High pressure returned to California on February 10th, bringing warmer temperatures. Only patchy fog formed that night, and again the next night, mainly along the Highway 198 corridor between NAS Lemoore and Visalia.
A weak upper-level trough moved through California during the evening of February 11th and the morning of the 12th. An upper-level ridge built into California behind the trough, and persisted for several days. Widespread dense fog developed over the San Joaquin Valley during the early morning of February 15th, but was confined to an area from the Highway 198 corridor north. The southern boundary of the fog was sharp in spots. For example, while the visibility at the Visalia Municipal Airport dropped below a quarter mile, the visibility at the Tulare Municipal Airport was still a mile. Above the fog, there were areas of clouds that moved into the Sierra foothills near Mariposa. Locally dense fog shrouded the Mariposa-Yosemite Airport shortly after sunrise, with the AWOS at the airport reporting visibilities of less than a quarter mile through mid morning.
The fog did not redevelop during the morning of February 16th, as an upper-level trough moved through California and brought mixing to the airmass. Dense fog reported only in the Hanford-Lemoore and Merced-Atwater areas. Dense fog was more widespread the following morning, pushing south northern Kern County.

Dense Fog in SE S.J. VALLEY, CALIFORNIA
From 19-FEB-10 01:00:00 to 19-FEB-10 10:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in E CENTRAL S.J. VALLEY, CALIFORNIA
From 19-FEB-10 01:00:00 to 19-FEB-10 10:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in SW S.J. VALLEY, CALIFORNIA
From 19-FEB-10 01:00:00 to 19-FEB-10 10:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in SE S.J. VALLEY, CALIFORNIA
From 15-FEB-10 06:00:00 to 15-FEB-10 08:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in SW S.J. VALLEY, CALIFORNIA
From 17-FEB-10 23:00:00 to 18-FEB-10 07:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in SE S.J. VALLEY, CALIFORNIA
From 17-FEB-10 23:00:00 to 18-FEB-10 07:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in E CENTRAL S.J. VALLEY, CALIFORNIA
From 15-FEB-10 02:00:00 to 15-FEB-10 10:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in SW S.J. VALLEY, CALIFORNIA
From 15-FEB-10 07:00:00 to 15-FEB-10 10:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in SE S.J. VALLEY, CALIFORNIA
From 17-FEB-10 03:00:00 to 17-FEB-10 09:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in E CENTRAL S.J. VALLEY, CALIFORNIA
From 17-FEB-10 23:00:00 to 18-FEB-10 07:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in E CENTRAL S.J. VALLEY, CALIFORNIA
From 17-FEB-10 04:00:00 to 17-FEB-10 09:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in SW S.J. VALLEY, CALIFORNIA
From 17-FEB-10 02:00:00 to 17-FEB-10 09:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet