Coastal Flood Advisory

* WHAT...For the High Surf Warning, large waves and dangerous surf conditions. Breakers up to 30 to 35 feet. For the Coastal Flood Advisory, tidal overflow flooding expected.

* WHERE...Clatsop and Tillamook Coast.

* WHEN...For the High Surf Warning, until noon PST Saturday. For the Coastal Flood Advisory, until 4 PM PST this afternoon.

* IMPACTS...Minor flooding, up to one foot above ground level, during high tides is expected in the low lying areas near bays, sloughs, and the lower reaches of the coastal rivers. Destructive waves may wash over beaches, jetties, and other structures unexpectedly. People can be swept off rocks and jetties and drown while observing high surf. Severe beach erosion may destroy coastal properties and buildings. Higher than normal water run-up is expected on beaches and low-lying shoreline.

* ADDITIONAL DETAILS...The threat of sneaker waves is extreme during these scenarios. Sneaker waves can suddenly knock people off of their feet and quickly pull them into the frigid ocean which may lead to serious injury or drowning. The sneaker wave threat will peak Friday evening into Friday night. In addition, the Tongue Point tidal gage in Astoria is forecast to reach approximately 10.5 feet during high tide this afternoon, which is high enough to result in tidal overflow flooding for a few hours around high tide.