Hurricane Hilary to threaten flooding rain in California, Nevada and ArizonaAccuWeather forecasters are growing increasingly concerned that flooding downpours will reach parts of the Southwest as Hilary’s moisture arrives, and experts say there are some parallels to a historic hurricane that caused a flooding disaster for some communities. CopiedAccuWeather forecasters are warning that Hilary will bring heavy rain to western Mexico and the southwestern U.S. in the coming days. However, once in a while these conditions, especially the impacts from heavy rain, occur in the region. Beginning Saturday, heavy rain will begin to affect Southern California, southern Nevada and western and central Arizona, AccuWeather Meteorologist Brandon Buckingham said. Kathleen produced up to 15 inches of rain in Southern California and triggered major flooding in the southwestern U.S.