Residual moisture from Tropical Cyclone Alberto will move into Southern California and the adjacent coastal waters this weekend. This supports the possibility of a few thunderstorms over the local waters this weekend. The chances are currently less than 20 percent at any one location. The most likely timing of this activity will be Saturday night, although a thunderstorm could occur 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 up to 98 expected. * WHERE. San Diego County Valleys. * WHEN. From 10 AM to 8 PM PDT Saturday. * IMPACTS. Hot temperatures may cause heat illnesses.

* WHAT. Dangerously hot conditions with temperatures up to 114 possible. * WHERE. San Diego County Deserts. * WHEN. From Saturday morning through Thursday evening. * IMPACTS. Heat related illnesses increase significantly during extreme heat events.

* WHAT. Elevations over 6,000 feet up to 85 degrees. Elevations over 2,000 up to 95 expected. * WHERE. Riverside County Mountains, San Bernardino County Mountains, and San Diego County Mountains. * WHEN. From 10 AM to 8 PM PDT Saturday. * IMPACTS. Hot temperatures may cause heat illnesses.