Boundary layer moisture remained elevated across the central deserts during the morning hours on December 11th following the passage of a wet winter storm system. As skies cleared and winds became light, the high humidity allowed for the formation of dense fog in portions of the greater Phoenix area, from the west valley southeastward and into the town of Maricopa. More than one trained spotter reported dense fog with visibility below one quarter of a mile; a spotter near the town or Maricopa reported visibility down to 100 feet as seen in a picture. Additionally, the official AWOS weather station at the Goodyear airport measured a visibility to one quarter of a mile at 0605MST. There were no reports of accidents due to the sharply reduced visibilities.

Dense Fog in NORTHWEST PINAL COUNTY, ARIZONA
From 11-DEC-20 05:00:00 to 11-DEC-20 10:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Humidity in the low levels remained high following the passage of a wet Pacific weather system and as skies cleared and winds became light, conditions became favorable for the formation of dense fog. According to trained spotters across northwest Pinal County, dense fog developed during the morning hours on December 11. At 0512MST a spotter 7 miles south of Sacaton reported that visibility had fallen to 100 yards or less in dense fog. Later in the morning at 0856MST, another spotter located 1 mile west of the town of Maricopa reported visibility down to 100 feet as seen in a photo taken by the spotter. A Dense Fog Advisory had been issued at 0505MST and was in effect at the time of the dense fog reports. There were no reports of accidents due to the sharply reduced visibility.

Dense Fog in SOUTH MOUNTAIN/AHWATUKEE, ARIZONA
From 11-DEC-20 05:00:00 to 11-DEC-20 10:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Low level  humidity remained high following the passage of a wet Pacific weather system and as skies cleared and winds became light, conditions became favorable for the development of dense fog across the central portions of the greater Phoenix area on December 11th. According to a trained weather spotter located 6 miles southeast of the Ahwatukee Foothills, at 0532MST dense fog formed with visibility lowering below one quarter of a mile. A Dense Fog Advisory was issued for the area at 0505MST and it remained in effect through 1000MST. There were no reports of any accidents due to the sharply reduced visibility and associated hazardous driving conditions.

Dense Fog in BUCKEYE/AVONDALE, ARIZONA
From 11-DEC-20 05:00:00 to 11-DEC-20 10:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Low level humidity remained high across western portions of the greater Phoenix area following the passage of a wet Pacific weather system. As skies cleared and winds became light, conditions became favorable for the formation of dense fog in the Goodyear / Avondale areas. At 0605MST the official AWOS weather station at the Goodyear airport measured a visibility to one quarter of a mile in dense fog. A Dense Fog Advisory had been issued for the area at 0505MST and it remained in effect through 1000MST.