SLO County weather forecast for the week of Jan. 8

Here is this week’s weather forecast by PG&E meteorologist John Lindsey.

A strong 997-millibar storm and associated warm and cold fronts, developing about 100 miles west of San Francisco late Sunday, will move southeastward toward the Central Coast.

The warm front will pass the Central Coast on Monday morning and will produce heavy drizzle/rain showers and moderate to fresh (13 to 24 mph) southerly winds. A well-defined cold front will follow, with increasing amounts of rainfall and southeasterly winds Monday afternoon into Monday night. Moderate gale-force to fresh gale-force (32 to 46 mph) southeasterly winds, with gusts of more than 55 mph, will develop along the coastline around midnight with the frontal passage.

The 997-millibar storm will travel southeastward and will move through San Luis Obispo and Santa Barbara counties Tuesday morning, with moderate gale-force to fresh gale-force (32 to 46 mph) southwesterly winds, with gusts of more than 55 mph, along the shoreline. Note: Gale-force winds out of the southwest are unusual and may cause more damage to trees than normally seen with northwesterly or southeasterly winds.

Rainfall rates will become heavy Monday night through Tuesday morning. Cold and unstable air behind this front will continue to produce rain showers, heavy at times and a chance for thundershowers Tuesday afternoon and night.

This system is expected to tap into subtropical moisture and will produce widespread moderate to heavy rain.

Due to the subtropical nature of this system, temperatures will be relatively mild, and will bring high snow levels to the Sierra Nevada ranging from about 7,000 and 7,500 feet. However, levels will lower Tuesday to 4,000 feet. Total rainfall amounts in San Luis Obispo and northern Santa Barbara counties are expected to range between 2 and 3 inches with higher amounts in the coastal mountains. Farther south, rainfall amounts will be ever greater.

Because of the position of the jet stream, a considerable amount of orographic enhancement is expected to develop over the burn areas of Santa Barbara and Ventura counties, resulting in heavy rain later Monday into Tuesday. In fact, the models are advertising total rainfall amounts of between 3 and 6 inches.

A high-pressure ridge will build back over California, producing gusty Santa Lucia (northeasterly) winds. These offshore winds will give mostly clear skies along the coastline, with fog likely forming during the night and morning hours across the inland valleys; cool mornings and warmer afternoons are expected Thursday into the Martin Luther King Jr. Day holiday weekend. The storm door is then forecast to open wide, with Pacific storm systems possibly moving into the Central Coast every couple of days into the last week of January.

Surf report

Moderate gale-force to fresh gale-force (32 to 46 mph) southerly winds along the coastline Monday afternoon into Tuesday morning will generate an 11- to 13-foot southerly (180-degree, shallow-water) seas, followed by an 11- to 13-foot west-northwesterly (280-degree, deep-water) sea and swell (with a 7- to 15-second period) Tuesday afternoon and night, decreasing to 10 to 12 feet (with an 8- to 14-second period) Wednesday.

An 8- to 10-foot northwesterly (300-degree, deep-water) swell (with an 11- to 22-second period) will arrive along our coastline Thursday, increasing to 9 to 11 feet (with a 13- to 18-second period) Friday and Saturday. A prolong period of high-energy west-northwesterly swell is forecast Jan.14 through Jan.18.

Seawater temperatures will range between 57 and 59 degrees through Tuesday, decreasing to 55 and 57 degrees on Wednesday into Friday.

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This story was originally published January 7, 2018 at 2:16 PM with the headline "SLO County weather forecast for the week of Jan. 8."