Which location and altitude forecast includes a temperature of -4°C with a wind of 230° true at 21 knots?

• A. DEN at 9,000 feet
• B. STL at 9,000 feet
• C. MKC at 6,000 feet
• D. STL at 12,000 feet

Answer: (A)

Interpreting winds aloft forecasts involves reading the temperature at a given altitude and the wind that accompanies that altitude, using true wind direction and speed. The forecast line for Denver at 9,000 feet shows a temperature of -4°C and a wind from 230° true at 21 knots. The temperature at 9,000 feet in ISA is about -3°C, so -4°C is plausible for a slightly cooler air mass, and the wind from 230° at 21 knots is a southwest breeze at that height. This combination matches the specified values, which is why the Denver forecast at 9,000 feet is the correct choice. The other options either have different altitudes or show different temperatures or wind directions/speeds that don’t align with -4°C and 230° true at 21 knots.