Phoenix, AZ hail storm history

What the National Weather Service wrote

With the subtropical high pressure centered near the Lower Colorado River Valley, the steering flow pattern across much of eastern and central AZ was from the north to northeast. Thunderstorm activity developed across the Mogollon Rim during the late morning into the early afternoon hours and was steered south to southwestward into south-central AZ. An upper-level disturbance moving in from New Mexico helped enhance the vertical ascent and thus resulted in the thunderstorm coverage to become quite numerous with deep and colliding outflow boundaries helping to spark new activity across the lower deserts of south-central AZ. MLCAPE values were in the 1000-1500 J/KG range, with DCAPE values of around 1500 J/KG. Thus the parameters were favorable for these thunderstorms to generate strong to severe downburst winds. The steering flow was very light, resulting in slow storm motions and thus heavy rainfall leading to isolated instances of flash flooding.