nbc's janet schamlian has more tonight. >> reporter: it came fast in the houston area. as much as eight inches of rain in just a few hours, triggering flash flooding and turning streets into rivers. >> it was just ridiculous. waters are at least 2 1/2 feet high in the right lane. it was nuts. >> reporter: drivers were stranded all across the city. firefighters made more than 150 water rescues in five hours as cars stalled in the fast rising water. >> just coming home from work. i decided to take a chance. but me not listening, i see other cars out here. i just gave it a shot and now i'm trying to start my calm -- i don't know what to do now. >> reporter: lightning and downed trees cut power to more than 40,000 customers. and in the south, something rare -- hail. >> on the ground is hail! >> reporter: in parts of tennessee the weekend was a washout. heavy rains pushed creeks over their banks, spilling on to nearby roads. as storms move out of tennessee and texas, the focus moves north. >> the big story this week is going to be watching the battle of the red river rising