Nearly 1,500 firefighters fought Thursday to contain the Spring Creek fire in southern Colorado — which had swelled to 103,357 acres by morning — as a flash flood watch was issued for the area in the afternoon and evening.

Containment of the fire near Fort Garland and La Veta leapt from 5 percent to 35 percent Thursday.

RELATED: [INTERACTIVE MAP] Active wildfires in Colorado

The rain in the forecast over parts of Colorado promised some relief for firefighters but threatened to trigger flash floods on erosion-prone hillsides where trees and bushes have burned up.

As temperatures from the fires increase, the soil cannot absorb rainwater, causing it to run off and increase the possibility of a flash flood occurring, said Kathy Torgenson, a meteorologist for the National Weather Service in Pueblo.

“When the fire burns really hot, it causes the soil to become hydrophobic,” Torgerson said. “The hotter the fire burns, the more it changes that soil’s ability to absorb water.”

RELATED: [INTERACTIVE MAP] Active wildfires in Colorado

Mark Wankowski, another weather service meteorologist, said even a little rain can cause flooding on a burn scar.

The battle against the “double-headed dragon” of a blaze, as some locals were calling it, was divided into north and south sections led by separate incident management teams.

It has destroyed 132 homes, seven garages and two other structures in the Forbes Park neighborhood in Costilla County, San Luis Valley emergency officials said Thursday evening.

It also damaged three homes, one garage and a deck.

The Spring Creek fire began June 27 from what investigators believe was a spark from a fire pit but quickly took off and hasn’t stopped growing. No injuries or fatalities have been reported.

Jesper Jorgenson, 52, a Danish man in the country illegally was arrested Saturday on suspicion of starting the blaze.

An erratic wildfire charging through extremely dry land near the small community of Basalt in Eagle County destroyed three homes and forced people to flee in the middle of the night. The Lake Christine fire grew rapidly after starting Wednesday, reaching 5,263 acres by Thursday afternoon with zero percent containment.

RELATED: [INTERACTIVE MAP] Active wildfires in Colorado

As of Thursday, about 2,000 people had been forced to evacuate, the Eagle County Sheriff’s Office said. No injures were reported. Smoke from the fire temporarily halted flights at Aspen’s airport about 20 miles away.

A man and woman allegedly started the blaze by firing tracer rounds Tuesday night at a shooting range in violation of a fire ban. Allison Marcus, 22, and Richard Miller, 23, both of El Jebel, were cited on suspicion of misdemeanor counts of arson, The Denver Post reported.

A tornado touched down Thursday afternoon at the edge of the Weston Pass fire, a doubly rare event that resulted in crews leaving the line for safety reasons. Trees reportedly were uprooted, but no one was injured.

National Weather Service meteorologist Russell Danielson said tornadoes are rare at that elevation and rare at any wildfire. Danielson says it’s only the sixth tornado recorded in Park County since record-keeping began in the 1950s.

The Weston Pass fire, which was set off by a lightning strike June 28 near Fairplay, had burned 12,902 acres as of Thursday night. It was 17 percent contained, and nearly 600 people worked to suppress it.

It moved into Buffalo Peaks Wilderness area, prompting the closure of U.S. Forest Service land south of County Road 22, north of Trout Creek Pass and west of U.S. Highway 285, the Forest Service announced Thursday. The Buffalo Peaks Wilderness in its entirety is closed, as are a slew of national forest system roads.

The Associated Press contributed to this report.

RELATED: [INTERACTIVE MAP] Active wildfires in Colorado