SIGMET & AIRMET phenomenon line
Phenomenon line: <FIR> <FIR NAME> FIR <criterion> <OBS/FCST> WI ... <vertical extent> <movement> <trend>=
| Field | Code | Meaning |
|---|---|---|
| Status | OBS (optionally OBS AT <hhmm>Z) |
Already observed |
| Status | FCST |
Expected, not yet observed |
| Vertical extent | FL<lower>/<upper> |
Layer, lower level first |
| Vertical extent | SFC/FL<nnn> |
Surface up to that level |
| Vertical extent | TOP FL<nnn> |
Cloud top only, no base |
| Trend | INTSF |
Intensifying |
| Trend | WKN |
Weakening |
| Trend | NC |
No change |
- Body ends with
=.
Trap: in a layer group the first flight level is always the LOWER one (FL190/340 = FL190 to FL340, not the reverse).
References
- TC AIM MET 5.8
- TC AIM MET 5.10
- TC AIM MET 5.16
- TC AIM MET 6.8
- TC AIM MET 6.10
- TC AIM MET 6.16