GFA Aviation Weather: How to Read the Map

What should you check before reading a GFA map?

Check the context before interpreting the colors.

AGL means above ground level; MSL means mean sea level. Keep the reference attached whenever you write an altitude or cloud height in your study notes.

Where do you start in the GFA interface?

Open the official GFA and choose a specific weather question before adding layers.

At aviationweather.gov/gfa, the Weather menu includes Observations, Ceiling & Visibility, Clouds, Precipitation, Thunderstorms, Temperature, Winds, Turbulence and Icing. The Products menu includes SIGMET, G-AIRMET, Center Weather Adv, TAF map, Prog charts and Forecast Discussions. These labels were checked in the interface on October 21, 2026.

For a first practice session, write down a fictional departure, destination and flight window. Choose one question, such as “What could make the arrival weather worse?” Start with one view and explain it aloud before switching to another. Turning on every overlay at once makes it harder to notice which product supplied an answer.

Use Search for a station to orient the map. Select active layers displayed shows the current overlay choices; Display legend explains the selected symbols. The interface also offers a Flight path/vertical cross-section tool. A drawn line helps organize an examination of weather; it does not approve a route.

An original reading checklist, not a screenshot or current forecast. Repeat it whenever you change products.

How do you match the map to your flight time?

Compare the weather at the time you expect to reach each part of the flight.

An observation time describes when something was reported. An issue time identifies when a product was released; a valid time identifies when its forecast applies. They can differ. A fresh-looking page does not make every item on it simultaneous.

Read the displayed date and time when moving the bottom time control. In Configure map options → Map Format, the current interface offers Use local time; otherwise it displays UTC. Confirm the displayed zone rather than assuming your laptop's local clock controls the map.

For a study exercise, write a departure time and a later arrival time on separate lines. Examine both, then the intervening period. If you change the proposed departure, redo the exercise rather than keeping a screenshot from the original window. The FAA preflight-briefing guidance organizes en route weather by climbout, en route and descent, and includes destination changes around the estimated arrival.

How do altitude and the legend change the answer?

Read the selected level and height reference before comparing a map with your intended altitude.

The Clouds view is not the same quantity as a ceiling forecast. A 6,000-foot-MSL cloud base over hypothetical 2,000-foot-MSL terrain would be about 4,000 feet above that terrain; it would not be a 6,000-foot-AGL ceiling. This subtraction is a simplified study example, not terrain-clearance or cloud-clearance planning. Actual terrain and cloud conditions vary along a route.

For winds or icing, a MAX selection does not identify the condition at one chosen cruise level. Switch to an applicable level and examine climb and descent too. A student should be able to finish the sentence: “This display describes ___, at ___, relative to ___.” If a blank cannot be filled confidently, pause the interpretation and read the legend or help.

Original study prompts. The table tells you what to investigate, not whether to fly.

What should you compare with the graphical view?

Open the reports and forecasts behind the picture, then explain any apparent disagreement.

Use METAR observations, TAF forecasts and G-AIRMETs, SIGMETs and PIREPs for their different purposes. A PIREP records encountered conditions associated with its report context; it does not promise the same experience later. The FAA's AC 91-92 briefing checklist calls for observations and route forecasts as parts of the broader review.

When two displays appear inconsistent, make a small comparison note: product name, location, time and height reference. A difference may be understandable once those are aligned. If it remains unclear, take that specific question to your instructor or Flight Service rather than choosing the more reassuring picture.

An empty-looking area deserves the same care. AWC cautions that weather beyond a product's domain may be masked, and ceiling/visibility graphics can use transparency. Check the legend, coverage, layers and filters before assigning meaning to an absence of color. Missing information cannot answer your weather question.

What does a student walkthrough look like?

Use a fictional timeline to practise changing the question as the flight progresses.

Suppose a classroom exercise departs at 1500Z, reaches an en route checkpoint at 1630Z and arrives at 1800Z. These are invented times, with no real airports or forecast attached. They are not recommended departure times, forecast availability intervals or a flight plan.

Original classroom example. Examine the relevant available forecasts across the window; the three checkpoints do not replace continuous route review.

At departure, record what the observations say and what still requires a forecast. At the en route checkpoint, ask which location and vertical layer you are evaluating. At arrival, compare the destination forecast with the expected arrival window and nearby changes. Do not invent an intermediate forecast frame if the chosen product does not offer that time.

Now move the fictional departure one hour later. Rewrite all three checkpoints and identify which parts of your earlier review need updating. The useful result is a list of changed questions, not a conclusion that the fictional flight is safe. This exercise reveals how easily a saved image can become detached from the flight it was meant to support.

Is a GFA map a complete preflight briefing?

A single map cannot establish that all required preflight information has been considered.

Section 91.103 requires the pilot in command to become familiar with all available information concerning the flight. Its weather, fuel, alternatives and delay provisions apply to IFR flights or flights away from an airport's vicinity; runway lengths and applicable performance information are also part of the rule. Looking at favorable weather colors does not complete those tasks.

A few broader briefing prompts from AC 91-92; this is not the complete checklist.

The AIM's preflight-briefing section recognizes self-briefings and explains Flight Service assistance. There is no general requirement to telephone a briefer for every flight. For training, use AC 91-92's checklist with your instructor to identify what your weather-map review has covered and what remains. Reassess when conditions or the flight change.

Check yourself

Try these original study questions before opening each explanation.

Frequently asked questions

These distinctions help keep the map connected to the underlying weather information.

Is everything in GFA a forecast?

No. It brings together observations, forecast guidance and advisories. Identify which kind you selected before interpreting it.

Are all GFA cloud heights AGL?

No. Ceiling grids use AGL, while the Clouds display's bases and tops use MSL. Read the product's own height reference.

Does a blank map prove there is no hazard?

No. Confirm the active layers, legend, filters and product coverage. An unshown or unavailable item cannot establish that conditions are favorable.

Do I have to call Flight Service after using GFA?

Not automatically. FAA guidance recognizes self-briefings. Use Flight Service for help interpreting information when needed, and ensure the complete preflight review meets the flight's requirements.

Sources and review notes

Use the live product instructions for current controls and FAA sources for briefing duties.

• AWC GFA and its Help: interface, time controls, legends and display limitations; checked October 21, 2026.
• AWC GFA product guide: height references, vertical selections and product coverage.
• FAA AIM 7-1-5, Preflight Briefing: briefing contents and Flight Service assistance.
• FAA AC 91-92, Pilot's Guide to a Preflight Briefing: self-briefing checklist and resources.
• 14 CFR 91.103, Preflight action: the controlling preflight-information requirement.

What should you practise next?

Return to the METAR weather-reports hub, then compare the TAF guide and weather-advisory guide. For each exercise, say which product answers your question and what remains unknown.

FirstSolo.ai is a study tool. It does not issue FAA knowledge-test endorsements, and it will not offer them in the future. FirstSolo.ai is independent of the FAA; use official, current information and instructor guidance for flight preparation.