Weather & Charts Cheat Sheet
Reading a surface observation
Reading a terminal forecast
20012KT P6SM SCT040
FM111800 22015G25KT P6SM SCT025
Airspace classes at a glance
| Class | Sectional symbol | sUAS requirement |
|---|---|---|
| B | Solid blue, tiered rings | ATC authorization required (LAANC where available) |
| C | Solid magenta rings | ATC authorization required |
| D | Dashed blue circle | ATC authorization required |
| E surface area | Dashed magenta | Authorization required only where surface-based |
| G | No boundary shown | No authorization required (still check TFRs/NOTAMs) |
Obstacle elevation figures
Top number = MSL height of the obstacle. Number in parentheses = AGL height. Always check the AGL figure against your 400 ft ceiling and any required clearance.
Front symbols
Sky cover progression
A ceiling is defined as the lowest BKN or OVC layer (or vertical visibility into an obscuration) — not any FEW/SCT layer.
Two shapes worth recognizing on sight
Decoding an FD group
2113 2721+08 2532+03
2721+08 at 6,000 ft → first two digits (27) = direction ×10 = 270°, next two (21) = speed in knots, last figure = temperature °C (a "+" is shown only below 24,000 ft).
Why hot + high hurts performance
Higher density altitude = thinner effective air = less lift and thrust for the same rotor RPM, harder-working motors, and shorter available flight time. Worth checking on hot days at higher-elevation sites.
Smooth vs. scalloped boundaries
Reflectivity color scale
Green (light) → yellow/orange (moderate-heavy) → red/purple (extreme). A dark red/purple core marks the most likely location of severe turbulence, hail, and lightning — stay well clear.
Which product covers which hazard
| Product | Covers |
|---|---|
| AIRMET Sierra | Widespread IFR and/or mountain obscuration |
| AIRMET Tango | Turbulence and sustained strong surface winds |
| AIRMET Zulu | Icing and freezing levels |
| Convective SIGMET | Severe thunderstorm lines (60+ mi, 40%+ coverage), 3/4" hail, 50+ kt gusts, or tornadoes |
Reading speed from a barb
Temporary Flight Restrictions
TFRs apply to all aircraft, including sUAS, within the stated lateral radius and vertical limits during the effective window — flying inside without specific authorization is a violation no matter how low you stay. Always check NOTAMs (e.g. via B4UFLY or the FAA's TFR list) before flying.
Military Operations Areas
Magenta hatched boundary. MOAs don't require ATC authorization by regulation, but they carry high-speed military traffic — check the charted floor against your altitude and scan NOTAMs for exceptions.
The RMK section can hide the real story
PK WND 25045/1638 — a peak wind of 250° at 45 kt occurred at 1638Z, even if the main body's wind group looks calm. Always scan remarks for peak wind, pressure tendency, and precipitation notes before trusting the headline numbers.
Compass rose with ID box
Marks a VOR ground station and frequency. sUAS don't navigate by VOR, but recognizing the symbol helps you understand where manned traffic concentrates along victor airways.
Trapped air near the surface
A surface-based inversion (temperature rising with height near the ground) caps vertical mixing, trapping haze, fog, or smoke close to the surface — often clearing once the sun heats the ground and breaks the cap. Visibility can erode even when the METAR still looks workable.