IDYLLWILD, Calif. - Cooler temperatures overnight have helped firefighters make some progress against a wildfire in Southern California.
The U.S. Forest Service says the 42-square-mile fire in the mountains near Palm Springs is now 25 percent contained.
But fire officials say thunderstorms this weekend could present a major threat to progress.
They worry that unstable air, combined with hot air on the ground, could create a strong updraft that draws smoke high into the atmosphere. If the smoke column rises too high, moisture at the top could freeze and the weight of the ice could cause the column to collapse, creating a powerful and dangerous downdraft in all directions.
On the other hand, mild cloud cover and high humidity could help in the firefight.
Mandatory evacuations remain in place for a fourth day for about 6,000 people, and another 700 have been advised to evacuate.
Some communities on the eastern edge of the fire were reopened to residents, but about 5,600 homes remain under potential threat.