Refer to Figure 17. For STL, the winds and temperatures aloft forecast at 12,000 feet is "2339-04". Decode it.

Choices

• ✓ Wind from 230° true at 39 knots, temperature −4°Ccorrect

  The first two digits are direction in tens (230°), the next two are speed (39 kt), and −04 is the temperature in Celsius.

• Wind from 233° at 9 knots, temperature +4°C

  Direction is the first two digits ×10 (230°) and speed is the next two (39 kt); the temperature is negative.

• Wind from 023° at 39 knots, temperature −4°C

  The direction group "23" means 230 degrees, not 023.

• Wind from 230° at 39 knots, temperature +4°C

  The header notes temperatures are negative; here it is explicitly −04, i.e. −4°C.