Aviation Weather — A Pilot’s Complete Guide

TAFs — What to Expect at Your Destination

A TAF (Terminal Aerodrome Forecast) covers conditions at a specific airport over a 24 or 30-hour window in a format similar to METARs. A few terms worth knowing:

• FM (From) marks the start of a new forecast period
• TEMPO means temporary — conditions expected to last less than an hour at a time
• BECMG (Becoming) indicates a gradual change over a defined period
• PROB followed by a percentage means probability — PROB30 is a 30 percent chance

A TAF showing PROB40 TS at your destination during your estimated arrival window isn’t automatically a no-go. But it demands a solid alternate plan and a serious look at the area forecast before you depart.

PIREPs — What Other Pilots Are Actually Seeing

Pilot Reports are firsthand observations filed by pilots in flight. They’re one of the most valuable weather products available because they reflect actual in-flight conditions rather than model forecasts. A PIREP might report turbulence at a specific altitude, icing with the aircraft type, cloud tops and bases, or thunderstorm locations.

Check PIREPs along your route before departing. Three pilots reporting moderate icing at 8,000 feet in the last two hours while your route takes you through 8,000 feet without de-icing equipment is a straightforward answer to the go/no-go question.

AIRMETs and SIGMETs

AIRMETs (Airmen’s Meteorological Information) cover three categories of hazardous weather: Sierra for IFR conditions and mountain obscuration, Tango for moderate turbulence and low-level wind shear, and Zulu for icing and freezing levels. AIRMETs are significant for lighter aircraft and VFR operations — not emergencies, but not background noise either.

SIGMETs cover severe or extreme weather: significant turbulence, severe icing, volcanic ash, sandstorms. Convective SIGMETs cover thunderstorms and are issued when conditions warrant immediate pilot attention.

If a convective SIGMET covers your route, you plan around it. Thunderstorms are non-negotiable.

Winds Aloft Forecasts

Winds Aloft forecasts give predicted wind direction and speed at altitudes from 3,000 to 45,000 feet. They’re essential for calculating groundspeed and fuel burn, picking the best cruise altitude, understanding turbulence potential, and identifying icing levels. The forecast shows up as a four-digit group — the first two digits are direction in tens of degrees, the last two are speed in knots. Temperatures are included at most levels.

The Preflight Weather Brief

A complete preflight brief covers adverse conditions, the synoptic weather pattern, the en route forecast, winds and temperatures aloft, destination weather, and NOTAMs. You can get a standard briefing from 1800wxbrief.com through Leidos Flight Service, or through ForeFlight, Garmin Pilot, or similar applications.

Go/No-Go Decision Making

The best pilots don’t make binary decisions. They build decision trees. “If conditions at my destination are below minimums when I arrive, where will I divert, and do I have the fuel to get there?” Every flight plan should have that answer before you start the engine.

That’s what makes weather judgment something that develops over time — it’s not about memorizing products, it’s about knowing what they tell you and, just as importantly, what they don’t. A forecast is a probability. Always leave yourself an out.