What is a Weather Depiction Chart?

Something that everyone will have to learn when they are becoming a pilot is how to read a weather depiction chart. This is just one of the many things that comes along with becoming a pilot, and there are lots of things that you will need to remember.

Looking at a weather depiction chart can easily become very confusing, especially if you don’t know how to read one. You might even be wondering what a weather depiction chart actually is. 

Whether you have seen one before or not, if you want to get ahead of the game and learn more about weather depiction charts, then you have come to the right place.

We are going to explain everything you need to know about them in this article.

What is a Weather Depiction Chart?

A weather depiction chart will detail all of the conditions that you can expect throughout your flight. This chart will be prepared and then transmitted by a computer every 3 hours.

This allows you to get more updated information throughout the flight. The data that it provides will be valid throughout this period. These charts are designed to be used for flight planning, and they will provide the pilot with a better picture of what they can expect the weather to be like.

A weather depiction chart will also provide a graphic display of IFR, VFR, and marginal VFR weather. Areas of IFR conditions will be shown by a hatched area that is outlined by a smooth line. MVFR regions are shown by a non-hatched area outlined by a smooth line. Areas of VFR will not be outlined.

Weather depiction charts will show a modified station model that will provide sky conditions in the form of total sky cover, ceiling height, weather, and obstructions to visibility. However, it will not include winds of pressure readings like a surface analysis chart.

How Do You Read a Weather Depiction Chart?

Isobars on a Weather Chart

The circular lines that you find on a chart are called isobars, which are similar to contour lines on a land map.

They join areas of equal barometric pressure, and air moves from high to low pressure. When the difference in pressure is greater, the airflow or wind will also be greater.

Those that are closer together will indicate stronger winds, and those that are further apart will indicate lighter winds. Isobars will also indicate the direction and speed of the wind.


When you see the lines with triangles and semicircles, you are looking at fronts. Warm fronts on the weather depiction chart are shown with the use of semi-circles and cold fronts with triangles.

The way that these shapes point will show the direction in which the front is moving.

Occluded Fronts and Troughs

If a cold front meets a warm front, it will create an occluded front, which is shown by lines that have overlapping semicircles and triangles.

If there are black lines with no semi-circles or triangles, these are troughs, which are areas where the air is unstable and showers will tend to form.

What Type of Weather Briefing Should a Pilot Request?

A pre-flight briefing is the best source for obtaining information that a pilot will need before they take off. This can include briefings and in flight weather information.

The weather information will include available forecasts and reports, which will describe the weather conditions that you can expect along your flight route and at your destination.

Standard Briefing

You should go ahead and request a standard briefing any time that you are planning a flight and have not received any previous briefing. You will be able to find out lots of valuable information through this briefing, which will provide you with pretty much everything that you need to know.

One of the things that you will be able to find out about in the briefing is adverse conditions, which are significant meteorological and/or aeronautical information that could influence the decisions that the pilot makes and even alter or cancel the flight entirely. Some of this information will include things like hazardous weather conditions, airport closures, air traffic delays, and more.

One of the most important things to look out for here is the current or forecast weather, as this could potentially reduce flight minimums below VFR or IFR conditions.

The pilot will also need to be ready for any forecasts of icing if the aircraft will not be able to operate in such conditions. If the pilot is to fly into areas of icing or below minimums, the results could be fatal.

The reported weather conditions that are applicable to the flight will be summarized from all available sources at the time. You can even request an abbreviated briefing if you need specific information or an update on a previous briefing.