National Weather Service United States Department of Commerce

Preliminary Storm Report for 2 August 2018
By NWS Phoenix -- last updated at 10 PM on 6 August 2018


Dust moving into Phoenix
Dust storm moving into Phoenix, AZ. Source: ABC15


The day started as another typical warm and humid day across much of Arizona. One wrinkle that was a little more unusual was a weak weather feature moving west-to-east through the Mountain West, the far southern tail of it dragging across Arizona. In addition, other weak features across northern Mexico slowly moving east-to-west were present. This setup caused showers and thunderstorms to develop during the afternoon hours, first over La Paz county and portions of northern Arizona, then across Pima county and far southern Arizona. The storms to the south took hold, developed into a cluster of strong storms, and moved northward into Maricopa and Pinal counties. Upper air maps from the NOAA Storm Prediction Center can be viewed here.


Radar at 630 PM on 2 August 2018
Radar at 630 PM on 2 August 2018. Click image for full event loop.


Satellite view at 630 PM on 2 August 2018
Satellite view at 630 PM on 2 August 2018. Click image for full event loop.


As the storms progressed, the strong outflow winds caused a large dust storm to develop and move south-to-north across the two counties. Numerous reports of near zero visibility were reported early in the storm, though the intensity of the dust storm waned as ti moved northward into the Phoenix area (primarily due to a lack of new dust to ingest and decreasing intensity as the flow fanned out).


Rainbow Valley/Buckeye Storm Reflectivity Rainbow Valley/Buckeye Storm Velocity
View of Rainbow Valley/Buckeye storm and downburst from FAA terminal doppler radar (reflectivity left, velocity right).


The thunderstorms reached their strongest intensity across the far Southwest and West Valley areas. Reports of several structures damaged or destroyed were received in the Rainbow Valley area, and specifically in the Estrella Mountain Ranch community. Additional damage was reported in Surprise and near Eloy in Pinal County. Click here to view storm reports for this event.


Lightning Data
Lightning cloud-to-cloud flashes. Hover over image to show cloud-to-ground strikes.


While some pockets of heavy rain did fall, most areas saw little to no rain. Average rainfall across the Phoenix area was 0.07" with about 20% coverage; official rainfall at Sky Harbor airport was 0.05". The highest observed amounts was 2.90" in Sun City (via CoCoRaHS).


Phoenix Rainfall Index
Phoenix Rainfall Index for 2 August 2018.

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