The Mosquito Fire, now burning for a week in Placer and El Dorado counties, quickly overtook the SoCal Fairview Fire as the largest fire currently burning in the state, and as of this morning reached 49,761 acres. But a favorable shift in the weather is at least helping the firefight.

"Thick smoke and clouds kept temperatures in the 70s to low 80s with higher relative humidity values throughout Monday," says Cal Fire in a Tuesday morning report. "An incoming weak weather system is forecasted to bring slightly stronger southwest winds that will bring drier air aloft today. This air movement should help break up the smoke inversion earlier today."

But, they add ominously, "The increase in clearer skies is projected to provide the fire with more available oxygen for active burning."

The Mosquito Fire reached 18% containment as of Tuesday morning, up from 16% a day earlier, but continues burning on two fronts. The eastern front covers a wide swath of the Sierra about 30 miles due west of Lake Tahoe, with many hotspots ablaze. On the western front, only a few hot spots remained Tuesday southeast of Todd Valley, with containment increasing near the slightly more populous area of Foresthill. KCRA has a story about a small, family-owned grocery store in that town that is behind the fire lines, but has remained open in order to serve firefighters and first responders on the front lines.

Map via #FireMappers

"Overnight, firefighters continued strengthening and securing control lines around most of the fire’s perimeter," Cal Fire reports. "Crews added containment on a large portion of the fireline in the Michigan Bluff area and continue to make great strides towards completing more containment lines all along the Foresthill Road corridor. Firefighters are remaining vigilant on the southern edge of the fire to ensure that there is no threat of escape across Volcanoville Road or towards Quintette."

Air quality has improved in the Tahoe Basin, however the air is still dangerous to breathe in a wide swath of the state northeast of Sacramento and into northern Nevada.

The fire so far has destroyed at least 46 structures and damaged five others, but damage assessments this early are typically low.

In this new interactive feature from Sunday, the New York Times reported that "some homes" have been destroyed in the Mosquito Fire, but some 5,800 structures remain under threat.

The Times notes that "Despite launching an all-out attack against the Mosquito Fire when it first spread, firefighters made little progress until days later, when temperatures dropped."

The fire broke out last Tuesday, September 6, amid the statewide heatwave, near OxBow Reservoir, east of Foresthill. Its cause remains under investigation.

Previously: Mosquito Fire Grows to Over 33,000 Acres, Becomes Largest CA Wildfire (So Far) This Year