California weather

* WHAT...Significant coastal flooding expected. * WHERE...San Diego County coastal areas and Orange County Coastal Areas. * WHEN...Until 1 PM PDT Thursday during high tides in the late mornings. * IMPACTS...Numerous roads may be closed. Low lying property including homes, businesses, and some critical infrastructure will be inundated. Some shoreline erosion will occur in the late mornings. * ADDITIONAL DETAILS...Coastal residents and managers of infrastructure in the warned area should prepare for rising water and take appropriate action to protect life and property. High tides each day will occur in the late morning. Observed high tides are 1.4 to 1.6 feet above astronomical tide predictions.

What to do: Take the necessary actions to protect flood-prone property. If travel is required, do not drive around barricades or through water of unknown depth.

* WHAT...Sub-freezing temperatures as low as 26 expected. * WHERE...Northern Mendocino Interior, and Northern Lake. * WHEN...From 1 AM to 9 AM PDT Wednesday. * IMPACTS...Frost and freeze conditions could kill crops, other sensitive vegetation and possibly damage unprotected outdoor plumbing.

What to do: Take steps now to protect tender plants from the cold. To prevent water pipes from freezing; wrap or drain or allow them to drip slowly.

* WHAT...Up to 2.1 ft of inundation above ground level is possible in low-lying areas near shorelines and tidal waterways. * WHERE...Pacific Coast. * WHEN...Until 5 PM PDT Friday. * IMPACTS...High tides will result in flooding of low-lying infrastructure, isolated road closures, and coastal erosion. Rising tides will bring water and waves farther up the beach than normal, restricting escape from beaches and coastal areas. * ADDITIONAL DETAILS...At the San Francisco tidal gauge, high tide is expected to be 1.9 ft above normal (7.7 ft MLLW) at 12:56 PM Wednesday 10/28, 1.7 ft above normal (7.5 ft MLLW) at 01:43 PM Thursday 10/29, and 1.6 ft above normal (7.4 ft MLLW) at 02:39 PM Friday 10/30. These predictions include up to 1.2 ft of surge that will enhance the astronomical tide and flooding threat. High tide varies up to 90 minutes earlier or later along the Pacific Coast and through the San Francisco Bay, respectively.

What to do: If travel is required, allow extra time as some roads may be closed. Do not drive around barricades or through water of unknown depth. Take the necessary actions to protect flood-prone property.

* WHAT...Up to 2.1 ft of inundation above ground level is possible in low-lying areas near shorelines and tidal waterways. * WHERE...Bay Shoreline locations of San Pablo Bay, San Francisco Bay, and Monterey Bay. * WHEN...Until 5 PM PDT Friday. * IMPACTS...High tides will result in flooding of low-lying infrastructure, isolated road closures, and coastal erosion. Rising tides will bring water and waves farther up the beach than normal, restricting escape from beaches and coastal areas. More substantial impacts are expected along bayshore Marin County where increased flooding is anticipated across low lying areas. * ADDITIONAL DETAILS...At the San Francisco tidal gauge, high tide is expected to be 1.9 ft above normal (7.7 ft MLLW) at 12:56 PM Wednesday 10/28, 1.7 ft above normal (7.5 ft MLLW) at 01:43 PM Thursday 10/29, and 1.6 ft above normal (7.4 ft MLLW) at 02:39 PM Friday 10/30. These predictions include up to 1.2 ft of surge that will enhance the astronomical tide and flooding threat. High tide varies up to 90 minutes earlier or later along the Pacific Coast and through the San Francisco Bay, respectively.

What to do: If travel is required, allow extra time as some roads may be closed. Do not drive around barricades or through water of unknown depth. Take the necessary actions to protect flood-prone property.

* WHAT...High astronomical tides will cause minor flooding in low lying areas around Humboldt Bay. Up to one half foot of saltwater inundation above ground level is possible near shorelines and tidal waterways. Between 9.0 and 9.3 feet MLLW at the North Spit tide gauge is predicted. * WHERE...Northern Coastal Humboldt County. * WHEN...From noon to 3 PM PDT Wednesday. High tide is at 1:13 PM at the Humboldt Bay North Spit tide gauge. Saltwater inundation will be possible 1 to 2 hours before and after high tide. * IMPACTS...Flooding of low lying areas around Humboldt Bay including parks and roads with only isolated closures expected. Flooding will likely impact Jackson Ranch Road in the Arcata Bottoms and several roads in King Salmon.

What to do: A Coastal Flood Advisory indicates that onshore winds and tides will combine to generate flooding of low areas along the shore. Feet Above Ground is locally defined as feet above the Highest Astronomical Tide or HAT.

* WHAT...Minor to moderate coastal flooding expected due to very high tides. * WHERE...Catalina and Santa Barbara Islands. * WHEN...Until 1 PM PDT Thursday. * IMPACTS...Minor to moderate flooding of sea water is likely over vulnerable low-lying coastal areas, especially around the time of high tide, including over beach parking lots, bike paths, and harbor walkways. Moderate to significant beach erosion is likely. Isolated damage of structures due to sea water inundation is possible to the most vulnerable areas. * ADDITIONAL DETAILS...High tides will likely reach 7.5-8.0 feet (MLLW) each late morning, which is 1.0 to 1.5 feet above astronomical projections. The highest tides will be through Wednesday. There is a small chance for isolated Coastal Flood Warnings Wednesday through Thursday if larger surf develops. The Coastal Flood Advisory may also need to be extended beyond Thursday.

What to do: Take the necessary actions to protect flood-prone property. Do NOT drive around barricades or through water of unknown depth.

* WHAT...Minor to moderate coastal flooding expected due to very high tides. * WHERE...San Luis Obispo County Beaches, Santa Barbara County Central Coast Beaches, Santa Barbara County Southwestern Coast, Santa Barbara County Southeastern Coast, Ventura County Beaches, Malibu Coast and Los Angeles County Beaches. * WHEN...Until 1 PM PDT Thursday. * IMPACTS...Minor to moderate flooding of sea water is likely over vulnerable low-lying coastal areas, especially around the time of high tide, including over beach parking lots, bike paths, and harbor walkways. Moderate to significant beach erosion is likely. Isolated damage of structures due to sea water inundation is possible to the most vulnerable areas. * ADDITIONAL DETAILS...High tides will likely reach 7.5-8.0 feet (MLLW) each late morning, which is 1.0 to 1.5 feet above astronomical projections. The highest tides will be through Wednesday. There is a small chance for isolated Coastal Flood Warnings Wednesday through Thursday if larger surf develops. The Coastal Flood Advisory may also need to be extended beyond Thursday.

What to do: Take the necessary actions to protect flood-prone property. Do NOT drive around barricades or through water of unknown depth.

* WHAT...Temperatures as low as 33 will result in frost formation. * WHERE...Humboldt Interior, Southeastern Interior Mendocino, and Western Lake. * WHEN...From 1 AM to 9 AM PDT Wednesday. * IMPACTS...Frost could harm sensitive outdoor vegetation. Sensitive outdoor plants may be killed if left uncovered.

What to do: Take steps now to protect tender plants from the cold.