Oct 20, 2015
A strong and cold upper level low pressure system was in place over the desert southwest on October 20th. The low was associated with elevated levels of moisture, instability and wind shear and as a result, scattered thunderstorms developed across south central Arizona, starting in the early morning hours and continuing throughout the day. Due in part to cold temperatures in the upper atmosphere, some of the stronger thunderstorms produced large hail with diameters greater than one inch. Funnel
Source: NOAA National Weather Service Storm Events Database (event 600807). 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.