Glendale, AZ hail storm history

What the National Weather Service wrote

The combination of the subtropical high over the Four Corners/Rockies and an area of low pressure near the southern CA coastline resulted in a modest southeasterly flow that advected modest amounts of moisture across much of central and southern AZ. With the moisture advection, PWAT values increased upwards of 1.3-1.5. This moisture quantity in combination with strong daytime heating led to moderate instability as MLCAPE increased upwards of 1000 J/KG. Thunderstorm activity during the early to mid afternoon hours on the 2nd developed across the higher terrain areas of south-central and southeast AZ with outflow boundaries migrating west to northwestward into the lower deserts, where additional thunderstorm activity developed, with the heaviest activity observed across the western half of Maricopa County through the western side of the Phoenix metro area. Another isolated cluster of thunderstorms developed across central La Paz County as well. The increasing upper-level forcing from the approaching low pressure system likely enhanced the thunderstorm activity. During the afternoon hours on the 3rd, additional thunderstorm activity, although much more isolated in nature, developed across portions of south-central AZ. This activity was aided by moderate instability as MLCAPE values were around 1000-1500 J/KG and the presence of the upper-level forcing from the aforementioned low pressure system as it was traversing the region. With DCAPE values of 1000-1500 J/KG throughout the entire time period, conditions were favorable for the generation of strong downburst winds as well as dense blowing dust. With PWATs values approaching 1.5, the environment was moist enough for heavy rainfall producing thunderstorms that would result in isolated flash flooding.