In Colorado at least three people are dead, streets are flooded, and mountain towns are isolated after days of heavy rain caused flash flooding that is expected to continue through Friday.
"In Boulder, the rainfall record for September set in 1940 was shattered," Keith Coffman of Reuters reports.
Surging Boulder Creek floodwaters, coming from Boulder Canyon above the city, are now running through its heart.
"There's so much water coming out of the canyon, it has to go somewhere, and unfortunately it's coming into the city," Ashlee Herring, spokeswoman for the Boulder office of Emergency Management, told Reuters.
The torrent triggered the evacuation of some 4,000 residents late on Thursday. On Friday the National Guard began evacuating at least 500 people from Lyons, north of Denver, after the town was cut off by rising floodwaters.
"There's no way out of town. There's no way into town. So, basically, now we're just on an island," Jason Stillman, 37, who was forced to evacuate his home in Lyons at about 3 a.m., told The Weather Channel.
It's clear why some people are stranded:
colorado flooding
The Colorado resident who took the following pictures told Business Insider: "It's so crazy here — just about every other street is closed and there are rocks and trees everywhere."
GNO
Geno Verucchi
GNO7
Geno Verucchi
GNO4
Geno Verucchi
As you can see, the water is starting to reach underneath homes.
GNO3
Geno Verucchi
And into homes. The caption for the photo below reads: "If anyone is free to help tomorrow. A friend of mine could use some. This is his living room." 
colorado flooding
REUTERS/Rick Wilking
Here's a video:
"This was the bear creek bike path earlier today just a few blocks from the house and Olmec office. This is now multiple feet higher and going over the road the photo was taken from!"

"Traffic is impossible during yesterday Thu. 12 sep. 2013"
"In Boulder we don't have streets but creeks"
colorado flooding
REUTERS/Mark Leffingwell
Neighbors survey a dike created to funnel water down 7th Street as heavy rains cause severe flooding in Boulder, Colorado September 12, 2013.