SAN FRANCISCO – Western states under siege from numerous wildfires may face a new threat this week as thunderstorms head their way, raising the possibility of flash flooding.

“Heavy rainfall from monsoonal activity will continue the potential for flash flooding, especially in complex terrain, burn scars, and urban areas” in those regions, the NWS said.

Spots left barren of vegetation by the rash of wildfires throughout the West are especially prone to flash flooding when pelted by heavy rainfall.

AccuWeather senior meteorologist Alex Sosnowski said that as opposed to last year, when the high-pressure area from the monsoon was set up to the west and blocked the flow of moisture from the Gulf of Mexico, this year it has been farther east over the Rockies and Plains.

“The clockwise circulation around the high is what pulls the moisture up from the Gulf of Mexico and Gulf of California into the Southwest,” Sosnowski said.