Gusts, squalls and wind shifts
| Phenomenon | Source | Criterion | Cite |
|---|---|---|---|
| Gust | General | varies 10 kt or more | FAA AWH 10.7.2 |
| Gust | TAF | G + peak when forecast to exceed mean by 10 kt or more |
TC AIM MET 7.3 |
| Gust | METAR | 5-sec average exceeds mean by 5 kt or more in previous 10 min, and peak 15 kt or more | TC AIM MET 8.1 Wind (a) |
| Variable wind | METAR | variation group when direction varies 60 deg or more and less than 180 deg in previous 10 min, and mean speed exceeds 3 kt | TC AIM MET 8.1 Wind (b) |
| Variable wind | TAF | VRB normally only when speed 3 kt or less |
TC AIM MET 7.3 |
- Gust: wind speed varies between peaks and lulls.
- Variable wind: changes direction frequently.
Other:
- Squall: code SQ (TC AIM MET 8.1, Table 8.1).
- Sudden wind shift: line or narrow zone with abrupt direction change. Either, even at low wind speed, can turn headwind into crosswind or tailwind (FAA AWH 10.7.4).
Trap: SQ is the squall code in the significant weather group.
References
- FAA Aviation Weather Handbook (FAA-H-8083-28) 10.7.2
- FAA Aviation Weather Handbook (FAA-H-8083-28) 10.7.4
- FAA Aviation Weather Handbook (FAA-H-8083-28) 7358 (weather code table)
- FAA Aviation Weather Handbook (FAA-H-8083-28) 7434 (hail GR)
- TC AIM MET 7.3
- TC AIM MET 8.1