Upper level ANAL & PROG charts
Upper level charts plot fixed pressure levels, not fixed altitudes. ANAL and PROG look alike: check label for type, date, valid time.
| Type | Shows | Levels | Timing | Cite |
|---|---|---|---|---|
| ANAL (analyzed) | Past conditions | 850, 700, 500, 250 hPa | Observed 0000Z and 1200Z daily; issued over 3 hr after observation | TC AIM MET 3.3 Table 3.3 |
| PROG (prognostic) | Forecast conditions | FL240, FL340, FL390, FL450 | Specific future time; issued 12 hr before valid time; valid 0000Z, 0600Z, 1200Z, 1800Z | TC AIM MET 11.0; MET 3.1 Table 3.1 |
Standard pressure levels (lower pressure = higher up):
| Level | Altitude |
|---|---|
| 850 hPa | 1,500 m / 5,000 ft |
| 700 hPa | 3,000 m / 10,000 ft |
| 500 hPa | 5,500 m / 18,000 ft |
| 250 hPa | 10,400 m / 34,000 ft (near tropopause) |
Upper Level Forecast Chart (PROG): WAFC graphical product, forecast wind and temperature (MET 3.1 Table 3.1, MET 11.2).
- Issuer: world area forecast centre (WAFC), via U.S. National Weather Service, Washington, D.C.
Chart symbols:
| Item | Symbol | Value |
|---|---|---|
| Wind direction | Arrow shaft | Degrees true (not magnetic) |
| Wind speed (barbs) | Pennant | 50 kt |
| Wind speed (barbs) | Full feather | 10 kt |
| Wind speed (barbs) | Half feather | 5 kt |
| Temperature | Bold, fixed grid points for chart level | °C; always negative unless otherwise noted |
Use:
- With FD (upper level wind and temperature forecast) and SIGWX charts: find wind shear and probability of clear air turbulence (CAT) at a point.
- Wind speed normally highest at tropopause, decreasing at fairly constant rate above and below: shows where CAT risk peaks.
Trap: ANAL chart shows the past, not the present; PROG shaft direction true, not magnetic; temperature negative unless noted, not positive.
References
- TC AIM MET 3.1 Table 3.1
- TC AIM MET 3.3 Table 3.3
- TC AIM MET 11.0
- TC AIM MET 11.2