‘Torrential rainfall’ in Reno is more than city has had all year

Anticipated bursts of intense rain soaking Reno this week prompted a flood watch from the National Weather Service.

The phenomenon, known as a pulsing storm, is caused by a monsoonal flow that works its way up from the Gulf of California and even the Gulf of Mexico.

When the monsoonal flow collides with high pressure, the result is “torrential rainfall,” said Heather Richards, meteorologist with NWS Reno. The effect was first felt Wednesday night when 1.22 inches of rain fell in just one hour at the Reno airport. This overwhelmed the drainage capabilities, flooded streams and washed out some downtown streets.

Taking the brunt of it were antique car drivers taking place in a Hot August Nights event.

“We had reports of people struggling with high water on the roads in their vintage cars,” said Richards. “I heard cars got water in their tailpipes.”

For context, Richards said the rainfall, recorded between 7:15 p.m. and 8:15 p.m. Wednesday, was more than Reno has had all year.

“We are anticipating

that we may very well see a repeat performance of Wednesday night on Thursday,’’ Richards said. “We will see more showers, and some of these storms could grow large enough that we could see some flash flooding.”

The storm systems battering Reno have thus far been east of the Lake Tahoe basin, Richards said, but even heavier rain has found Markleeville, south of Tahoe on Highway 89. During the same onehour period that the storm hit Reno Wednesday night, a separate storm dropped 2.5 inches of rain on Markleeville.

This caused mud and debris to flow down the mountainsides from the burn scars of the Tamarack and Caldor wildfires of 2021, and made portions of Highway 89 unpassable.

As a result, Caltrans closed Highway 89 in Alpine County north of Markleeville on Wednesday evening, and it remained closed Thursday. Crews were clearing the mud and debris, and there was no estimated time for the reopening of Highway 89.

According to Richards, the monsoonal flow is common, but this year it is hitting a stubborn ridge of high pressure over the Four Corners region of Utah, Arizona, New Mexico and Colorado. That was causing the flow to move west over Nevada.

“This is a rather rare situation for us to see this much rain in such a short time frame,” Richards said.