‘Astronomically High Tides’ With Rain Expected Thursday

A cold front moving in from the Gulf of Alaska is expected to arrive in Southern California on Thursday, bringing heavy rain to the north, lighter sprinkles in the Southland and “astronomically high tides” statewide, forecasters said Tuesday.

Waves that already were predicted to be high because of the moon phase could swell even more, in part because of the incoming storm system, meteorologists reported.

The incoming system “is putting waves on top of already high tides,” said meteorologist Jeff House of WeatherData Inc., the agency that provides forecasts for The Times.

Also, warmer than usual waters off the coast are increasing wave height by as much as half a foot, House said.

In Orange County, waves are likely to climb to about 8 feet Thursday. Meteorologists predict a 50% chance of showers on Thursday. More rain is expected during the weekend as a separate Western Pacific storm system is expected to move in behind the northwestern one.

Los Angeles and areas to the north and west also will have a chance of rain Thursday and again Saturday.

Temperatures in the Southland are expected to be in the upper 60s today, the mid-60s on Thursday and Friday and perhaps into the low 60s on Saturday, House said.

The mercury is expected to rise back into the seasonal mid-60s by Sunday, he said.

* HOW FOG FORMS: Chart shows how humidity and temperatures interact. B3