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Convective SIGMET — what is it and when is it issued?
maybe weather

Significant Meteorological advisory for aviation: - Severe thunderstorms / lines of thunderstorms / embedded storms - Hail ≥ ¾ inch, tornadoes - Issued by Aviation Weather Center, CONUS - Valid ~2 hours

If active in your area — do not fly.

weather/convective-sigmet ✎ edit content

METAR field order?
likely weather

Example: KDKB 151235Z AUTO 01011KT 10SM OVC110 02/M01 A3013 RMK AO2

  1. 🏷️ Station ID — KDKB
  2. 📅 Day + time Zulu — 151235Z (15th day, 12:35 UTC)
  3. 🤖 Modifier — AUTO (automated)
  4. 💨 Wind — 01011KT (from 010° true at 11 kt)
  5. 👁️ Visibility — 10SM (statute miles)
  6. ☁️ Weather / sky — OVC110 (overcast 11 000 AGL)
  7. 🌡️ Temp / dewpoint — 02/M01 (+2 °C / −1 °C)
  8. 📊 Altimeter — A3013 (30.13 inHg)
  9. 💬 Remarks — RMK AO2
weather/metar-order ✎ edit content

Cloud base estimate from temp/dewpoint spread?
likely weather

📐 Rule of thumb: cloud base (ft AGL) ≈ (T − Td) °C × 400

  • 🌡️ Worked example: temp 5 °C, dewpoint 2 °C → spread 3 °C → cloud base ≈ 1 200 ft AGL
  • 🛸 Part 107 needs 500 ft clearance below clouds. If cloud base < 900 ft AGL at your flight spot, you cannot fly.

METAR gives you T/Td as 02/M01 (M = minus). Compute the spread, multiply by 400.

weather/cloud-base-rule ✎ edit content