The fire grew by about 150,000 acres since Wednesday morning, when it was reported to be at around 19,000 acres.

By Thursday evening, the blaze expanded to about 170,000 acres, becoming the second largest wildfire by acreage in Colorado history, according to the Rocky Mountain Area Coordination Center and Colorado State Forest Service.

“Obviously yesterday [Wednesday] was a significant fire day. We saw about 20 miles of fire growth through the afternoon and into the night, which equates to about 100,000 acres of additional fire activity,” Noel Livingston, the incident commander of the East Troublesome Fire, said at a Thursday briefing.

“That’s really unheard of for a fire in this part of the world, in timber,” he added.

Grand County Sheriff Brett Schroetlin said: “We prepare for the worst. This is the worst of the worst of the worst.”

In addition to the East Troublesome blaze, there are five other large active fires in Colorado, which have collectively burned 232,358 acres so far, according to the latest report Thursday by the National Interagency Fire Center.

Here are some of the latest updates on the current fires across Colorado.

East Troublesome Fire

Size: 170,163 acres. Containment: 5 percent. Location: Grand County.

“Extreme fire behavior continues into the evening [Thursday] and continues to burn active in upper elevations through the night. Fire continues to move east, north, and south. Moderate to large growth can be expected and impacts to highway 40 can be expected,” the NWCG noted Thursday.

A Red Flag Warning in effect for Friday, with west winds 15 to 20 miles per hour (mph) expected, along with gusts of 30 to 40 mph. “High winds will continue on Saturday, predicting WSW [west southwest winds] 20-25 with gusts of 35 to 45 mph. Snow showers are predicted overnight on Saturday,” the NWCG warned.

New evacuation orders were issued for the area north of the town of Granby as well as the area south of Highway 40 around County Road 57 “due the growth and close proximity of the East Troublesome Fire,” the Grand County Office of Emergency Management noted Thursday.

The Grand County Sheriff’s Office also issued pre-evacuation orders, warning residents to prepare for a potential evacuation, for the Granby Ranch and Tabernash area as well as the area stretching from Grand Elk to Hot Sulphur Springs, County Road 55 to County Road 88.

See the website of the Grand County Office of Emergency Management for more information on the latest evacuations.

Cameron Peak Fire

Size: 206,977 acres. Containment: 57 percent. Location: Larimer County.

The Cameron Peak Fire, the current largest wildfire in Colorado history, saw increased activity Thursday. The East Zone of the fire was reported to be at 1,200 acres, according to the latest NWCG report Thursday.

Crews were reported to have made “good progress on strengthening containment lines and reinforcing lines around structures.

“Firefighters reported areas of fog along Buckhorn Road/ 44H. Tonight [Thursday] there were reports of black ice developing on the roads as the night shift was heading to the line,” according to the NWCG report.

Fears were raised over the possibility of the East Troublesome Fire merging with the Cameron Peak Fire.

Livingston warned Thursday: “It is a potential, and certainly this year has been one of those years where those low potential events seem to be happening with high frequency.”

Williams Fork Fire

Size: 14,670 acres. Containment: 30 percent. Location: Grand County.

The Williams Fork Fire was expected to see continued short range spotting and single tree torching on Thursday, with periodic heavy smoke visible, according to the latest report Thursday by the NWCG.

“Air support will continue dropping water in the northwest portion of the fire to keep it in check. Sprinkler systems and hose lays remain in place. Monitoring continues along the unsecured edge near Jones Pass,” the report said.

No evacuation orders or pre-evacuation warnings are in effect.

Other fires

Calwood Fire, Boulder County (10,073 acres; 55 percent contained). Ice Fire, Silverton (596 acres; 30 percent contained). Lefthand Canyon Fire, Boulder County (460 acres, 100 percent contained).