An upper-level short-wave moved through the Pacific Northwest and northern California on February 5th. The short-wave brought breezy conditions to the region and generated enough mixing to keep fog development from becoming as widespread as on the previous days.
High temperatures had been near normal under the ridge, except for above-normal temperatures on the 1st, but the short-wave brought a push of cold air into the central California interior. The high at Fresno on February 6th was 52 degrees, 12 degrees cooler than the previous day. The high at Bakersfield on the 6th of 61 degrees was down 10 degrees from the 5th.
The upper-level ridge rebounded on February 6th, with some San Joaquin Valley fog redevelopment. The ridge was short-lived, however, giving way to the first Pacific storm of the month the next day.
Precipitation associated with this storm reached the central California interior during the afternoon of February 7th, spreading south during the evening hours. This was a cold system, and snow levels fell to 2500-3000 feet on the 8th. By midday on the 8th, a few mountain roads were closed due to snow and ice. That afternoon, ice pellets or small hail fell on Visalia and near Tipton. Interstate 5 over the Grapevine was closed by late afternoon due to snow, but reopened by late evening. Shortly after midnight, Highway 33 was closed due to snow and ice, and did not reopen until the late morning of February 9th. There were several reports of snow accumulations of 3-7 inches in the Southern Sierra Nevada, and 1-3 inches in the Tehachapi Mountains. Below the snow line, rainfall amounts in the mountains and foothills ranged from a few hundredths to around an inch, and on the San Joaquin Valley floor, the Visalia Municipal Airport had the highest rainfall with 0.66 inch, while rain-shadowed Los Banos only received 0.01 inch.
The storm brought more cold air into the region. Lows in the central and southern San Joaquin Valley on the morning of February 9th were in the upper 20s to mid 30s, and with even lower minimum temperatures forecast the next two nights, a Freeze Warning was in place for the San Joaquin Valley for the mornings of the 10th and 11th.
Only a few central and southern San Joaquin Valley sites dropped below 28 degrees on the morning of February 10th, and the majority of these were on the west side of the Valley. Stratus formed along the lower elevations of the Southern Sierra Nevada on the 9th, and a light easterly wind pushed the stratus over parts of the San Joaquin Valley overnight. This inhibited radiational cooling over the eastern San Joaquin Valley, resulting in stronger cooling on the west side where skies remained mostly clear. Skies were clearer on the early morning of February 11th, but dewpoints were higher due to evaporation of standing water on the San Joaquin Valley floor. The higher dewpoints capped the cooling during the night of the 10th-11th, and only a few sites in the central and southern San Joaquin Valley fell to 28 degrees or lower.
Aloft, the ridge became tilted, nosing into the Pacific Northwest. At the same time, the upper- level trough extended southwest from a low over southern Minnesota to Utah and eastern Nevada. This set up a northeasterly flow over the Southern Sierra Nevada. At the surface, the combination of high pressure centered over southeastern Idaho and low pressure over the lower Colorado River generated an offshore flow across California. Although this had been expected to trigger downslope winds through the west-facing canyons of the Southern Sierra Nevada, the upper-level jet stayed north of the region. Winds remained mostly light with a few strong gusts confined to the crest.
The upper-level ridge began to build into California on February 11th. Temperatures warmed to near normal on the 11th, then continued to warm above normal the next few days. A few patches of fog formed around sunrise in the central and southern San Joaquin Valley, but they were relatively shallow and short lived.

Winter Weather in KERN CTY MTNS, CALIFORNIA
From 08-FEB-13 08:00:00 to 08-FEB-13 20:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in S SIERRA MTNS, CALIFORNIA
From 08-FEB-13 08:00:00 to 08-FEB-13 20:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in TULARE CTY MTNS, CALIFORNIA
From 08-FEB-13 08:00:00 to 08-FEB-13 20:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Frost/Freeze in W CENTRAL S.J. VALLEY, CALIFORNIA
From 10-FEB-13 05:00:00 to 11-FEB-13 07:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Frost/Freeze in E CENTRAL S.J. VALLEY, CALIFORNIA
From 10-FEB-13 05:00:00 to 11-FEB-13 07:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Frost/Freeze in SW S.J. VALLEY, CALIFORNIA
From 10-FEB-13 05:00:00 to 11-FEB-13 07:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Frost/Freeze in SE S.J. VALLEY, CALIFORNIA
From 10-FEB-13 05:00:00 to 11-FEB-13 07:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Frost/Freeze in W CENTRAL S.J. VALLEY, CALIFORNIA
From 12-FEB-13 02:00:00 to 12-FEB-13 05:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Frost/Freeze in E CENTRAL S.J. VALLEY, CALIFORNIA
From 12-FEB-13 02:00:00 to 12-FEB-13 05:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Frost/Freeze in SW S.J. VALLEY, CALIFORNIA
From 12-FEB-13 02:00:00 to 12-FEB-13 05:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Frost/Freeze in SE S.J. VALLEY, CALIFORNIA
From 12-FEB-13 02:00:00 to 12-FEB-13 05:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dense Fog in W CENTRAL S.J. VALLEY, CALIFORNIA
From 07-FEB-13 05:00:00 to 07-FEB-13 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 07-FEB-13 05:00:00 to 07-FEB-13 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 07-FEB-13 05:00:00 to 07-FEB-13 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 07-FEB-13 05:00:00 to 07-FEB-13 10:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet