Weather
Reporting - METARs
METARs are the reports that come out hourly and generally report the current period from 15 minutes before the hour to 5-10 minutes after. This is a real time indication on what is going on at the airport and can be updated as necessary when conditions change. Let’s take a look at a METAR from KLGA.
KLGA 032351Z 23007KT 10SM FEW040 BKN190 BKN250 27/17 A2961 RMK AO2 SLP028 60006 T02720172
The red section of a METAR first gives the reporting station for identification followed by the date in DD format and the time reported in HHMM zulu. In this case it is KLGA on the 3rd of the month at 2351Z. The blue portion begins the field observations which will give you wind direction (230 degrees) and velocity (07 knots), visibility (10 statute miles), cloud coverage (few clouds at 4,000 feet AGL, broken clouds at 19,000 feet AGL, and another broken layer of clouds at 25,000 feet AGL). The orange section gives you the field gauge readings which include your temperature (27 degrees Celsius) and dewpoint (17 degrees Celsius), and the altimeter setting (29.61). The final portion with green text is the remarks section which indicates in this specific METAR. For a comprehensive list of these remarks and how to decode them, we recommend this guide published by Weather.gov (https://www.weather.gov/media/wrh/mesowest/metar_decode_key.pdf).
Forecast - TAFs
The Terminal Area Forecast (TAF) is utilized by pilots and dispatchers to plan the destination information based on the predicted weather. TAFs are updated every six hours, starting at 0000Z, and cover 24 hours of weather forecasts for the specified airport. There are also “short TAFs” which are released on the same schedule but cover timeframes that are within 12 hours. METARs and TAFs share the same basic information and coding structure which makes them pretty easy to read and understand.
From left to right starting on the top line we can see that this TAF is for KLGA and was issued on the 4th day of the month at 0524Z. It is a valid forecast from the 4th day at 0600Z (0406) to the 5th day at 1200Z (0512). The general winds for that time period will be from 250 degrees at 4 knots, with visibility greater than 6 statute miles (P6SM). The cloud coverage will be few at 7,000 feet AGL and another broken layer at 25,000 AGL. FM stands for “from” and alerts you to a change in weather at a certain time. For the next line we see that from the 4th day at 1200Z the winds will be from 300 degrees at 6 knots, visibility greater than 6 SM, and a broken layer at 25,000 feet AGL. The interesting change we see is from the 5th day of the month at 0000Z when the code “VCSH” is added, alerting you that there will be forecasted rain showers in the vicinity.
It is very important to be able to read the TAFs and understand the forecast for what will be going on at the arrival airport at your scheduled time of arrival. This allows you to ensure you meet all requirements for approaches, alternates, and have a basic understanding of what you are going to encounter.
Cloud Coverage Chart
An important thing to keep in mind when considering cloud coverage is the reported ceiling. A ceiling is defined as the lowest reported broken or overcast layer.
| Abbr. | Name | Sky Coverage |
|---|---|---|
| CLR/SKC | Clear/Sky Clear | 0/8 |
| FEW | Few Clouds | 0.1/8-2/8 |
| SCT | Scattered Clouds | 3/8-4/8 |
| BKN | Broken Clouds | 5/8-7/8 |
| OVC | Overcast Clouds | 8/8 |
Weather Sources
vAAirlines recommends utilizing both your SimBrief OFP as well as https://www.aviationweather.gov for your comprehensive weather information. NOAA also has very helpful guides and keys located all over the website to help you dig even deeper into understanding the weather.