Dense Fog in Central Deserts, Arizona

A wet Pacific weather system produced significant rain across the central deserts on January 31st and then exited to the east. Ample lingering low level moisture combined with clearing skies and light winds to produce areas of dense fog across much of northwest Pinal county during the morning hours on February 1st. According to the official weather station at Casa Grande Airport, visibility dropped to one quarter mile at 0435MST as a result of the dense fog. As late as 1023MST a trained spotter 4 miles east of Sun Lakes estimated visibility below one half mile in dense fog. The dense fog created very hazardous driving conditions and a Dense Fog Advisory was in effect for the central deserts through 1200MST.

A very wet Pacific weather system brought significant precipitation to Arizona on Friday January 31st and then moved off to the east. Ample lingering surface based moisture combined with clearing skies and light winds to produce widespread dense fog across south central Arizona. Many locations from Globe westward to Gila Bend reported visibilities at or below one quarter of a mile; in many cases visibility dropped to near zero miles for several hours. Many airports in the greater Phoenix area, including Phoenix Sky Harbor Airport, were negatively impacted by dense fog and low visibility. Dense Fog Advisories were issued for south central and southwest Arizona starting early in the morning and continuing through noon.