(CNN) — After heavy rains and flash flooding across parts of the Southwest this weekend, more than nine million people in the Southern Plains are under a flood watch this Sunday, including the Dallas-Fort Worth metro area and Shreveport, Louisiana.
Heavy rains falling on the Texas/Oklahoma border on Sunday morning are expected to continue into Monday, with 4-8 inches of rain forecast overall across the region. Some areas may have more than 203mm and flash flooding.
“We don’t know which areas will get more than 8 inches of extreme rain, but if it happens near you, there will be significant flash flooding,” warned the Fort Worth/Dallas office of the National Weather Service.
Flood warnings in effect this Sunday.
“Everyone in the alert area should plan for extra travel time, especially Monday morning,” the weather service said.
The Weather Prediction Center has issued a level 3 out of 4 “moderate risk” for excessive rain, primarily in North Texas, where up to 3 inches of rain could fall per hour during Sunday’s heaviest storms.
“Much of this rain will be beneficial and welcome due to the effects of an ongoing drought, but there is still the potential for flash flooding in urban areas and places with poor drainage,” the Center said.
More than 90% of the state of Texas is currently experiencing drought conditions with nearly 62% under extreme or exceptional drought conditions, the two highest categories.
Additional flood watches could be added for surrounding locations later this Sunday.
Some rain lingers in parts of Arizona and New Mexico this Sunday after flooding in parts of the Southwest on Saturday.
Rain accumulation forecast from Sunday to Wednesday.
In Utah, several hikers were “swept away” Friday in Zion National Park by flash flooding. Search and rescue team members were still working Saturday to find a missing hiker near the Virgin River, the park reported.
In New Mexico, about 160 people had to take shelter for several hours in Carlsbad Caverns National Park on Saturday due to flash flooding, the city of Carlsbad said. in a Facebook post.
The park is closed on Sunday, the National Park Service said.
“Maintenance crews will begin assessing and clearing debris from the road,” the National Park Service added.
Paradise Afshar and CNN’s Raja Razek contributed to this report.