Monsoon Surge Brings Flash Flood Risk to the Southwest, Fire Risk to the Northwest

The North American monsoon season is on its last legs, but it is not quite done yet. An influx of moisture will continue to dump heavy rain at times across the Southwest. Meanwhile, the Northwest will be dealing with the threat of wildfires thanks to dry thunderstorms. Here is a look at the weather happenings out West.

Pervasive Flash Flooding Threat Across the Desert Southwest

A deep plume of monsoonal moisture from Mexico will support the development of widespread rain showers and storms throughout the interior West this weekend. The threat of flash flooding will stretch to the north from Arizona and New Mexico on Thursday and Friday, reaching as far as Wyoming and Montana. Cities such as Phoenix are currently in the zone of high risk.

The greatest risk of flooding will be in urban areas and across recent burn scars. Campers, hikers, and mountain bikers should avoid canyons and small streams over the next few days due to this threat.

Moving farther to the north, a dry storm system is forecast to speed through parts of Northern California, Oregon, and northern Idaho on Thursday. Although cold air is circulating in the upper levels of the atmosphere, it is much warmer at surface level. The clash of these temperature gradients will lay the groundwork for storms packing little to no rain, small hail, and gusty winds. The lightning associated with this storm will pair with the high winds to increase the chance of new wildfire ignition.

Widespread rainfall totals of 1 to 4 inches are in the forecast for much of Arizona, New Mexico, Colorado, and eastern Utah. More localized rain totals of up to 8 inches are possible in areas that see repeated waves of moisture.