METAR present weather group grammar
Group format: 2 to 9 characters = intensity or proximity qualifier + descriptor + phenomenon. As many groups as needed per METAR (TAF caps at three).
Intensity (overall group intensity, not one ingredient of a mix):
| Code | Meaning |
|---|---|
- |
Light |
| none | Moderate |
+ |
Heavy |
Proximity: VC = observed within 5 SM of station, not at it.
- Only with
SH,FG,FC,+FC,TS,BLSN/BLDU/BLSA,PO,DS,SS.
Descriptor (max one per group):
| Code | Meaning | Combines only with |
|---|---|---|
MI |
Shallow | FG |
BC |
Patches | FG |
PR |
Partial | FG |
DR |
Drifting | SN, DU, SA |
BL |
Blowing | SN, DU, SA |
SH |
Shower | RA, SN, GR, GS |
FZ |
Freezing | DZ, RA, FG |
TS |
Thunderstorm | alone, or one or more precipitation types (MET 8.2) |
TSandSHnever combine.
Precipitation:
| Code | Meaning |
|---|---|
DZ |
Drizzle |
RA |
Rain |
SN |
Snow |
SG |
Snow grains |
IC |
Ice crystals |
PL |
Ice pellets |
GR |
Hail |
GS |
Snow pellets |
UP |
Unknown precipitation type (AWOS only) |
Other:
| Code | Meaning |
|---|---|
PO |
Dust/sand whirls |
SQ |
Squall |
FC |
Funnel cloud |
+FC |
Tornado or waterspout |
SS |
Sandstorm |
DS |
Dust storm |
Examples: +TSRA thunderstorm with heavy rain. MIFG shallow fog. -SHRA light rain showers.
Combining and separating groups (MET 8.2):
| Situation | Coding |
|---|---|
| Several precipitation types | One group: predominant first, intensity overall |
Freezing precipitation (FZRA, FZDZ) |
Exception: always its own separate group |
| Blowing snow with snow | Two groups, e.g. SN BLSN |
| Obscuration with precipitation | Its own separate group |
Special cases (MET 8.2):
SHGSambiguous: snow-pellet showers or small hail (small-hail size: see precipitation-type-definitions). If small hail: diameter in remarks, CB usually present.- Thunderstorm over = last thunder heard + 15 minutes, no further thunder.
- Funnel cloud, tornado, waterspout: coded in present weather, also written in full in remarks.
Trap: descriptor paired with wrong phenomenon family (DRFG, BLDZ, MIRA, TSSH).
References
- TC AIM MET 8.1 (Table 8.1, Significant Present Weather Codes)
- TC AIM MET 8.2 (groups, thunderstorm end)
- TC AIM MET 7 (TAF: three significant weather groups)