Why must the forecast wind direction be drawn against the actual route?
Short answer
It shows where shelter ends and where the same wind can create drift away, a lee shore, difficult entry, opposing-stream sea or a harder return
Wind direction is named from where the air comes and gains meaning through the coastline, route, stream and return. The other models reverse the wind, exempt powered craft or treat direction as a substitute for local evidence. Draw it at each route gate and revise Wind Direction and Exposure.
Quick check
Why must the forecast wind direction be drawn against the actual route?