Oct 5, 2021
As the region transitioned out of the monsoon, a compact low created a high shear - modest CAPE environment. Parameters were sufficient for supercell development and a few supercells did develop amongst isolated to scattered storms in the afternoon across South-central Arizona, including a right-mover that pushed into Phoenix and a left split. The environment was supportive of severe to large hail with lower freezing levels and steep mid-level lapse rates. Measured hail stones up to 1.0 to 1.5 d
Source: NOAA National Weather Service Storm Events Database (event 990414). Narrative written by NWS staff at the time of the event.
This event is one of many recorded floods in Maricopa County. See the full FEMA flood zone map, NFIP claim totals, and disaster history for the area.