* WHAT...Flash flooding caused by excessive rainfall is possible. * WHERE...All of northern and central Arizona. * WHEN...Through Thursday evening. * IMPACTS...Flash flooding will be possible in creeks, normally dry washes, swimming holes, and over recently burned areas. Low-water crossings may be flooded. * ADDITIONAL DETAILS... - An upper-level trough will bring a deep surge of subtropical and tropical moisture into our region. Showers and thunderstorms will develop across much of northern and central Arizona early Wednesday morning and continue through Thursday evening. Stronger thunderstorms will bring threats of Flash Flooding, while more prolonged rainfall could lead to elevated flow in streams, rivers, and washes. - Additional information is available at weather.gov/flagstaff.