3.7 Weather Information Sources

Where to Get Weather

No single product gives the full picture. Build a layered briefing before launch and keep monitoring during the flight.

Primary Sources

Types of Briefings

In-Flight Advisories

AIRMET (Airmen's Meteorological Information) — widespread moderate conditions, valid 6 hours, issued as needed in three flavors:

SIGMET (Significant Meteorological Information) — severe conditions affecting all aircraft (severe turbulence, severe icing, widespread dust/sand, volcanic ash). Valid 4 hours.

Convective SIGMET — thunderstorm-specific (embedded storms, lines, severe storms, large hail, tornadoes). Issued at 55 past the hour and valid only 2 hours.

PIREPs (Pilot Reports)

Real observations from pilots aloft — the only source describing actual conditions rather than a forecast. They report turbulence, icing, cloud bases/tops, and visibility. UA = routine; UUA = urgent. Highly valued for go/no-go because they confirm or refute the forecast.

Winds and Temperatures Aloft (FB) Forecast

Forecast wind direction, speed, and temperature at fixed altitudes (3,000, 6,000, 9,000, 12,000 ft MSL and up). Direction is referenced to TRUE north — unlike METARs and TAFs, which use magnetic north. This contrast is a frequent exam item.

Radar and Satellite

NEXRAD radar shows precipitation intensity and movement on a color scale: green (light) to yellow (moderate) to red (heavy) to purple (extreme). It is essential for tracking storms.

Satellite imagery:

• Visible — clouds as the eye sees them; daylight only
• Infrared (IR) — cloud-top temperatures, 24/7; colder/higher tops appear brighter
• Water vapor — moisture in the mid and upper atmosphere

A Pre-Flight Weather Routine

1. Check METARs at nearby stations for current conditions
2. Check the TAF for the planned window
3. Scan radar for precipitation and storm motion
4. Review AIRMETs/SIGMETs and any PIREPs
5. Check NOTAMs and TFRs for restrictions
6. Evaluate winds (surface and aloft) against the aircraft
7. Make the go/no-go decision, then keep monitoring — conditions change fast

Choosing the Right Briefing

For a drone job planned in the next hour or two, a focused look at aviationweather.gov plus current radar usually suffices, but for a flight several hours out an outlook briefing sets expectations, and for a same-day operation a standard briefing captures adverse conditions, the synopsis, current weather, the forecast, winds aloft, and NOTAMs in one package. If you already pulled a standard briefing and just want what changed, request an abbreviated briefing rather than repeating the whole thing. Matching the briefing type to your timeline is a common exam scenario.

Why PIREPs Carry Special Weight

Forecasts and advisories predict; a PIREP reports what a pilot actually encountered. If a TAF calls for smooth air but a PIREP a few miles away reports moderate turbulence at low altitude, believe the PIREP for your go/no-go. Urgent reports (UUA) flag hazards like severe turbulence, severe icing, or low-level wind shear that demand immediate attention. For a low-altitude drone operation near terrain or structures, a recent low-level PIREP is some of the most decision-relevant data available.

Tying the Sources Together

No product stands alone. The METAR tells you what is happening now, the TAF what is forecast, AIRMETs and SIGMETs flag area hazards, PIREPs confirm reality, radar shows where the precipitation actually is, and winds aloft reveal what your drone will feel as it climbs. The Remote PIC weaves these into a single picture, makes the call, and keeps watching, because a fast-building cumulonimbus can invalidate a clean briefing within the hour.

Common Source Traps

• Swapping AIRMET letters. Sierra = IFR/visibility, Tango = turbulence/wind, Zulu = freeZing/icing.
• Confusing hazard tiers. AIRMET = moderate; SIGMET = severe and affects all aircraft.
• Missing the validity periods. AIRMET 6 hr, SIGMET 4 hr, convective SIGMET only 2 hr.
• North reference. Printed products — winds-aloft (FB) forecasts, METARs, and TAFs — are all referenced to true north. Only winds spoken over ATIS/AWOS/tower are magnetic ("if you read it, it's true").

Quick-Reference: Product, Issuer, and Use

For a Part 107 preflight, the FAA-recommended one-stop tools are 1800wxbrief.com (Leidos Flight Service) and the Aviation Weather Center (aviationweather.gov); the B4UFLY app layers airspace and TFR status on top of the weather picture.

For the exam: Lock in the validity periods (AIRMET 6 hr, SIGMET 4 hr, convective SIGMET 2 hr) and the AIRMET hooks (Sierra = IFR/visibility, Tango = turbulence/wind, Zulu = freeZing/icing).