* WHAT...Flash flooding caused by excessive rainfall is possible. * WHERE...Northern Gila County, Yavapai County, and Oak Creek and Sycamore Canyons. * WHEN...From Saturday afternoon through late Saturday night. * IMPACTS...Flash flooding will be possible in creeks, normally dry washes, and swimming holes, and over recently burned areas. Low-water crossings could also become flooded, which would create deadly travel conditions. * ADDITIONAL DETAILS... - Thunderstorms are expected to develop this afternoon and continue through much of the weekend. With deep monsoonal moisture in place, any stronger storm will have the potential to produce heavy rainfall and cause flash flooding. - Additional information is available at weather.gov/flagstaff.