No injuries have been reported, but the fire has consumed two residences and five outbuildings, Snyder said. (Click here for update.)
The fire crossed into Mariposa County on Monday, Snyder said. Tuesday, it was moving east rather than southeast.
"This is a new development," he said.
The fire started Saturday afternoon in a remote area. The cause remains under investigation.
More firefighters from throughout the state have been dispatched to fight the blaze, which had grown to more than 16,200 acres as of 8:30 a.m. today.
A strike team from Stanislaus County that had been working the Bridges fire in Calaveras County has been redeployed to the Rim fire, Modesto Regional Fire Authority Division Chief Sean Slamon said. Another Stanislaus strike team left from Oakdale on Tuesday afternoon.
"Stanislaus County now has 10 engines battling that fire," Slamon said.
Highway 120 is closed from Smith Station to the west and four miles east of Buck Meadows, a small community that has been evacuated. Authorities aren’t allowing any westbound traffic out of Yosemite National Park.
Transportation officials had no estimate when Highway 120 might be reopened, but said it likely will be at least two days.
National Weather Service forecasters issued a red flag warning for lightning through Wednesday. Several strikes hit the area Monday night. Associated rain helped a bit, stopping the spread of the fire toward the incident command camp.
"We are expecting thunderclouds moving in again today," Snyder said Tuesday. "If it follows last night’s weather, then it’ll stay high in elevation, which is fine by us. There’s plenty of granite up there."
If the storm drops down to about 3,500 feet, however, that could create further problems for firefighters battling for the upper hand. “If those cells produce wind, that could be another problem for us,” Snyder said.
Breaking News Editor Patty Guerra can be reached at email@example.com or (209) 578-2343. Follow her on Twitter, @pattyguerra.