Southern California residents should prepare for an unusual June weather pattern as meteorologists forecast showers and thunderstorms through Sunday, marking a rare departure from the region's typically dry early summer conditions. The National Weather Service San Diego office has issued advisories for light to moderate precipitation across multiple counties, with the highest chances for thunderstorm activity concentrated in mountain and desert areas.
Current Weather System and Forecast Details
A cold low pressure system from the northwest is moving into southern California this weekend, slowly weakening and moving east for Monday and Tuesday, bringing light rainfall expected to be heaviest in the mountains and locally into the deserts if storms occur, according to NWS San Diego. The low to the south will eventually drift northward tonight, providing a chance for showers across most of Southern California into the morning hours.
Areas west of the mountains will generally receive light precipitation under one tenth of an inch, with parts of Orange County receiving none, the weather service reported. However, WRF/HRRR models depict heaviest thunderstorm cells across parts of the Riverside and San Diego County mountains with rainfall rates nearing one half inch per hour. The higher rain chances will be from 5 a.m. until 11 p.m. Sunday, with rainfall accumulations expected to be from 0.05''-0.20'' for the coast, with higher amounts expected over the mountains, as reported by NBC San Diego.
Atmospheric Conditions and Thunderstorm Risk
This aligns fairly well with model depictions of highest CAPE over this area near 300-600 J/kg, indicating sufficient atmospheric instability for thunderstorm development. Due to the instability in the atmosphere, there's a chance for thunderstorms as well. The weather service warns that brief outflow gusts over 25-30kts are possible with any developing SHRA or TSRA, along with near zero visibility in any storm with heavy rain, along with erratic and gusty winds.
Marine areas will experience a slight chance of showers across the coastal waters in the afternoon today and especially Sunday, according to the National Data Buoy Center. Isolated thunderstorms are possible both this afternoon primarily for the San Diego Mountains and then more widespread generally after 18z Sunday.
Regional Weather Patterns and Historical Context
This June weather activity represents an unusual pattern for Southern California, which typically experiences its driest months during early summer. We're getting into the time of year when these types of colder systems can bring heavy small hail accumulations locally down to sea level in such localized convective cells, or perhaps an isolated severe thunderstorm/mini-supercell or two if local surface wind convergence and jet-level winds cooperate, explained meteorologists at Weather West.
The broader climate pattern has been characterized by significant variability this year. A north-south gradient in drought conditions shows this water year's drought depended on when, where, and how much precipitation was received, with February and March storms bringing some improvements to a record-setting dry start to the water year in southern California and Nevada, according to Drought.gov.
Marine and Beach Conditions
Surf will be building this weekend thanks to that tropical storm to the south, with an SSW swell with 4'-6' waves by Monday, and higher rip current danger as a result. A Beach Hazard Statement is in effect from Sunday morning through Tuesday afternoon for Orange County Coastal Areas and San Diego County Coastal Areas, the National Weather Service reported.
Water temperatures are starting to warm up as well, with some buoys off the coast reporting 68 degree water. However, beachgoers should exercise caution due to elevated surf conditions and increased rip current risks associated with the incoming weather system.
Extended Forecast and Recovery
Monday will be drier and cool to start off the work week, ahead of some warming for later next week. After Sunday, dry weather will continue with quiet conditions, providing relief from the unsettled weekend weather pattern.
The National Weather Service encourages residents to stay informed about changing conditions and report significant weather observations. Skywarn activation is not requested, however weather spotters are encouraged to report significant weather conditions.
