New subtropical storm could send more rain to San Diego County early next week

A new subtropical weather system is likely to form off southern Mexico early next week and could send more rain and lightning to San Diego County, the National Weather Service says.

It’s unclear whether the system would become as sizable as former Tropical Storm Mario, which produced 1.72 inches of rain on Wednesday and Thursday in the Borrego Springs area, about 1.5 inches on Palomar Mountain, and more than a half-inch of rain in several areas of San Diego. It’s unusual for the region to get that much precipitation in September.

Mario also sparked nearly 2,900 lightning bolts in the eastern half of the county on Thursday, which is even rarer for the final days of summer.

And four communities tied or broke records for the highest minimum overnight temperature on Thursday. Ramona’s overnight low was 66, 2 degrees above the record for that date, set in 1981. Campo was 66, 6 degrees higher than the previous record set in 1963. Vista was 69, tying a record set in 1984, and Escondido was 70, tying a record set in 1984.

Forecasters say the next system is currently composed of disorganized showers and thunderstorms far below the southern tip of Baja California. If it turns into a significant tropical depression, it would send lots of moisture and unstable air toward Southern California.