San Diego Mountains, Desert Under Flash Flood Watch on Labor Day

By Monday afternoon, the National Weather Service had issued a flash flood warning in north central San Diego County

Labor Day brought wild weather to parts of San Diego County including a flash flood warning in the north-central region and pea-sized hail over Palomar Mountain.

The National Weather Service in San Diego issued a flash flood warning in north-central San Diego, in effect through 4:30 p.m. Monday, as thunderstorms hit the area. The warning spanned areas including Anza, Warner Springs, State Route 79 between Warner Springs and Oak Grove, Borrego Palm Canyon, and Lake Henshaw, to name a few places.

The NWS said doppler radar indicated thunderstorms were producing heavy rain across the area. Just before 1:40 p.m., one inch of rain had fallen and flash flooding was expected to follow. The NWS said another inch of rain in those impacted areas was possible.

By 9 p.m. Palomar Mountain had seen just under a half inch of rain.

A flash flood watch was also issued for San Diego County mountains and deserts.

The NWS also issued a special weather statement just before 2:50 p.m. for San Diego County inland valleys, with a focus on Palomar Mountain, through 3:30 p.m.

There, the NWS said trained weather spotters reported "a strong thunderstorm producing pea-size hail over Palomar Mountain," about 12 miles northeast of Valley Center.

"This storm was nearly stationary," the agency said.

This special weather statement also impacted State Route 79 between Warner Springs and Oak Grove, Pauma Valley, and the Pauma Valley Indian Reservation, among other communities.

The flash flood warning and special weather statement came hours after the NWS had issued a flash flood watch through the evening for local mountains, including communities like Julian and Pine Valley, and deserts like Borrego Springs, Banning and other desert areas in Southern California. That watch would remain in effect in those areas through 8 p.m.

According to the NWS, rainfall rates on Labor Day could exceed flash flood thresholds in these local areas, with rain expected through the evening.

NBC 7 Meteorologist Llarisa Abreu said there was a possibility of an evening thunderstorm in the mountians, but said by 9 p.m. the region would dry out.

Tuesday high temperatures were expected to reach 85 along the coast and 92 inland, while the mountians would see heat in the low 80s. Triple digits were expected in the deserts.

NBC 7 Meteorologist Sheena Parveen said thunderstorms in local desert regions like Borrego Springs could “provide locally heavy rain.” Parveen said those thunderstorms were expected to hit some of the local foothills, too.

An NBC 7 employee filmed several flashes of lightning on Sunday night. People from Vista to National City called NBC 7 to say they could see the flashes.

Also in her forecast: some lightning with the thunderstorms and flash flood watch, likely after 1 p.m. Parveen expected temperatures around 84 degrees in the mountains and up to 107 degrees in the desert.

Parveen said there’s a chance of thunderstorms through Wednesday in local deserts, and through Thursday in the mountains.

Meanwhile, for those heading to San Diego County beaches on Labor Day, Parveen said conditions would be sunny and pleasant.

The NBC 7 First Alert Forecast mapped out these highs for the coastline on the holiday:

  • Imperial Beach: 80 degrees
  • Coronado: 81 degrees
  • Mission Beach: 78 degrees
  • Pacific Beach: 79 degrees
  • Del Mar: 78 degrees
  • Encinitas: 80 degrees
  • Oceanside: 81 degrees

Parveen said San Diego County can expect a warming trend over the next few days; after this week, a cool-down is on the horizon.

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