Areas of dense fog are expected to impact the coastal waters during the overnight and morning hours each day through this weekend and early next week. Mariners should be prepared for abrupt visibility changes down to one nautical mile or less. Reduce speeds and be on the lookout for exposed rocks and other vessels, including large ships in the shipping lanes. Use radar or GPS navigation if available, and consider remaining in harbor if such equipment is unavailable. In addition, remnant upper-level moisture from Tropical Cyclone Alberto will advance into Southern California and the adjacent coastal waters this weekend. Present indications are that this weather pattern will support the possibility for a few thunderstorms to form over the local waters this weekend. Most locations will remain dry, and chances for thunderstorms are currently very low, less than 20 percent. In fact, there is a good chance that no storms form anywhere across the region. However, if enough moisture is able to move into the area this weekend, isolated thunderstorms will have the potential to form. Right now, the most-likely timing of this activity will be Saturday night, though a couple storms cannot be ruled out as early as Saturday afternoon or as late as Sunday afternoon. Any thunderstorms would be capable of producing dangerous cloud- to-water lightning strikes, gusty winds, small hail, and brief heavy rain. This is a highly uncertain situation, and those with interests over the coastal waters are encouraged to closely monitor the latest situation, and consider making alternative plans if the chances for thunderstorms were to increase.

* WHAT. Temperatures in the 90s to around 102 degrees expected with warm overnight low temperatures in the 60s to lower 70s offering little reprieve from the heat. * WHERE. Cuyama Valley, Eastern San Fernando Valley, Los Angeles County San Gabriel Valley, San Luis Obispo County Interior Valleys, San Luis Obispo County Mountains, Santa Clarita Valley, Southern Salinas Valley, and Western San Fernando Valley. * WHEN. From 10 AM Saturday to 8 PM PDT Sunday. * IMPACTS. Hot temperatures may cause heat illnesses.

The South Coast Air Quality Management District has issued an Air Quality Alert due to elevated ozone air pollution. This Air Quality Alert is in effect from 11 AM Friday to 7 PM PDT Tuesday. Elevated levels ozone, the predominant summertime pollutant, are likely to result in poor air quality in the afternoon and early evening hours. Ozone air pollution can cause respiratory health problems, including trouble breathing, asthma attacks, and lung damage. Children, older adults, and people with asthma or COPD may be more sensitive to health effects of ozone. Air quality can change depending on time of day and weather conditions. Increased emissions of chemicals and faster ozone formation rates due to heat, along with low winds and stagnant weather can cause unusually high and persistent levels of ozone pollution. To help minimize ozone air pollution levels: - Limit the use of gasoline powered lawn and garden equipment until the evening hours - Conserve electricity and set your air conditioner at a higher temperature - Try to delay trips to the gas station and the use of household chemicals until the evening Check air quality levels and take appropriate action as needed. When air quality index (AQI) are Unhealthy for Sensitive Groups (orange), people with heart or lung disease, pregnant women, children, and older adult should limit prolonged or heavy outdoor exertion. When air quality reaches Unhealthy (red) AQI levels, everyone may experience adverse health effects and sensitive groups should avoid time outdoors. As Very Unhealthy (purple) AQI levels, sensitive groups should avoid all outdoors physical activity and everyone else should avoid prolonged or heavy outdoor exertion. To view current and forecasted air quality levels, visit the South Coast Air Quality Management District website at aqmd.gov or download the mobile app at www.aqmd.gov/mobileapp. Additional details for this air quality alert may be available at www.aqmd.gov/advisory. For the additional information, call the South Coast Air Quality Management District.