Thunderstorms and Lightning Expected in San Diego County

News Summary

San Diego County is bracing for thunderstorms and lightning due to a weak low-pressure system arriving from the north. The National Weather Service warns that conditions may pose dangers, especially with the potential for fire hazards and flash flooding in areas with low seasonal rainfall. Residents are advised to seek shelter if they hear thunder or see lightning. The storms are likely to impact various regions, with particular attention on the eastern parts of San Diego County and nearby areas experiencing a shortage of rainfall.

San Diego, CA – A weak low-pressure system is predicted to bring thunderstorms and lightning to San Diego County and parts of Southern California on Tuesday night. According to the National Weather Service, unstable air from the north is expected to arrive around 6 p.m., potentially reaching coastal areas where lightning is relatively rare.

Thunder and lightning activity may persist into the evening hours and could include brief periods of rain. Residents are urged to seek shelter immediately upon hearing thunder or witnessing lightning, as conditions may present danger.

Lightning strikes are no small threat, as each bolt can reach temperatures of around 50,000 degrees, substantially hotter than the surface of the sun. The eastern half of San Diego County is particularly vulnerable to lightning, with many regions currently experiencing only about half of their typical seasonal rainfall, raising concerns for fire hazards and flash flooding.

The forecast indicates a 15% to 20% chance of thunderstorms moving from higher elevation areas toward Southern California’s coastline. A cutoff low-pressure system previously impacting San Francisco is now shifting southward, leading to an uptick in thunderstorm potential in Los Angeles, Orange, and San Diego counties.

This low-pressure system is anticipated to draw in moist air from the Gulf of California, a process vital for the development of thunderstorms. The moisture levels in the atmosphere are projected to reach near-record highs, with values in the 99th percentile over Southern California.

Thunderstorm development is most likely in the Santa Barbara, Santa Monica, San Gabriel, Santa Ana, and San Jacinto mountain ranges, as well as in Antelope Valley. However, uncertainty remains regarding whether these thunderstorms will drift westward towards the southern metropolitan areas of Los Angeles and San Diego.

The predicted thunderstorms might bring mixed impacts, including damaging winds, hail, and cloud-to-ground lightning. Notably, dry lightning poses a significant wildfire risk while wetter thunderstorms could lead to debris flows, particularly in areas previously affected by fire damage.

Concerns about debris flows are heightened around the Bridge Fire burn scar in Angeles National Forest, where a low chance exists for such phenomena. Likewise, the Eaton Fire burn scar shows a slight risk of flooding due to possible heavy rainfall during the storm.

For the deserts stretching from Joshua Tree to Las Vegas to the Grand Canyon, a flood watch is in effect as heavy rains are expected throughout the afternoon and evening on Tuesday.

Wider Regional Weather Impacts

In Northern California, smoky conditions from wildfires in Canada are anticipated to create hazy skies. In the San Francisco Bay Area, widespread fog is forecasted for the morning hours, transitioning to temperatures near typical June levels, with coastal highs in the 60s, bay area temperatures in the 70s, and inland highs reaching the 80s.

San Francisco is set to experience morning fog, with anticipated highs between the upper 50s to low 60s. In the North Bay, fog will blanket the valleys, with temperatures varying from the upper 60s to the mid-80s depending on location. The East Bay will also face considerable fog in certain areas, with temperatures likely ranging from the upper 60s to low 80s.

Along the Pacific Coast, sunshine is forecasted to be minimal, as clouds will linger with temperatures remaining in the upper 50s to mid-70s. Conversely, the South Bay could enjoy warmer sunshine, with temperatures climbing to the upper 70s to mid-80s. Fog is expected to return to the Monterey Bay coastline overnight, marking another shift in weather patterns.

This convergence of changing weather conditions underscores the importance of staying vigilant during the impending thunderstorms, particularly in fire-prone areas and regions prone to flash flooding.

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Additional Resources

• San Diego Union-Tribune
• Google Search: thunderstorms San Diego
• NBC San Diego
• Wikipedia: Thunderstorm
• Fox 5 San Diego
• Encyclopedia Britannica: Lightning
• KTLA
• Google News: Southern California weather
• San Francisco Chronicle
• Google Scholar: thunderstorm forecast