Dust Storm — Northwest Valley, Arizona

2021-07-03 · Northwest Valley, Arizona

Event narrative

A trained spotter in Wittman reported visibility briefly fell to less than 1/4 mile in blowing dust generated by a strong southwestward-moving outflow boundary with reinforcing thunderstorms. There were no reports of damages or injuries.

Wider weather episode

Strong thunderstorms developed in the afternoon over the high terrain of central and southern Arizona before spreading to the lower deserts through the evening, with new development driven mostly by strong outflow boundaries. The primary outflow boundary moved southwest with widespread 30-40 mph wind gusts observed across south-central Arizona and a few stronger gusts, including a 59 mph gust in southern Gila county. The winds were strong enough to cause hundreds of power outages in the Phoenix metro area and generate dense blowing dust over the open deserts in Pinal and western Maricopa counties. With above normal moisture levels, storms also produced localized flash flooding mostly in foothill/high terrain areas, including flash flooding enhanced by recent burn scars.

Source: NOAA Storm Events Database, event_id 973328. Narrative written by the NWS forecast office that issued the report.