Numerous pockets of individuals remain cut off from help even with more than 1,750 people and 300 pets already rescued from communities and individual homes swamped by rivers and streams overflowing from unrelenting rain last week, but, officials said.
Twenty military helicopters planned to expand the search from Boulder County east to Fort Morgan, but the window of opportunity was closing with clouds rolling in and up 2 to inches (5 centimeters) of rain expected to fall.
"It will affect our air operations if it keeps raining," Colorado National Guard Lt. James Goff said Sunday. "We'll look at ground operations of any other courses of action."
The additional rain falling on ground that has been saturated by water since Wednesday created the risk of more flash flooding and mud slides, according to the National Weather Service.