A mid-level atmospheric disturbance that tracked across central California during the late afternoon and early evening of January 17th squeezed some drizzle out of the stratus, but the layer remained intact. The stratus persisted through the 18th before an upper-level trough brought some clearing to the west side of the San Joaquin Valley during the morning of January 19th. An offshore flow developed over California on the 20th, drying the airmass over the San Joaquin Valley and breaking up the stratus.
Although the fog and stratus kept central and southern San Joaquin Valley temperatures near or below normal, mountain and desert locations once again experienced above normal temperatures. Once the stratus broke up, central and south Valley temperatures also warmed to above normal for a few days before sufficient moisture had evaporated and resaturated the lowest levels of the atmosphere. While dense fog had been a nightly occurrence since January 21st, by the 24th, the fog was lingering well into the late morning with only partial afternoon clearing. Locations experienced near zero visibility at times during most of late January. This persistent dense fog continued for the next several days, affecting air travel into and out of the San Joaquin Valley and keeping high temperatures well below normal.

Dense Fog in W CENTRAL S.J. VALLEY, CALIFORNIA
From 25-JAN-11 20:00:00 to 26-JAN-11 13:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in E CENTRAL S.J. VALLEY, CALIFORNIA
From 25-JAN-11 20:00:00 to 26-JAN-11 13:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in SW S.J. VALLEY, CALIFORNIA
From 25-JAN-11 20:00:00 to 26-JAN-11 13:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in SE S.J. VALLEY, CALIFORNIA
From 25-JAN-11 20:00:00 to 26-JAN-11 13:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in W CENTRAL S.J. VALLEY, CALIFORNIA
From 24-JAN-11 20:00:00 to 25-JAN-11 13:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in E CENTRAL S.J. VALLEY, CALIFORNIA
From 24-JAN-11 20:00:00 to 25-JAN-11 13:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in SW S.J. VALLEY, CALIFORNIA
From 24-JAN-11 20:00:00 to 25-JAN-11 13:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in SE S.J. VALLEY, CALIFORNIA
From 24-JAN-11 20:00:00 to 25-JAN-11 13:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in SW S.J. VALLEY, CALIFORNIA
From 23-JAN-11 21:00:00 to 24-JAN-11 12:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in SW S.J. VALLEY, CALIFORNIA
From 21-JAN-11 22:00:00 to 23-JAN-11 12:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in SE S.J. VALLEY, CALIFORNIA
From 21-JAN-11 22:00:00 to 23-JAN-11 12:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in W CENTRAL S.J. VALLEY, CALIFORNIA
From 23-JAN-11 21:00:00 to 24-JAN-11 12:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in E CENTRAL S.J. VALLEY, CALIFORNIA
From 23-JAN-11 21:00:00 to 24-JAN-11 12:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in W CENTRAL S.J. VALLEY, CALIFORNIA
From 21-JAN-11 00:00:00 to 21-JAN-11 12:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in E CENTRAL S.J. VALLEY, CALIFORNIA
From 21-JAN-11 00:00:00 to 21-JAN-11 12:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in SE S.J. VALLEY, CALIFORNIA
From 21-JAN-11 00:00:00 to 21-JAN-11 12:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in W CENTRAL S.J. VALLEY, CALIFORNIA
From 21-JAN-11 22:00:00 to 23-JAN-11 12:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in E CENTRAL S.J. VALLEY, CALIFORNIA
From 21-JAN-11 22:00:00 to 23-JAN-11 12:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in SW S.J. VALLEY, CALIFORNIA
From 21-JAN-11 00:00:00 to 21-JAN-11 12:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in SE S.J. VALLEY, CALIFORNIA
From 23-JAN-11 21:00:00 to 24-JAN-11 12:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet