The Collaborative International Dictionary of English v.0.48:
Northwesterly \North`west"er*ly\, a. Toward the northwest, or from the northwest. [1913 Webster]WordNet (r) 3.0 (2006):
northwesterly adj 1: coming from the northwest; "northwesterly winds" [syn: northwesterly, northwest] 2: situated in or oriented toward the northwest [syn: northwestern, northwesterly, northwest]