SCU Lightning Complex fires reach 374,000+ acres, 40% containment

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The large wildfires raging south of the Tri-Valley in seven different counties continued slight growth during the day to more than 374,000 acres while containment increased to 40%, according to Cal Fire’s evening update on Friday.

Weather conditions, including a morning marine layer and more favorable winds, aided the firefighting effort in the 12th day of the SCU Lightning Complex, though some evacuation orders and warnings remain in effect, including a longstanding warning for rural unincorporated Tri-Valley to the far south and east.

Originally 20 different vegetation fires ignited by lightning on Aug. 16, the SCU Lightning Complex now consists mainly of one large wildfire — after other fires merged last weekend — that is broken into two branches. This fire, and others raging in other parts of Northern California, are causing the smoky skies and poor air quality in the Bay Area.

As of Friday evening, the SCU Lightning Complex stood at 374,471 acres in mainly rural vegetative land in parts of Alameda, Contra Costa, Santa Clara, San Joaquin, Stanislaus, Merced and San Benito counties, according to Cal Fire.

Five injuries have occurred so far — three first-responders and two civilians. In total, 28 buildings and 20 minor structures were destroyed, nine other structures were damaged and another 20,065 structures remained under threat.

Containment, which was difficult to come by during the first week but improved as more favorable weather conditions arrived starting Monday, increased by 5% to 40% overall as of Friday evening.

Nearly 2,000 personnel were assigned to the SCU Lightning Complex.

“Slow progress is being made for firing operations in heavy dense brush fields that have had no recorded burn history,” Cal Fire stated Friday evening. “An abundant amount of large diameter trees, that have been fire weakened, continue to release resulting in blocked roadways, rollout into the bottoms of the drainages, and deep-seated stump holes with extreme heat in them.”

“Temperatures ranged from the mid-80s to mid-90s across the fire today with humidity values ranging from 15-25%. Winds remained light from the west to southwest, however transport winds had an easterly component that brought some of the smoke back westward over the Santa Clara Valley,” according to Cal Fire.

“For tonight, the main concerns will be poor nighttime humidity recovery above 2,000 feet as the marine layer surges into the Santa Clara Valley. Overnight lows of 65-75 degrees above 2,000 with poor humidity recovery 20%-35%. No big weather changes Saturday. A warming trend starts Sunday and lasts through next week as strong high pressure builds with hot temperatures and low humidity,” Cal Fire officials added.

As of Friday evening, the evacuation warning for rural unincorporated Tri-Valley to the south and east still remained in effect due to potential fire danger.

The warning applied generally south of Interstate 580 and east of Highway 84. It excluded the cities of Pleasanton and Livermore, as well as some more-populated unincorporated areas.

The evacuation warning area for unincorporated parts of the Tri-Valley (“Zone 15A”) includes south of Tesla Road, south of the Livermore city limits (excluding the cities of Livermore and Pleasanton); south of Highway 84 in between Vineyard Avenue and I-680; south of I-680 to the fire perimeter and the Alameda/Santa Clara county line; and west of the Alameda/San Joaquin county line to the Livermore city limits to Calaveras Road.

It also includes north of the fire perimeter and the Alameda/Santa Clara county lines to Highway 84 to the Livermore city limits to I-580.

Evacuation warning Zone 15B is south of Welch Creek Road to the fire perimeter and the Alameda/Santa Clara county line; and east of Calaveras Road at Welch Creek Road to the fire perimeter.

The warning zones do not include the incorporated cities of Livermore or Pleasanton, as well as some unincorporated areas in Pleasanton close to the city such as Happy Valley, Castlewood and Foothill Road. Additionally, the warning zone does not include anything north of I-580 such as Dublin or west of I-680 such as parts of Pleasanton.

The only evacuation order areas in Alameda County were Zone 12 (all of Mines Road, south of mile marker 10 to the county line) and Zone 15F (south of fire perimeter to the Alameda/Santa Clara county line).

Evacuation information related to the SCU Complex fires can be found on the Cal Fire website.