Dense Fog in Greater Phoenix Area, Arizona

A wet Pacific low pressure system moved across the central Arizona deserts on January 31st and then exited to the east. Ample lingering surface moisture combined with light wind and clearing skies to allow for widespread dense fog across the greater Phoenix area during the morning hours on February 1st. Many locations, including a number of local airports, reported dense fog with visibility at or below one quarter mile for several hours or more during the morning. At 0355MST, both the KIWA and the Buckeye airports reported visibility at one quarter mile in dense fog. At 0522MST, visibility at Phoenix Sky Harbor Airport lowered to one quarter mile, and stayed there for several hours, severely disrupting air traffic and forcing a number of delays and diversions. This was a major problem due to the fact that February 1st was Super Bowl Sunday and as a result air travel into the airport on the morning before the game was at near record levels. Additionally, the dense fog created very hazardous driving conditions for motorists arriving at or leaving the various airports around the greater Phoenix area. The dense fog persisted into the late morning; at about 1000MST a trained spotter 3 miles northwest of Goodyear estimated visibility below one quarter mile in dense fog and at 1016MST a trained spotter 2 miles northwest of the Arizona State Fairgrounds estimated visibility down to one fifth of a mile.

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.