PARADISE, Calif. (KTVU) - Fire crews battling Butte County's Camp Fire are keeping one eye on the fire line and the other on the sky.
Rain is forecasted to begin falling Wednesday. Every fire official we spoke with on Tuesday said the coming rain is a mixed blessing.
While it will help extinguish the fire, it creates problems of its own.
Crews in the area devastated by the deadly fire, which has now killed at least 81 people with hundreds still missing, spent the day working.
Butte County Sheriff Kory Honea said Tuesday that the number unaccounted for has increased to 870. He said the the additional 171 names came from a backlog of voicemails that detectives worked through Tuesday.
Authorities stressed that many of the people on the list may be safe and unaware they have been reported missing.
Meanwhile, one of the priorities: cutting down and trimming trees.
Crews say trees marked with "Ps" take top priority. They're in imminent danger of coming down, especially as the coming storm turns the baked ground into mud.
"The rain event coming in...we're going to start raining tomorrow morning," said Aviva Braun a meteorologist from the National Weather Service.
Teams of National Weather Service meteorologists are working hard to forecast the rainfall. Predicting steady rain, heavy at times.
"The heavier the rain comes all at once the more hazardous it becomes," said Braun.
Meteorologists say the scorched ground will not be able to absorb much water. So, they're looking at maps trying to figure out which areas may get hit with debris flows once that rain comes.
A mix of water, ash, mud and everything else left over from the fire is expected to flow with about 4-6 inches of rain over the fire area.
"The firefighters are trying to get their hose lines out so that if there's any movement of soil that they can find everything," said Braun.
Crews spent another day searching the burned out remains of homes looking for victims who couldn't escape the flames.
Firefighters said the rain could impact those recovery efforts as well.
"I would say they might need to cease their operations for a time, during heavier downpours," said Keith Wade of the Sacramento Fire Department.
CalFire said the rain will obviously help extinguish those flames still burning. But with that rain comes an increased risk for fire crews.
"It can cause some access problems, they'll have to deal with the mud and the different stuff that the rain brings. But, what it will do is slow that fire down not give it a chance to grow further, and give them a chance to reach their containment lines," said Wade.
Fire crews said what they'd like to see is a light steady rain, enough to help put out those areas that are still burning, but, not enough to trigger those debris flows.
As of Tuesday evening the Camp Fire is at 152,250 acres and has destroyed more than 13,000 homes
Associated Press contributed to this report.