PHOENIX (3TV/CBS 5) – After a prolonged absence, the jet stream is buckling back into Arizona, bringing with it wetter and colder weather beginning late Thursday afternoon. A Winter Weather Advisory has been issued for the mountains above 6,000 feet in northern and eastern Arizona. The Sky Islands of southern Arizona are also included in that advisory. In the Valley, we expect rain to begin falling by around sunset on Thursday, although it could start a little earlier.