intervals barring any unusual and suddenly arising weather events.
The acronym SPECI is a special code name given to METAR formatted products issued in addition to the regular schedule of METAR reports. These additional reports are issued when there is a change in conditions outside the parameters of the expected conditions.
What is TAF?
TAF stands for Terminal Aerodrome Forecast. It forecasts the expected meteorological conditions for the surrounding area of the issuing airport up to five statute miles. A TAF report is a forecast valid for approximately 24 hours. The TAF reports are usually updated four times daily.
There are many differences between a METAR and a TAF report, beginning with their use. A TAF report is used for flight planning since it is valid for a more extended time. It’s important to note that different airports have different validity periods.
Another main difference between a METAR and TAF report is the information that they contain. A METAR report includes wind direction and speed, temperature, barometric pressure, and cloud cover. On the other hand, a TAF report provides the same weather information as a METAR, plus information relating to whether rapid, gradual or temporary change is expected in some of the meteorological conditions.
While METAR is mostly auto-generated, a TAF is mostly human-produced. Auto-generated reports tend to be more limited, so TAFs often contain more information.
Which report should you use when?
Ultimately, you will want to use both. However, a TAF is generally more reliable than a METAR, as it is less likely to be auto-generated. The general guideline is that a TAF will override a METAR (unless the METAR has a trend report appended to it).
How to read a METAR weather report
Both METAR and TAF reports are not easy for a layperson to read without some explanation. Let’s look at an example of a METAR report as follows:
METAR EHLE 280925Z AUTO 21009G19KT 060V130 5000 -RA FEW007 BKN014CB BKN017 02/M01 Q1001 BECMG 6000
Each series of numbers and letters within the sequence pertains to a specific place, time, or weather element. Look again at the example above; we can break down the first few pieces into separate segments of information to give you an idea of how it works.
METAR: This labels the report as an observation, not a forecast.
EHLE: The four-letter code for the Lelystad Airport in the Netherlands. There will be a four- or five-letter coded abbreviation that signifies the location (airport/weather station) from where the report is issued. Airports codes have four letters; weather stations have five.
280925Z: This corresponds to the day and time of the report; this sequence indicates:
the 28th day of the month (28), the 9th hour (09), the 25th minute (25), and the Z means the time zone (UTC);
AUTO: Referring to the fact that this is an automatically generated observation.
From this point on, the report becomes highly technical and requires more space to explain in detail than we have available in this article; get more detailed information here.
Why use aviation weather forecasts?
Aviation weather forecasts are essential as they are a standardized approach to formulating the bare minimum weather requirements for a legal flight.
The goal of METAR and TAF, as with all the advances in weather reporting, is to improve communication, efficiency, and safety. In addition, you can combine these weather reporting and forecasting methods with sophisticated weather forecasting technology.
These applications give you access to skilled and experienced meteorologists that can help you interpret and act on the data offered in the METAR and TAF reports prepared by local authorities. When you put these powerful tools to work for you, you get an advantage that is critical for flight safety and efficiency.
Our patented aviation forecast applications allow you to survey and track global flight operations. We combine public and proprietary weather information with accurate and detailed preflight and inflight decision support.
DTN weather models and 4D flight route alerting solutions give you relevant and up-to-the-minute airspace data in a single view. With DTN weather applications and solutions, you’ll be able to stay ahead of developing weather conditions and disruptive events.