Kirk,
The wind is always coming from 045 degrees, but if you imagine yourself in a plane sitting on runway 27, facing 270 degrees; 50% of the wind would be classified as tail wind and 50% classified as cross wind, but would still be called 045 deg @ 4 kts. If the wind was coming from 360 (or 0?), it would be 100% crosswind, if from 090, it would be 100% tailwind.
Gonzo - thanks for the confirmation
cj